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homeostasis and response Flashcards

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1
Q

what is homeostasis

A

homeostasis is the maintenance of a constant internal environment in order to maintain optimum conditions for enzyme and cellular function

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2
Q

give examples of conditions maintained by homeostasis in the body

A

blood glucose concentration
body temp
water levels

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3
Q

what two types of responses are used in body control systems

A

nervous and chemical

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4
Q

3 components do all control systems have

A

receptors
coordination centres
effectors

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5
Q

function of a receptor

A

receptor detect changes in the environment

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6
Q

function of coordinate centre

A

coordinate centres obtain and process information from receptors

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7
Q

function of effector

A

effectors bring about responses to the stimuli

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8
Q

function of nervous system

A

the nervous system allows the body to react to its surroundings and coordinate an appropriate response

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9
Q

how does a stimulus lead to a response being carried out by the body

A
  • stimulus is converted into an electrical implies by the receptors
  • the electrical impulse passes along sensory neuron’s to the central nervous system
  • the CNS coordinates an appropriate response and an electrical impulse is sent along motor neuron’s to the effector, which carries out the response
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10
Q

what sequence of events describes how the nervous system works

A

stimulus, receptor, coordinator, effector, responce

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11
Q

what is a reflex action

A

a reflex action is an automatic and rapid response which does not involve any conscious input from the brain

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12
Q

why are reflex actions important

A

reflex actions aid survival by preventing harm to the body

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13
Q

describe how a reflex action occurs via a reflex arc

A
  • the stimulus is detected by a receptor
  • an electrical impulse passes along a sensory neurone to the spinal cord
  • at a synapse between a sensory neurone and a relay neurone, a chemical diffuses across the gap and stimulates a new impulse which passes along the relay neurone
  • the same process occurs at a synapse between a relay neurone and a motor neurone
  • at the effector, an appropriate response is carried out
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14
Q

what is the difference between a reflex pathway and a conscious pathway

A

within a reflex pathway, the coordination centre is a relay neurone found in the spinal cord. in a conscious pathway, the coordination centre is in the conscious part of the brain

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15
Q

function of the cerebral cortex

A

control consciousness, intelligence, memory, and language

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16
Q

function of cerebellum

A

controls muscular coordination

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17
Q

function of medulla

A

controls unconscious activities

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18
Q

example of what the medulla controls

A

breathing
heart rate

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19
Q

why is the investigation and treatment of the brain difficult

A

the brain is a complex and delicate organ
the brain is easily damaged and destroyed
certain membranes prevent drugs from reaching the brain
the east function of each part of the brain is not known

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20
Q

what methods are used by scientist to determine brain function?

A

studying patients with brain damage
electrical stimulation of the brain
MRI scans

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21
Q

what stimuli are the receptor of the eye sensitive too

A

light intensity
colour

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22
Q

2 main functions of structures found within the eye

A

focusing on near or distant objects
adaptation to dim light

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23
Q

describe the structure of the retina

A

the retina is a light sensitive layer found at the back of the eye

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24
Q

describe the function of eye

A

light stimulates the retinal cells, resulting in impulses being sent to the brain

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25
Q

describe function of the optic nerve

A

it carries impulses to the brain so that an image can be visualised

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26
Q

describe the optic nerve

A

the optic nerve connects eye and brain

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27
Q

describe the structure of sclera

A

the tough outer layer of the eye

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28
Q

function of sclera

A

protects its internal structures

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29
Q

describe the structure of the cornea

A

the cornea is the curved transparent layer at the front of the eye

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30
Q

describe the function of the cornea

A

lets light into the eye and allows light to be focused onto the retina

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31
Q

what is the iris

A

a muscle which controls the size of the pupil by contracting or relaxing

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32
Q

function of the iris

A

allows the eye to adjust to bright and dim lighting

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33
Q

function of the ciliary muscles and suspensory ligaments

A

hold the Len in place and control its shape

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34
Q

describe how the iris alters the size of the pupil in bright light

A

circular muscles contract and radial muscles relax
makes pupils smaller to avoid retinal damage

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35
Q

describe how the iris alters the size of the pupil in dim light

A

circular muscles relax and radical muscles contract
makes pupil larger so more light can enter the eye

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36
Q

what is accommodation

A

accommodation is the alteration of the lens shape in order to focus on near or distant objects

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37
Q

how does the eye focus on nearby objects

A

ciliary muscles contract
suspensory ligaments loosen
lens becomes thicker and more curved
light rays are refracted strongly

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38
Q

how does the eye focus on a far away object

A

ciliary muscles relax
suspensory ligaments tighten
lens becomes thinner
light rays are refracted weakly

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39
Q

describe myopia

A

myopia usually occurs when the lens of the eye is too curved
as a result the light is focused in front of the retina so images appear blurry

