topic 1 Flashcards
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.
2
Q
Give examples of conditions maintained
by homeostasis in the body
A
● Blood glucose concentration
● Body temperature
● Water levels
3
Q
What two types of responses are used in body control systems?
A
Nervous and chemical
4
Q
What three components do all control systems have?
A
● Receptors
● Coordination centres
● Effectors
5
Q
What is the function of a receptor?
A
Receptors detect changes in the
environment (stimuli).
6
Q
What is the function of a coordination centre?
A
obtain and process information from receptors.
7
Q
What is the function of an effector?
A
Effectors (muscles or glands) bring about responses to stimuli.
8
Q
What is the function of the nervous system?
A
allows the body to
react to its surroundings and coordinate an
appropriate response.
9
Q
How does a stimulus lead to a response being carried
out by the body?
A
- Stimulus is converted into an electrical impulse by the
receptors.
● The electrical impulse passes along sensory neurones to
the central nervous system (CNS).
● The CNS coordinates an appropriate response and an
electrical impulse is sent along motor neurones to the
effector, which carries out the response.
10
Q
What sequence of events describes how
the nervous system works?
A
stimulus
receptor
sensory neurone
relay/CNS
motor neurone
effector
response
11
Q
What is a reflex action?
A
automatic and rapid
response which does not involve any
conscious input from the brain
12
Q
Why are reflex actions important?
A
aid survival by preventing
harm to the body.
13
Q
what is a synapse
A
gap between any neurone
a neurotransmitter diffuses across and produces an electrical impulse in the next neurone
14
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
(part of the CNS).
● 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
15
Q
What is the function of the cerebral cortex?
A
controls consciousness,
intelligence, memory and
language.
16
Q
What is the function of the cerebellum?
A
controls muscular
coordination
17
Q
What is the function of the medulla?
A
controls
unconscious
activities
18
Q
Why is the investigation and treatment of the
brain difficult?-
A
● complex and delicate organ.
● easily damaged and destroyed.
● Certain membranes prevent drugs from reaching
the brain.
● The exact function of each part of the brain is not
known
19
Q
What methods are used by scientists to determine
brain function?
A
● Studying patients with brain damage
● Electrical stimulation of the brain
● MRI scans
20
Q
What stimuli are the receptors of the eye sensitive to?
A
Light intensity
colour
21
Q
what is the iris
A
controls light entry
22
Q
what is the cornea
A
refracts light
23
Q
what is the pupil
A
allows light to pass through and enter the eye
24
Q
what is the lens
A
refracts light to focus on the retina
25
what is the sclera
white part
26
What are the two main functions of structures
found within the eye?
● Focusing on near or distant objects -
accommodation.
● Adaptation to dim light
27
Describe the structure of the retina
The retina is a light-sensitive
layer found at the back of the
eye.
28
Describe the function of the retina
Light stimulates the retinal cells,
resulting in impulses being sent
to the brain.
rod cells - black and white
cone cells - colour
29
what are cilliary muscles
adjust the shape of the lens to alter the refraction of light
30
what are suspensory ligaments
slacken or stretch to adjust the thickness of lens
31
eye adjust to focus on near object
cilliary muscles contract
suspensory ligaments loosen
lens is thicker
refracts light more
32
eye adjust to focus on
distant object
cilliary muscles loosen
suspensory ligaments pull tight
lens is thinner
refracts light slightly
33
Describe how the iris alters the size of the pupil in dim light
circular muscles relax and radial muscles contract - makes pupil larger so more light can
enter the eye.
34
Describe how the iris alters the size of the pupil in bright light
circular muscles contract and radial muscles relax - makes pupil smaller to avoid retinal
damage.
35
What is accommodation?
the alteration of the
lens’ shape in order to focus on near or distant objects.
36
What is myopia?
short sightedness
lens of the eye is too curved. As a result, light is focused in front of the retina
37
How can myopia be treated?
glasses with a concave lense, which spreads out light rays so they can be focused on the retina.
38
What is hyperopia?
the lens of the eye is too flat. As a result, light is focused behind the retina
39
How can hyperopia be treated?
glasses with a convex lense, which brings the light rays together so they can be focused on the retina
40
What are the two types of contact lenses?
