the nervous system

Question 1

define a stimulus

Answer 1

a change in the internal or external environment that can cause a response

Question 2

give an example of an internal stimulus

Answer 2

drop in ph

Question 3

give an example of an external stimulus

Answer 3

rise in temperature

Question 4

define a receptor

Answer 4

a cell or a group of cells that are able to detect this change

Question 5

give 3 examples of receptors

Answer 5

• rods and cones in the eye
• pain receptors in the skin
• sense organ

Question 6

define an effector

give 2 examples

Answer 6

a cell or a group of cells that can carry out some action

• muscle
• gland

Question 7

what is the connection between receptors and effectors provided by (2)

Answer 7

the nervous system and sometimes the endocrine or hormonal system

Question 8

the nervous system is …. and involves …

Answer 8

the nervous system is electrical and involves ions

Question 9

the endocrine system is….

Answer 9

hormonal

Question 10

what is the human nervous system divided into?

Answer 10

the CNS and the PNS

Question 11

what does CNS stand for?

Answer 11

the central nervous system

Question 12

what does PNS stand for?

Answer 12

the peripheral nervous system

Question 13

what does the CNS consist of?

Answer 13

the brain and the spinal cord

Question 14

what does the PNS consist of?

Answer 14

nerve fibres made up of dendrites or axons carrying impulses to and from the CNS

Question 15

what is another term for neurons?

Answer 15

nerve cells

Question 16

neurons are…

they…

Answer 16

neurons are the basic unit of the nervous system

they carry nerve impulses from one place to another

Question 17

nerve impulses are…

Answer 17

electrical

Question 18

name the 3 different types of neurons?

Answer 18

• motor neuron
• sensory neuron
• interneuron

Question 19

what do motor neurons do?

Answer 19

they carry nerve impulses from the CNS to an effector (muscle or gland) causing them to respond.

Question 20

what do sensory neurons do?

Answer 20

carry nerve impulses from the receptor to the CNS

Question 21

what do interneurons do?

where are they found?

Answer 21

carry nerve impulses between sensory and motor neurons and are found only in the CNS

Question 22

draw a diagram of a motor neuron

Answer 22

notes

Question 23

some dendrites have….

Answer 23

myelin

Question 24

another word for synaptic endings is…

Answer 24

synaptic knobs

Question 25

draw a diagram of a sensory neuron

Answer 25

notes

Question 26

the cell body of the sensory neuron is ..... the CNS

Answer 26

outside

Question 27

draw a diagram of the interneuron | no labels required

Answer 27

notes

Question 28

what are axons?

Answer 28

long fibres that carry nerve impulses out of the cell body of the neuron

Question 29

what are schwann cells?

Answer 29

cells that secrete the myelin sheath

Question 30

what is myelin sheath? | give the 2 functions of myelin sheath

Answer 30

- the fatty material secreted by the schwann cells - protects and insulates the axons - speeds up nerve impulses

Question 31

what are the nodes of ranvier? | what is there function?

Answer 31

- gaps between 1 schwann cell and the next | - allow rapid passage of the nerve impulse

Question 32

what are dendrites?

Answer 32

(short) nerve fibres that receive nerve impulses from other neurons and carry nerve impulses into the cell body of the neuron

Question 33

what do synaptic endings do?

Answer 33

they synapse (meet) with other nerve cell bodies or with effectors

Question 34

what 2 actions does the cell body of the neuron do?

Answer 34

- receives nerve impulses from dendrites | - sends nerve impulses into axons

Question 35

give 3 differences between motor and sensory neurons

Answer 35

-the cell body of the motor neuron is at 1 end of cell the cell body of the sensory neuron is in the middle or to one side of the cell -the cell body of the motor neuron is in the CNS the cell body of the sensory neuron is outside of the CNS -the motor neuron carries impulses from from the CNS to an effector the sensory neuron carries nerve impulses from the receptor to the CNS

Question 36

nerve fibres (...)

Answer 36

nerves

Question 37

what are nerve fibres (or nerves)?

Answer 37

bundles of axons surrounded by myelin sheaths

Question 38

what is a ganglion?

Answer 38

a bundle of nerve cell bodies located outside the CNS

Question 39

discuss the nature of the nerve impulse | give 6 points

Answer 39

1- in neurons the inside of the cell is negative in respect to the outside -this is due to the movement of ions in and out of the axon -when a nerve cell is stimulated a wave of charge travels along the axon in the form of electricity 2- -the stimulus which causes the impulse must be strong enough to trigger the impulse ie the stimulus must be a minimum threshold level (the level of stimulus). -if the stimulus is below the threshold level the impulse will not be transmitted -if the stimulus is above the threshold level the impulse will be transmitted -this is known as the ALL OR NOTHING LAW ie an impulse i either transmitted or not