Chapter 14: Coordination and response

Question 1

Define nerve impulse:

Answer 1

an electrical signal that passes along nerve cells called neurons.

Question 2

What does the human nervous system consist of?

Answer 2

• central nervous system (brain and spinal cord)
• peripheral nervous system (nerves that connect to CNS)
• coordination and regulation of bodily functions

Question 3

Order of reaction of a reflex arc:

Answer 3

stimulus – receptor – sensory neuron – spinal cord – motor neuron – effector – response

Question 4

define synapses:

Answer 4

a junction between two neurons

Question 5

How do synapses work?

Answer 5

1. stimulus triggers the release of chemical
2. neurotransmitter is moved to end and released into gap
3. chemical neurotransmitter diffuses across gap
4. receptor binds to neurotransmitter
5. starts the electrical signal in next neuron.

Question 6

Define sense organs:

Answer 6

a group of receptor cells responding to specific stimuli.

Question 7

function of cornea:

Answer 7

refracts light in eye

Question 8

Function of iris:

Answer 8

controls how much light enters pupil

Question 9

Function of lens:

Answer 9

focus light onto retina

Question 10

Function of retina:

Answer 10

contains light receptors, cones (sensitive to colour) and rods (sensitive to light)

Question 11

Function of optic nerve:

Answer 11

carries impulses to brain

Question 12

What happens to the pupil of the eye in a high light intensity?

Answer 12

pupil gets smaller
circular muscles contract
radical muscles relax

Question 13

What happens to the pupil of the eye in a low light intensity?

Answer 13

pupil gets bigger
circular muscles relax
radical muscles contract

Question 14

What happens to the lens, ciliary muscle and suspensory ligament in the eye when looking at an object a far distance away?

Answer 14

lens: thin
ciliary muscle: relaxed
sensory ligament: tight

Question 15

What happens to the lens, ciliary muscle and suspensory ligament in the eye when looking at an object that is nearby?

Answer 15

lens: thick
ciliary muscle: contracted
suspensory ligament: loose

Question 16

Define hormone:

Answer 16

The chemical substance, produced by a gland and carried by the blood, which alters the activity of one or more specific target organs.

Question 17

adrenaline source, role and effect:

Answer 17

source: adrenal glands
role: fight or flight response
effect: raises heart and breathing rate and dilates pupils

Question 18

insulin source and function:

Answer 18

source: pancreas
function: lower blood glucose levels by converting it into glycogen in the liver

Question 19

Define homeostasis:

Answer 19

the control of internal conditions within set limits

Question 20

What happens when blood glucose levels get too high?

Answer 20

insulin is released from pancreas and glucose is taken up and made into glucagon in liver

Question 21

What happens when blood glucose levels get too low?

Answer 21

glucagon is released from liver and it is broken down into glucose.

Question 22

Symptoms of type 1 diabetes?

Answer 22

• very thirsty
• urinate a lot
• loose weight
• lots of glucose in urine

Question 23

Treatment of type 1 diabetes?

Answer 23

carefully regulate diet

get regular injections of insulin

Question 24

What does the brain do when our body temperature gets too low?

Answer 24

shunt vessels take blood away from skin surface (VASOCONSTRICTION)
sweat production stops
shivering instituted to use more energy

Question 25

What does the brain do when our body temperature gets too high?0

Answer 25

arterioles in skin widen so blood is close to skin surface and looses heat to surroundings (VASODILATION)
sweat production increases to loose heat by evaporation

Question 26

How does a synthetic plant hormone 2.4-D affect weeds?

Answer 26

It speeds up there growth and respiration so much that it uses it’s resources too quickly and dies.