Topic 5 Homeostasis Flashcards
(110 cards)
1
Q
Define Homeostasis
A
The regulation of internal conditions of a cell or organism to maintain optimum conditions for function in response to internal + external changes
2
Q
What does Homeostasis maintain optimum cellular conditions for?
A
Enzyme action
3
Q
Name three examples of homeostatic control in the body
A
- blood glucose concentration
- body temperature
- water content in blood + cells
4
Q
Name two types of responses that control conditions of the human body
A
- nervous
- chemical
5
Q
What is a receptor cell?
A
Cells that detect stimuli (changes in the environment)
6
Q
Name three coordination centres
A
- brain
- spinal chord
- pancreas
7
Q
Name two types of effectors
A
- muscle
- gland
8
Q
State what the effectors do to bring about a response
A
- muscle contracts
- gland secretes enzyme/hormone
9
Q
What is the role of the nervous system?
A
Enables humans to react the their surroundings and coordinate behaviour
10
Q
What is CNS?
A
Central Nervous System, including brain and spinal chord
11
Q
Nervous system:
a->b->c->d->e
A
a) stimulus
b) receptor
c) coordinator
d) effector
e) response
12
Q
Name the three types of neurone
A
- sensory
- relay
- motor
13
Q
What is a synapse?
A
The gap between two neurones where a signal passes from one neurone to the next
14
Q
Summarise how a synapse works
A
- impulse arrives at the end of a neurone
- neurotransmitter released into synaptic gap
- neurotransmitter diffuses across synaptic gap
- neurotransmitter binds to receptors on a second neurone
- a new electrical impulse is generated in the second neurone
15
Q
Why are reflex actions rapid?
A
They don’t involve the brain so no conscious thought
16
Q
What are reflex actions for?
A
Reactions to remove the body from danger
17
Q
What is the brain made up of?
A
Billions of interconnected neurones
18
Q
Name the three main parts of the brain
A
- cerebal cortex
- cerebellum
- medulla
19
Q
Why is investigating functions of the brain difficult?
A
It is a complex and delicate organ
20
Q
How can scientists investigate brain function?
A
- electrically stimulating areas in a conscious patient and recording their response
- MRI scans
21
Q
Name the two stimuli the eye is sensitive to
A
- light intensity
- colour
22
Q
Name the muscle that changes the shape of the lens of the eye
A
Ciliary muscle
23
Q
Name the ligaments in the eye that help change the lens shape
A
Suspensory ligaments
24
Q
Name the part of the eye that controls how much light enters through the pupil
A
Iris
25
Name the part of the eye that allows light through
Pupil
26
Name the part of the eye that is transparent and covers the eyeball
Cornea
27
Name the part of the eye that focuses light into the eye
Lens
28
Name the part of the eye that gathers information and sends it to the brain
Optic nerve
29
Name the part of the eye with no light receptor cells
Blind spot
30
Name the white part of the eye which acts as a protective layer
Sclera
31
Name the part of the eye which is a thin layer containing millions of receptor cells
Retina
32
What happens to the suspensory ligaments and ciliary muscles when the eye focuses light NEAR objects?
- suspensory ligaments LOOSEN
| - ciliary muscles CONTRACT
33
What happens to the suspensory ligaments and ciliary muscles when the eye focuses light FAR objects?
- suspensory ligaments TIGHTEN
| - ciliary muscles RELAX
34
What shape is the lens when the eye focuses NEAR an object?
Thicker, more curved
35
How does the shape of the lens when it is thicker + more curved affect light refraction?
Refracts light strongly
36
What shape is the lens when the eye focuses on FAR objects?
Thinner, less curved
37
How does the shape of the lens when it is thinner and less curved affect light refraction?
Refracts light slightly
38
Name the two muscle types in the eye that control the amount of light end
Radical and circular
39
In high light intensity, what happens to the muscles to cause pupils to dilate?
- radical muscles RELAX
| - circular muscles CONTRACT
40
In low light intensity what happens to these muscles to cause to dilate?
- radical muscles CONTRACT
| - circular muscles RELAX
41
What kind of lens would correct myopia (short sightedness)?
Concave
42
What kind of lens would correct hyperopia (long sightedness)?
Convex
43
What monitors and controls body temperature?
The thermoregulatory centre of the brain
44
Name two ways the body responds if temperature is too high
- blood vessels dilate (vasodilation)
| - sweat produced from sweat glands
45
How do these responses lower body temp?
Cause energy to be transferred from skin to the environment
46
Name three ways the body responds if temperatures are too low
- blood vessels constrict (vasoconstriction)
- sweating stops
- skeletal muscles contract rapidly (shivering)
47
What is the endocrine system composed of?
Glands which secrete chemicals called hormones
48
How is a chemical ‘message’ transported to the target organ in animals?
Via the bloodstream
49
Compare the speed and duration of hormonal control to nervous control
(Hormonal) slower but acts for longer
50
What is referred to as the ‘master gland’?
