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BIOLOGY-EVIE > Topic 5-Homeostasis > Flashcards

Topic 5-Homeostasis Flashcards

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1
Q

what is homoeostasis

A

homeostasis is 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 maintains optimal conditions for

A

enzyme action and all cell

functions.

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3
Q

what does homeostasis control in the human body

A

blood glucose concentration
body temperature
water levels.

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4
Q

what three things does the automatic control system contain

A

effectors, receptors and the co ordination centre

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5
Q

what do receptors do

A 
detect stimuli (changes in the
environment)
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6
Q

give examples of co ordination centres

A

(such as the brain, spinal cord and pancreas)

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7
Q

what do co ordination centres do

A

receive and process information from receptors

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8
Q

what do effectors, muscles or glands do

A

bring about responses which

restore optimum levels.

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9
Q

what is negative feedback

A

a mechanism where your auto matic control systems keep your internal environment stable

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10
Q

what does stimuli mean

A

change in the environment

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11
Q

whats the difference between multicellular and single celled organisms in terms of response

A

single celled organisms can just respond to its environment bu the cells of multi cellular organsims need to communicate with each other first

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12
Q

what does the nervous system mean for humans

A

that they can react to their surroundings and co ordinate their behaviour

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13
Q

what is the CNS and what does it consist of

A

CNS- central nervous system- recieves info from the receptors and then coordinates a response

vertebrates- brain and spinal cord

mammals- CNS is connected to the body by sensory neurons and motor neurons

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14
Q

what are sensory neurons

A

neurons that carry info as electrical impulses from the RECEPTORS to the CNS

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15
Q

what are motor neurons

A

the neurons that carry electrical impulses from the CNS to the EFFECTORS

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16
Q

what are effectors

A

all your muscles and glands which respond to nervous impulses

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17
Q

explain the order of the body’s response to a stimulus

A 
Stimulus
receptor
sensory neuron
CNS
motor neuron
effector
response
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18
Q

what is a synapse

A

the connection between two neurons

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19
Q

how is the nerve signal transferred

A

by chemicals that diffuse across the gap

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20
Q

what do the chemicals between the gap in the neurons do

A

set off a new electrical signal in the next neuron

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21
Q

what are reflexes

A

Reflex actions are automatic and rapid; they do not involve the conscious part of the brain

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22
Q

whats a reflex arc

A

the passage of information in a reflex (from receptor to effector)

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23
Q

what does the refelx arc pass through

A

the CNS (spinal chord or unconscious part of the brain)

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24
Q

what happens in the reflex arc

A

a stimulus (eg. bee sting) is detected by the receptors
impulses travel along a sensory neuron
chemicals are passed, causing an impulse to be passed along a synapse from the sensory neuron to the relay neuron
impulses are passed along the synapse to the motor neuron in the same way
impulses travel form motor neuron to the effector
the muscle contracts and moves the hand away from the bee

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25
Q

what does the brain do

A

controls complex behaviour

It is made of billions of interconnected neurones

has different regions that carry out different functions.

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26
Q

name three parts of the brain

A

cerebral cortex
medulla
cerebellum

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27
Q

what does the medulla do

A

controls unconscious activities

eg, breathing and your heartbeat

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28
Q

what does the cerebral cortex do

A

(outer wrinkly bit)

responsible for things like consciousness, intelligence memory and language

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29
Q

what does the cerebellum do

A

responsible for muscle coordination

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30
Q

what three things can a scientist do to study the brain and map out which bit does what

A

studying patients with brain damage
electrically stimulating the brain
MRI scans

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31
Q

how can studying a patient with brain damage help discover more about the brain

A

Eg. if an area at the back of the brain was damaged by a stroke and the patient went blind you know that that area has something to do with vision.

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32
Q

how does electrically stimulating the brain help scientists

A

by pushing an electrode into the tissue of the brain and giving it a small zap of electricity, the scientist can observe what stimulating different parts does

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33
Q

how do MRI scans help scientists discover about the brain

A

find out which parts are active when people are doing different things

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34
Q

what are some consequences of treatment of brain damage or disease

A

physical damage to the brain

increased problems with brain function

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35
Q

what is the eye

A

a sense organ containing receptors sensitive to light intensity and colour.