● Hard - rigid material, last a long time, must be kept
sterile.
● Soft - flexible material, last for a shorter time, more
comfortable.
41
risks of replacement lenses
retinal damage, cataracts
and infections.
42
What is laser eye surgery?
lasers either reduce thickness (myopia)
alter curvature (hyperopia)
43
Where is body temperature controlled in the
body?
thermoregulatory centre in the hypothalamus
of the brain
44
when the temp is too high
● 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.
45
How is temperature monitored by the body?
● Thermoregulatory centre has receptors
sensitive to blood temperature.
● Skin has receptors sensitive to skin
temperature - sends impulses to
thermoregulatory centre.
46
What physiological changes occur when the
body temperature is too low?
Vasoconstriction - blood vessels near the surface
of the skin constrict - less heat radiated away.
● Shivering - respiration allows muscles to contract.
It is an exothermic process, so heat energy is
released.
● Sweating stops.
47
what is the endocrine system
made from glands
body’s coordination system
which involves hormones
48
What is a hormone?
A hormone is a chemical messenger
secreted by a gland. It travels in the blood to
a target organ, where it causes a response.
49
what is the pituitary gland
master gland
secretes several hormones
sometimes they act upon other glands to release hormones
50
How does the pancreas respond when blood
glucose levels are too high?
secretes insulin
causes glucose to move from blood into the cells
in the liver excess glucose is converted to glycogen for storage
51
How does the pancreas respond when blood
glucose levels are too low?
secretes the hormone
glucagon. Glucagon binds to liver cells, causing glycogen to be converted into glucose and released into the blood.
52
what is type 1 diabeties
pancreas doesnt produce enough insulin
insulin injections
53
what is type 2 diabeties and their risk factors
body cells to stop responding to insulin
obsitity
54
How can Type 1 diabetes be treated?
● Insulin injections before meals - allows
glucose to be converted into glycogen.
● Limiting carbohydrate intake.
55
How can Type 2 diabetes be treated?
● Following a carefully-controlled diet
● Doing regular exercise
● Losing weight
● Use of drugs which increase insulin production and effectiveness
56
How is blood glucose concentration controlled using
a negative feedback loop?
● When the blood glucose concentration rises or falls
below the optimum, a hormone is secreted by the
pancreas.
● The action of either hormone (insulin or glucagon)
helps bring back the concentration to the correct
level
57
In what ways is water lost from the body?
● During exhalation via the lungs
● Sweating
● Urine (some reabsorbed in the kidney)
58
what happens if cells gain/loose too much water
do not function effectively
59
In what ways are ions lost from the body?
● Sweating
● Urine (some reabsorbed in the kidney)
60
How are excess amino acids excreted from the
body?
● Excess amino acids are deaminated in the liver to
form ammonia.
● Ammonia is toxic, therefore it is converted into urea
● Urea is excreted from the body via sweat and urine.
61
kidney fuction
produce urine by filtration
urea is not reabsorbed
glucose ions and water are reabsorbed
62
what is in dyalisis fluid
glucose concentration similar to blood level
similar ion level
no urea
63
not enough water in blood
increase ADH
increases the permeability of tubules
more water reabsorbed
concentrated urine
64
too much water in blood
decrease ADH
decreases the permeability of tubules
less water reabsorbed
dilute urine
65
Why is kidney failure dangerous?
● A build-up of toxic molecules (eg. urea) in the
body.
● An uncontrolled ion and water balance and cells
being damaged as a result of osmosis.
66
What are the two main ways of treating kidney failure?
● Dialysis
● Transplant
67
What is kidney dialysis?
use of a specialist machine
to carry out the function of kidneys
68
What is the main male reproductive hormone?
testosterone, which is produced by the testes and controls sperm production.
69
What is the main female reproductive hormone?
oestrogen, which is produced by the ovaries
and is involved in the menstrual cycle.
70
What is the menstrual cycle?
monthly cycle of
physiological changes that occur in females,
involving the shedding of the uterus lining
(menstruation) and ovulation.
71
Describe the events of the menstrual cycle
● Uterus lining thickens and eggs begin to mature in the
ovaries.
