BIOL 482 LAB EXAM 2 Questions and Complete Solutions Graded A+

BIOL 482 LAB EXAM 2 Questions and Complete Solutions Graded A+ Equilibrioception - Answer: the perception of balance related to the vestibular system in the inner ear. Nociception - Answer: =the perception of pain =Nociceptors consist of free nerve endings embedded in the skin, muscles, joints, and viscera that respond to chemical, thermal, or mechanical stimuli. ="pain" is in fact a perceived sensation in response to stimuli that are likely to cause tissue damage. Pain is an adaptive interpretation of the stimulus, not the stimulus itself. =two types of pain. ="Fast pain" is sharp pain carried from injured tissue by myelinated A-delta fibers. ="Slow pain" is dull aching delivered to the central nervous system by unmyelinated C fibers. series elastic components - Answer: Elastic elements in line with the muscle fibers at the ends of the muscle Elasticity - Answer: -the ability of muscle fibers to return to resting length after contraction or stretching, so that they are ready to contract again. In restrictive lung disease, RV and TLC are both .... FEV1 and FVC are both ..... so the FEV1/FVC ratio is relatively ..... - Answer: reduced, reduced, normal or even increased Peak flow readings reflect.... - Answer: the degree of resistance to flow in the airways (for example, from bronchial constriction or mucus secretion blocking the bronchi) External intercostal muscles - Answer: =run downward between the ribs and their contraction increases the volume of the thoracic cavity. =These muscles are innervated by intercostal nerves, and their contraction is important in both quiet and forced inspiration. Inspiration - Answer: provides the alveoli with fresh atmospheric air why is the mean QRS vector is dominated by left ventricular depolarization? - Answer: The muscle mass of the left ventricle is far greater than that of the right ventricle. The cardiac axis - Answer: =is the general direction in which the heart depolarizes =specifically, it is the mean electrical axis (also called the mean QRS vector) during ventricular depolarization. Electrocardiography - Answer: =can show changes in the electrical activity in different regions of the heart. In addition, it can help detect areas which have too little blood flow or have been damaged by blockage to a major coronary artery. =It is typical for patients with a heart problem to have an electrocardiogram (ECG) recorded to help diagnose their condition. What events generate the P wave, QRS complex, and T wave? - Answer: P wave: Depolarization of the atrial cardiac muscle QRS Complex: Depolarization of the ventricular cardiac muscle (atrial repolarization also occurs but is hidden within the signal) T wave: repolarization of ventricles What is the dicrotic notch, and why does it follow the T wave? - Answer: The dicrotic notch is a short-lived decrease in pressure in the ascending aorta, which occurs following the closure of the aortic valve. Blood that has just been pumped out of the left ventricle temporarily flows back against the closed valve, which gives rise to the characteristic v-shaped notch in the pulse pressure wave. It follows the T wave because repolarization of the ventricles causes them to relax and close the aortic valve. How many physical electrodes are there in a 12-lead ECG? - Answer: 10 Can you explain why the different waves of the ECG (that is, P wave, QRS complex, and T wave) are seen as an upward deflection in some leads but a downward deflection in others? - Answer: Each lead of the ECG provides different "views of the heart from different angles. Imagine the electrical activity of the heart as a series of waves. First a wave of depolarization causes contraction, then repolarization allows the muscle to relax. Let's consider what happens to the QRS complex. The QRS complex is a wave of depolarization that causes the ventricles to contract. If the wave is moving toward a positive electrode, we see an upward deflection in that lead (depolarization is positive by convention). If the wave is moving away from the positive electrode it produces a downward deflection. In contrast, the opposite applies for a wave of repolarization (such as a T wave). Lead I - Answer: Left arm is positive and right arm is negative (LA-RA) ECG Lead II - Answer: Left Leg is positive and right arm is negative (LL-RA) Lead III - Answer: Left leg is positive and left arm is negative (LL-LA) aVR - Answer: The right arm is positive and the other limbs are negative. aVL - Answer: The left arm is positive and the other limbs are negative. aVF - Answer: The left leg (or foot) is positive and the other limbs are negative. What are some examples of static measures of air flow? - Answer: tidal volume(VT), vital capacity(VC), residual volume(RV), inspiratory reserve volume(IRV), expiratory reserve volume (ERV) What are some examples of dynamic measures of air flow? - Answer: forced expiratory volume (FEV), forced expiratory volume in 1s (FEV1), forced vital capacity (FVC) How did you make the distinction between static and dynamic types of tests? - Answer: Static tests are purely volume based, while dynamic tests are also based on time In your own words describe the physiological significance of the FEV1/FVC ratio. - Answer: The FEV1/FVC ratio measures the volume of air a person can forcefully exhale. The ratio can be used to determined if a person's lungs are in good health, as some diseases such as COPD lower the FEV1/FVC ratio. It can also be used to differentiate between obstructive and restrictive lung diseases, as restrictive diseases don't show much change in the ratio. what are conditions of lower airway obstructions? - Answer: asthma, cystic fibrosis, chronic bronchitis, emphysema what are conditions of upper airway obstructions? - Answer: upper airway tumor, epiglottitis, foreign body obstruction Compared to normal breathing, how are FEV1 values affected by simulating airways obstruction? - Answer: The FEV1 values are greatly reduced in obstructed breathing compared to normal breathing. What factors do you think could contribute to differences in pulmonary parameters between individuals? - Answer: Some factors that might contribute are lung size, physical and aerobic fitness, illnesses, smoking, and age. Why is PEF used more widely than FEV1 to monitor airflow in patients with asthma? - Answer: FEV1 is a good measure of airway obstruction, but it is harder to measure than PEF. PEF is easier for patients to use by themselves on a daily basis, so they can monitor their asthma symptoms regularly. An elderly man has a chest infection and a history of asthma. How would you expect his chest