BCS 205 Midterm Exam Study Guide
Homeostasis
Understanding Dis-ease and Disease
Dis-ease: Refers to the early stages of health issues where the body shows an inability to
respond to stimuli, indicating a potential progression towards a disease.
Disease: A fully developed condition characterized by known signs and symptoms (s/sx),
recognized and named by medical professionals.
Feedback Loops in Homeostasis
Positive Feedback Loop: A process that amplifies changes; examples include childbirth,
breastfeeding, and blood coagulation, where the response continues to reinforce the initial
stimulus.
Negative Feedback Loop: A mechanism that counteracts changes to maintain stability; examples
include temperature regulation, hunger, thirst, and hormonal responses.
Dynamic Range and Set Points
Dynamic Range: The range within which a physiological variable can fluctuate while still
maintaining homeostasis; for example, sleep duration can vary from 6 to 10 hours around a set
point.
Set Point: A specific value that the body aims to maintain, such as the hypothalamic set point
for sleep being 8 hours.
Homeostasis and Homeostatic Processes
Homeostasis: The ability of the body to maintain stable internal conditions despite external
changes; involves complex feedback mechanisms.
Homeostatic Processes: Include feedback loops that help regulate physiological functions to
achieve homeostasis.
The 5Ds Loop in Homeostasis
1D: Detect: Receptors identify changes in the environment.
2D: Deliver: Sensory (afferent) pathways transmit information to the central nervous system.
, 3D: Decide: The hypothalamus processes the information and determines the response.
4D: Deliver: Efferent pathways carry the response signal to effectors (muscles or glands).
5D: Do: The final action is executed by the muscles or glands to restore balance.
Signs and Symptoms
Signs (S): Objective measures that can be quantified and observed, serving as reference points
for diagnosis.
Symptoms (Sx): Subjective experiences reported by the patient, which may not be measurable.
Cardiac Muscle, Cardiac Physiology, and BP Regulation
Role of ANP in Blood Pressure Regulation
Atrial Natriuretic Peptide (ANP): A hormone secreted by the heart in response to increased
blood volume, promoting diuresis (increased urine production) to lower blood volume and
pressure.
ECG Waves and Complexes
P-wave: Represents atrial depolarization and contraction.
QRS Complex: Indicates atrial repolarization and ventricular depolarization (contraction).
T-wave: Reflects ventricular repolarization (relaxation).
Understanding ECG Results
ECG results provide insights into the electrical activity of the heart, which correlates with muscle
contractions and overall cardiac function.
Cardiac Output Calculation
Cardiac Output (CO): Calculated using the formula CO = Stroke Volume (SV) x Heart Rate (HR).
Example: CO = 70 mL x 60 bpm = 4200 mL/min; CO = 70 mL x 100 bpm = 7000 mL/min.
Frank-Starling Law
Frank-Starling Law: States that the more the heart muscle is stretched (due to increased blood
volume), the stronger the contraction will be, enhancing cardiac output.
Ischemia and Cardiac Muscle Cells
Homeostasis
Understanding Dis-ease and Disease
Dis-ease: Refers to the early stages of health issues where the body shows an inability to
respond to stimuli, indicating a potential progression towards a disease.
Disease: A fully developed condition characterized by known signs and symptoms (s/sx),
recognized and named by medical professionals.
Feedback Loops in Homeostasis
Positive Feedback Loop: A process that amplifies changes; examples include childbirth,
breastfeeding, and blood coagulation, where the response continues to reinforce the initial
stimulus.
Negative Feedback Loop: A mechanism that counteracts changes to maintain stability; examples
include temperature regulation, hunger, thirst, and hormonal responses.
Dynamic Range and Set Points
Dynamic Range: The range within which a physiological variable can fluctuate while still
maintaining homeostasis; for example, sleep duration can vary from 6 to 10 hours around a set
point.
Set Point: A specific value that the body aims to maintain, such as the hypothalamic set point
for sleep being 8 hours.
Homeostasis and Homeostatic Processes
Homeostasis: The ability of the body to maintain stable internal conditions despite external
changes; involves complex feedback mechanisms.
Homeostatic Processes: Include feedback loops that help regulate physiological functions to
achieve homeostasis.
The 5Ds Loop in Homeostasis
1D: Detect: Receptors identify changes in the environment.
2D: Deliver: Sensory (afferent) pathways transmit information to the central nervous system.
, 3D: Decide: The hypothalamus processes the information and determines the response.
4D: Deliver: Efferent pathways carry the response signal to effectors (muscles or glands).
5D: Do: The final action is executed by the muscles or glands to restore balance.
Signs and Symptoms
Signs (S): Objective measures that can be quantified and observed, serving as reference points
for diagnosis.
Symptoms (Sx): Subjective experiences reported by the patient, which may not be measurable.
Cardiac Muscle, Cardiac Physiology, and BP Regulation
Role of ANP in Blood Pressure Regulation
Atrial Natriuretic Peptide (ANP): A hormone secreted by the heart in response to increased
blood volume, promoting diuresis (increased urine production) to lower blood volume and
pressure.
ECG Waves and Complexes
P-wave: Represents atrial depolarization and contraction.
QRS Complex: Indicates atrial repolarization and ventricular depolarization (contraction).
T-wave: Reflects ventricular repolarization (relaxation).
Understanding ECG Results
ECG results provide insights into the electrical activity of the heart, which correlates with muscle
contractions and overall cardiac function.
Cardiac Output Calculation
Cardiac Output (CO): Calculated using the formula CO = Stroke Volume (SV) x Heart Rate (HR).
Example: CO = 70 mL x 60 bpm = 4200 mL/min; CO = 70 mL x 100 bpm = 7000 mL/min.
Frank-Starling Law
Frank-Starling Law: States that the more the heart muscle is stretched (due to increased blood
volume), the stronger the contraction will be, enhancing cardiac output.
Ischemia and Cardiac Muscle Cells