● An egg is released from one of the ovaries (ovulation)
- uterus lining remains thick.
● If the egg is fertilised, pregnancy may occur. If not,
both the egg and the uterus lining are shed during
menstruation.
72
what is FSH
pituitary gland
matures the egg
simulates oestrogen release
73
LH
stimulates the release of the egg
74
What is the role of oestrogen in the menstrual cycle?
it causes
the regrowth of the uterus lining.
It triggers the production of LH and restricts the
release of more FSH.
75
What is the role of progesterone
It sustains the uterus lining and
inhibits FSH and LH.
76
what is ovulation
the realease of a mature eggh
77
how often dos ovulation occur
28 days
78
what are the four main hormones
● Oestrogen
● Progesterone
● Follicle stimulating hormone (FSH)
● Luteinising hormone (LH)
79
what is contreception
any method of prevneting pregnacy
80
What are the two types of oral contraceptives?
● Combined contraceptive pill (contains
oestrogen and progesterone).
● Mini pill (contains only progesterone).
81
How does the contraceptive pill prevent
pregnancy?
● Inhibits FSH - eggs do not mature.
● Prevents the development of the uterus lining -eggs cannot implant.
● Increases the thickness of cervical mucus - immobilises sperm cells.
82
What is the contraceptive patch?
● Contains both oestrogen and
progesterone.
● It is a patch that is placed onto the skin for 7 days at a time.
83
What is the contraceptive implant?
A small rod inserted under the skin which continuously releases the hormone progesterone - lasts for 3 years
84
what is the contraceptive injection
injection containing progesterone
85
what is an IUD
small copper-containing device inserted into the uterus, which prevents the implantation of embryos.
86
what is spermicide
kills/ imboblises serm
not very effective
87
How do fertility drugs increase the chance of
pregnancy?
Many fertility drugs contain FSH - which
stimulates oestrogen production and the
maturation of eggs in the ovary. They also
contain LH which triggers ovulation.
88
what is IVF
mother is given FSH/LH to simulate the maturation of the egg
eggs are collected and fertilized by sperm in a lab
which develop into embryos
when a tiny ball of cells they are separated 1 or 2 in the womb the rest are frozen
89
advantages of IVF
● Allows infertile couples to have children
● Can store a woman’s eggs for later
90
disadvantages of IVF
● It can be a very expensive process.
● It has a low success rate - especially for older couples.
● Increases chance of multiple pregnancies - dangerous for mother and babies.
emotionally and physically stressful
91
What is negative feedback?
a type of control where
the body responds to an increase or
decrease in a factor by returning it to the optimum level.
92
where is thryroxide produced
in the thyroid gland
93
role of thyroxine
stimulates the basal metabolic rate
increase metabolism
so more fat is used up and more energy required ( weight loss)
important in growth and development
94
How is the release of thyroxine controlled by negative
feedback?
● Levels of blood thyroxine falls - detected by
receptors in the brain.
● Pituitary gland releases more TSH.
● More thyroxine produced and released by the
thyroid gland.
● Blood thyroxine level returns to normal.
95
what is adrenaline
produced in the adrenal glands
stimulates heart rate
boosts oxygen and glucose to the brain and muscles
for flight or fight
96
What are the effects of adrenaline?
● Dilation of pupils.
● Increased mental awareness.
● Blood diverted away from digestive system to
muscles
97
What is a tropism?
A tropism is the response of a plant to a
specific stimulus
98
What is phototropism?
Phototropism is the response of a plant’s
shoot or root to light
99
What is geotropism?
Gravitropism is the response of a plant’s
shoot or root to gravity.
100
what is auxin
a plant growth hormone
responds to light and gravity
unequal distribution causes an unequal growth rate in plants
101
How do plant shoots show positive
phototropism?
● One side of the shoot is in the light, causing auxin
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.
102
How do plant shoots show negative
gravitropism?
● 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.
103
what are gibberellins
initiate seed germination
- termination of seed dormancy
- promotion pf flowering
- increase fruit size
104
what is ethene
controls cell division ripening of fruits
105
uses of auxins
weedkillers - rapid growth which leads to death
rooting powder - grow quicker