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36
Q

that is the sclera

A

the tough supporting wall of the eye

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37
Q

what is the cornea

A

the transparent outer layer
at the front of the eye
it refracts (bends) light into the eye

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38
Q

what is the iris

A

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

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39
Q

what is the lens

A

focuses the light onto the retina

which contains receptor cells sensitive to light intensity and colour

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40
Q

the shape of the lens is controlled by…

A

the ciliary muscles and suspensory ligaments

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41
Q

what does the optic nerve do

A

carries impulses from the receptors on the retina to the brain

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42
Q

what does the iris reflex mean

A

adjusting for bright light

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43
Q

what happens when light receptors in the eye detect a very bright light

A

the circular muscles in the iris contract and the radial muscles relax - pupil gets smaller
this reduces the amount of light that can enter the eye

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44
Q

what happens to the eye in dim light

A

radial muscles contract
circular muscles relax
pupil gets wider
more light can get into the eye

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45
Q

what is accomodation

A

the process of changing the shape of the lens to

focus on near or distant objects.

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46
Q

To focus on a near object what happens to the eye

A
  • the ciliary muscles contract
  • the suspensory ligaments loosen
  • the lens is then thicker and refracts light rays strongly.
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47
Q

To focus on a distant object what happens to the eye

A
  • the ciliary muscles relax
  • the suspensory ligaments are pulled tight
  • the lens is then pulled thin and only slightly refracts light rays.
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48
Q

what is short sightedness called

A

myopia

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49
Q

what is long sightedness called

A

hyperopia

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50
Q

what does my/hyper opia mean for the eye

A

rays of light do not focus on the retina.

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51
Q

what is long sighted-ness and how does it occur

A

unable to focus on near objects
occurs when lens is wrong shape and doesn’t refract light enough, or eyeball is too short
SO the images of near objects are brought to focus behind the retina

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52
Q

how can L sightedness be fixed

A

use glasses with a convex lens (curves outwards)

lens refracts the light rays so they focus on the retina

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53
Q

what is short sighted-ness and how does it occur

A

unable to focus on distant objects
occurs when lens is wrong shape and refracts the light too much or the eye ball is too long
SO the images of distant objects is brought into focus in front of the retina

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54
Q

how can S sightedness be fixed

A

use glasses with a concave lens (curves inwards) so that the light rays focus on the retina

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55
Q

name three treatments for vision defects

A

contact lenses, laser eye surgery and replacement lens surgery

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56
Q

what do contact lenses do

A

thin lenses that are thin and compensate for fault in focusing
lightweight and almost invisible
hard and soft lenses
soft- more comfy but carry a higher risk of infection

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57
Q

what does laser eye surgery do

A

laser vaporises tissue which changes the shape of the cornea, which changes how strongly it refracts light into the eye
slimming down=less powerful= improve short sight
more powerful= improves long sight
risks= infection, bad reaction

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58
Q

explain what replacement lens surgery is

A

long-sightedness treated by replacing lens of the eye

risks- damage to retina- loss of sight

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59
Q

which hormones control blood glucose levels

A

insulin and glucagon

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60
Q

where is body temperature is monitored

A

its monitored and controlled by the thermoregulatory

centre in the brain

61
Q

what does the thermoregulatory centre contain

A

receptors

sensitive to the temperature of the blood

62
Q

what does the skin contain

A

temperature receptors which send nervous impulses to the thermoregulatory centre.

63
Q

what happens if the body temperature is too high

A

blood vessels dilate (vasodilation)
sweat is produced from the sweat glands

both these mechanisms
cause a transfer of energy from the skin to the environment.

plus hairs stand flat

64
Q

what happens if the body temperature is too low

A

blood vessels constrict (vasoconstriction)
sweating stops
skeletal muscles contract (shiver)
hairs stand up

65
Q

how does sweat cool you down

A

its produced by sweat glands
it evaporates from the skin
this transfers energy to the environment

66
Q

how does vasodilation help cool down the body

A

the blood vessels dilate so more blood flows closer to the skin
this helps transfer energy from the skin to the environment

67
Q

how does hairs standing up help you warm up

A

trap an insulating layer of air

68
Q

how does vasoconstriction help you warm up

A

blood vessels constrict to close off the skins blood supply

69
Q

how does shivering help you warm up

A

your muscles contract automatically

this needs respiration which transfers some energy to warm the body

70
Q

what is the endocrine system

A

The endocrine system is composed of glands which secrete chemicals called hormones directly into the bloodstream

71
Q

how are hormones carried around the body

A

The blood carries the hormone to a target organ where it produces an effect.

72
Q

which has longer effects, the nervous system or the hormonal system

A

nervous system has
fast action
act for a short time
very precise area

endocrine system
slower action
act for a longer time
act in a more general way

73
Q

what does the pituitary gland do

A

a ‘master gland’ which secretes
several hormones into the blood in response to body conditions.
These hormones in turn act on other glands to
stimulate other hormones to be released to bring about effects.

