5- Homeostasis And Response Flashcards
1
Q
What is homeostasis
A
Maintaining a stable internal environment
2
Q
What are the three main components in automatic control systems
A
Receptors,
Coordination centres,
Effectors
3
Q
What is a stimulus
A
A change in the environment
4
Q
What is negative feedback
A
When the receptor detects that a stimulus is too high or too low and your body brings it back to normal
5
Q
What is the central nervous system (CNS)
A
In vertebrates, it consists of the brain and spinal cord only but in mammals it also connected to the body by sensory and motor neurones
6
Q
What is the role of a sensory neurone
A
They carry information as electrical impulses from the receptors to the CNS
7
Q
What is the role of the motor neurone
A
They carry electrical impulses from the CNS to the effector
8
Q
What is an effector
A
All muscles and glands.
They respond to nervous impulses and bring about a change
9
Q
What is the role of receptors
A
They detect stimuli
10
Q
What is a synapse
A
The connection between two neurones
11
Q
How does a synapse transport the signal
A
The nerve signal is transferred by chemicals that diffuse across the gap. These chemicals then set off a new electrical signal in the next neurone
12
Q
What are reflexes
A
A rapid automatic response to certain stimuli that don’t involve the conscious part of the brain.
They reduce the chances of being injured
13
Q
What is a reflex arc
A
The passage of information in a reflex from receptor to effector
14
Q
What is the order of response in the reflex arc
A
Stimulus, Receptor, Sensory neurone, Synapse Relay neurone Synapse Motor neurone Effector
15
Q
Why is a reflex quicker than a normal response
A
Because you do not have to think about a response
16
Q
What is reaction time
A
The time it takes to respond to a stimulus
17
Q
What can effect reaction time
A
Age, gender, drugs etc
18
Q
How does caffeine affect reaction time
A
Speeds up reaction time
19
Q
How can u test the effect of caffeine on reaction time
A
Drop test
Have a person do the drop test and then have a caffeinated drink and repeat the test
20
Q
Why are computers better for testing reaction time than a drop test
A
Remove the possibility of human error,
Can record in milliseconds,
More accurate,
Remove chance that the person can predict when to respond
21
Q
What is the role of the cerebral cortex
A
Responsible for things like consciousness, intelligence, memory and language
22
Q
What is the role of the cerebellum
A
Responsible for muscle coordination
23
Q
What is the role of the medullla
A
Controls unconscious activities like breathing and your heartbeat
24
Q
What are different methods of studying the brain
A
Studying patients with brain damage,
Electrically stimulating the brain,
MRI scans
25
What is the sclera
The tough, white, supporting wall of the eye
26
What is the cornea and its role
The transparent outer layer at the front of the eye.
| It refracts light into the eye
27
What is the role of the iris
It contains muscles that allow it to control the diameter of the pupil
28
What the pupil
The hole in the middle of the eye that lets light through
29
What is the role of the lens
It focuses the light onto the retina
30
What is the retina
It contains receptor cells sensitive to light intensity and colour
31
What is the role of the optic nerve
It carries impulses from the receptors in the retina to the brain
32
When light receptors detect very bright light, what happens to the circular muscles and radial muscles
The circular muscles in the iris contract and the radial muscles relax.
This makes the pupil smaller
33
What happens to the circular and radial muscles when in dim lighting
The circular muscles relax and the radial muscles contract
| This makes the pupil wider
34
What is accommodation (in terms of eyes)
Changing the shape of the lens so that light focuses on the retina
35
What happens to the ciliary muscles and suspensory ligaments when trying to focus on near objects
The ciliary muscles contract and the suspensory ligaments relax
36
What shape is the lens when focusing on a near object
Fat, more curved
37
What happens to the ciliary muscles and the suspensory ligaments when looking at a distant object
The ciliary muscles relax and the the suspensory ligaments pull tight
38
What shape is the lens when looking at a far object
Thin, less curved
39
What is the medical name for long-sightedness
Hyperopia
40
What lens is used to correct long-sightedness
Convex (curves outward)
41
What is the medical name for short-sightedness
Myopia
42
What lens is used to correct short-sightedness
Concave lens (curves inward)
43
What are treatments for vision defects
Contact lenses,
Laser eye surgery,
Replacement lens surgery
44
How does laser eye surgery work
A laser can be used to vaporise tissue, changing the shape of the cornea and so how strongly it refracts the light
45
What are the two types of lenses
Hard and soft lenses
46
What are the risks of laser eye surgery
Infection or the eye reacting in a way that makes ur vision worse than before
47
What is involved in replacement lens surgery
The natural lens of the eye is removed and an artificial lens is inserted in its place
48
What is the thermoregulatory centre
It contains receptors that are sensitive to temperature of the blood flowing through the brain
49
What are the responses to when u are too hot
Sweat is produced and evaporates from the skin which transfers energy to the environment.
Vasodilation.
50
What are responses to being too cold
Hair stand up to trap an insulating layer of air,
No sweat produced,
Vasoconstriction,
Shivering
51
What is vasodilation
Blood vessels supplying the skin dilate so more blood flows close to the surface of the skin
52
What is vasoconstriction
The blood vessels supplying in no the skin constrict to close off the skin’s blood supply
53
What is a hormone
A chemical messenger that is sent in the blood
54
Give 4 glands
```
Any from:
Pituitary gland,
Thyroid gland
Ovaries,
Adrenal gland,
The pancreas,
Testes,
Hypothalamus,
etc.