infection to affect the peak flow meter results? - Answer: His peak flow would be reduced due to the narrowing of airways and increased R caused by inflammation in his lungs. As you increase the voltage applied to the muscle, how does the output from the muscle change? - Answer: In the beginning, the weaker voltages don't produce a noticeable effect on output. However, as you increase the voltage from .35 V to .5 V, the output increases rapidly. After .5 V, the output increases less and less dramatically as voltage increases. What was the smallest voltage required to produce a contraction (the threshold voltage)? What proportion of the fibers in the muscle do you think were contracting to produce this small response? - Answer: The smallest voltage was .35 V. Because the force produced was so small, probably only a small portion of muscle fibers were being recruited for the response. What was the smallest voltage required to produce the maximum (largest) contraction? What proportion of the fibers in the muscle do you think were contracting to produce this maximal response? - Answer: The smallest voltage was .5 V. Because the strength of the contraction did not increase much after this point, probably most or all of the muscle was recruited for the contraction. What is recruitment, and how does that apply to this experiment? - Answer: Recruitment is described as the total number of active motor units during a response. It applies to this experiment because as the strength of the stimulus is increased (voltage), the number of motor units recruited increases. As recruitment increases, the force of the contraction increases. Force only increases up to a certain point, however, because muscles contain a finite amount of motor units. Describe how the isolated muscle behaved as it was stretched progressively. - Answer: The contraction force increases initially and the passive force doesn't visibly increase until the muscle is stretched to 2mm. At lengths greater than 2mm, the passive force increases and the amplitude of contraction force decreases as the muscle is extended to its farthest point What effect does stretching the muscle have on contraction strength? What is happening at a cellular level that causes this? - Answer: The contraction strength weakens as stretching increases past a certain length. As muscle is stretched past a certain point, the myosin and actin fibers within it are pulled away from each other and cannot produce as much force because they don't overlap as extensively. These layers need to interact to generate force, so the further away they are, the less force is produced. Examine the table above. Can you describe what happens to the frequency of stimulation when you decrease the interval between the pulses? - Answer: The frequency of stimulation increases as you decrease the interval between pulses. How does varying the frequency affect contractile force? Which interval caused the greatest contraction? - Answer: Increasing stimulus frequency will eventually result in muscle fibers not relaxing completely. When this occurs a second stimulus causes another contraction before complete relaxation. Eventually, the 2 stimuli come so close together that the muscle doesn't relax at all before the second contraction occurs. This produces a greater force of contraction. This is because the second stimulus arrives before Ca2+ can be removed from the cytoplasm and returned to the sarcoplasmic reticulum. Therefore, more Ca2+ is available in the cytosol to initiate sliding of the contractile proteins. The smallest interval causes the greatest contraction Describe how the isolated muscle behaved as the stimulus interval was further decreased. - Answer: As the stimulus interval decreased, the wave pattern of force peaks reduced until there was no longer a wave. Eventually the force curve flattened (reached tetanus). What is tetanus? Explain the mechanism behind this phenomenon. - Answer: Tetanus occurs when muscle contractions occur at such a high frequency that they produce a smooth sustained response. As the frequency of a stimulation increases, the time for the muscle fiber to relax between stimuli decreases. As a result, eventually the contractions fuse into a single large contraction response. At which stimulus interval did you observe tetanus? What frequency of stimulation does that correspond to? - Answer: Tetanus occurred at an interval of 20 ms. It's associated with a frequency of 50 Hz. At what time point did your muscle begin to fatigue? Comment on the percentage decrease in contraction force by the end of the experiment. - Answer: The muscle began to fatigue about 10 seconds after the stimulation was applied. The percentage decrease in force is quite dramatic when compared to the maximum force the muscle was able to obtain initially. The muscle wasn't able to maintain it's maximum force for very long before fatigue began taking place. Provide a possible mechanism for why the muscle was unable to maintain a prolonged contraction. - Answer: The fatigue could have been a result of the muscle depleting its energy stores. Initially the energy available was plentiful, but as the energy was used the muscle no longer had adequate amounts to maintain its maximum force. Would your results have differed if you were measuring from smooth muscle tissue? Why? - Answer: If we measured smooth muscle tissue, there would be no decrease in force because smooth muscles don't experience fatigue. Theory of selective attention for Stroop tests - Answer: color recognition requires more attention than reading a word Theory of processing speed for Stroop tests - Answer: since recognizing colors is not an automatic process, there is hesitancy to respond Theory of parallel distributed processing for Stroop tests - Answer: some neural pathways are stronger than others, which determines processing speed Theory of automaticity for Stroop tests - Answer: the brain reads words faster than it recognizes colors, resulting in lag Compare the volunteer's reaction times over the two trials. Explain why you think this change in reaction time occurred? If one didn't occur, why not? - Answer: There was a decrease in time between the first and second trial for volunteer 1. This may because the volunteer has adapted to the test by the time they take the second trial, so it takes less time for them to process the words they are reading. For volunteer 2, their time increased. This may have been because they made more mistakes in the second trial, which caused them to fumble over their words and add time. When people are asked to read aloud the name of each shape listed, they tend to take longer to read out