nervous system (booklet 2)

Question 1

what are the 2 parts of the nervous system?

Answer 1

central nervous system - brain and spinal chord, peripheral nervous system - nerves extending from spine

Question 2

what are the 2 parts of the peripheral nervous system and their functions?

Answer 2

somatic nervous system - deliberate movement, autonomic nervous system - involuntary actions

Question 3

what is the function of neurones?

Answer 3

transmit messages in the form of electrical impulses

Question 4

what is the function of the receptor / sensory neurone?

Answer 4

transmit an impulse from the receptor / sense organ to CNS

Question 5

what is the function of the motor or effector neurone?

Answer 5

transmit an impulse from the CNS to to the effector

Question 6

what is the function of the inter / connector / relay neurone?

Answer 6

connects the sensory and motor neurones, transmits electrical impulse within the CNS

Question 7

What is the cell body / soma?

Answer 7

contains organelles such as nucleus, protein synthesis occurs here

Question 8

what are dendrites?

Answer 8

extensions protruding from surface of cell body that collect the impulse from neighbouring cells

Question 9

what are axons?

Answer 9

longest extension of the neurone which transmits an impulse a long distance from the cell body to another cell/effector

Question 10

what are axon terminals?

Answer 10

found at the end of the axon with tiny swellings

Question 11

what is myelin sheath?

Answer 11

mixture of protein and phospholipid which insulates the axon and speeds up transmission of the impulse, made of schwan cells

Question 12

what is the node of Ranvier?

Answer 12

gap in myelin sheath allowing electrical impulse to ‘hop’ along the axon, increasing transmission rate of the impulse

Question 13

how is an electrical impulse created?

Answer 13

due to movement of sodium ions into and potassium ions out of the axon across the cell membrane creating an action potential

Question 14

how does myelin sheath increase speed of electrical transmissions?

Answer 14

the impulse ‘hops’ between gaps of myelin sheath called nodes of Ranvier

Question 15

what is the synapse?

Answer 15

junction between adjacent neurones or a receptor cell/effector and neurone

Question 16

what is neurotransmitter?

Answer 16

chemical messengers released from neurones which function to transmit signals across the synaptic cleft

Question 17

how does an impulse transmit across the synapse?

Answer 17

electrical impulse reaches the axon terminal triggering opening of calcium channels, calcium diffuses into cell and promotes fusion of vesicles containing neurotransmitter with cell membrane, neurotransmitters are released from axon terminal via exocytosis and diffuse across the synaptic cleft, neurotransmitters bind to complementary receptors on the post-synaptic neurone and open ion channls on post-synaptic membrane generating an electrical impulse in the post-synaptic neurone, neurotransmitters released in synapse are recycled or degraded

Question 18

what are sensory receptors?

Answer 18

receptors and specialised neurones detect and respond to stimuli, external and internal environmental changes. They respond according to the intensity, duration and location of a stimulus.

Question 19

photoreceptor

Answer 19

detect light and provide sight, in eyes

Question 20

mechanoreceptor

Answer 20

detect mechanical stimuli (eg pressure and touch), provide hearing and touch senses, in ears and skin

Question 21

thermoreceptor

Answer 21

detect temperature changes, in skin and hypothalamus

Question 22

chemoreceptor

Answer 22

detects chemical stimuli (ie blood glucose), provide tasta and smell, in tongue and nose

Question 23

nocireceptor

Answer 23

detects pain and tissue damage, in skin

Question 24

externoreceptor

Answer 24

on skin, detect external stimuli

Question 25

internoreceptor

Answer 25

inside body (ie blood vessels), detect stimuli from blood and organs

Question 26

propioreceptor

Answer 26

in areas such as muscles and tendons, detects stimuli from muscles, tendons, ligaments and provides information such as body position

Question 27

what is a reflex?

Answer 27

an automatic response to a stimulus, all reflexes occur rapidly whithout conscious control or thought

Question 28

what is the functional structure of reflexes?

Answer 28

involve very few nerves in the reflex arc therefore are rapid and can protect the body from harm

Question 29

describe the pathway of a reflex response?

Answer 29

stimulus is detected by receptors, nerve impulse is transmitted from receptor through the sensory neurone and to the CNS (commonly only involves spinal chord), impulse crosses synapse to relay neurone and passes across second synapse to motor neurone, impulse travels down from motor neurone to the effector and brings about a response

Question 30

what is the set point for blood CO2 concentration?

Answer 30

5-6%, maintaining blood pH 7.4 (CO2 is acidic)

Question 31

Explain the stimulus response model of CO2 concentration in the blood

Answer 31

stimulus of increased CO2 is recognized by chemoreceptors in the aorta, carotid artery and medulla (brain), transmission pathway involving sensory, relay and motor neurones transmits the nerve impulse to the effectors - intercostal muscles diaphragm and cardiac muscle, this brings about a response where the muscles contract to increase rate and depth of breathing, producing negative feedback - CO2 level decrease