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biology gcse > homeostasis and response (paper 2) > Flashcards

homeostasis and response (paper 2) Flashcards

1
Q

what is homeostasis

A

the regulation of the internal conditions of a cell or organism to maintain optimum conditions for function in response to internal and external changes

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2
Q

what does homeostasis control in the human body

A

blood glucose concentration

body temperature

water levels

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3
Q

what do all control systems include

A

receptors - which detect stimuli

co-ordination centres - that recieve and process information from receptors - brain, spinal cord

effectors, muscles or glands - bring about responses which restore optimum levels

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4
Q

what does the nervous system enable us to do

A

react to their surroundings and coordinate their behaviour

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5
Q

how is a response co-ordinated

A

infomation from the receptors passes along the neurones as electrical impulses to the CNS (brain or spinal cord)

the CNS then co-ordiantes the response of effectors which may be muscles contracting or lands secretin hormones

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6
Q

order of a response bein created

A

stimulus

receptor

coordinator

effector

response

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7
Q

what are reflexes

A

involuntary responses to a stimuli

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8
Q

what is a reflex arc

A

the nerve pathway that bypasses the conscious part of the brain

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9
Q

how the reflex arc co-ordinates a response

A

the receptor detects the stimuli ex heat

the sensory neurone sends an electrical message to the CNS

effector - the organ is stimulated to respond

the relay neurone passes the message to the motor neurone (the coordinator)

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9
Q

the cerebral cortex

A

most important part of the brain

consists of four lobes which do a specific role - consciousness, intelligence, memory, language

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10
Q

the cerebellum

A

located at the base of the brain and is responsible for - muscle activity and balance

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10
Q

the medulla

A

is responsible for all unconscious activities - heart rate, breathing , digestion

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11
Q

difficulties of electrical stimulation (treatment)

A

immoral - subject participants to unknown reactions

hard to select specific neurones and be certain of areas responsible

if people have illnesses or heart problems it could affect this (cause palpitations)

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11
Q

difficulties of brain damage (treatment)

A

differences may be due to previous injuries

many processes are a result of multiple areas of the brain or connections between them

hard to rely on as sample may be small

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12
Q

possible difficulties of MRI (treatment)

A

can be uncomfortable if claustrophobic

requires costly specialist equipment

if people have a pace maker or other medical implants they cannot use MRI

some suggest a risk of bein exposed to magnetic fields but there is no evidence to support this

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13
Q

advantages of brain damage (treatment)

A

scientists can learn which parts of the brain are responsible for doing different jobs

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14
Q

advantages of electrical stimulation (treatment)

A

scientists have stimulated different parts of the brain with a weak electrical current and them asked patients to describe what they experienced

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15
Q

ciliary muscle and sensory ligament

A

controls the shape of the lens

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15
Q

advantages of MRI (treatment)

A

taking images of the brain has enabled scientists to link the loss of certain functions such as speech of control of movement down one side of the body with damage to a particular region

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16
Q

sclera

A

protects the eyeball from damage

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17
Q

retina

A

where most of the light sensitive cells are found

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18
Q

optic nerve

A

sends messages received by the light receptor cells to the brain

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19
Q

lens

A

fine tunes the focus of the light rays once they have passed through the cornea

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20
Q

cornea

A

lets light into the eye and helps to focus it on the retina

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21
Q

iris

A

controls the size of the pupil

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22
Q

how does the eye adapt to dim light

A

in dim light the pupil dilates

this is because the circular muscles relax

and the radial muscles contract

the opposite happens in bright light

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23
Q

how does the eye accommodate to focus on a near object

A

the ciliary muscles contract

the suspensory ligaments loosen

the lens is then thicker

light rays are refracted strongly

23
Q

what is accommodation

A

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

24
Q

how does an eye accommodate to focus on a distant object

A

the ciliary muscles loosen

the suspensory ligaments contract

the lens is then thinner

light rays are only slightly refracted

25
Q

myopia

A

short sightedness

26
Q

hyperopia

A

long sightedness

27
Q

what are defects in the eye caused by

A

the light rays do not focus on the retina

28
Q

how are eye defects treated

A

spectacle lenses - which refract the light rays so they do focus on the retina

hard and soft contact lenses

laser eye surgery

29
Q

where is body temperature monitored and controlled

A

thermoregulatory centre in the brain

30
Q

vasoconstriction

A

blood vessels near the skins surface become narrow

less blood flows through

less blood reaches the surface

less heat is lost by radiation

you warm up

31
Q

vasodilation

A

blood vessels near the skins surface widen

more blood flows through

more blood reaches the surface

more heat is lost by radiation

you cool down

32
Q

where is adrenal gland located

A

above the kidneys

33
Q

where is the thyroid gland located

A

the throat

34
Q

how does insulin control blood glucose levels in the body

A

by signaling the liver and muscle and fat cells to take in glucose from the blood, it therefore helps cells to take in glucose to be used for energy

if the body has sufficient energy, insulin signals the liver to take up glucose and store it as glycogen

35
Q

type 1 diabetes

A

a disorder in which the pancreas fails to produce sufficient insulin

it is characterized by uncontrolled high blood glucose levels and is normally treated with insulin injections

36
Q

type 2 diabetes

A

the body cells no longer respond to insulin produced by the pancreas

a carbohydrate controlled diet and an exercise regime are common treatments

obesity is a risk factor for type 2 diabetes

37
Q

what happens if blood glucose concentration is too low

A

the pancreas produces the hormone glucagon that causes glycogen to be converted into glucose and released into the blood

38
Q

explain the effect on cells of osmotic changes in body fluids

A

Water leaves the body via the lungs during exhalation.

