Unit 1 chapter 1 body regulation systems

Question 1

What is homeostasis

Answer 1

the steady state of body functioning a state of equilibrium characterized by a dynamic interplay between the outside environment and the internal control mechanisms that oppose such changes. These changes are done around a narrow, set point inside your body

Question 2

what is positive feedback

Answer 2

body ENHANCES original stimulus to make deviation greater
- reinforces or exaggerates deviations from normal

Question 3

What is negative feedback

Answer 3

Body REVERESES an original stimulus to regain balance
- most common form of feedback loop
- variations from the normal that are decreases are brought back up

Question 4

What are the two human systems that control homeostasis?

Answer 4

endoctrine system
and nervous system

Question 5

what is endocrine system?

Answer 5

the body’s “slow” chemical communication system; a set of glands that secrete hormones into the bloodstream
-Glands secrete hormones that regulate processes such as growth, reproduction, and nutrient use (metabolism) by body cells.

Question 6

what is the nervous system ?

Answer 6

the network of nerve cells and fibers that transmits nerve impulses between parts of the body.
brain, spinal cord, nerves

Question 7

What is the function of glial cells?

Answer 7

cells in the nervous system that support, nourish, and protect neurons
- glial or neuroglia cells provide: scaffoldings for neurone for neutrons to form, make myelin sheaths and offer defence against bacteria and cellular waste.

Question 8

what is the difference between glial and neurones?

Answer 8

Neurons are the structural and functional cells reacting to the physical and chemical changes in their environment. Neuroglia are the supporting cells necessary for nourishing and maintaining the neurons, among other functions.

Question 9

what are the three different neurones?

Answer 9

1.motor neuron
2. Interneuron
3. sensory neuron

Question 10

What is a motor neuron?

Answer 10

neurons that carry outgoing information from the central nervous system to the muscles and glands
- the cell body is located at the top of the neuron
- has myelin sheaths
- physically moves body into homeostasis

Question 11

what is a interneuron ?

Answer 11

a neuron that carries nerve impulses from one neuron to another
-has no myelin sheaths and has the cell body located at the middle of the structure
- receives incoming sensory information and sends out motor information via the spinal cord to the CNS only

Question 12

what are afferent neurons?

Answer 12

Nerve cells that carry impulses towards the central nervous system

Question 13

what are efferent neurons?

Answer 13

Nerve cells that conduct impulses away from the central nervous system

Question 14

what is a sensory neuron?

Answer 14

A neuron that picks up stimuli from the internal or external environment and converts each stimulus into a nerve impulse.

Question 15

What is the cell body?

Answer 15

Largest part of a typical neuron; contains the nucleus and much of the cytoplasm

Question 16

What are dendrites?

Answer 16

a neuron’s bushy, branching extensions that receive messages and conduct impulses toward the cell body

Question 17

What is an axon?

Answer 17

the extension of a neuron, ending in branching terminal fibers, through which messages pass to other neurons or to muscles or glands
1. speeds up the role of transmission because the impulse jumps from node to node and skips the parts covered by the myelin sheaths.
2. myelin can regenerate due to the presence of neurilemma
3. myelin protects the impulse and keeps it moving along the correct pathway.

Question 18

What are axon endings or axon terminal endings?

Answer 18

Axon branches and forms endings that innervate muscle fibres or other neurons. to pass along information regarding a sensation or to communicate a homeostatic response.
Ends of axons that contain vesicles with NTs (neurotransmitter)

Question 19

What is neurilemma ?

Answer 19

additional external myelin sheath that is formed by Schwann cells and found only on axons in the peripheral nervous system

Question 20

What is threshold potential?

Answer 20

The minimum membrane potential that must be reached in order for an action potential to be generated.

Question 21

What is resting potential?

Answer 21

the state of the neuron when not firing a neural impulse

Question 22

What is depolarization?

Answer 22

The process during the action potential when sodium is rushing into the cell causing the interior to become more positive.

Question 23

What is action potential?

Answer 23

a neural impulse; a brief electrical charge that travels down an axon.
- here all the Na+ ions are inside the axon
- maximum depolarization
- causes it to spike

Question 24

What is repolarization

Answer 24

Na+ channels close and K+ channels open will occur all along the axon.
-k+ ions rush outside the cell membrane

Question 25

What is refractory period?

Answer 25

time taken to actively pump NA+ out of the axon and to actively pump k+ ions into the axon using an enzyme and ATP - the cell cannot be stimulated again until refractory period is complete. -only when ions and charge are back to their original conditions can the neuron fire a successive time.

Question 26

What is the threshold potential or threshold stimulus

Answer 26

minimum stimulus required to make the neuron fire

Question 27

all or none law?

Answer 27

principle that the action potential in a neuron does not vary in strength; the neuron either fires at full strength or it does not fire at all

Question 28

What is sodium potassium pump?

Answer 28

a carrier protein that uses ATP to actively transport sodium ions out of a cell and potassium ions into the cell -helps maintain the resting potential of the membrane - and makes sure that action potential not does arise again (not being able to fire again)

Question 29

What is a synapse and explain how acetylcholine is used to transmit an impulse across the synapse?

Answer 29

Gap between neurons - the acetylcholine helps to send impulse across the neurons. - the process of acetylcholine causing impulse to the muscle involves: 1. action potential arrives 2. exocytosis : calcium channels open allowing calcium ions to diffuse in. This process allows for the vesicles containing NT (neurotransmitters) such as acetylcholine to fuse with the cell membrane through exocytosis in the synapse. 3. diffusion across the synapse 3. Depolarization : ACh diffuses across the synapse and binds to a receptor on the postsynaptic membrane. 4. degradation- enzymes: Depolarization ends as acetylcholine is broken down by enzymes 5. endocytosis: the degraded molecules diffuse back across the synapse and are taken into the synaptic knob (presynaptic neuron) by the vesicles, then the cycle repeats as the ACh are resythesized back into the vesicles.

Question 30

What will the mehcanism of excitatory and inhibitory NT's have on the use of the function neuron transmission?

Answer 30

-When the NT is inhibitory it causes hyperpolarization which reduces the level in the postsynaptic neuron to fire or the action potential to occur in this area (reduces excitability in the neuron. On the other hand Excitory NT's cause a higher likelihood to fire and cause action potential in the postsynaptic neuron leading to transmission and impulse. To much of inhibitory can lead to epilepsy, too much of excitatory can lead to Alzheimers.