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15 Cards in this Set
- Front
- Back
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Central Nervous System (CNS) |
Made up of the brain and the spinal cord |
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Peripheral Nervous System (PNS) |
Made of peripheral nerves which link the CNS with the body's receptors and effectors |
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Sensory Neurons |
Conduct nerve impulses from receptors to the CNS (afferent pathway) |
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Relay Neurons |
Conduct nerve impulses within the CNS (also called interneurons or connector neurons) |
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Motor Neurons |
Conduct nerve impulses from the CNS to effectors (efferent pathway) |
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Resting Potential |
The charge difference across the membrane when a neuron is not firing (-70 mV), as maintained by the sodium-potassium pump |
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Action Potential |
The charge difference across the membrane when a neuron is firing (about 30 mV) |
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Depolarisation |
The change from a negative resting potential to a positive action potential (caused by opening of sodium channels) |
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Repolarisation |
The change from a positive action potential back to a negative resting potential (caused by opening of potassium channels) |
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How does Nerve impulse passes along a non-myelinated neuron |
1. Resting potential rises above threshold level.
2. Voltage gated sodium channels open. 3. Sodium ions flow into the cell, more sodium channels open. 4. Inside of cell develops a net positive charge compared to the outside and results in depolarization. 5. Voltage gated potassium channels open. 6. Potassium ions flow out of the cell. 7. Cell develops a net negative charge compared to the outside and results in repolarization. 8. Concentration gradients restored by sodium-potassium pumps. 9. Resting potential is restored. |
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principles of synaptic transfer |
1. Action potential reaches the end of a presynaptic neuron.
2. Voltage gated calcium channels open. 3. Calcium ions flow into the presynaptic neuron. 4. Vesicles with neurotransmitters inside the presynaptic neuron fuse with the plasma membrane. 5. Neurotransmitters diffuse in the synaptic cleft and bind to receptors on the postsynaptic neuron. 6. The receptors are channels which open and let sodium ions into the postsynaptic neuron. 7. The sodium ions cause the postsynaptic membrane to depolarize. 8. This causes an action potential which passes down the postsynaptic neuron. 9. Neurotransmitters in the synaptic cleft are degraded and the calcium ions are pumped back into the synaptic cleft. |
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State that the endocrine system consists of glands that release hormones that are transported in the blood. |
The endocrine system consists of glands that release hormones that are transported in the blood. |
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Explain that homeostasis involves monitoring levels of variables and correcting changes in levels by negative feedback mechanisms |
1. Homeostasis maintains the internal environment between limits.
2. Negative feed back is used to do so. Any change from a set point results in an opposite change. |
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Explain the control of blood glucose concentration, including the roles of glucagon, insulin and the alpha and beta cells in the pancreatic islets |
When blood glucose levels are high (e.g. after feeding): * Insulin is released from beta cells in the pancreas and causes a decrease in blood glucose concentration* This may involve stimulating glycogen synthesis in the liver (glycogenesis), promoting glucose uptake into the liver and adipose tissue or increasing the rate of glucose breakdown (increase cell respiration) * Glucagon is released from alpha cells in the pancreas and cause an increase in blood glucose concentration * This may involve stimulating glycogen breakdown in the liver (glycogenolysis), promoting glucose release from the liver and adipose tissue or decreasing the rate of glucose breakdown (decrease cell respiration) |
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Distinguish between type I and type II diabetes |
Type I : - The onset is usually early, sometime during childhood. - β cells do not produce enough insulin. -Diet by itself cannot be used to control the condition. Insulin injections are needed to control glucose levels.
Type II : - The onset is usually late, sometime after childhood. - Target cells become insensitive to insulin. - Insulin injections are not usually needed. Low carbohydrate diet can control the condition. |
