Homeostasis

Question 1

what is a stimulus

Answer 1

a stimulus is a change in the environment

Question 2

why do the internal conditions of your body need to be regulated?

Answer 2

they need to be regulated to maintain the right conditions for cells to function properly and for enzyme action

Question 3

name the component of a control system that detects stimuli

Answer 3

the component is the receptor

Question 4

what are the 3 main components of the automatic control system?

Answer 4

the 3 main components are receptors, coordination centres and effectors

Question 5

what is negative feedback?

Answer 5

negative feedback is when the receptors detect a stimulus level is too high/low and so the coordination centre and the effector organise and produce a response to bring the level back to normal

Question 6

what is the central nervous system made up of?

Answer 6

the CNS is made up of the brain and spinal chord and is connected to the body via sensory and motor neurones

Question 7

what is the order of the coordination to the response?

Answer 7

stimulus, receptor, sensory neurone, CNS, motor neurone, effector response

Question 8

what is the 3rd component in the coordination order?

Answer 8

sensory neurone

Question 9

what is the 6th component in the coordination order?

Answer 9

effector

Question 10

what is the 5th component in the coordination order?

Answer 10

motor neurone

Question 11

what is the connection between 2 neurones known as?

Answer 11

the synapse

Question 12

what happens when an impulse reaches a synapse between the sensory neurone and the relay neurone?

Answer 12

chemicals are released which cause impulses to be sent along the relay neurone

Question 13

what is a reflex?

Answer 13

a reflex is a rapid, automatic response to certain stimuli that don’t involve the conscious past of the brain

Question 14

what is the reaction time?

Answer 14

the reaction time is the time it takes to respond to a stimulus

Question 15

what is the cerebral cortex responsible for?

Answer 15

it is responsible for consciousness, intelligence, memory and language

Question 16

what is the medulla responsible for?

Answer 16

it is responsible for unconscious activities like breathing and your heartbeat

Question 17

what is the cerebellum responsible for?

Answer 17

it is responsible for muscle coordination

Question 18

what is the sclera?

Answer 18

the sclera is the tough, supporting wall of the eye

Question 19

what is the cornea?

Answer 19

the cornea is the transparent outer layer found at the front of the eye

Question 20

what does the cornea do?

Answer 20

the cornea refracts light into the eye

Question 21

what does the iris contain that make it good at its job?

Answer 21

the iris contains muscles that allow it to control the diameter of the pupil and therefore how much light enters the eye

Question 22

what does the lens do?

Answer 22

the lens focuses light onto the retina

Question 23

what does the retina contain?

Answer 23

the retina contains receptor cells sensitive to light intensity and colour

Question 24

what is the shape of the lens controlled by?

Answer 24

the ciliary muscles and suspensory ligaments

Question 25

what does the optic nerve do?

Answer 25

the optic nerve carries impulses from the receptors on the retina to the brain

Question 26

to look at near objects, what happens to the ciliary muscles!

Answer 26

they contract

Question 27

when looking at near objects, what happens to the suspensory ligaments?

Answer 27

they slacken

Question 28

when looking at near objects, what happens to the lens?

Answer 28

it becomes fat (more curved)

Question 29

what does the increase in the size of the lens do?

Answer 29

it increases the amount by which it refracts light

Question 30

to look at distant objects, what happens to the ciliary muscles?

Answer 30

they relax

Question 31

when looking at distant objects, what happens to the suspensory ligaments?

Answer 31

they pull tight

Question 32

what happens to the lens when looking at distant objects?

Answer 32

the lens goes thin

Question 33

what does the thinning of the lens mean?

Answer 33

it means that it refracts light by a smaller amount

Question 34

what is the medical term for short sightedness?

Answer 34

myopia (MY)

Question 35

what is the medical term for long sightedness?

Answer 35

hyperopia

Question 36

what size is the eyeball for shortsightedness to occur?

Answer 36

too long (meets in the middle of the eye)

Question 37

what size is the eyeball for long sightedness to occur?

Answer 37

too short (meets behind the eye)

Question 38

what is vasodilation?

Answer 38

this is when the blood vessels supplying the skin dilate so more blood flows close to the surface of the skin which helps transfer energy to the environment

Question 39

why do you shiver?

Answer 39

you shiver because your muscles contract automatically, which requires respiration which transfers energy to warm the body

Question 40

what is the area of the brain that controls body temperature?

Answer 40

the thermoregulatory centre