74
Q

what do the ovaries do

A

produce oestrogen- involved in the menstrual cycle

75
Q

what do the testes do

A

produce testosterone- controls puberty and sperm production

76
Q

what does the thyroid do

A

produces thyroxine- regulates metabolism, heart rate and temperature

77
Q

what does the adrenal gland do

A

produces adrenaline- prepares body for fight or flight response

78
Q

what does the pancreas do

A

produces insulin which is used to regulate the blood glucose level

79
Q

Blood glucose concentration is monitored and controlled by…

A

the pancreas

80
Q

If the blood glucose concentration is too high, what happens

A

The pancreas produces the hormone insulin that causes glucose to move from the blood into the cells

81
Q

what happens to excess glucose in the liver and muscle cells

A

it’s converted to glycogen for storage.

82
Q

what happens when the blood glucose level is too high

A

insulin is secreted by the pancreas
insulin enters the liver and makes it turn glucose into glycogen
glucose moves from the blood into the liver and muscles cells
BLOOD GLUCOSE IS REDUCED

83
Q

what happens when the blood glucose level is too low

A

glucagon is secreted by the pancreas
glucagon enters the liver and makes it turn glycogen into glucose
glucose is released into blood by the liver
BLOOD GLUCOSE IS INCREASED

84
Q

what is type 1 diabetes

A

Type 1 diabetes is a disorder in which the pancreas fails to produce sufficient insulin

85
Q

what is type 2 diabetes

A

In Type 2 diabetes the body cells no longer respond to insulin produced by the pancreas

86
Q

how is type one diabetes characterised

A

by uncontrolled high blood glucose levels

87
Q

how is type one diabetes treated

A

normally treated with insulin injections.

88
Q

how is type two diabetes charictarised

A

can cause persons blood sugar levels to rise to a dangerous level

89
Q

how can type two diabetes be treated

A

by having a carbohydrate controlled diet and an exercise regime

90
Q

what’s a risk factor for type two diabetes

A

obesity

91
Q

how do the kidneys make urine

A

by filtration of the blood and selective
reabsorption of useful substances such as glucose, some ions and
water.

92
Q

what does filtration do

A

filters substances out of the blood as they pass through the kidneys

93
Q

what is selective re absorption

A

when useful substances like glucose, some ions and the right amount of water are absorbed back into the blood

94
Q

name three substances that are removed from the body in urine

A

water, urea and ions

95
Q

what happens to proteins and the amino acids that they are broken down into in the liver?

A

they cant be stored by the body, so any excess amino acids are converted into fats and carbohydrates, which can be stored- involves a process called deamination

96
Q

what happens to ammonia in the liver?

A

ammonia is produced as a waste product from deamination
its toxic so is converted to urea in the liver
urea is then transported to the kidneys where it’s filtered out of the blood and excreted from the body in urine

97
Q

how do ions enter the body

A

ions, such as sodium are taken into the body via food and then absorbed into the blood

98
Q

how does water leaves the body

A

via the lungs during exhalation

99
Q

how are water, ions and urea lost

A

from the skin in sweat.

100
Q

what is there no control over the loss of

A

water, ion or urea loss by the lungs or skin

101
Q

Excess water, ions and urea are removed via what

A

the kidneys in the urine.

102
Q

what happens if body cells lose or gain too much water by osmosis

A

they do not function efficiently

103
Q

where is ADH released

A

released into the blood stream by the pituitary gland

104
Q

what is the concentration of urine controlled by

A

a hormone called anti-diuretic hormone (ADH)

105
Q

what does the brain do for the water content of the body

A

the brain monitors the water content of the blood and instructs the pituitary gland to release ADH into the blood according to how much is needed.

106
Q

what happens if the water content increases

A

a receptor in the brain detects it’s too high

the coordination centre in the brain receives the info and coordinates a response.

the pituitary gland releases less ADH, so less water is reabsorbed from the kidney tubules

107
Q

what happens if the water content decreases

A

a receptor in the brain detects this

the coordination centre receives this and coordinates a response

the pituitary gland releases more ADH, so more water is reabsorbed from the kidney tubules

108
Q

what happens if the kidneys dont work properly

A

waste substances build up in the blood and you eventually lose your ability to control the levels of ions and water in your body

results in death

109
Q

what is a dialysis machine

A

a machine which the person’s blood flows between partially permeable membranes, surrounded by dialysis fluid.

