Co-ordination and control

Question 1

What 2 organ systems help humans respond to change?

Answer 1

-nervous system
-endocrine system

Question 2

What 3 things does a co-ordinated response require?

Answer 2

-stimulus
-receptor
-effector

Question 3

What is a stimulus?

Answer 3

change in animal’s surroundings

Question 4

What is the receptor?

Answer 4

organ that detects the change (e.g. your eye)

Question 5

What do receptors do?

Answer 5

detect the stimulus and change its energy into nerve impulses

Question 6

What organs are our receptors?

Answer 6

sense organs - e.g. the eye

Question 7

The eye converts…

Answer 7

light into nerve impulses

Question 8

The ear converts…

Answer 8

sound into nerve impulses

Question 9

What is the central nervous system?

Answer 9

consists of brain and spinal chord - coordinates all of the nervous responses

Question 10

What is the order an impulse travels in?

Answer 10

receptor - sensory neurone - CNS - relay neurone - motor neurone - effector

Question 11

What is the dendrite?

Answer 11

tree like projections that connect motor neurones to different neurones

Question 12

What is the axon?

Answer 12

long section of motor neurone - electrical impulses travel through it

Question 13

What is the myelin sheath?

Answer 13

insulates axon and speeds up transmission of impulse

Question 14

What is a reflex?

Answer 14

automated action which does not involve the brain

Question 15

What is the steps of a reflex arc?

Answer 15

1. receptor detects stimulus
2. impulse is sent along sensory neurone
3. sensory neurone carries impulse to spinal chord (to a relay neurone)
4. relay neurone passes impulse through spinal chord to a motor neurone
5. motor neurone causes effector to move from stimulus

Question 16

What is a synapse?

Answer 16

small gap between 2 neurones

Question 17

How do impulses travel across the synapse?

Answer 17

1. electrical impulse travels along axon
2. neuron releases chemical messengers (neurotransmitters)
3. these chemicals diffuse across the synapse and bind with receptor molecules on next neuron
4. receptor molecules only bind to the specific chemicals released from the first neurone - this stimulates the second neuron to transmit the electrical impulse

Question 18

What is the cornea?

Answer 18

curved transparent disc at front of the eye - refracts light

Question 19

What is the function of the iris?

Answer 19

-set of muscles to control size of pupil
-regulates light reaching retina

Question 20

What is the function of the ciliary muscles and suspensory ligaments?

Answer 20

change the shape of the lens to focus light rays on the retina

Question 21

What is the retina made up of?

Answer 21

light sensitive receptor cells - rods and cones

Question 22

What is the function of the optic nerve?

Answer 22

carry impulses from retina to brain

Question 23

What is the fovea?

Answer 23

part of retina with highest conc. of cone cells

Question 24

Where in the eye is light reflected the most?

Answer 24

fovea

Question 25

What happens when the iris contracts?

Answer 25

restricts the pupil

Question 26

What happens when the iris relaxes?

Answer 26

pupil dilates

Question 27

The cornea is transparent to...

Answer 27

allow light to enter

Question 28

Cones are sensitive to...

Answer 28

colour

Question 29

Rods are sensitive to...

Answer 29

low light intensity

Question 30

In dim lights the radial muscles...

Answer 30

contract and the circular muscles relax

Question 31

In bright light the radial muscles

Answer 31

relax and the circular muscles contract

Question 32

In dim light the iris is...

Answer 32

narrower - pupil dilates

Question 33

In bright light the iris is...

Answer 33

wider - pupil constricts

Question 34

What is the reflex arc?

Answer 34

when light intensity is detected by the retina and the effectors are the iris muscles

Question 35

What is accommodation?

Answer 35

changes the eyes makes to see objects at different distances

Question 36

What happens to the eye when it is looking at a far away object?

Answer 36

-ciliary muscles relax -suspensory ligaments tighten -lens is thin and less convex shape -LESS REFRACTION

Question 37

What happens to the eye when it is looking at a close up object?

Answer 37

-ciliary muscles contract -suspensory ligaments slacken -lens is thick and more convex shape -MORE REFRACTION

Question 38

What is homeostasis?

Answer 38

maintenance of internal conditions/ our internal environment (e.g. temperature, water content)

Question 39

What does the tissue fluid contain?

Answer 39

water, salts, glucose

Question 40

How does the skin control loss of heat?

Answer 40

-impermeable -detects change in temp + pressure -sweat is evaporated to help us cool down

Question 41

When cold, hair follicles...

Answer 41

stand up - air is and insulator so less heat is radiated from skin

Question 42

What are the two types of thermoregulation?

Answer 42

vasoconstriction vasodilation

Question 43

Vasoconstriction occurs in...

Answer 43

cold conditions

Question 44

What is vasoconstriction?

Answer 44

-arterioles supplying the capillaries nearer the surface of the skin get NRROWER (they constrict) -less blood flows through capillaries near surface of skin -LESS HEAT LOST by radiation

Question 45

Vasodilation occurs in...

Answer 45

hot conditions

Question 46

What is vasodilation?

Answer 46

-arterioles supplying the capillaries near the surface of skin get WIDER (they dilate) -more blood flows through capillaries near surface of skin -MORE HEAT LOST by radiation