homeostasis and response - RESPONSE

Question 1

NS
what do eyes detect

Answer 1

light - light receptors

Question 2

NS
what do ears detect

Answer 2

sound and orientation - sound/balance receptors

Question 3

NS
what does the nose detect

Answer 3

smell - smell receptors

Question 4

NS
what does the tongue detect

Answer 4

different tastes - taste receptors

Question 5

NS
what does skin detect

Answer 5

temperature and pressure - touch, pressure, temperature receptors

Question 6

NS
what are the two types of nervous system

Answer 6

central - brain + spinal chord
periphery - nerves and sense organs

Question 7

NS
what is a nerve

Answer 7

an organ containing a bundle of nerve cells
–> they carry electrical messages called impulses throughout the day

Question 8

NS
peripheral nervous system

Answer 8

• neurons are wired together through the body
• neurons (carrying messages as electrical impulses) move from one to another to keep the body functioning
• limited ability to repair themselves - nerve cells cannot be repaired or damaged

Question 9

NS
what are the 3 main nerve cells

Answer 9

• sensory neuron
• relay neuron
• motor neuron
  they come in many shapes and sizes depending on what their function is

Question 10

NS
what is the function of the 3 main nerve cells

Answer 10

sensory N - carries signals from outer part of body (periphery) into the central nervous system

motor N - carries signals from the central nervous system to the outer parts of your body (muscles, skin, glands)

relay N - connects various neurons within the brain & spinal cord (relays info basically)

Question 11

NS
what is the purpose of receptors

Answer 11

• they sense the environment (chemicals, light , sound, touch)
• they encode this info into electrochemical messages transmitted by sensory neurons

Question 12

NS
how does information flow from neurons (explain)

Answer 12

information flows from 1 neuron to another across a synapse.
synapse - a small gap separating neurons
the electrical impulse is converted into a chemical signal which crosses the gap

sensory . .. . . neuro . . . . . . relay
neuron . . . transmitters. neuron
–> . .. . . . . . . .. . –> . . .. . .. –>

–> - electrical impulse

———->|

Question 13

NS
describe the steps of a
conscious action/voluntary response

Answer 13

voluntary response involves a person’s brain making conscious decisions - response is fast since the brain processes info quickly and impulses travel quickly

1 - receptors in your skin detect a stimulus
2 - impulse is carried by SENSORY NEURONS to the spinal cord
3 - relay neuron carries signal to the brain
4 - brain decides to move away hand
5 - the impulse is sent by MOTOR NEURONS to the hand muscles via spinal cord

stimulus –> receptor –> sensory neuron –> co-ordinator –> motor neuron –> response

Question 14

NS
describe the steps of reflex actions

Answer 14

conscious action may be too slow to prevent harm
so the body bypasses the brain and produces a quicker response

1 - sensory neurons send electrical impulses to relay neurons (in the spinal cord)
2 - they connect sensory neurons to motor neurons
3 - motor neurons send electrical impulses to an effector
4 - the effector produces a response (muscle contracts to move hand away)

receptor –> sensory neuron –> relay neuron –> motor neuron –> effector response

Question 15

TE
function of optic nerve

Answer 15

carries impulse from retina –> brain

Question 16

TE
function of sclera

Answer 16

tough outer layer for protection - holds eye in place

Question 17

TE
function of cornea

Answer 17

transparent region of sclera at the front of the eye
refracts light - bends it as it enters eye

Question 18

TE
function of iris

Answer 18

muscles in the iris regulate the amount of light reaching the retina

Question 19

TE
function of ciliary muscles and suspensory ligaments

Answer 19

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

Question 20

TE
how does light intensity change the iris’ muscles

Answer 20

low light intensity - radial muscles in iris contract and pupils become larger

high light intensity - circular muscles contract and pupil becomes smaller

Question 21

TE
the retina

Answer 21

• made up of 2 light sensitive receptor cells - cones & rods
• cones - sensitive to colour
• rods - sensitive to low light intensity and allow us to see very dim light (1000x more sensitive than cones)
• receptor converts light into electrical energy of a nerve impulse

Question 22

TE
explain short-sightedness

Answer 22

the light focuses before the retina - focus is too forwards - long eye

you cannot see objects at long distances
it occurs when the eyeball is too long for the strength of the lens OR when the cornea is too sharply curved

when producing an image, it falls short of the retina

it can be corrected by a concave lens - diverges light

Question 23

TE
explain long-sightedness

Answer 23

the light focuses after the retina - focus is too far back - short eye

you cannot see objects at short distances
it occurs when the lens is too weak because it is not thick enough OR the eyeball is too short OR when the cornea is not curved enough

when producing an image, it falls behind the retina

it can be corrected by a convex lens - converges light

Question 24

TE
looking at a distant object..

Answer 24

• flat (pancake) lens
• ciliary muscles relax
• suspensory ligaments contract

Question 25

TE
looking at a near object…

Answer 25

• fat (pea) lens
• ciliary muscles contract
• suspensory ligaments slacken

Question 26

TB
cerebrum

Answer 26

controls complex behaviour
it is made of billions of connecting neurons and has different regions that carry out different functions

• there are 4 lobes: frontal, parietal, visual, temporal
• these lobes are involved in different functions:
  thinking
  learning
  interpreting sight, sound, smell
  feeling emotions
  forming/storing memories
  controlling voluntary movement

Question 27

TB
hypothalamus (1)

Answer 27

this controls many functions in the body

• it is found above the pituitary gland and below the thalamus
• it is involved in these functions:

homeostasis
osmoregulation (control of the body’s water, salts, ions)
release of hormones from pituitary glands
response to stress
release of sleepy hormone - melatonin - from pineal gland
hunger and feeling full after eating
blood pressure

Question 28

TB
hypothalamus (2)

Answer 28

the hypothalamus works with the pituitary gland to produce:

• antidiuretic hormone - for water reabsorption in kidney
• oxytocin - makes uterus contract during childbirth and triggers breast milk production
• growth hormone (regulates)
• prolactin - milk production
• hormones that control the gonads - reproductive system
• hormones that control thyroid + adrenal system
• dopamine - neurotransmitter

Question 29

TB
cerebellum

Answer 29

coordinates how your muscles work

• found at back of the brain tucked under the cerebrum
• has wrinkly, crumpled cortex (thin, specialised covering layer)
• coordinates movement & balance (writing and walking)

damage could cause difficulty with muscle coordination and keeping balance

Question 30

TB
medulla (1)

Answer 30

controls the unconscious activities such as heartbeat, breathing and digestion

aka medulla oblongata

• sits at base of brain/top of spinal cord –> closest to CNS
• medullary nerve cells connect with –>

CNS to send messages down spinal cord

vagus nerve (separate from spinal cord) which extends from medulla –> abdomen via heart/lungs

Question 31

TB
medulla (2)

Answer 31

• it carries out complex functions like:

control of movement
relay of sensory info from internal organs
control of arousal
control of sleep
blood pressure regulation

• it has activities in the autonomic nervous system:

control of movement
control of HR relating to BP
control of HR relation got blood pH
control of breathing rate
swallowing
digestive process

Question 32

TB
cerebral cortex

Answer 32

• outer layer of the cerebrum
• centre of conscious thought
• recalls memories and alters behaviour in the light of experience
• contains sensory areas, motor areas and association areas involved in language processing, personality, imagination and intelligence