Term
| State that the nervous system consists of... |
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Definition
| the central nervous system (CNS) and peripheral nerves, and is composed of cells called neurons that can carry rapid electrical impulses. |
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Term
| State that nerve impulses are conducted... |
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Definition
| from the receptors to the CNS by sensory neurons, within the CNS by relay neurons, and from the CNS to effectors by motor neurons. |
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Term
| Define: 1. Resting potential |
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Definition
| 1. An electrical potential across a cell membrane when not propagating an impulse. |
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Term
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Definition
| 2. The localised reversal (depolarization) and then restoration (repolarization) of electrical potential between the inside and outside of a neuron as the impulse passes along it. |
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Term
Explain how a nerve impulse passes along a non-myelinated neuron.
Role of Na+ ions |
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Definition
- resting potential: Na+ ions concentrated outside membrane
- action potential: Na+ ions rush to inside of membrane |
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Term
Explain how a nerve impulse passes along a non-myelinated neuron.
Role of K+ ions |
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Definition
- resting potential: K+ ions are concentrated inside membrane
action potential: K+ ions rush to outside of membrane |
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Term
Explain how a nerve impulse passes along a non-myelinated neuron.
Role of ion channels |
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Definition
- resting potential: Na+ and K+ ion channels closed
- action potential: Na+ channels open 1st, then close, just as K+ ion channels open |
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Term
Explain how a nerve impulse passes along a non-myelinated neuron.
Role of active transport |
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Definition
- Na+/K+ pump moves Na+ to outside and K+ to inside of membrane
- pumps ions against concentration gradients; ATP expended
- changes in membrane polarization:
1. resting potential: -70mV potential across membrane
2. action potential:
a) Na+ channels open, reversing membrane potential to +30mV
b) K+ channels open, restoring membrane potential to -70mV |
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Term
Explain the principles of synaptic transmission.
Ca+2 influx and release |
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Definition
- action potential open CA+2 channels; Ca+2 flows in
- Ca+2 cause exocytosis of neurotransmitter at synaptic cleft |
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Term
Explain the principles of synaptic transmission.
Diffusion and binding of neurotransmitter |
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Definition
-neurotransmitter diffuses across synaptic cleft
-neurotransmitter binds to post-synaptic receptor |
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Term
Explain the principles of synaptic transmission.
Polarization of the post-synaptic membrane. |
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Definition
- Na+ channels open; post-synaptic membrane depolarization
- K+ channels open; post-synaptic membrane hyperpolarization |
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Term
Explain the principles of synaptic transmission.
Subsequent removal of neurotransmitter. |
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Definition
| - enzymes hydrolyze neurotransmitter; pre-synaptic recycling |
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Term
Explain the principles of synaptic transmission.
Communication between neurons and glands or muscles takes place in... |
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Definition
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Term
| State that the endocrine system consists of glands that... |
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Definition
| release hormones that are transported in the blood. |
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Term
| State that homeostasis involves... |
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Definition
| maintaining the internal environment between limits, including blood pH, blood carbon dioxide concentration, blood glucose concentration, body temperature and water balance. |
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Term
Explain that homeostasis involves monitoring levels of variables and correcting changes in levels by negative feedback mechanisms.
Set-Point |
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Definition
| - set-point: a constant value to which a variable is constrained, such that any time the variable fluctuates outside a given set-point range, negative feedback takes actions to return the variable to its set-point |
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Term
Describe the control of body temperature including the transfer of heat in blood, the roles of the hypothalamus, sweat glands, skin arterioles and shivering.
Body Temperature:
-set-point
-sensors
-control centre |
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Definition
- set-point: core body temperature = 37 degrees C
- sensors: stimulus = body and blood temperatures above adn below 37degrees C
a) hypothalamus thermostat sensitivity to blood temperature
b) skin warmth receptors
c) skin cold receptors
- control centre:
a) hypothalamus thermostat
b) cerebral cortex |
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Term
Describe the control of body temperature including the transfer of heat in blood, the roles of the hypothalamus, sweat glands, skin arterioles and shivering.
-Effectors:
a) If T > 37 degrees C |
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Definition
a) If T > 37 degrees C
1. Involuntary responses by sympathetic nervous system
a) vasodilation => increases in heat loss
b) decreased basal metabolic rate => decreases heat production
c) sweating => increases heat loss
d) lethargy => decreases heat production
2. voluntary responses directed by cerebral cortex
a) rest => decreases heat production
b) behavioural responses (fanning, change to cooler clothing, cool drink) |
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Term
Describe the control of body temperature including the transfer of heat in blood, the roles of the hypothalamus, sweat glands, skin arterioles and shivering.
-Effectors:
a) If T < 37 degrees C |
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Definition
b) if T < 37 degrees C
1. Involuntary responses by sympathetic nervous system
a) vasoconstriction => decreases heat loss
b) increase basal metabolic rate => increases heat production
c) shivering => increases heat production
d) piloerection (goose bumps) => decreases heat loss
2. voluntary responses directed by cerebral cortex
a) rest => decreases heat loss
b) behavioral responses (muscular activity, change to warmer clothing, warm drink, curling up, eating) |
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Term
Describe the control of body temperature including the transfer of heat in blood, the roles of the hypothalamus, sweat glands, skin arterioles and shivering.
- Response
b) if T < 37 degrees C, effectors: |
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Definition
1) increase heat production,
2) decrease heat loss
3) until T = 37 degrees C |
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Term
Describe the control of body temperature including the transfer of heat in blood, the roles of the hypothalamus, sweat glands, skin arterioles and shivering.