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40
Q

what is myopia

A

short sightedness

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41
Q

how can myopia be treated

A

myopia can be treated using glasses with a concave lens
which spreads out light rays so they can be focused on the retina

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42
Q

what is hyperopia

A

long sightedness

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43
Q

describe hyperopia

A

occurs hen the lens is to flat, as a result, light is focused behind the retina so images appear out of focus

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44
Q

how can hyperopia be treated

A

can be treated using glasses with a concave lens, which brings the light rays together so they can be focused on the retina

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45
Q

2 types of contact lenses

A

hard: rigid material, long lasting, must be kept sterile
soft: flexible material, short lasting, more comfortable

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46
Q

what is laser eye surgery

A

laser eye surgery is the use of lasers to fix visual defects in adults,
to treat myopia, lasers reduce the thickness of the cornea so light is refracted less strongly
to treat hyperopia, lasers alter the curvature of the cornea so that light is refracted correctly

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47
Q

how can replacement lenses be used to treat visual defects

A

a replacement lens can either be implanted into the eye or it may replace the natural lens all together.

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48
Q

disadvantage to replacement lens

A

risk of lens replacement include retinal damage, cataracts, or infections

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49
Q

where is body temp controlled in the body

A

body temp is controlled by the thermoregulatory centre in the hypothalamus of the brain

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50
Q

how is temp monitored by the body

A

thermoregulatory centre has receptors sensitive to blood temp
skin has receptors sensitive to skin temp - so sends impulses to the thermoregulatory centre

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51
Q

what physiological changes occur when the body temp is too high

A

vasodilation: blood vessels near the surface of the skin dilate, more heat is radiated away
sweating: evaporation of water takes away heat energy from the surface of the skin

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52
Q

what physiological changes occur when the body temp is too low

A

vasoconstriction: blood vessels near the surface of the skin constrict - less heat radiated away
shivering: respiration allows muscles to contract. an exothermic process, so heat energy is released
sweating stops

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53
Q

give the name of the body coordination system which involves hormones

A

the endocrine system

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54
Q

what is a hormone

A

a hormone is a chemical messenger secreted by a gland. it travels in the blood to a target organ, where it causes a response

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55
Q

what type of organ secretes hormones

A

glands

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56
Q

which gland controls many other glands in the body

A

the pituitary gland

57
Q

why is the pituitary gland considered a master gland

A

it secrets a wide range of hormones some of which may stimulate other endocrine glands

58
Q

what is the role of the pituitary gland in the endocrine system

A
  • secrets human growth hormone, controls human growth
  • stimulates the thyroid gland
  • stimulates ovulation and the production of oestrogen in the ovaries
  • stimulates the production of sperm and testosterone in the testes
59
Q

what is the role of the thyroid gland in the endocrine system

A

secretes the hormone thyroxine - controls metabolism, heart rate, and body temp

60
Q

what is the role of the pancreas in the endocrine system

A

secrets the hormone insulin, controls blood glucose levels

61
Q

what is the role of the adrenal gland in the endocrine system

A

secretes adrenaline, controls the body’s “fight or flight” response

62
Q

what is the role of the ovaries in the endocrine system

A

secrete oestrogen, which coordinates the menstrual cycle and the development of female secondary sexual characteristics

63
Q

what is the role of the testes in the endocrine system

A

secrete testosterone, which coordinates the production of sperm and the development of male secondary sexual characteristics

64
Q

which organ monitors and controls blood glucose concentration

A

the pancreas

65
Q

how does the pancreas respond when blood glucose levels are too high

A

the pancreas secretes the hormone insulin
insulin binds to receptors on the liver and the muscles, causing excess glucose to be converted into glycogen and stored

66
Q

how does the pancreas respond when blood glucose levels are too low

A

the pancreas secretes the hormone glucagon. glucagon binds to liver cells, causing glycogen to be converted into glucose and released into the blood.

67
Q

how is blood glucose concentration controlled using a negative feedback loop

A

when the blood glucose concentration rises or falls below the optimum, a hormone is secreted by the pancreas
the action of either hormone helps bring back the concentration to the correct level.

