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biology > homeostasis and response - B5 > Flashcards

homeostasis and response - B5 Flashcards

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1
Q

what is the definition of homeostasis?

A

the regulation of the internal conditions of the body in order to maintain an stable, optimum internal environment in response to internal and external changes

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2
Q

in what order does the body respond to changes?

A

receptor
coordination center
effector

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3
Q

where is the coordination center?

A

brain and spinal chord

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4
Q

what are the two types of effectors and how do they work?

A

muscles - contract when stimulated
glands - secrete hormones when stimulated

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5
Q

what is negative feedback?

A

when your body produces and opposite action to something that has happened in order to get conditions back to normal.

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6
Q

explain each stage of the control system

A

-receptors = detect change and sends info to coordination center
-coordination center =receives and processes info and coordinates a response
-effector + produces a response

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7
Q

describe the structure of a neuron

A

long, thin and branches to connect to other neurons

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8
Q

what and how do synapses work?

A

-they are gap between nerve cells
-when an electrical signal reaches the end of 1 nerve cell it stimulates the release of chemicals
-these chemicals diffuse across the synapse
-when the reach the next neuron is stimulates another electrical signal to be generated

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9
Q

what makes up the nervous system

A

receptors ,sensory neurons, cns, motor neurons, effectors

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10
Q

what is the cns made up of

A

brain and spinal chord

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11
Q

what is a reflex arc made up of

A

receptor, sensory neuron , relay neuron, motor neuron, effector

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12
Q

what are reflexes

A

rapid automatic actions

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13
Q

what does a motor neuron do

A

pass a signal from cns to effector

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13
Q

why are reflexes important?

A

they protect us from harm

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13
Q

why doesn’t the reflex arc involve the brain?

A

because reflexes are quick subconscious, automatic actions

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14
Q

what does a sensory neuron do

A

passes a signal form the receptor to the cns

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14
Q

what makes up the brain

A

cerebral cortex, cerebellum, hypothalamus, medulla + brainstem

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15
Q

where is the cerebral cortex and what does it do?

A

-the wrinkly layer
-controls consciousness, intelligence, memory, senses ( sight and hearing), language

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16
Q

where is the cerebellum and what does it do?

A

-the back of the brain
-controls muscle coordination and balance

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17
Q

where is the hypothalamus and what does it do?

A

-the middle of the brain
-regulates body temperature and sends signals to pituitary gland

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18
Q

where is the medulla and what does it do?

A

-in the brain stem
-controls unconscious actions like breathing and heart beat

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19
Q

how can we study the brain?

A

by studying people who have brain damage, electrically stimulating certain areas of the brain and my scans ( CT, MRI PET)

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20
Q

how is studying the brain dangerous

A

-the brain is very complex so we don’t know all of it
- its easy for the brain to catch diseases from infection which are hard to treat
- the brain is hard to access as its encased by the skull

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21
Q

what are the structures that make up the eye

A

cornea, iris, pupils, lens retina, fovea, optic nerve

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22
Q

describe cornea

A

transparent part that allows light through and bends it

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23
Q

describe iris

A

the coloured part of the eye that changes in response to light intesity

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24
Q

describe pupil

A

the gap in the iris that allows light to pass through to lens

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25
Q

describe lens

A

the place where light bends to focus on the retina

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26
Q

describe the retina

A

the back of the eye that contains cone cells and rod cells

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27
Q

describe the fovea

A

the part of the retina that has the most cone cells so the lens aims to focus light there as it produces the best image

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28
Q

what is a cone cell

A

cells that are sensitive to colour

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29
Q

what is a rod cell

A

cells that are sensitive to light and therefore help us to see better in the dark, but only in black and white

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30
Q

what is the optic nerve

A

sends signals from receptors in eye to cns

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31
Q

what is the iris effect

A

how the iris constricts or dilates in order to let in the optimum amount of light

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32
Q

what are the two muscles in the iris

A

radial muscles and circular muscles

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33
Q

how does the iris change in a lot of light

A

it constricts
-the circular muscles contract and the radial muscles relax
-the pupil is smaller and less light can pass through

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34
Q

how does the iris change in low light

A

it dilates
-the circular muscles relax and the radial muscles contract
-the pupil is bigger

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35
Q

why is the iris effect important

A

because too much light can damage retina

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36
Q

what helps the lens to change shape

A

suspensory ligaments and ciliary muscle

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37
Q

how does light need to be refracted for near by objects

A

it needs to be refracted strongly because the light enters at a wide angle

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38
Q

how does the lens change so that we can see near objects

A

it becomes short and fat

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39
Q

how do the suspensory ligaments and ciliary muscles change to make the lens short and fat

