Unit A

Question 1

What is the Central Nervous System?

Answer 1

consists of the brain and spinal cord. processes info sent from the nerves

Question 2

What is the Peripheral Nervous System (PNS)?

Answer 2

it carries sensory info to the CNS and info from the CNS to muscles and glands. Is divided into two systems

Question 3

somatic system

Answer 3

A subdivision of the peripheral nervous system. Enables voluntary actions to be undertaken due to its control of skeletal muscles, bones and skin

-contains sensory nerves and motor nerves

Question 4

the autonomic system

Answer 4

A subdivision of the peripheral nervous system. Controls involuntary muscles

Question 5

glial cells

Answer 5

nourish, remove wastes from and defend against infection

Question 6

sensory neurons

Answer 6

receive stimuli and transmit it to the interneurons

Question 7

interneurons

Answer 7

are found in the CNS and act as integrators

Question 8

motor neurons

Answer 8

conduct impulses from the interneurons to the effectors (muscles or glands)

Question 9

The autonomic system consists of

Answer 9

sympathetic and parasympathetic nerves

Question 10

sympathetic nerves

Answer 10

-prepares the body for stress

-can pump you up/ “on” switch

-neurotransmitter involved is norepinephrine

-come from thoracic and lumbar region, mid section of spinal cord

Question 11

parasympathetic nerves

Answer 11

-returns body to normal

-brings you down (like a parachute)

-come from brain, upper & lower spinal cord

-acts as “off” switch

-neurotransmitter is acetylcholine

Question 12

functions of the nervous system

Answer 12

-gathers & processes info from external and internal environments

-then relays a response to the necessary areas of the body

Question 13

sensory nerves

Answer 13

transmits info about internal & external environments to the CNS

Question 14

motor nerves

Answer 14

carry response from the CNS to the appropriate muscles/glands

Question 15

reflex arc

Answer 15

-is the simplest nerve pathway
-is involuntary
-occurs without brain coordination

Question 16

what are the five components of the reflex arc and what are their functions

Answer 16

1. receptor-> to recognize stimulus
2. sensory neuron -> sends impulse to spinal cord
3. interneuron in spinal cord -> selects response
4. motor neuron -> sends impulse back to muscle
5. effector -> muscle produces response

Question 17

what is the structure of neurons?

Answer 17

neurone are cells; they contain organelles including mitochondria, lysosomes, nucleus, also contain specialized structures

Question 18

what do neurons contain?

Answer 18

dendrites, cell body, axon

Question 19

what are dendrites?

Answer 19

they receive info from sensory receptors or other neurons and carry it toward the cell body

Question 20

what is the cell body?

Answer 20

-sometimes called the soma
-contains the nucleus
-processes input from dendrites
-may relay input to axon

Question 21

what is an axon?

Answer 21

it conducts nerve impulses away from the cell body
-some are surrounded by a myelin sheath

Question 22

myelinated axons are what type of matter?

Answer 22

white matter

Question 23

unmyelinated axons are what type of matter

Answer 23

grey matter

Question 24

what is a myelin sheath?

Answer 24

the presence of this term, speeds up the rate of impulse transmission

Question 25

Schwann cell

Answer 25

a type of glial cell

Question 26

what does the nerve impulse do/ its roles?

Answer 26

the transmission of a ________ relies on the movement of ions across the cell membrane of the axon
-when a neuron is at rest, it maintains its “resting membrane potential”

_________ “jump” from one node to another, increasing the speed of the _______ _________.

Question 27

resting membrane potential

Answer 27

potential difference across the membrane in a resting neuron

Question 28

what happens during resting membrane potential

Answer 28

-using a membrane protein “pump” which uses ATP to move 3Na + toward the outside of the membrane while moving 2 K + inside
-this causes a build-up of positive charges on the outside of the membrane
-the neural cell membrane is more permeable to K + than Na + so more positives move to the outside than the inside
-larger, negatively charged proteins are generally kept within the cell (they can’t pass through the membrane)

Question 29

what is the nerve impulse

Answer 29

a series of action potentials.

All cells have a membrane potential, but the neuron is unique in that it can change the potential of its membrane to generate an impulse.

Question 30

the threshold potential

Answer 30

the minimum stimulus required to generate an Action Potential in a neuron (this can vary amongst different neurons)

Question 31

What is Action Potential

Answer 31

only in myelinated neurons, they occur at the Nodes Of Ranvier

they are “all or none” meaning that they occur maximally or not at all

Question 32

what happens during the Action Potential

Answer 32

when the threshold potential is reached (usually around 55mV) special protein channels in the membrane open allowing Na + to rush inside the axon.
-this causes the inside of the neural membrane to now contain more positives than the outside (thus reversing the normal charge distribution)
-this reversal of charge is called depolarization
- as a result of the change in the membrane potential, the Na + gates close and the K + gates open.
-this moves positive charges back to the outside of the membrane
-this process is called repolarization
-once this is complete, the K + gates close
- the Na + / K + pump then restores the original resting potential
-there is a short refractory period when the membrane cannot depolarize

Question 33

what is depolarization

Answer 33

in a neuronal membrane, reducing a membrane potential to less than the resting potential of -70mV

Question 34

what is repolarization

Answer 34

return of a nerve to its resting potential following depolarization

Question 35

what is refractory period

Answer 35

a brief time ( a few milliseconds) between the triggering of an impulse along an axon and the axon’s readiness for the next impulse; during this time, the axon cannot transmit an impulse

Question 36

why in myelinated neurons, does depolarization move from one node of Ranvier to the next

Answer 36

this happens because the Na + ions will naturally diffuse down their concentration gradient toward the next node

Question 37

Node of Ranvier

Answer 37

gap in the myelin sheath insulating the axon of a myelinated nerve cell; the membrane of the axon is exposed and action potentials occur only at these node; nerve impulses jump from one node of Ranvier to the next

Question 38

what is a neuron?

Answer 38

a nerve cell that gets triggered by chemical/ physical stimuli and sends electrical impulses through nervous system to trigger a response

Question 39

what is a neuron made of?

Answer 39

cell body: nucleus In it, metabolic reaction occurs
dendrites: signal gets carried to cell body
axon: carry impulse from cell body t effector
synapse: effector

Question 40

what is a nerve?

Answer 40

message pathway of the nervous system; made up of many neurons grouped into bundles and surrounded by protective connective tissue

Question 41

nervous system

Answer 41

in animals, system made up of cells and organs that let an animal detect changes and respond to them; made up of the brain and spinal cord, as well as the nerves that emerge from them and connect them to the rest of the body

Question 42

neurotransmitter

Answer 42

chemical messenger secreted by neurons to carry a neural signal from one neuron to another, or from a neuron to an effector, such as a gland or muscle fibre

Question 43

Norepinephrine belongs to which system and what type of

Answer 43

the autonomic system

Question 44

acetylcholine belongs to which system

Answer 44

autonomic system