the bottom line correctly. Why do you think this is? - Answer: interference In terms of reaction time, in which conditions did the volunteers do the best and worst? Why do you think this is? - Answer: Normally reading in monochrome has the shortest reaction time followed by word reading, rectangles, and lastly color naming. The increased reaction time in color naming is due to Stroop interference, where the volunteers receive conflicting information and have to override their automated processes (that is, reading the word). In terms of accuracy, in which conditions did the volunteers do the best and worst? Why do you think this is? - Answer: Normally, the monochrome or word condition has the least (if any) amount of errors as the volunteer doesn't have to register conflicting information. The color naming condition generally has more errors than any other condition, due to Stroop interference. Were there any changes in heart rate in the four conditions? How did these changes come about? - Answer: Heart rate may increase in the more difficult tasks, as the autonomic nervous system is influenced by cognitively challenging tasks. Some of the changes seen could be attributed to the actual stress of the situation rather than the cognitive stress itself. For example, people watching you read. Does peripheral skin temperature change? What mechanism is involved in this? What role does it play? - Answer: You may have seen a slight decrease in finger temperature throughout the trials. If so, this was likely caused by peripheral vasoconstriction due to increased sympathetic nervous system arousal during the cognitive stress. As in the previous question, some of the changes seen could be attributed to the actual stress of the situation rather than the cognitive stress itself. The Stroop test is often used as an experimental "stressor", meaning experimenters use it in lab situations to induce a stress response. Based on your results do you think this is appropriate? - Answer: This is largely determined by your own results. It should be a good lab stressor, but other factors may impair results. Limitations can include the following: The length of the test (time). Most research has used this test for longer periods. For example, 12 minutes in some cases; doing the same test 3 times; varying the amount of time between tests. There is no right or wrong answer as long as you are able to interpret what you found, and are able to relate it to other situations. examples of proprioceptors - Answer: muscle spindles (skeletal muscles) and golgi tendon organs (tendons) pain receptors - Answer: nociceptors hearing receptors - Answer: hair cells sight receptors - Answer: retinal cells (rods and cones) smell receptors - Answer: olfactory receptors temperature receptors - Answer: thermoreceptors touch receptors - Answer: mechanoreceptors vibration receptors - Answer: pacinian corpuscles (high frequency) and meissner's corpuscles (low frequency) Describe what you saw when you performed the convergence of gaze activity. - Answer: When I focused on my finger while holding it in front of a distance object, the image of the distance object was split into 2 separate images. When I covered my right eye, the right image disappeared, and when I covered my left eye the left image disappeared. When I focused on a distant object while holding my fingers in front of me, the tips of my fingers converged and produced a "floating" finger in between. What is meant by "binocular vision"? Why do you suppose this is useful? - Answer: Binocular vision means that the single image we see is produced by interpreting 2 images from both our left and right eyes. Binocular vision enhances our depth perception, so we can more accurately interpret the relative positions of objects surrounding us. Critical thinking: Which of the following is correct? A:Students who are nearsighted (myopic) should have a significantly shorter near point than those with normal vision. B:Students who are nearsighted (myopic) should have a significantly longer near point than those with normal vision. - Answer: A When you change your focus from a near object to a far object, what occurs in the eye to allow you to focus on the object? - Answer: The lens changes shape. For near objects, ciliary muscles contract and the lens becomes rounder, shortening the focal length. For distant objects, the ciliary muscles relax and the lens flattens, lengthening the focal length. the structures of the eye that contract to release tension on the lens, which allows its curvature to increase for near vision - Answer: ciliary muscles Describe and explain your observations on eye movement. - Answer: Even though I know I was moving my eyes, I couldn't actually perceive that my eyes were moving. This is due to saccadic masking. This occurs because, during rapid eye movement, the optic nerve ceases to transmit visual information. From your results, what do you conclude about the blind spot? - Answer: You can only perceive it when one eye is closed. This is because when both eyes are open, the vision from one eye compensates for the blind spot in the other eye. What is the anatomical basis for the blind spot? - Answer: The optic disc where the nerves and retinal blood vessels enter and exit the retina is devoid of receptors, so the eye can't detect images from that area. What did you observe when you mechanically stimulated your retina? - Answer: A small bright disc appeared opposite to the area I touched the eye. When I moved my finger up or down, it moved in the opposite direction. Describe what you saw during the positive afterimage activity. - Answer: When I opened and closed my eyes, the rectangular image of the doorframe I looked at appeared as a bright image on the back of my eyelid. Describe what you saw during the negative afterimage activity. - Answer: When I stared at the black pen for thirty seconds and then shifted my gaze, I saw a bright afterimage of the pen. When I stared at the red pen for thirty seconds and then shifted my gaze, I saw a bright greenish afterimage of the pen. What do your results from the afterimage activities suggest about the response time of photoreceptors to light? - Answer: Photoreceptors have both a fast and slow response to light, so in some instances they need time to adapt to rapid changes in vision. Describe your observations of retinal blood vessels. - Answer: As the flashlight moved back and forth near the right corner of my eye, I saw dark tendrils that branched all over my field of vision. Given the number of blood vessels in the retina, why do you suppose that you are not able to see them normally? - Answer: .The brain suppresses the