-Response
a) If T > 37 degrees C, effectors: |
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Definition
1) decrease heat production
2) increase heat loss
3) until T = 37 degrees C |
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Term
| Summary Table - Involuntary Responses to Overheating |
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Definition
| 1. Skin arterioles become wider, so more blood flows through the skin. This blood transfers heat from the core of the body to the skin. The temperature of the skin rises, so more heat is lost from it to the environment. 2. Skeletal muscles remain relaxed and resting so that they do not generate heat. 3. Sweat glands secrete large amounts of sweat making the surface of the skin damp. Water evaporates from the damp skin and has a cooling effect. |
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Term
| Summary Table - Involuntary Responses to Chilling |
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Definition
1. Skin arterioles become narrower and they bring less blood to the skin. The blood capillaries in the skin do not move, but less blood flows through them. The temperature of the skin falls, so less heat is lost from it to the environment.
2. Skeletal muscles do many small rapid contractions to generate heat. This is called shivering.
3. Sweat glands do not secrete sweat and the skin remains dry.
4. Piloerection to trap air around the skin, so less heat is lost from it to the environment. |
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Term
Explain that homeostasis involves monitoring levels of variables and correcting changes in levels by negative feedback mechanisms.
Sensors |
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Definition
| - sensors: sensors respond to stimuli, gathering information about a variable in question, signalling when its value fluctuates from the set-point |
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Term
Explain that homeostasis involves monitoring levels of variables and correcting changes in levels by negative feedback mechanisms.
Control Centre |
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Definition
| - control centre: receives information from sensors, comparing the value to a set-point, and if necessary, directing actions to return the variable to its set-point |
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Term
Explain that homeostasis involves monitoring levels of variables and correcting changes in levels by negative feedback mechanisms.
Effectors |
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Definition
| A mechanism for taking action to return a variable to its set-point, switching on or off under the direction of the control centre |
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Term
Explain that homeostasis involves monitoring levels of variables and correcting changes in levels by negative feedback mechanisms.
Responses |
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Definition
| The resulting action produced by an effector, returning a variable to its set-point value |
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Term
Explain the control of blood glucose concentration, including the roles of glucagon, insulin and A and B cells in the pancreatic islets.
Levels of blood glucose: Set-point |
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Definition
| Set-point: blood glucose = 90mg/100ml |
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Term
Explain the control of blood glucose concentration, including the roles of glucagon, insulin and A and B cells in the pancreatic islets.
Levels of blood glucose:Sensors |
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Definition
Sensors: stimulus = blood glucose levels above and below 90mg/100ml
a) glucose detectors in pancreas islet beta cells detect high glucose levels
b) glucose detectors in pancreas islet alpha cells detect low glucose levels |
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Term
Explain the control of blood glucose concentration, including the roles of glucagon, insulin and A and B cells in the pancreatic islets.
Levels of blood glucose:Control Center |
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Definition
a) pancreas islet beta cells
b) pancreas islet alpha cells |
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Term
Explain the control of blood glucose concentration, including the roles of glucagon, insulin and A and B cells in the pancreatic islets.
Levels of blood glucose: Effectors |
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Definition
a) if blood glucose > 90mg/100ml, then pancreas beta cells produce and release insulin
b) if blood glucose < 90mg/100ml, then pancreas alpha cells produce and release glucagon |
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Term
Explain the control of blood glucose concentration, including the roles of glucagon, insulin and A and B cells in the pancreatic islets.
Levels of blood glucose: Response |
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Definition
a) If blood glucose > 90mg/100ml
1. Insulin binds to receptors in muscle and liver cells membranes
2. Moving glucose from the blood into liver and muscle cells
3. Where glucose is either metabolized or stored as glycogen or fatty acids
4. In fat cells, insulin promotes glucose entry where it is converted to triglycerides
5. Until blood glucose = 90mg/100ml
b) if blood glucose < 90mg/100ml
1. Glucagon binds to receptors in liver cell membranes
2. Which activates a cascade of enzymes which degrade glycogen into glucose
3. Glucose moves from the liver into the blood
4. Until blood glucose = 90mg/100ml |
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Term
| Summary Table - Responses to high blood glucose levels |
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Definition
- B cells in the pancreatic islets produce insulin
- Insulin stimulates the liver and muscle cells to absorb glucose from the blood and convert it to glycogen. Granules of glycogen are stored in the cytoplasm of these cells. Other cells are stimulated to absorb glucose and use it in cell respiration instead of fat. These processes lower the blood glucose level. |
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Term
| Summary Table - Responses to low blood glucose levels |
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Definition
- A cells in the pancreatic islets produce glucagon
- Glucagon stimulates liver cells to break glycogen down into glucose and release the glucose into the blood. This raises the blood glucose level. |
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Term
Distinguish between type 1 and type II diabetes.
Introduction |
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Definition
| In some people the control of blood glucose does not work effectively and the concentration can rise or fall beyond the normal limits. The full name for this condition is diabetes mellitus. There are two forms of this condition, which are compared in the table below. |
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Term
Distinguish between type 1 and type II diabetes.
Type I diabetes |
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Definition
- The onset is usually during childhood
- B cells produce insufficient insulin
- Insulin injections are used to control glucose levels
- Diet cannot by itself control the condition |
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Term
Distinguish between type 1 and type II diabetes.
Type II diabetes |
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Definition
- The onset is usually after childhood
- Target cells become insensitive to insulin
- Insulin injections are not usually needed
- Low carbohydrate diets usually control the condition |
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