The pituitary gland
51
Name the gland which produces human growth hormone + found in the brain
Pituitary gland
52
Name the gland which produces many digestive enzymes
Pancréas
53
Name the gland which produces testosterone
Testes
54
Name the gland which produces thyroxine
Thyroid
55
Name the gland which produces adrenaline
Adrenal gland
56
Name the gland which produces hormones such as oestrogen and progesterone
Ovary
57
What is monitored for changes in glucose concentration?
The blood
58
What controls the response to changes in blood glucose concentration?
The pancreas
59
What is produced if blood glucose concentration is too high?
Insulin, a hormone
60
State two ways insulin lowers blood glucose concentration
Causes glucose to move from blood to cells
| Triggers conversion of glucose into glycogen
61
What is produced if blood glucose concentration is too low?
Glucagon, a hormone
62
State how glucagon helps to increase blood glucose concentration
Triggers breakdown of glycogen into glucose which is released into the blood
63
Name two places in the body glycogen is stored
Muscle cells
| Liver
64
What is the process called which responds to the change from normal levels in the body by restoring them back to normal levels?
Negative feedback
65
Type 1 diabetes is caused by..
An inhability to male insulin in the pancreas
66
Type 2 diabetes in caused by..
A lack of response by cells to insulin
67
What happens to human cells if they lose too much water?
Shrivel and eventually die
68
What happens to the cells of the gain too much water?
Swell and eventually burst (lyse)
69
Name two ways other than excretion in which water is lost front the body
Exhalation from the lungs
| Sweat from the skin
70
In addition to water, what else is lost via sweat?
Ions and urea
71
What is removed from the body by the kidneys via urine?
Excess water, excess ions and urea
72
Excess amino acids are broken down into…
Ammonia
73
Within the body, ammonia immediately converts into what?
Urea
74
Where does conversion of ammonia to urea occur?
The liver
75
Which hormone controls water balance of the body and where is it made?
ADH
76
Which part of the kidney does ADH effect?
Kidney tubule walls
77
When is ADH released?
When cells lose too much water
78
What is the effect in urine concentration and volume when ADH is released?
Higher concertation
| Lower volume
79
What is the effect on urine concentration and volume when ADH is not released?
Lower concentration
| Higher volume
80
How does ADH affect the walls of the kidney tubes?
Increases number of aquaporin channels, increasing volume of water reabsorbed into the blood
81
State two methods of treating kidney failure
Dialysis and kidney transplant
82
Name the main female hormone involved in development and reproduction
Oestrogen
83
What does testosterone cause to happen in men?
Stimulates sperm production
84
Approx how often is an egg released from the ovaries + what is this process called?
Every 28 days, ovulation
85
What does the release of FSH cause?
Maturation of an egg in ovaries
86
The release of which hormone stimulates the release of an egg from the ovaries?
Luteinising hormone (LH)
87
Which hormones are involved in the maintenance of the uterus lining?
Oestrogen and progesterone
88
How do oral contraceptives containing hormones prevent pregnancy?
Inhibits FSH production so no eggs mature
89
How does an injection, implant or skin patch containing slow release progesterone prevent pregnancy?
Inhibits the maturation of eggs
90
How do barrier methods such as condoms and diaphragms prevent pregnancy?
Prevent sperm from reaching the egg
91
How do intrauterine devices prevent pregnancy?
Prevents implantation of an embryo and/or releases hormones
92
How do spermicidal agents prevent pregnancy?
Kills or disable sperm
93
How does abstaining from sexual intercourse prevent pregnancy?
Reduces chance of sperm meeting an egg in the oviduct
94
How does surgical sterilisation prevent pregnancy?
Prevents sperm or eggs being released
95
Name two hormones given to a woman to increase fertility
FSH and LH
96
Detail the four steps in IVF treatment
- mother is given FSH and LH to stimulate maturation of several eggs
- eggs are collected from the mother and fertilised by sperm from the father in the lab
- fertilised eggs develop into embryos
- one or two embryos are inserted into the woman’s womb
97
State three drawbacks to IVF treatment
- very emotionally and physically stressful
- success rate is low
- can lead to multiple births which are a risk to babies and mother
98
State a positive of IVF treatment
Allows pregnancy when not previously possible
99
Name a hormone which controls ‘fight or flight’ reaction in humans
Adrenaline
100
Explain two effects of adrenaline on the body
- increases heart rate
| - increases oxygen delivery and glucose to the brain
101
Where is thyroxine made?
Thyroid gland
102
What does thyroxine do in the body?
Increase base metabolic rate, therefor increasing growth and development
103
What is the plant response to light called?
Phototropism
104
What is gravitropism or geotropism?
The plant response to gravity
105
What is the role of gibberellins?
Initiates seed germination
106
What is the plant hormone that controls cell division + ripening fruits?
Ethene
107
In which industries are plant hormones regularly used?
Agricultural and horticulture
108
State three ways in which auxins are used
- weed killers
- rooting powders
- promoting growth of plant tissue cultures
109
How is ethene used in the food industry?
To control the ripening of fruit during storage and transport
110
How are gibberellins used in industry?
- end dormancy
- promote flowing
- increase fruit size