image of the retinal blood vessels. Which cones are affected in deutan type color blindness? - Answer: green Which cones are affected in protan type color blindness? - Answer: red Which cones are affected in tritan type color blindness? - Answer: blue Describe your observations regarding two-point discrimination? - Answer: If a part of the body is more sensitive to touch, it can distinguish between two touch points at much smaller distances. Where was your tactile discrimination best? What can you say about the density of tactile receptors on your arm? - Answer: It was best on my fingertips. The density of tactile receptors on my arm is less great than the density on my fingers and hands but more great than the density on my back. Describe and discuss your observations regarding the thermal illusion. - Answer: Putting the cold hand in the lukewarm water made it feel warm. Putting the hot hand in lukewarm water made it feel cold. The illusion probably occurred because each hand adapted to the temperature of the original bowl. Therefore, a change to lower temperature felt like an absence of heat while a change to a warmer temperature felt like a gain in heat. Were you able to correctly identify the candy each time? Which time was easier? Why? - Answer: Yes, but the second time without holding my nose was much easier. The first time I was only able to guess correctly because I knew that skittles were slightly more round than M&Ms. Describe your observations here. Is our taste sensitivity uniform across the tongue? - Answer: For the sucrose solution, the taste was slightly more noticeable at the back of the tongue and on the side than in the tip. For the tonic water and salt solutions, the sensation felt much stronger at the back of the tongue than any other region. For the acid solution, the taste was most intense at the tip. From these observations, it's obvious that taste is not felt uniformly across the tongue. Based on your findings, what can you say about the distribution of the different types of taste receptors? - Answer: The classical interpretation of taste distribution is that various regions of the tongue are sensitive to different tastes; the "tongue map" theory. This has now been disproved. It is believed that all areas of the tongue can detect all tastes, but some areas are more sensitive than others to particular tastes Describe your observations regarding the affect of rotation. - Answer: After several rotations, you should be relatively inaccurate when trying to identify your new orientation Was it easy to tell the direction when each of the following scenarios occurred? a) The chair had just started spinning.b) The chair had been spinning for some time. c) The chair had stopped spinning. Explain your observations for these three scenarios. - Answer: When the chair first started to spin you should have easily been able to tell the direction and relative speed at which you were moving. After some time (~10-30 seconds, depending on the speed and the individual), your vestibular system cannot accurately detect that you are spinning. However, due to other sensory inputs (such as sight and sound) it is likely that you were able to detect movement. Finally, once the chair had stopped spinning you should have felt like you were rapidly spinning in the opposite direction. The reason for these observations lies in how the semicircular canals detect acceleration. This is achieved by the fluid contained within the semicircular canals (endolymph) being able to move independently of the cupula (the gelatinous structure that contains the sensory cells' cilia). Thus a difference in velocities between these two structures can result, which can cause the cilia to bend and activate their respective sensory cells. So when the chair first started to move (left, for example) the cupula anchored to the wall of the semicircular canals via their respective ampullary crests, and also started to move in that direction. However, due to the fact that the fluid is in a continuous loop within the semicircular canals it stays relatively stationary. Thus the cupula is being spun through this stationary fluid, resulting in the cupula being bent in the opposite direction. This signals to the brain that you are moving in that particular direction (in this case, left). After spinning for some time, the fluid in the semicircular canals also starts to spin until eventually it is also spinning at the same velocity as the cupula. Now the cupula is not being forced through a stationary fluid, but through one that is moving at the same velocity. Thus the cupulae return to their resting positions and the ve pacemaker cells - Answer: generate a rhythmic electrical signal that travels along a conduction pathway to ensure coordinated contraction of the heart. The main pacemaker action potential is initiated in the ....... and then spreads through the heart's electrical conduction pathway - Answer: sinoatrial (SA) node the heart's electrical conduction pathway includes the following elements: - Answer: • Atrioventricular (AV) node • Bundle of His • Left and right bundle branches • Purkinje fibers An ECG provides a ... - Answer: visual representation of the electrical events in the heart. It is detected on the surface of the body using recording electrodes The shape of an ECG depends on .... - Answer: which leads are used and the pattern of electrical activity in the heart leads - Answer: recordings of heart activity from several angles around the heart using pairs of electrodes A common ECG recording made by physicians uses 12 standard ECG leads: - Answer: • The standard limb leads I, II, and III (3 leads) • The augmented limb leads aVR, aVL, and aVF (3 leads) • The unipolar chest leads V1 to V6. (6 leads) standard limb leads - Answer: bipolar leads formed by connecting the electrocardiograph between any two corners of Einthoven's triangle. (lead I, II, III) Einthoven's triangle - Answer: a useful imaginary triangle spanning the trunk, which can quickly give an idea about which lead will best show certain electrical activity augmented limb leads - Answer: =unipolar leads formed using a combination of the standard leads at the corners of Einthoven's triangle. =The word "augmented" is used because the ECG obtained in this way is greater in magnitude. =These composite leads are formed by comparing a single positive electrode with a combination of two other electrodes. (aVR, aVL, aVF) chest leads - Answer: A chest lead ECG is obtained via an "exploring" electrode placed on the chest (V1-V6) and a composite electrode consisting of the three limb leads connected together. These unipolar leads are numbered according