Coordination and Control

All sample questions with matching correct answer in chapter 5 negative tropisms - Answer-growth away from a stimulus Define homeostasis - Answer-Homeostasis is the regulation of internal conditions in the body. It is necessary to maintain optimal conditions for body functioning. These internal conditions can change as a result of processes within the body and as external conditions change. systems responsible for homeostasis - Answer-the nervous system - uses electrical impulses to communicate the endocrine system - uses chemical molecules to communicate. what does the body need to control - Answer-blood glucose concentration body temperature water levels control systems in the body order - Answer-RECEPTOR -detect stimuli COORDINATION CENTRE -brain, spinal cord, pancreas -receives and process information from receptors EFFECTOR -muscles, glands -bring about responses which restore optimum levels what are neurones - Answer-Neurones are specialised for transmitting messages in the form of an electrical impulse. The part of the cell containing the nucleus is called the cell body. The cell body of all neurones is found in the CNS. Neurones, however, have an extended shape so that they can carry nerve impulses from one part of the body to another. Neurones also have fine branches at their tips to communicate with other neurones. what are receptors - Answer-Receptors are cells that detect any changes in the environment. Receptors are sometimes grouped to form sense organs. Sensory neurones relay nerve impulses from these receptors to the CNS. The CNS processes the information and coordinates how the body should respond. Motor neurones relay impulses from the CNS to the effector - for instance, a muscle or gland. The sequence of events is: stimulus → receptor → coordinator → effector → response Reflex actions why are they important - Answer-are rapid, automatic responses to a stimulus. We do not have to think about them. Reflex actions form the basis of behaviour in simpler organisms. In humans, they prevent us from getting hurt. In other animals, our human ancestors and babies they are also related to survival. give examples of reflex actions - Answer-removing our hand from a hot or sharp object the grasping reflex, in which a baby grips a finger blinking our eyes if an object approaches rapidly the pupil reflex, whereby the pupil gets wider in dim light and narrower in bright light reflex arc pathway - Answer-a sensory neurone - transmits nerve impulses from the receptor to the CNS a relay neurone, in the spinal cord - transmits the impulses from the sensory to the motor neurone a motor neurone - sends impulses from the CNS to the effector. Other neurones in the spinal cord link via synapses with those of the reflex arc, so a message is sent to the brain after the hand has been removed (number 8 in the figure). It tells us that the plate was hot. Explain how a synapse works - Answer-nerve impulse is sent, the chemical transmitter molecules are released to the synapse. transmitter molecules diffuse across the synapse the chemical transmitter molecules bind to receptors channels in the next neurone open the nerve impulse is intitated to the next neurone. the brain - Answer-controls behaviour mad up of billions of interconnected neurones and has regions that carry out different functions cerbral cortex what it holds where it is - Answer-highly folded outer layer concerned with: intelligence consciousness memory language cerebllum - Answer-lower part concerened with coordination of muscular activity medulla - Answer-controls unconscious activities: heartbeat, breathing in level with space between lips and nose hupothalamus pituity gland - Answer-small in level with eye not main brain what are electroencephalograms (EEG's) - Answer-used to monitor abnormal electrical activities in the brain, but can be used for brain mapping What is transcranial magnetic stimulation (TMS) - Answer-a magnetic field changes the electric activity in parts of the brain targeted. changes in the patients behaviour as different areas are stimulated are used to map the brain Magnetic resonance imaging (MRI) - Answer-MRI scanning uses strong magnetic fields and radiowaves to produce very detailed images of the nervous system (or any other region of the human body). MRI scanning is very safe. It's non-invasive and doesn't use ionising radiation. It's therefore safer than the alternatives - a CT scan or a PET scan. what MRI - Answer-neuroscientistis have been able to map the regions of the brain to particular functions by studting the patient with brain damage, elecrtcially stimulating different parts of the brain Treating nervous system disorders - Answer-Surgery is often needed to save a life, such as by removing a tumour, draining excess fluid (from a bleed or infection) or adding a brain implant. risks: such as infection and the possibility of a stroke. Surgery has to be carried out with minimal damage to the surrounding tissue. But in the case of a tumour, cancer cells must be removed as completely as possible. For this reason, surgery is followed up (or replaced) by radiotherapy and chemotherapy to kill remaining cancer cells. Both procedures affect normal cells as well and have serious side effects. In future, there may be safer and more effective alternatives. Monoclonal antibodies and gene therapy may be used to treat brain cancer, while stem cells offer hope for repairing damaged nervous tissue. what is the eye - Answer-eye is a sense organ containing receptors sensitive to light intenisity and colour what does the cornea do - Answer-transparent region of the sclera at the front of the eye what does the lens do - Answer-Focuses light onto retina what does the pupil do - Answer-the hole in the center of the iris that allows light to pass through what does the iris do - Answer-has set of muscles that control the size of pupil and regulate the light reaching the retina what does the suspensory ligaments, and ciliary muscles do - Answer-change the shape of the lens to focus light rays on the retina what does the retina do - Answer-made up of light-sensitive receptor cells Receptor cells in the retina that perceive colour are called cones. A different type of receptor cell is also responsible for our vision at low light intensities - rods. Rods are around 1000 times more sensitive to light than cones. It's also much less acute. what does the optic nerve do - Answer-carries impulses from the retina to the brain to focus on near objects how does the eye change - Answer-the ciliary muscles contract the suspensory ligaments lossen the lens is then thicker and refracts light rays strongly to focus on distant objects what does the eye do - Answer-the ciliary muscles relax the suspensory ligaments are pulled tight the lens is then pulled thin and only slightly refracts light Short-sightedness - Answer-myopia when people can see objects at short distances away, but struggle to see objects at a distance. the eyeball is too long for the strength of the lensor the cornea is too sharply curved. This can be corrected by a concave lens. Long-sightedness - Answer-hyperopia, is when people can see objects at long distances away, but struggle to see near objects. I the lens is too weak - it is not thick enoughor the eyeball is too shortor the cornea is not curved enough. When the eye attempts to produce an image, it falls behind the retina. It can be corrected by a convex lens. Lazer eye surgery - Answer-sed to change the shape of the cornea. The eye normally recovers in a few days. A flap is cut in the cornea and folded back. A laser is used to change the shape of the cornea, and the flap is repositioned contact lenses - Answer-Most are made from a gel based on silicone. These are freely permeable to oxygen, allowing oxygen to be transmitted to the cornea. They're considered more comfortable than hard contact lenses, which are more rigid and durable. Today's hard lenses are also gas permeable. Modern contact lenses can be worn for varying periods of time. Some are disposable after a day's use; others require cleaning and disinfection. body temperature - Answer-monitored and controlled by the thermoregulatory centre in his brain. The centre has receptors that are sensitive to a change in the temperature of the blood circulating through it. The skin has temperature receptors that send nervous impulses to the thermoregulatory centre. The body temperature decreases - Answer-After the race, Huan's body temperature drops. He is