A

the ciliary muscle contracts and the suspensory ligaments slacken

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40
Q

how does light need to be bent for objects that are farther away

A

the lens doesn’t need to refract as much because the light comes in at a smaller angle

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41
Q

how does the lens change when the light is farther away

A

it becomes wide and thin

42
Q

how do the suspensory ligaments and the ciliary muscle change to make the lens wide and thin

A

the ciliary muscle relaxes and the suspenspry ligaments becocme taut

43
Q

what is long sightedness

A

when a person struggles to see objects that are near

44
Q

what does the lens to that cause long - sightedness

A

-the lens does not refract enough
-near objects need a stronger refraction
- so the light focuses behind the retina which means the image appears blurry

45
Q

how can long- sightedness be treated

A

-with a convex lens
-this refracts the light more strongly so that it focuses on the fovea

46
Q

what is the medical name for long sightedness

A

hyperopia

47
Q

what is short sightnedness?

A

when a person stuggles to see objects that are far away

48
Q

what does the lens do that causes short sightnedness

A

-it refracts light too much
-objects that are farther away don’t need to be refracted as much
-so the increased refraction of the lens means that the light is focused and an image is formed before the retina so the image is blurry

49
Q

how can short sightedness be treated

A

with a concave lens
-they refract light outwards and so counteract the effect of the lens

50
Q

what is the medical term for short sightedness?

A

myopia

51
Q

what is thermoregulation

A

the controlling of body tempreture

52
Q

where is the thermoregulatory centre

A

the hypothalamus in the brain

53
Q

how do we make our bodies warmer?

A

1.vasoconstriction - blood vessels in skin capillaries narrow = less blood flows near surface of the skin = less heat lost
2.erector muscles contract = this causes the hairs on the skin to rise which creates a layer of insulating air
3. shivering - automatic muscle contraction/ relaxing = needs energy from respiration = heat energy produced a a waste product

54
Q

how do we cool ourselves down ?

A

1.vasodilation - blood vessels dilate = more blood flows near the surface = more heat lost
2.erector muscles relaxing = hairs are flat and no layer of insulating air formed
3. sweating - water and salt that we secrete, when it evaporates it takes heat with it

55
Q

how does the endocrine system work?

A
  • it has glands that secrete hormones that flow through the bloodstream
  • the bind to receptors on specific cells that cause the cells to bring about change
56
Q

where and what does the pituitary gland do?

A

connected to brain
secrete lots of hormones, some that stimulate other glands to secrete hormones e.g TSH - stimulate thyroid gland to secrete thyroxine

57
Q

where and what does the thyroid gland do?

A

in neck
secret thyroxine
- controls rate of metabolism and helps with growth and development

58
Q

where and what does the adrenal gland do?

A

on top of kidneys
secretes adrenaline
- stimulates flight of fight response e.g increased heart rate and increased blood pumping around the body

59
Q

what does the pancreas so

A

secretes insulin
-controls blood glucose levels

60
Q

what do the testes do

A

secrete testosterone
and produces sperm

61
Q

what do the ovaries do

A

secretes oestrogen
produces eggs

62
Q

which system is faster, endocrine or nervous

A

nervous system because of the electrical impulses

63
Q

which system has longer lasting effects

A

the endocrine system

64
Q

what does each system target?

A

nervous - precise areas
endocrine - more general areas

65
Q

what happens when glucose levels fall too low?

A

tissue can’t respire properly

66
Q

what happens when glucose levels get too high?

A

-the pancreas detects it and secretes insulin
-this binds to cells mainly in the liver and muscles and makes them absorb glucose and store it as glycogen

67
Q

what happens when blood glucose levels fall too low

A

-the pancreas detects it and secretes glucagon
- this goes to cells mainly in liver and makes them break down their glycogen into glucose and release it into the blood

68
Q

what happens to people with diabetes?

A

they cannot control their blood glucose levels

69
Q

what is type 1 diabetes

A

when the pancreas cannot produce any or enough insulin

70
Q

who usually gets type 1 diabetes

A

children and teenagers because its genetic

71
Q

how is type 1 diabetes regulated?

A

by injecting insulin after every meal, monitoring diets and exercising regularly

72
Q

what is type 2 diabetes

A

when the tissue cells becomes resistant to insulin because of poor diets and lock of exercise

73
Q

who usually gets type 2 diabetes

A

older people

74
Q

how is type 2 diabetes treated?

