Homeostasis And Response (B5)

Front 1

define homeostasis

Back 1

regulation of the internal conditions of a cell or organism in response to external changes

Front 2

receptors

Back 2

detect stimuli

Front 3

effectors

Back 3

bring about responses

Front 4

negative feedback response

Back 4

receptor detects change in a stimulus

coordinating centre compares the stimulus to a set point

effector produces a response to correct any difference

Front 5

human body temp

Back 5

37°C

Front 6

what monitors and controls body temp

Back 6

thermoregulatory centre

Front 7

digestion of proteins leads to

Back 7

excess amino acids

Front 8

if body temp is too low

Back 8

-vasoconstriction (blood vessels narrow directing blood away from the surface of the skin)

-sweating stops

-skeletal muscles uncontrollably contract and relax quickly (shiver) to transfer heat to the blood

Front 9

central nervous system

Back 9

brain and spinal cord

Front 10

reflex action

Back 10

1) pain stimulus detected by receptors

2) impulses pass along a sensory neutrons to the CNS

3) impulse passes through a relay neurone

4) motor neurone carries impulse to effector

5) effector responds

Front 11

synapse

Back 11

gap between neurones

Front 12

when an electrical impulse reaches a synapse

Back 12

chemical is released that diffuses across the gap causing an electrical impulse to be generated in the second neurone

Front 13

cerebral cortex

Back 13

responsible for consciousness, intelligence, memory and language

Front 14

medulla

Back 14

controls automatic actions such as heartbeat and breathing

Front 15

cerebellum

Back 15

coordinates movement and balance

Front 16

how neuroscientists map the regions of the brain

Back 16

-studying patients with brain damage

-electrically stimulating different parts of the brain

-using MRI scanning techniques

Front 17

retina

Back 17

contains receptor cells which are sensitive to light

Front 18

optic nerve

Back 18

carries impulses from retina to the brain

Front 19

sclera

Back 19

forms tough outer layer with a transparent region at the front called the cornea

Front 20

iris

Back 20

controls the size of the pupil

Front 21

ciliary muscles and suspensory ligaments

Back 21

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

Front 22

accommodation

Back 22

process of changing the shape of the lens to focus on near or distant objects

Front 23

focus on a near object

Back 23

ciliary muscles contract

suspensory ligaments loosen

lens becomes thicker and refracts light strongly

Front 24

to focus on a distant object

Back 24

ciliary muscles relax

suspensory ligaments tighten

lens is pulled thin and only slightly refracts light

Front 25

myopia

Back 25

short sightedness

corrected by concave

Front 26

hyperopia

Back 26

long sightedness

corrected with convex lens

Front 27

endocrine system

Back 27

glands that secrete hormones directly into the bloodstream

Front 28

hormones

Back 28

chemical messengers that are carried in the blood to a target organ where they produce an effect

Front 29

effects of hormones

Back 29

slower and last for longer

Front 30

master gland in the brain

Back 30

pituitary gland

Front 31

adrenaline

Back 31

produced by adrenal glands in times of fear or stress

increases the heart rate, boosting the delivery of oxygen and glucose

fight or flight

Front 32

thyroxine

Back 32

produced by thyroid gland

increases metabolic rate

controls growth and development

controlled by negative feedback

Front 33

blood glucose conc controlled by

Back 33

pancreas

Front 34

if blood glucose is too high

Back 34

pancreas releases more insulin

insulin causes glucose to move from blood into cells

excess glucose converted to glycogen for storage in liver and muscle cells

Front 35

if blood glucose is too low

Back 35

pancreas releases glucagon

glucagon stimulates glycogen to be converted into glucose and released into blood

negative feedback

Front 36

type 1 diabetes

Back 36

caused by pancreas failing to produce sufficient insulin

uncontrolled blood glucose levels

treated with insulin injections

Front 37

type 2 diabetes

Back 37

body cells no longer respond to insulin

obesity is a risk factor

treated with carb controlled diet and exercise

Front 38

water loss

Back 38

breath

sweat

urine

Front 39

urea

Back 39

excreted as a waste product produced by the liver from the breakdown of proteins and contains nitrogen

Front 40

digestion of proteins leads to

Back 40

excess amino acids

Front 41

amino acids converted to ammonia

Back 41

deamination

Front 42

kidneys produce urine by

Back 42

1) filtering blood

2) selective reabsorption of useful substances like glucose some ions and water

3) leaves urea and excess water and ions to form urine (takes place in tubules)

Front 43

water levels controlled by hormone

Back 43

ADH

Front 44

ADH released by pituitary gland when

Back 44

the blood is too concentrated

it causes more water to be reabsorbed into the blood

Front 45

kidney failure treated by

Back 45

dialysis

removes waste products from the blood through osmosis

Front 46

during puberty sex hormones cause

Back 46

secondary sexual characteristics

Front 47

main female sex hormone

Back 47

oestrogen

Front 48

main make sex hormone

Back 48

testosterone

Front 49

FSH

Back 49

secreted by pituitary

causes eggs to mature

stimulates ovaries to produce oestrogen

Front 50

oestrogen

Back 50

secreted by ovaries

inhibits FSH release

stimulates LH release

makes uterus lining grow after menstruation

Front 51

LH

Back 51

secreted by pituitary

stimulates ovulation

Front 52

progesterone

Back 52

maintains lining of uterus during second half of cycle

inhibits both FSH and LH release

Front 53

fertility drug

Back 53

FSH and LH

Front 54

IVF treatment

Back 54

giving a woman FSH and LH to stimulate the growth of many eggs

collecting eggs

fertilising eggs with sperm

inserting embryos into womb

Front 55

disadvantages of IVF

Back 55

emotionally and physically stressful

low success rates

lead to multiple births

Front 56

tropisms controlled by

Back 56

auxins

Front 57

experiments showing response to light

Back 57

more light reaches one side of shoot

more auxin sent down shaded side

cells on shaded side elongate more

shoot bends towards light

Front 58

in roots auxin

Back 58

auxin moves to the bottom of the root and causes less elongation so the root goes downwards

Front 59

gibberellins

Back 59

initiating seed germination

Front 60

ethene

Back 60

controls cell division

ripens fruit

Front 61

auxin weedkillers

Back 61

selective

kills weeds not grass

make weeds grow so rapidly they use up food reserves and die

Front 62

auxin rooting powders

Back 62

they make cuttings produce roots when planted

promote growth in tissue culture