to the position of the exploring electrode. V1 lead placement - Answer: right side of sternum, 4th intercostal space V2 lead placement - Answer: 4th intercostal space to the left of the sternum V3 lead placement - Answer: Midway between V2 and V4 V4 lead placement - Answer: midclavicular line, 5th intercostal space V5 lead placement - Answer: anterior axillary line at same level as V4 V6 lead placement - Answer: midaxillary line at same level as V4 The ECG tracing will look different in each lead depending on... - Answer: the direction of the heart's electrical axis relative to the position of that lead. Pathologies that affect electrical conduction in the heart will... - Answer: alter the cardiac axis and the way the heart contracts. Therefore, using an ECG to estimate the cardiac axis can help reveal problems with the heart's electrical activity and contractions. The direction of the mean QRS vector provides the... - Answer: cardiac axis. Hexaxial system - Answer: =a system that includes limb leads I, II, III and the augmented leads a VL, a VR, and a VF =is a way of representing the orientation and polarity of the limb leads. • It helps us to determine the heart's electrical axis in the coronal plane. • The hexaxial system can be used in conjunction with ECG tracings to calculate a single cardiac axis for a person. • The hexaxial system can help us to recognize when a patient has a deviated cardiac axis, which can indicate problems in the heart. The normal direction of the cardiac axis is between.... - Answer: -30° and +90°. Deflections on Lead I and Lead aVF ECGs can be used to calculate the cardiac axis following these steps: - Answer: • Calculate the net QRS deflection for Lead I. • Calculate the net QRS deflection for Lead aVF. • Mark the net QRS deflection on the Lead I axis. • Mark the net QRS deflection on the Lead aVF axis. • Intercept perpendicular lines to get the cardiac axis vector. expiration - Answer: removes air with decreased oxygen and increased carbon dioxide concentrations. Why measuring respiratory parameters accurately is important - Answer: Gas exchange occurs across the walls of alveoli and their surrounding capillaries. Thus, the efficiency of gas exchange is dependent on adequate ventilation of alveoli. what is the role of the diaphragm in respiration? - Answer: Contraction of the muscle causes it to flatten and increase the volume of the thoracic cavity. This creates an area of lower pressure and allows the lungs to fill with air. Relaxation of the muscle causes it to become dome-shaped, which decreases the volume and increases the pressure of the thoracic cavity. This helps push air out of the lungs. The diaphragm - Answer: =is a large muscle that separates the thoracic and abdominal cavities. =primary muscle involved in breathing in mammals, and each half is innervated by a phrenic nerve. Internal intercostal muscles - Answer: =run downward and backwards between ribs. =Their contraction results in lower thoracic volume which assists in forced expiration. Accessory muscles - Answer: (such as the sternocleidomastoid and scalene muscles of the neck) are used to aid in respiration when breathing is difficult (either from an increased respiratory rate or a disease such as COPD). Abdominal muscles - Answer: relax during inspiration and contract during forced expiration which decreases the volume of the thoracic cavity. what is the difference between a volume and a capacity? - Answer: lung capacities are always the sum of at least two lung volumes. expired minute volume - Answer: The product of respiratory rate and VT (expired minute volume = RR x VT). This is the amount of air exhaled in one minute of breathing. ERV: - Answer: the maximum volume that we can exhale from our lungs at the end of a normal breath IRV: - Answer: the maximum volume above the tidal volume that we can inhale into our lungs VT: - Answer: the volume inhaled and exhaled during quiet breathing RV: - Answer: the volume of air remaining in the lungs after a full expiration. We can never empty them completely Inspiratory capacity (IC): - Answer: all the air breathed in during a maximal inhalation at the end of a normal exhalation (VT + IRV) Expiratory capacity (EC): - Answer: all the air breathed out in a maximal exhalation after a normal breath (VT + ERV) Functional residual capacity (FRC): - Answer: the volume of air remaining in the lungs at the end of a normal expiration (ERV + RV) Total lung capacity (TLC): - Answer: all the air that it is possible for the lungs to contain (RV + ERV + VT + IRV) Vital capacity (VC): - Answer: all the air that can be expired from a maximal inhalation (ERV + VT + IRV) Resistance - Answer: =a measure of the "difficulty" of flow, and differs between areas of the respiratory system. =results from friction between particles as they move in a gas, and from friction between the gas and the tube wall. resistance depends on... - Answer: =The dimensions of the airway (length and radius) ● The density of the gas ● The flow profile (whether the flow through the airway is laminar or turbulent) Flow Rate (Q) Equation - Answer: delta P/R For laminar flow... - Answer: the rate at which air flows (Q) is proportional to the pressure gradient (ΔP) driving that flow. That is, Q ∝ ΔP. Thus, the rate of flow is determined by ΔP and by R the upper respiratory tract has ...... resistance and ...... flow, while the lower respiratory tract has ...... resistance and ..... flow - Answer: higher, turbulent lower, laminar why is the resistance in the lower respiratory tract reduced? - Answer: Respiratory bronchioles have small individual radii. However, the parallel arrangement of these small airways results in a large total cross-sectional area, which reduces resistance to airflow. Patients with chronic lung diseases fall into three main categories: - Answer: ● Obstructive lung disease or chronic obstructive pulmonary disease (COPD) ● Restrictive disease ● Asthma peak flows - Answer: the rates of flow at the beginning of inspiration or expiration Dyspnea - Answer: =refers to difficulty in breathing =has a psychological dimension. =can be a consequence of a mismatch between the afferent inputs that stimulate breathing (for example, decreased partial pressure of oxygen (PO2), increased partial pressure of carbon dioxide (PCO2), decreased pH, and activation of lung and chest wall receptors), and the efferent output to the muscles of respiration. =that is, breathing cannot increase sufficiently to match the perceived central nervous system requirements which leads to feelings of distress and breathlessness Illnesses that can be associated with acute dyspnea - Answer: pneumothorax, acute