A

by having a healthy diet and exercising regularly

75
Q

what is glucose

A

a carbohydrate

76
Q

what do the kidneys do?

A

excrete urea from the body and regulate the levels of water and ions

77
Q

what is urea and is it formed

A

a waste product
- it comes from deamination, where the converts excess amino acids into fats and carbohydrates for storage
-this produces ammonia which is toxic

78
Q

why do ion levels need to be regulated

A

-too high/ low ion levels can damage our cells
-if the levels are wrong, it can disrupt the balance between water levels and ion level and cells may absorb too little/much water
-we also lose ions from sweating

79
Q

why do water levels need to be regulated

A

-so that cells absorb the right amount of water my osmosis
-too much water= cells absorb more water swell and burst
-too little = cells do not absorb enough water and shrink
- we also lose water from breathing out and sweating

80
Q

how does the kidney regulate levels and excrete urea

A
  • there are tiny structures called nephrons in the kidneys
    -they have tubules and capillaries
    -the tubules absorb small molecules from the blood in he capillaries like glucose water, ions, amino acids and urea but NOT large proteins and red blood cells = FILTRATION
    -the capillaries reabsorb any small molecules they need not all and not any urea and almost all glucose and amino acids = SELECTIVE REABSORPTION
    -what is left is waster and produces urine
81
Q

what happens if water levels in the blood are too low

A

the hypothalamus sends a signal to the pituitary gland
-this stimulates it too secrete ADH
-this hormone goes around the body to the nephrons and stimulates the capillaries to reabsorb more water

82
Q

how does blood enter and exit the kidneys

A

enters via renal arteries
exits via renal veins

83
Q

what transports urine from kidneys to bladder

A

ureters

84
Q

what transport urine from bladder out of body

A

urethras

85
Q

what is at the start of a nephron

A

the glomerulus ( blood capillaries) and the bowman’s capsule(tubule) this is where things are filtered out

86
Q

what are the consequences of kidney failure

A

build up of waste in the blood and cannot regulate water and ion levels

87
Q

how does dialysis work

A

the blood goes though the machine and meets the dialysis fluid
-they are separated by a partially permeable membranes
-the dialysis fluid contains the same amount concentrations as healthy blood
- so the right amount of water and ions and all urea diffuse into the dialysis fluid
- the blood then goes back into the body

88
Q

why does dialysis fluid regularly have to be changed

A

to maintain a concentration gradient

89
Q

what are the disadvantages of dialysis

A

time- consuming
expensive
unpleasant and risk of infection

90
Q

what is the advantage of a kidney transplant

A

its cheaper

91
Q

what are the disadvantages of kidney transplants

A

the body can reject the kidney
the person will have to take immunosupressants for the rest of their life
their is not enough kidneys for all the transplants

92
Q

what is puberty

A

the development of secondary sexual characteristics in a person

93
Q

give examples of secondary sexual characteristics

A

breast development, deepened voice, pubic hair, increased height

94
Q

what is stage 1 of the menstrual cycle

A

menstruation
-bleeding as uterus lining breaks down

95
Q

what is stage 2 of the menstrual cycle

A

the uterus lining begins to build up again

96
Q

what is stage 3 of the menstrual cycle

A

ovulation
-day 14
an egg is released from the ovaries after it matures and

97
Q

what is stage 4 of the menstrual cycle

A

the uterus lining is maintained
is the egg is not fertilised it breaks down and the cycle begins again

98
Q

what does fsh do

A

stimulate the maturing of an egg in the ovaries
stimulates release of oestrogen
secreted by pituitary gland

99
Q

what does oestrogen do

A

inhibits release of fsh
builds uterus lining
stimulates release of lh

100
Q

what does LH do

A

stimulate the release of an egg from ovaries

101
Q

what does progesterone do

A

maintains uterus lining
inhibit release of lh and fsh

102
Q

what is contraception

A

preventing sperm from meeting egg

103
Q

what are hormonal methods of contraception

A

the pill
a patch
an injection
an implant
a plastic intrauterine device
these all release progesterone, oestrogen or both

104
Q

what are physical methods of contraception

A

condoms
diaphragms
sterilisation
spermicide

105
Q

what are the stages of ivf

A

1.the woman is given lh and fsh
2. the eggs are collected from the ovaries
3. sperm is taken from the male and if fertilised with egg in lab
3. they are left to grow into embryos in the lab
4. when they are ready they are injected back into the uterus

biology (7 decks)

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