110
Q

whats a dialysis machine permeable to

A

ions and waste substances, but not big molecules like proteins

111
Q

whats the concentration like of dissolved ions and glucose like in the dialysis fluid and why?

A

its the same concentration as healthy blood

this means it wont be lost from the blood during dialysis

112
Q

which substances diffuse across the barrier in dialysis

A

urea and excess ions and water

113
Q

advantages of dialysis treatment

A

can buy a patient with kidney failure valuble time until a donor organ is found

114
Q

disadvantages of dialysis treatment

A

not pleasant
time consuming (3-4 hours) three times a week
dialysis may cause blood clots or infection
expensive for the NHS to run

115
Q

what is the only cure for kidney failure at the moment?

A

kidney transplant

116
Q

whats a risk of kidney transplant and how is it prevented

A

donor kidney can be rejected by the patient’s immune system

treated with drugs to try and prevent it, but can still happen

117
Q

advantages for kidney transplants

A

cheaper in the long run than dialysis

no hours sat at machine

118
Q

disadvantage to kidney transplants

A

there is a long waiting list

119
Q

During puberty reproductive hormones cause what

A

secondary sex characteristics to develop.

120
Q

what happens in stage one of the menstrual cycle

A

menstruation starts- the uterus lining breaks down for about four days

121
Q

what happens in stage two of the menstrual cycle

A

the uterus lining builds up again, from day 4 to 14, into a thick spongy layer full of blood vessels, ready to receive a fertilised egg

122
Q

what happens in stage three of the menstrual cycle

A

an egg develops and is released from the ovary at day 14- ovulation

123
Q

what happens in stage four of the menstrual cycle

A

the wall is then maintained for about 14 days until day 28. if no fertilised egg has landed on the uterus wall by day 28, spongy lining starts to break down and process starts again

124
Q

name the four hormones that control menstruation

A

FSH, oestrogen, LH and progesterone

125
Q

what does FSH do

A

Follicle-stimulating hormone- FSH
causes egg to mature in one of the ovaries in a structure called a follicle
stimulates the ovaries to produce oestrogen

126
Q

what produces FSH

A

the pituitary gland

127
Q

where is oestrogen produced

A

ovaries

128
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

129
Q

what produces LH

A

pituitary gland

130
Q

what does LH do

A

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

131
Q

what does progesterone do

A

maintains the lining of the uterus during the second half of the cycle.
when the level of progesterone falls, the lining breaks down
inhibits the release of LH and FSH

132
Q

where is progesterone produced

A

ovaries by the remains of the follicle after ovulation

133
Q

name hormonal contraception methods and what they do

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

intrauterine devices which prevent the implantation of an embryo or
release a hormone

134
Q

name barrier methods of contraception

A

spermicidal agents which kill or disable sperm

condoms and diaphragms which prevent the
sperm reaching an egg

135
Q

name other methods of contraception

A

abstinence- when an egg may be in the oviduct

surgical methods of male and female sterilisation.

136
Q

how can fertility be increased using hormones

A

giving FSH and LH in a ‘fertility drug’ to a woman

137
Q

advantages of the FSH and LH drug

A

helps a lot of women to get pregnant when they previously couldnt

138
Q

disadvantages of the FSH and LH drug

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.

139
Q

what happens in IVF

A
  • mother given FSH and LH to stimulate the maturation of several eggs.
  • The eggs are collected from the mother and fertilised by sperm from the father in the laboratory.
  • The fertilised 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 (womb).
140
Q

pros to IVF

A

can give an infertile couple a child

141
Q

cons of IVF

A

multiple births can happen
low success rate- 26%
stressful and upsetting
strong reaction to the hormones- eg. abdominal pain, vomiting, dehydration

142
Q

what have developments of

microscopy techniques done

A

enabled IVF treatments to develop.

143
Q

why are some people against IVF

A

results in unused embryos that are eventually destroyed- unethical- destroying a life

preferred characteristics

144
Q

when and where is adrenaline produced

A

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

145
Q

what does adrenaline do

A

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’.

146
Q

where is thyroxine produced

A

thyroid gland

147
Q

what does thyroxine do

A

stimulates the basal metabolic rate and plays an important role in growth and development

148
Q

why do plants produce hormones

A

to coordinate and control growth and

responses to light (phototropism) and gravity (gravitropism or geotropism)

149
Q

what does unequal distributions of auxin cause

A

unequal growth rates in plant roots and shoots

BIOLOGY-EVIE (8 decks)

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