asthmatic attacks, pneumonia, myocardial infarction, and rapidly developing heart failure The major respiratory diseases associated with chronic dyspnea - Answer: COPD and restrictive lung disease COPD - Answer: =results in airways that become permanently narrowed. =narrowed airways increase resistance so that airflow to the alveoli becomes limited, which causes shortness of breath. =In contrast to asthma, this limitation is often not reversible and usually worsens over time. =These patients are also prone to acute respiratory infections, which may lead to acute respiratory failure. How is COPD triggered - Answer: =COPD starts with noxious particles or gases triggering an abnormal inflammatory response in the lung. =Over time, repetitive exposure results in a chronic inflammation. The condition is called chronic bronchitis when the bronchi are affected. =When the alveoli are involved there is a destruction of lung tissue with loss of the normal lung elasticity. This leads to the development of emphysema. why does RV increase in patients with COPD? - Answer: As a consequence of the tissue damage, air is trapped in the lungs at the end of expiration. Therefore, the RV gradually increases and the patient breathes with a hyperinflated lung. Hyperinflation of the lungs flattens the diaphragm, which causes it to become less effective at regulating the pleural pressures necessary for efficient breathing. Therefore, the chest and neck muscles must work harder to assist with breathing. This increases the work of breathing significantly so that patients suffer from dyspnea. what are typical characteristics of people with COPD? - Answer: =Patients breathe faster in an effort to ventilate their lungs normally. =Major findings on physical examination are a larger than normal chest (which is often barrel-shaped), and decreased movements during the respiratory cycle. =Hyperinflation of the lungs is also demonstrated by an increase in FRC in lung function tests. =Characteristically, expiration becomes prolonged relative to inspiration. =As the condition worsens, the alveolar surface area available for gas exchange is reduced. This leads to an increase in alveolar PCO2, and a decrease in alveolar PO2 at the end of expiration. The decreased arterial PO2 may result in central cyanosis, why does VC appear normal or increased in people with COPD? - Answer: Respiratory tests reveal that RV and total lung capacity (TLC) are usually increased in COPD. If RV and TLC increase proportionally, the vital capacity will appear normal. However, in most cases RV increases to a greater extent than TLC, and vital capacity is decreased. A standard FEV1/FVC ratio is - Answer: at least 70% (In COPD this ratio is less than 70%, and does not improve after administration of a bronchodilator) what is characteristic of the blood of COPD patients? - Answer: Blood tests often reveal an increased hemoglobin level, with an increased red blood cell count and a raised hematocrit. These findings reflect the body's attempt to compensate for the lower PO2, by increasing the O2 carrying capacity of the blood. The raised PCO2 results in chronic respiratory acidosis. how does the function of PCO2 in a healthy individual compare to that of someone with COPD? - Answer: In a healthy individual, arterial PCO2 acts as a respiratory stimulant. Under COPD circumstances, the arterial PCO2 can be so high that CO2 becomes a central nervous system depressant. Therefore, the low PO2 (acting through peripheral chemoreceptors) is providing the only respiratory drive. Restrictive disease - Answer: =results from either lung (intrinsic) or chest wall (extrinsic) conditions =the major problem is an inability to ventilate the lung adequately. =The main symptoms are shortness of breath and coughing. This is because the lungs are either "stiffer" (due to fibrosis) or the chest wall is less expandable. In either case, there is a loss of lung compliance. =In severe cases, patients are hypoxic but with a normal arterial PCO2. This is because CO2 diffuses some 30 times faster across membranes than does O2. Intrinsic restrictive lung disease may result from the following: - Answer: ● Inorganic dust exposure (for example, asbestosis or silicosis) ● Organic dust exposure (for example, farmer's lung) ● Collagen diseases (for example, scleroderma) Extrinsic restrictive diseases may result from the following: - Answer: ● Neuromuscular disorders (for example, various myopathies) ● Disorders causing kyphoscoliosis (for example, ankylosing spondylitis) Asthma - Answer: =chronic lung disease in which the bronchi are hypersensitive to a variety of dusts, pollens, or other air particles, and also hypersensitivity to cold air. These trigger chronic inflammation with excess production of mucus and narrowing of the airways. Sometimes, exercise is a trigger. =The airway narrowing causes symptoms such as recurring episodes of wheezing, breathlessness, tightness in the chest, and coughing, particularly at night or in the early morning. During an asthma attack, the FEV1/FVC ratio is .... - Answer: below normal (that is, less than 70%). This ratio is usually improved significantly after administration of a bronchodilator. The basic unit of a muscle is the .... (which is also referred to as a muscle fiber). - Answer: muscle cell 3 types of muscle - Answer: skeletal, cardiac, smooth striated muscle - Answer: skeletal and cardiac smooth muscle - Answer: makes up the muscular lining of our digestive system and lacks striations cardiac muscle - Answer: has fibers connected by intercalated disks and gap junctions, and that branch; these features enable the muscle cells to have highly synchronized contractions skeletal muscle - Answer: lacks intercalated disks, gap junctions, and branches. These differences allow skeletal muscle fibers to act more independently than cardiac muscle fibers. hierarchal structure of muscle - Answer: whole muscle > fascicle (which are groups of fibers bound by connective tissue) > fiber > myofibrils > repeated segments of the contractile proteins actin and myosin (along with troponin, tropomyosin, and other structural elements) sarcomeres - Answer: repeated segments of actin and myosin sliding-filament mechanism of muscle contraction - Answer: Actin and Myosin slide past each other in the presence of Ca2+ and ATP to produce muscle shortening (contraction) motor neurons - Answer: Multiple motor neurons innervate a skeletal muscle. Each motor neuron branches and innervates a group of fibers that act together. motor unit - Answer: a single motor neuron and all the muscle fibers that it innervates. The smaller the motor unit... - Answer: the finer the