Water, ions and urea are lost from the skin in sweat.

There is no control over water, ion or urea loss by the lungs or skin.

Excess water, ions and urea are removed via the kidneys in the urine.

If body cells lose or gain too much water by osmosis they do not function efficiently.

39
Q

what does the digestion of proteins in the diet result in

A

results in excess amino acids which need to be excreted safely.

In the liver these amino acids are deaminated to form ammonia.

Ammonia is toxic and so it is
immediately converted to urea for safe excretion

40
Q

describe the function of kidneys in
maintaining the water balance of the body

A

substances are filtered out of the blood as it passes through the kidneys, this process is called filtration

useful substances like glucose, some ions and the right amount of water are then absorbed back into the blood, this process is called selective reabsorption

41
Q

describe the effect of ADH on the permeability of the kidney tubules

A

there is a negative feedback loop that controls water content

the receptor in the brain detects the water content is too low / or too high

the co-ordination centre in the brain receives the information and coordinates a response

the pituitary gland will either release more ADH or less ADH so more or less water is reabsorbed from the kidney tubules

42
Q

how does dialysis work

A

in the dialysis machine ethe persons blood flows through a partially permeable membranes surrounded by dialysis fluid

the membranes are permeable to things like ions and waste substances, not big molecules like proteins

the dialysis fluid has the same concentration of dissolved ions and glucose as healthy blood

this means that useful dissolved ions and glucose wont be lost from the blood during dialysis

43
Q

advantages and disadvantages of kidney dialysis

A

advantages - gives people valuable time until a donor organ is found

disadvantages - not a pleasant experience, can be expensive for the NHS to run, sessions take a longtime and have to be done very regularly

44
Q

advantages and disadvantages of kidney transplants

A

advantages - they are cheaper than dialysis, the only cure to kidney failure

disadvantages - could be rejected, the wait times are very long, there is a small risk to the person donating the kidney, it can be hard to find a match

45
Q

what does FSH do

A

causes an egg to mature in one of the ovaries , in a structure called a follicle

stimulates the ovaries to produce oestrogen

46
Q

what does oestrogen do

A

causes the lining of the uterus to grow

stimulates the release of LH and inhibits the release of FSH

47
Q

what does LH do

A

stimulates the release of an egg at day 14 (ovulation)

48
Q

what does progesterone do

A

maintains the lining of the uterus during the second half of the cycle, when the level of progestrone falls, the lining breaks down

inhibits the release of LH and FSH

49
Q

examples of contraception

A

oral contraceptives that contain hormones to inhibit FSH production so that no eggs mature

injection, implant or skin patch of slow release progesterone to inhibit the maturation and release of eggs for a number of months or years

50
Q

how does IVF work

A

IVF involves giving a mother FSH and LH to stimulate the maturation of several eggs.

The eggs are collected from the mother and fertilized by sperm from the father in the laboratory.

The fertilized eggs develop into embryos.

At the stage when they are tiny balls of cells, one or two embryos are inserted into the mother’s uterus.

51
Q

disadvantages to fertility treatments

A

it is very emotionally and physically stressful

the success rates are not high

it can lead to multiple births which are a risk to both the babies and the mother

52
Q

what does adrenaline do

A

Adrenaline is produced by the adrenal glands in times of fear or stress.

It increases the heart rate and boosts the delivery of oxygen and glucose to the brain and muscles, preparing the body for ‘flight or fight’

53
Q

what does thyroxine do

A

Thyroxine from the thyroid gland stimulates the basal metabolic rate.

It plays an important role in growth and development

54
Q

are thyroxine levels controlled by negative feedback

A

YES

55
Q

why do plants produce hormones

A

Plants produce hormones to coordinate and control growth and responses to light (phototropism) and gravity (gravitropism or
geotropism).

56
Q

what does an unequal distribution of auxin cause

A

Unequal distributions of auxin cause unequal growth rates in plant roots and shoots

57
Q

what are Gibberellins important for

A

initiating seed germination

58
Q

what controls cell division and ripening of fruits

A

ethene

59
Q

method for investigating plant growth responses

A

1 - put 10 cress seeds into three different Petri dishes, each lined with moist filter paper (remember to label dishes)

2 - shine a light onto one of the dishes from above and two of the dishes from different directions

3 - leave your cress seeds alone for a week until you can observe their responses (you will find your seedlings grow towards the light)

60
Q

what are auxins used for

A

weed killers

rooting powders

promoting growth in tissue culture

61
Q

what is ethene used for

A

used in the food industry to control ripening of fruit during storage and transport

62
Q

what are Gibberellins used for

A

end seed dormancy

promote flowering

increase fruit size

biology gcse (7 decks)

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