11 CO-ORDINATION + CONTROL

Question 1

Define homeostasis

Answer 1

The maintenance of a constant internal enviroment

Question 2

What is needed for a coordinated response

Answer 2

Stimulus, receptor, effector

Question 3

What is in the central nervous system

Answer 3

The brain and spinal cord

Question 4

How is the CNS linked to sense organs

Answer 4

Neurones

Question 5

Types of neurone

Answer 5

• Sensory
• Relay
• Motor

Question 6

How do the 3 types of neurones interlink

Answer 6

• Impulse from receptor pass along sensory neurones until they reach the CNS
• Impulses pass to relay neurones in the CNS
• Impulse passed to effectors along motor neurones

Question 7

Role of myelin sheath

Answer 7

Insulates axon and speeds up transmission of impulse

Question 8

Why are reflexes rapid

Answer 8

They do not involve the brain

Question 9

Describe the process of a reflex arc

Answer 9

• Receptors detect the stimulus
• Send an electrical impulse along the sensory neurone
• Sensory neurone passes impulse to spinal cord to a relay neurone
• By neurotransmitters across the synapse
• Relay neurone passes the impulse through the spinal cord to a motor neurone
• Motor neurone causes effector to move away from stimulus

Question 10

Describe what happens at the synapse

Answer 10

• Electrical impulse travels along axon
• Triggers neurotransmitters to be released and to diffuse across synapse
• Bind with receptor molecules on second neurone
• Stimulates another electrical impulse

Question 11

Function of cornea

Answer 11

Focuses objects on the front of the eye

Question 12

Function of pupil

Answer 12

Circular opening that’s controlled by the iris

Question 13

Function of iris

Answer 13

Controls how much light enters pupil

Question 14

Function of ciliary muscles

Answer 14

Contracts = lens gets thicker, relaxes = lens gets thinner

Question 15

Function of suspensory ligament

Answer 15

Attach to ciliary muscle

Question 16

Function of lens

Answer 16

Focuses light onto retina

Question 17

Function of retina

Answer 17

Contains rods and cones

Question 18

What happens to iris muscles in dim light

Answer 18

• Radial muscles contract
• Circular muscles relax
• Pupil dialtes

Question 19

What happens to iris muscles in bright light

Answer 19

• Circular muscles contract
• Radial muslces relax
• Pupil constricts

Question 20

How does the eye focus on a far object

Answer 20

• Ciliary muslces relax
• Suspensory ligaments pulled tight
• Lens pullled thin
• Less refraction of light

Question 21

How does the eye focus on a near object

Answer 21

• Ciliary muslces contract
• Suspensory ligaments slack
• Lens thick and convex
• More refraction of light

Question 22

What releases hormones

Answer 22

Glands

Question 23

Hormonal vs Nervous: speed

Answer 23

Slow (except adrenaline) vs fast

Question 24

Hormonal vs Nervous: type of message

Answer 24

Chemical vs electrical impulse

Question 25

Hormonal vs Nervous: method sent

Answer 25

Via blood (dissolved in plasma) vs along neurones

Question 26

Hormonal vs Nervous: response to message

Answer 26

Only target organs respond but still sent across body vs send directly to muscle

Question 27

Hormonal vs Nervous: role in body

Answer 27

Controls long term processes vs used when a fast response needed

Question 28

Insulin gland

Answer 28

Pancreas

Question 29

Adrenaline gland

Answer 29

Adrenal glands

Question 30

Testosterone gland

Answer 30

testis

Question 31

Oestrogen gland

Answer 31

Ovary

Question 32

Progesterone gland

Answer 32

Ovary

Question 33

Insulin target organs

Answer 33

Liver and muscles

Question 34

When the body is too hot, what changes take place

Answer 34

* Hairs stand on end - trap layer of air providing insulation * Less sweat released - less heat loss by evaporation * Vasoconstriction - arterioles under skin surface constrict, so less heat loss by radiation

Question 35

When the body is too cold, what changes take place

Answer 35

* Hairs lie flat - insulating layer of air not formed * More sweat released - upon evaporation heat energy is taken away from the skin * Vasodilation - arterioles under skin surface dilate, so more blood flows by skin, so more heat loss by radiation

Question 36

ADH gland

Answer 36

Pituitary gland

Question 37

How does ADH affect the permability of the collecting duct

Answer 37

* ADH diffuses out of blood and binds with receptors on collecting duct * More ADH that binds = more premeable to water * More water reabsorbed * Less urine * More concentrated urine

Question 38

How does auxin affect phototrophic responses

Answer 38

* Tip of shoot produces auxin * Diffuses down the shoot causing elongation of cells * Auxin builds on shaded side * Shoot bends towards light

Question 39

How does auxin affect phototrophic responses

Answer 39

* Tip of shoot produces auxin * Diffuses down the shoot causing elongation of cells * Auxin builds on shaded side * Shoot bends towards light

Question 40

What tropism is growth towards a light

Answer 40

Positive phototropism

Question 41

What tropism is growth away from a light

Answer 41

Negative phototropism

Question 42

What tropism is growth down due to gravity

Answer 42

Positive geotropism

Question 43

What tropism is growth against gravity

Answer 43

Negative geotropism

Question 44

What tropism is growth against gravity

Answer 44

Negative geotropism