control of movement in that muscle. Thus, the muscles controlling the movements of the fingers and eyes have small motor units. what kind of APs are generated in muscle? - Answer: all-or-none twitch - Answer: The contractile response to a single action potential The strength of a muscle contraction can be increased in two ways: - Answer: • Increasing the number of active motor units (termed recruitment) • Stimulating motor units more frequently The maximum force that a muscle can generate is dependent on ... - Answer: the total number of muscle fibers in parallel. Muscles with large cross-sectional areas can generate larger forces than those with small cross-sectional areas. Excitability - Answer: the ability to respond to a stimulus. how are muscle cells excited? - Answer: -the stimulus is provided by excitation of the motor neuron and results in the release of the neurotransmitter acetylcholine (ACh). -The release of Ach causes a change in post-synaptic membrane potential (however, in this case the post-synaptic cell is a muscle fiber rather than another neuron). -The result is a contraction of the muscle. how does the duration of the muscle AP compare to the length of the twitch? - Answer: the twitch lasts much longer summation. - Answer: If a second stimulus arrives before the muscle has fully relaxed, a second twitch occurs on top of the first one and a greater peak tension is developed. tetanus or a tetanic contraction. - Answer: As the frequency of stimulation increases, time for the muscle fiber to relax between stimuli decreases. Eventually, the contractions fuse and produce a smooth, maximal contraction. Stretchability (or extensibility) - Answer: -the ability to be able to be stretched out again after a muscle has finished contracting. -This occurs when the joint is pulled in the opposite direction by an external force (such as from antagonistic muscles or gravity). Parameters that affect contractile speed and force of muscle - Answer: muscle length, type of activation (e.g., at fixed length, while shortening, or while being stretched), and load isometric force - Answer: The generation of force without muscle movement. (constant length) isotonic force - Answer: Results in a change in the length of a muscle performed against a constant load active force - Answer: generated by the contraction when the fibers are stimulated (active components are myofibrils) passive force - Answer: reflect the contributions of elastic elements in the muscle, both extracellularly (e.g., connective tissues around fibrils, fibers, whole muscle, and in the tendons the ends of the muscle) and within the fibers themselves (e.g., structural proteins that hold the contractile elements in place). parallel elastic components. - Answer: elastic elements in parallel with (around) the muscle components how is active force determined? - Answer: from difference between the total force and the passive force at a given muscle length fatigue - Answer: a reduction in force after activity what contributes to fatigue? - Answer: Muscle contraction requires metabolic energy. A depletion of energy stores and other physiological alterations that occur with contraction contribute to muscle fatigue what muscles are resistant to fatigue? which do not fatigue? - Answer: -Those with a greater capacity for oxidative metabolism. -smooth muscle Examples of central nervous disorders affecting muscle activity include - Answer: strokes, brain tumors, Parkinson's disease, and multiple sclerosis. Examples of peripheral nervous diseases affecting muscle include - Answer: motor neuron disease and peripheral neuropathies. Peripheral neuropathy - Answer: -associated with various combinations of motor, sensory, and autonomic dysfunction. -Motor problems include weakness, cramps, spasms, muscle wasting, and fasciculations. -Sensory symptoms can include both loss of sensations and disordered sensations with tingling, numbness, and a heightened sense of pain. Balance may be impaired. --Autonomic involvement can result in abnormal control of blood pressure and heart rate, decreased ability to sweat, constipation or diarrhea, incontinence, and sexual dysfunction. Neuromuscular junction diseases - Answer: (also referred to as motor endplate diseases) affect muscle contractions. Includes botulism, myasthenia gravis, LEMS Lambert-Eaton myasthenic syndrome (LEMS): - Answer: an auto-immune disease-causing muscle weakness, resulting from antibodies that affect voltage-gated calcium channels of motor endplates, inhibiting acetylcholine release Myasthenia gravis: - Answer: an autoimmune disease resulting most commonly from antibodies to acetylcholine receptors Botulism: - Answer: a paralytic illness caused by the botulinum toxin, a neurotoxic protein produced by the bacterium Clostridium botulinum. The toxin acts directly on the neuromuscular junction to inhibit acetylcholine release resulting in muscle paralysis. myopathies. - Answer: -Diseases affecting muscle itself -Among these are the muscular dystrophies, a group of genetically inherited diseases, which are characterized by progressive muscle weakness as a result of the death of muscle cells. Duchenne's muscular dystrophy, - Answer: -a recessive X-linked condition that usually develops in young boys before the age of five. -Both skeletal muscle and cardiac muscle can be affected by this muscular dystrophy. -The disorder is caused by a mutation in the dystrophin gene located on the X chromosome. The gene codes for dystrophin, a protein that connects the cell cytoskeleton to the extracellular matrix. -Defects in dystrophin, result in excess Ca2+ entering muscle cells, which leads to cell death. As cells die, there is increasing muscle weakness. This disease becomes lethal when it affects the respiratory muscles strongly. Stroop Facilitation - Answer: When the written word and the text color used are the same (that is, there is an association between the word and the color). In this condition, most volunteers experience a decrease in reaction time when reading the word aloud. Interference condition - Answer: When the written word and the text color used are different. In this condition, volunteers experience an increase in reaction time when speaking aloud the color that the word is written in. Individuals struggle to dissociate the word written from the color used, as this requires greater cognitive processing than just reading the words. anterior cingulate cortex (ACC) - Answer: -responsible for a range of emotional responses and thought processes, and is located in the frontal portion of the brain between the left and right hemispheres. -The functions of the ACC are highly complex, but