68
Q

what type one diabetes

A

type one diabetes is an autoimmune disorder in which the pancreas does not produce sufficient, insulin to control the blood glucose concentration. as a result, blood glucose levels are often very high, leading to excessive urination, tiredness and weight loss

69
Q

how can type one diabetes be treated

A

insulin injections before meals, allows glucose to be converted into glycogen.
limiting carbon dioxide intake
attempts using pancreas and pancreatic cell transplants, investigations into genetic engineering of pancreatic cells

70
Q

what is type 2 diabetes

A

type 2 diabetes is a disorder in which the body cells stop responding to insulin, leading to an unrolled blood glucose concentration. its onset is linked with increasing age and obesity

71
Q

how can type 2 diabetes be treated

A

following a carefully controlled diet
doing regular exercise
loosing weight
use of drugs which increase insulin production and effectiveness

72
Q

what is osmosis

A

osmosis is the movement of water from a diet solution to a concentrated solution through a partially permeable membrane

73
Q

in what ways is water lost from the body

A

during exhalation via the lungs
sweating
urine

74
Q

in what ways are ions lost from the body

A

sweating
urine

75
Q

how are excess amino acids excreted from the body

A

excess amino acids are deaminated in the liver to form ammonia
ammonia is toxic, therefore it is converting into urea
urea is excreted from the body via sweat and urine

76
Q

how do the kidneys maintain the balance of water and other substances in the body

A

filter blood in order to remove waste products
selectively reabsorb useful molecules

77
Q

why is kidney failure dangerous

A

when the kidneys are damaged, they may be unable to filer the blood properly, this could lead to:

  • a build-up of toxic molecules in the body
  • an uncontrolled ion and water balance and cells being damaged as a result of osmosis
78
Q

what are two main ways of treating kidney failure

A

dialysis
transplate

79
Q

what is kidney dialysis

A

kidney dialysis is the use of specialist machine to carry out the function of kidneys. dialysis fluid contains the same concentration of glucose and ions as healthy food. as result, only excess and water molecules are lost from the blood, and glucose and ions remain

80
Q

what is function of reproductive hormones during puberty

A

males: cause the development of secondary sexual characteristics
females: cause the development of second sexual characterises an the maturation of eggs

81
Q

what is the main male reproductive organ

A

testosterone
produced by the testes and controls sperm production

82
Q

main female reproductive hormone

A

oestrogen
produced in the overrates and is involved in the menstrual cycle

83
Q

what is the menstrual cycle

A

is the monthly cycle of physiological changes that occur in females, involving the shedding of the uterus lining and ovulating

84
Q

describe the events of the menstrual cycle

A
  • uterus lining thickens and eggs begin to mature in the ovaries
  • an egg is released from one of the ovaries, uterus lining remains thick
  • if the egg is fertilised, pregnancy may occur. if not both the egg and uterus lining are shed during menstruation
85
Q

what is ovulation

A

ovulation is the release of a mature egg from the ovaries, which occurs ever 28 days, approx

86
Q

4 main hormones involved in the menstrual cycle

A

oestrogen
progesterone
follicle stimulating hormone
luteinising hormone

87
Q

what is the role of FSH is the menstrual cycle?

A

FHS is secreted by the pituitary gland
it controls the maturation of eggs within the ovaries and triggers the production of oestrogen by the ovaries.

88
Q

what is the role of oestrogen in the menstrual cycle?

A

oestrogen is produced by the ovaries and released due to the action of FSH - it causes the re-growth of the uterus lining
it triggers the production of LH and restricts the release of more FSH

89
Q

what is the role of LH in the menstrual cycle

A

LH is produced in the pituitary gland as a result of oestrogen.
its release triggers ovulation

90
Q

what is the role of progesterone in the menstrual cycle

A

progesterone is secreted from the follicle of the ovary. it sustains the uterus lining and inhibits FSH and LH

91
Q

what is contraception

A

contraception refers to any method of preventing pregnancy

92
Q

2 types of oral contraceptives

A

combined contraceptive pill
mini pill

93
Q

what does the combined contraceptive pill contain

A

contains oestrogen and progesterone

94
Q

what does the mini pill contain

A

only progesterone

95
Q

how does the contraceptive pill prevent pregnancy

A
  • inhibits FSH, eggs do not mature
  • prevents the development on the uterus lining, eggs cannot implant
  • increases the thickness of cervical mucus, immobilise sperm cells
96
Q

what does the contraceptive patch contain

A

contains both oestrogen and progesterone

97
Q

what is the contraceptive implant

A

a small rod inserted under the skin which continuously releases the hormone progesterone

98
Q

what is the contraceptive injection

A

an injection containing the hormone progesterone

99
Q

how long does the contraceptive injection last

A

3 months

100
Q

how long does the contraceptive patch last for

A

for 7 days at a time

101
Q

how long does the contraceptive injection last for

A

3 years

102
Q

what is the IUS

A

the IUSE is a small plastic device that is inserted into the uterus
releases progesterone which thickens cervical mucus and prevents the build-up of the uterine lining

103
Q

what is the IUD

A

the IUD is a small copper-containing device inserted into the uterus, which prevents the implantation of embryos

104
Q

what is a spermicide

A

a spermicide is a chemical that kills or immobilises sperm cells

105
Q

what is the issue with a spermicide

A

not very effective
work better when combined with other barrier methods

106
Q

define barrier method of contraception

A

a barrier methods of contraception involves a physical separation between the sperm and the egg

