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Control & Communication
National 5 Control & Communication Mr G Davidson
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The Nervous System Our nervous system controls every action we make, although we may not be aware of it at the time. Most activities require us to move more than one part of our bodies at a time in a controlled way. The brain is in control of all of our systems and is capable of doing a number of different things at once. 14/11/2018 G Davidson
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Central Nervous System
Our nervous system controls our body and consists of the brain, spinal cord and nerves. Nerves contain many nerve cells. The brain and spinal cord together make up the Central Nervous System (C.N.S.) Information is passed along nerves to the C.N.S. in the form of electrical messages called IMPULSES. 14/11/2018 G Davidson
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Central Nervous System
Our sense organs detect information from our surroundings. The information is the stimulus which triggers off a nerve impulse. This impulse is carried along a sensory nerve cell to the C.N.S. 14/11/2018 G Davidson
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Central Nervous System
The information is sorted out in the C.N.S. and another impulse is then sent along a motor nerve cell to the effectors. The muscles contract and this is called a RESPONSE. 14/11/2018 G Davidson
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Brain The brain is the control centre in the C.N.S. and is made up of 3 parts: Cerebrum Cerebellum Medulla 14/11/2018 G Davidson
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Brain Cerebrum Cerebellum Medulla 14/11/2018 G Davidson
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Brain Part Function Cerebellum Controls Balance Medulla
Controls vital functions Cerebrum Conscious thought, reasoning, memory 14/11/2018 G Davidson
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Reflex Actions A reflex action is a rapid automatic response to a stimulus. It is an involuntary action, which does not always involve the brain. They happen so fast that there is often no time for them to reach the brain. 14/11/2018 G Davidson
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Reflex Actions Often the impulses only go to the spinal cord and the brain becomes aware of the action only after it has happened. E.g. knee jerk, blinking, iris changing, etc.. Reflex actions protect parts of our body from serious damage. 14/11/2018 G Davidson
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Reflex Arc 14/11/2018 G Davidson
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Reflex Arc 14/11/2018 G Davidson
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Reflex Actions The reflex arc is an arrangement of nerve cells which makes sure that we react quickly to hazardous stimuli. The stimulus is detected by receptors which triggers an electrical impulse along the sensory neuron. When the impulse reaches the spinal cord, it passes into a relay neuron. 14/11/2018 G Davidson
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Reflex Actions The impulse is then quickly passed to the motor neuron which is connected to the effector (usually muscle cells). Since neurons don’t actually touch each other, and there is a tiny gap between them, the impulse has to cross this gap, called a synapse. The impulse crosses the synapse using chemicals called neurotransmitters. The chemical diffuses across the gap and triggers an impulse in the next neuron. 14/11/2018 G Davidson
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Synapse Wednesday, November 14, 2018 Mr G Davidson
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Hormones As well as the nervous system there is also another communication system using chemicals called hormones. Hormones are produced in the endocrine glands. They are released into the blood where they are transported to other parts of the body. 14/11/2018 G Davidson
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Hormones They have an effect on the target tissue.
These tissues have special receptors on their surfaces. When the hormone binds with these receptors it brings about changes in the cells. Other cells in the target tissue without the receptors remain unaffected. 14/11/2018 G Davidson
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Hormones Pituitary gland Thyroid gland Adrenal gland Pancreas
Ovaries (female) Testes (male) 14/11/2018 G Davidson
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Oestrogen & progesterone
Hormones Endocrine gland Hormone produced Pituitary gland Growth hormone Thyroid gland Thyroxine Adrenal gland Adrenalin Pancreas Insulin Ovaries Oestrogen & progesterone Testes Testosterone Wednesday, November 14, 2018 Mr G Davidson
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Blood Glucose The levels of glucose in the blood are controlled by a hormone called insulin. Most of our energy comes from the respiration of glucose. This glucose is transported to all of our cells by the bloodstream. Wednesday, November 14, 2018 Mr G Davidson
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Blood Glucose However, the concentration of glucose in the bloodstream has to be very carefully controlled. A rise in blood glucose concentration is detected by cells in the pancreas. The pancreas responds by producing the hormone insulin. Wednesday, November 14, 2018 Mr G Davidson
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Blood Glucose This insulin is transported to the liver where it brings about the conversion of glucose into glycogen. The glycogen is then stored in the liver until it is required. Wednesday, November 14, 2018 Mr G Davidson
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Blood Glucose When the blood sugar level falls this is also detected by the pancreas and it responds by producing the hormone glucagon. This is then transported to the liver in the blood where it brings about the conversion of glycogen back to glucose, which raises the blood glucose level. Wednesday, November 14, 2018 Mr G Davidson
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Glucose converted to glycogen Glycogen converted to glucose
Blood glucose Blood sugar level rises Blood sugar level falls Pancreas produces insulin Pancreas produces glucagon Insulin transported to liver Glucagon transported to liver Glucose converted to glycogen and stored in the liver Glycogen converted to glucose Blood sugar level rises Blood sugar level falls Wednesday, November 14, 2018 Mr G Davidson
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Diabetes If the blood sugar level cannot be controlled a person would suffer from diabetes. This is a fairly common condition in our population and we will all know at least one person who is diabetic. Wednesday, November 14, 2018 Mr G Davidson
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Diabetes There are 2 forms of diabetes:
Type 1 diabetes Type 2 diabetes Both are caused by a breakdown in a communication pathway. Type 1 diabetes usually appears early in a person’s life whereas type 2 usually appears later in life. Wednesday, November 14, 2018 Mr G Davidson
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Type 1 Diabetes Type 1 diabetes is a result of the person not producing enough insulin. This results in the person having high blood glucose levels as the glucose is not converted to glycogen in the liver. It is treatable using insulin injections, but the person must test their blood to find out how much insulin they need to inject. Wednesday, November 14, 2018 Mr G Davidson
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Type 2 Diabetes Type 2 diabetes is a result of the insulin having no effect in the liver. This also results in high blood glucose levels. It is treatable by the person regulating their diet, exercising regularly and losing weight. Wednesday, November 14, 2018 Mr G Davidson
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