the area works as a link between lower, more impulse-driven brain regions, and higher, more rationally driven behaviors. -It is hypothesized that conflicting information during Stroop tests is sent to the anterior cingulate in the brain, where it is filtered to produce an appropriate response. The time required to filter this information is a potential cause for the delay in reaction. what are some applications of the Stroop test? - Answer: -test attentional fatigue -used as an experimental stressor what reactions do individuals show during a stroop test? - Answer: a range of cardiovascular responses is seen: vasodilation to skin and skeletal muscle; increases in heart rate, cardiac output, and blood pressure occur. These changes are thought to reflect an increase in sympathetic nervous activity, and a decrease in parasympathetic nervous activity. control conditions for stroop test - Answer: -Monochrome: read the words of colors written in black (for example, green, red, brown, blue, purple). -Rectangles: name the color of each rectangle (for example, purple, blue, brown, red, green). experimental conditions for stroop test - Answer: ● Words: read the words that are written in a different color (for example, purple, brown, green, red, blue) ● Colors: name the color that the word is written in (for example, green, red, blue, brown, purple). organization of sensory systems - Answer: sensory system > sensory organ> sensory receptor cells transduction - Answer: conversion of one form of energy into another. In sensation, the transforming of stimulus energies, such as sights, sounds, and smells, into neural impulses our brains can interpret. perception - Answer: the process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events what is the general pathway for sensory transduction? - Answer: a stimulus is transduced by a specialized receptor cell, which directly (when the receptor is part of a neuron) or indirectly (by releasing neurotransmitters) activates a sensory neuron Adaptation - Answer: refers to the process by which a sensory system adjusts sensitivity to a continuing source of stimulation. what receptors do not adapt? - Answer: nociceptors vision - Answer: generally describes the ability to detect electromagnetic energy. The visible range for humans (often referred to as the visible spectrum) is from about 380 nm to 750 nm There are two types of these photoreceptive cells in the mammalian eye: - Answer: =cones, which are primarily responsible for color differentiation =rods, which are responsible for contrast (light and dark) resolution. fovea - Answer: area in which densely packed cones provide high visual acuity. Rods are not found there to any extent, but are distributed fairly evenly throughout the remainder of the retina. optic disc - Answer: area where the nerves and retinal blood vessels enter and exit the retina which is devoid of receptors. Hence it is often referred to as the "blind spot." Our binocular vision and visual processing typically mask out the blind spot the 3 sets of cones - Answer: red--->564nm green--->534NM Blue---> 420nm =our perception of color is determined by the extent to which the different types of cones are excited. protanomaly - Answer: altered sensitivity in the red cone function Protanopia - Answer: lack of functioning red cones deutanomaly - Answer: altered sensitivity in the green cone function deutanopia - Answer: complete green cone deficiency Tritanopia - Answer: lack of functioning blue cones Hearing or audition - Answer: =the sense of sound perception and results from tiny hair fibers in the inner ear detecting motion of the membrane (ear drum). =This ear drum vibrates in response to changes in air pressure. =Humans with perfect hearing can detect vibrations in the range of 20-20,000 Hz. Taste or gustation - Answer: =is one of the two main "chemical" senses. =The 5 taste receptors detect sweet, salt, sour, and bitter and umami (detects the amino acid glutamate) =The actual "sense of taste" is a combination of the taste receptors, olfactory receptors, touch (mouth feel), temperature, and sight. Smell or olfaction - Answer: =the other chemical sense. =There are hundreds of olfactory receptors, each binding to a particular molecular feature. =All of these receptors are found in a specialized region in the roof of the nasal cavity. =Each odor molecule fits into a binding site on a receptor neuron, and can trigger an action potential. Touch (tactition) - Answer: =the perception of pressure on the skin. =There are several types of specialized tactile receptors that may be found in the skin, muscles, and viscera. =range from simple nerve endings found in hair follicles, to the relatively complex Pacinian corpuscles embedded in tissues. Thermoception - Answer: =the sense of heat and cold (absence of heat). =Cold receptors are sensitive to temperatures lower than about 37°C (98.6°F), =warm receptors are sensitive from 37°C (98.6°F) to about 45°C (113°F). Above this temperature, nociceptors are activated. =receptors are found in the deeper layers of the skin and underlying tissue. The receptors adapt (that is, they lose sensitivity) between 20°C (68°F) and 40°C (104°F). =At high and low temperatures, these receptors do not adapt, thereby helping to prevent temperature-related injury to tissues. homeostatic thermoceptors - Answer: =provide feedback on internal body temperature =They are located close to the hypothalamus in the brain and are responsible for setting the internal "thermostat." The vestibular system has two components: - Answer: =the semicircular canals that are filled with fluid (endolymph) and detect rotational movements of the head =the utricle and saccule that detect linear acceleration and the effects of gravity (which is a downward linear acceleration). crista ampullaris - Answer: =the ampullae of the semicircular canals contains this receptor apparatus =This consists of a gelatinous, wedge shaped structure (the cupula) that is influenced by the flow of endolymph =The cilia of the receptor cells are embedded in this gel. =When the head moves, the gel is distorted and the cilia bend. Thus, rotational movements of the head are detected. otolith organs - Answer: =in saccule and utricle =The cilia of the receptor cells are embedded in a gel that also contains calcium carbonate crystals: the octonia. =The weight of the otoconia allows detection of gravitational forces. Proprioception - Answer: =the perception of body position ; the "unconscious" awareness of where the various regions of the body are located at any one time. =Stretch receptors in the joints and muscles feed this three-dimensional information back to the brain.