```
55
Where is the pituitary gland
In the brain
56
Why is the pituitary gland sometimes called the ‘master gland’
Because it releases hormones that act on other glands, making them release hormones
57
What hormone does the thyroid gland produce
Thyroxine
58
What is the function of thyroxine
Regulates things like rate of metabolism, heart rate and temperature
59
What hormone does the adrenal gland produce
Adrenaline
60
What hormone is produced by the ovaries
Oestrogen
61
What hormone is produced by the testes
Testosterone
62
What hormone does the pancreas produce
Insulin
63
What are the differences between hormones and nerves
Hormones:
- Slower action
- Act for a long time
- Act in a more general way
Nerves:
- Very fast action
- Act for a very short time
- Act on a very precise area
64
How and where is excess glucose stored
Stored as glycogen in the liver
65
Where are glucagon and insulin produced
The pancreas
66
What does insulin do
It makes the liver turn glucose into glycogen
67
What does glucagon do
It makes the liver turn glycogen into glucose
68
When is insulin secreted
When the blood glucose level is too high
69
When is glucagon secreted
When the blood glucose level is too low
70
What is the problem in type 1 diabetes
The pancreas produce little or no insulin, which means that the person’s blood glucose levels are high
71
What are the treatments for type 1 diabetes
Insulin injections,
Reducing intake of food rich in sugars,
Regular exercise
72
What is the problem in type 2 diabetes
The person becomes resistant to their own insulin.
| This can cause blood sugars to rise to a dangerous level
73
What can increase the chance of getting type 2 diabetes
Obesity
74
How can type 2 diabetes be controlled
Eating a carbohydrate-controlled diet and regular exercise
75
What is filtration in terms of kidneys
When kidneys filter out waste products from the blood
76
What is selective reabsorption
When useful substances like glucose are absorbed back into the blood
77
What is deamination
Turning excess amino acids into fats and carbohydrates
| This occurs in the liver
78
What is a waste product of deamination
Ammonia
79
What is ammonia converted into and where
Converted into urea in the liver
80
What is wrong with having too high or too low ion content in the body
Upset the balance between water and ions and could mean that too much or too little water is drawn into cells by osmosis and having the wrong amount of water damages cells
81
What are two ways that water leaves the body with uncontrolled quantities
Sweating,
| Breathing out
82
What hormone controls the concentration of urine
Anti-diuretic hormone (ADH)
83
What gland releases ADH
The pituitary gland
84
How does ADH work
The more ADH released then the more water is reabsorbed
85
If lots of ADH is released, with the urine be diluted or concentrated
It will be concentrated because the water has been reabsorbed so there is less water in the urine
86
What is in dialysis fluid
It has the same concentration of glucose and dissolved ions as healthy blood
87
What happens in a dialysis machine
The person’s blood flows between partially permeable membranes, surrounded in dialysis fluid.
The membrane is permeable to ions and waste substances and the dialysis fluid carries this out
88
What are the problems with dialysis
Many need to have it 3 times a week and each session takes 3-4 hours,
Can cause blood clots or infections,
Expensive for the NHS
89
What are the problems with kidney transplants
The kidney can be rejected by the patient’s immune system,
| Long waiting lists for transplants
90
What r the positives of kidney transplants
They are cheaper in the long run than dialysis,
They cure kidney failure,
Patients do not have to spend hours on dialysis,
Rejection of the kidney can be treated by drugs
91
How many stages of the menstrual cycle is there
4
92
Describe stage 1 of the menstrual cycle
The uterus lining breaks down for about 4 days
93
Describe stage 2 of the menstrual cycle
The uterus lining builds up again, from day 4-14, into a thick spongy layer full of blood vessels ready to receive a fertilised egg
94
Describe stage 3 of the menstrual cycle
An egg develops and is released from the overt at day 14 - this is called ovulation
95
Describe stage 4 of the menstrual cycle
The uterus lining is maintained from day 14 to 28.
If no fertilised egg has landed in the uterus wall by day 28 then the lining starts to break down and the cycle starts again
96
Where is FSH produced
The pituitary gland
97
What is the role of FSH (Follicle-Stimulating Hormone)
It causes the egg to mature in one of the ovaries in a structure called a follicle,
Stimulates the ovaries to produce oestrogen
98
Where is oestrogen produced
The ovaries
99
What is the role of oestrogen
Causes the lining of the uterus to grow,
| Stimulates the release of LH and inhibits the release of FSH
100
Where is LH produced
The pituitary gland
101
What is the role of LH (Luteinising Hormone)
Stimulates the release of an egg at day 14
102
Where is progesterone produced
The ovaries
103
What is the role of progesterone
It maintains uterus lining during the second half of the cycle,
Inhibits the release of LH and FSH
104
How does oestrogen reduce fertility
If the level is permanently high, it inhibits the production of FSH and egg development and production stop
105
How does progesterone reduce fertility
It inhibits FSH and LH
| And it stimulates the production of thick mucus that prevents any sperm getting through and reaching the egg
106
What hormones does the pill contain (combined oral contraceptive pill)
Oestrogen and progesterone
107
What are the problems with the pill
Headaches and nausea,
| Does not protect against STDs and STIs
108
Give examples of contraceptives that use hormones
```
The combined pill
The mini pill (progesterone only)
Contraceptive patch
Contraceptive implant
Contraceptive injection
Intrauterine device (IUD)
```
109
What does a plastic IUD do
Releases progesterone
110
What does a copper IUD do
Prevents sperm from surviving in the uterus