107
Q

examples of barrier methods of contraceptions

A

condoms
diaphragms

108
Q

what is a condom
huh

A

thin sheath worm on the penis or inside the vagina, protects against STI’s but may tear

109
Q

what is a diaphragm
(Monica friends)

A

a thin cap placed over the cervix, preventing entry of sperm

110
Q

what surgical methods of contraception are available
(chop chop)

A

sterilisation in males - the sperm ducts are tied together
a vasectomy
and
in females, the oviducts are tied

111
Q

what is abstinence

A

abstinence is the practice of not having sex, helps avoid pregnancy
some people abstain from sex around the time of ovulation

112
Q

how do fertility drugs increase the chance of pregnancy

A

many fertility drugs contain FSH, which stimulates oestrogen production and the maturation of eggs in the ovary. the also contain LH which triggers ovulation

113
Q

what is IVF

A

a type of fertility treatment
mother is given FSH and LH - stimulates maturation of eggs and ovulation
eggs are fertilised using sperm in a lab, developed into embryos
1 or 2 embryos inserted into the mother womb

114
Q

advantages of the fertility treatment

A
  • allows infertile couples to have children
  • can store a women’s eggs for later
115
Q

disadvantage of fertility treatment

A
  • very expensive
  • low success rate
  • increases chance of multiple pregnancies, dangerous for mothers and babies
  • side effects of fertility drugs
116
Q

what is negative feedback

A

negative feedback is a type of control where the body responds to an increase or decrease in a factor by returning it to the optimum level

117
Q

why is thyroxine

A

thyroxine is a hormone is released by the thyroid gland. its release is triggered by the thyroid stimulating hormone. thyroxine controls the body’s metabolic rate, growth and development

118
Q

how Is the release of thyroxine controlled by negative feedback

A
  • levels of blood thyroxine falls, detects by receptors in the brain
  • puituaity gland releases more TSH
  • more thyroxine produced and released by thyroxine gland
  • blood thyroxine levels return to normal
119
Q

what is adrenaline

A

adrenaline is a hormone secreted by the adrenal gland in time of stress, responsible for flight or fight responses

120
Q

effects of adrenaline

A
  • increased heart rate and breathing rate
  • stored glycogen converted to glucose
  • dilation of pupils
  • increased mental awareness
  • blood diverted away from digestive system to muscles
121
Q

what is a tropism

A

a tropism is the response of a plant to a specific stimulus

122
Q

what is phototropism

A

phototropism is the response of a plants shoot or root to light

123
Q

what is gravitropism

A

gravitropism is the response of a plants shoot or root to gravity

124
Q

what is auxin

A

auxin is a hormone which controls growth of a plant roots and shoots. when auxin in unevenly distributed in a growing plant, the growth of the plant will be unequal

125
Q

how do plants shoots show positive phototropism

A

one side of the shoot is in the light, causing to move to the shaded side
at the shaded side, the cells are stimulated to grow - the shoot bends towards the light
as a result, photosynthesis can occur at a faster rate

126
Q

how do plant shoots show negative gravitropism

A

in a horizontal shoot, auxin accumulates in the lower side due to gravity
cells on the lower side of shoot grow more, causing the shoot to bend away from the direction of gravity
as a result, more light is usually available for photosynthesis

127
Q

how do plant roots show positive gravitropism

A

in a horizontal root, auxin accumulates in the lower side, causing cels to grow less
the root bends in the direction of gravity
as a result, more water and nutrients are available to the plant roots

128
Q

what are gibberellins

A

gibberellins are a type of plant hormone involved in seed germination

129
Q

what is ethene

A

ethene is a type of plant hormone involved in cell division and ripening

130
Q

what are the uses of auxins

A

weedkillers - causes cells to grow at a rapid rate, causing plant death
rooting power - causes new plant to grow very quickly
tissue culture - promotes growth of roots and shoots

131
Q

uses of ethene

A

control of food ripening in the food industry
allows fruit to be ripened just before they are sold

132
Q

uses of gibberellins

A

termination of seed dormancy
promotion of flowering
increase fruit size

133
Q

components of the CNS

A

spinal cord
brain

134
Q

what are synapses

A

synapses are gaps between neurons and can be found at each junction of a reflex arc

135
Q

what are neurotransmitters

A

chemicals that diffuse across synapses and bind to receptors on the next neurone

136
Q

what is a reflex arc

A

a reflex arc is the unconscious response that allows a person to respond to a dangerous situation automatically and rapidly via a reflex arc

137
Q

what type of signal are neurotransmitters

A

chemical

138
Q
A

Biology (8 decks)

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