Homeostasis & Response Flashcards
1
Q
What is homeostasis?
A
Homeostasis describes all the processes that happen in a cell or organism to maintain optimal conditions. This is needed to respond to changes in the internal and external environment.
2
Q
Why must humans regulate the body’s internal conditions?
A
Because humans are organisms that live in a changing environments, we must regulate the body’s internal conditions to make sure the enzymes and cells in the body function well.
3
Q
What happens if the body’s internal conditions are not optimal?
A
The enzymes can denature, which reduces their ability to catalyse metabolic reactions.
4
Q
What conditions need to be regulated in the body?
A
- Urea concentration
- Water levels
- Internal body temperature
- Carbon dioxide levels
- Blood sugar levels
5
Q
Control systems use what responses?
A
Nervous and chemical responses
6
Q
What are the three parts that make up the control system and what do they do?
A
- coordination centres = Receive and process information arriving from receptor cells.
- Receptors = Receptor cells detect changes in the environment
- Effectors (muscles or glands) = They carry out responses to stimuli that help to restore optimum levels
7
Q
What Will happen if our body temperature rises well above 37°C?
A
Automatic mechanisms will work to reduce the body’s temperature.
8
Q
How would our control systems respond to an increase in body temperature?
A
1) Receptor cells detect the increase in temperature.
2) The coordination centres receive and process information arriving from receptor cells.
3) The message is sent to effectors, which are muscles or glands.
4) Effectors carry out responses to stimuli to help restore optimal levels.
9
Q
What does the nervous system do?
A
The nervous system protects organisms from harm by responding to changes in the environment. It does this by coordinating communication between different parts of organisms.
10
Q
What is the nervous system made up of?
A
- The brain
- The spinal cord
- The neurones (nerve cells)
11
Q
How does the brain work in the nervous system?
A
- The brain is part of the central nervous system. (CNS)
- The CNS coordinates the response of effectors.
12
Q
How does the spinal cord work in the nervous system?
A
The spinal cord is the other component of the CNS.
It is important in coordination the response of effectors to change in the environment.
13
Q
How do neurones work in the nervous system?
A
Neurones carry electrical impulses between receptors, the central nervous system and effectors.
14
Q
What are synapses?
A
Synapses are gaps between neurones, found at each junction of a reflex.
15
Q
What happens at the arrival of the synapse?
A
The electrical impulse reaches the end of the neurone before the synapse.
This triggers the release of chemicals called neurotransmitters.
16
Q
What are some examples of reflexes?
A
Sneezing
Dropping hot objects
Blinking
17
Q
How does the control nervous system respond to stimuli?
A
Via a reflex arc
18
Q
What are some factors of human reaction times?
A
Caffeine and exercise (tested by dropping and catching a ruler)
19
Q
How does the brain function?
A
The brain is made up of mullion of interconnecting neurones.
Different regions of the brain are responsible for coordinating different functions.
20
Q
What are the three main parts of the brain?
A
Cerebellum
Medulla
Cerebral cortex
21
Q
What is the cerebellum?
A
The cerebellum is responsible for muscle coordination and is important for movement, posture, balance and speech.
22
Q
What is the medulla?
A
The medulla is responsible for unconscious activities like breathing and heartbeat.
23
Q
What is the cerebral cortex?
A
The cerebral cortex is responsible for consciousness thought like memory, language and intellectual.
24
Q
What are MRI Scanners?
A
Magnetic Resonate Imaging
MRI scanners have allowed us to learn areas of the brain that are active during different activities, such as moving, speaking and listening.
25
What is electrical stimulation?
Electrical stimulating has been able to treat certain brain disorders.
Electrical stimulation is used to help treat conditions (such as parkinson's) because the nervous system communicates using electrical impulse.
26
How could having brain damage help the research of the brain?
By studying patients who have brain damage where parts of their brain don't function, neuroscientists have been able to link particular regions of the brain to particular functions.
27
Why is it hard to treat brain injuries?
The brain is complex, delicate and not well understood.
28
What is the retina?
The retina is packed with receptor cells, which are sensitive to both brightness and the colour of light.
29
What is the optic nerve?
Transmits visual information, in the form of electrical impulses, from the retina to the brain.
30
What is the sclera?
The white of the eye; the opaque protective outer layer.
31
What is the cornea?
The transparent frontal portion of the eye responsible for refracting light.
32
What is the pupil?
A hole in the centre of the iris, through which light passes.
33
What is the iris?
Controls pupil diameter and the quantity of light reaching retina.
34
What is the suspensory ligaments?
A ring of fibres that connect ciliary muscles to the lens.
35
What are the ciliary muscles?
A ring of smooth muscle that changes the shape of the lens to focus light.
36
What happens when our eyes focus on a distant object?
- Lens become flatter and thinner
- Suspensory ligaments tighten
- Ciliary muscles relax
- Minor refraction of light rays
37
What size do pupils change to with light?
Dim light - larger pupil
Too much light - smaller pupil
38
What is hyperopia?
Hyperopia happens when rays of light focus behind the retina (long-sightedness)
39
What is myopia?
Myopia happens when rays of light focus in front of the retina (short-sightedness)
40
How can myopia and hyperopia be treated?
Both can be treated using glasses fitted with lenses that refract light rays to allow the imagine to form on the retina.
Both contact lenses and laser eye surgery can correct these issues.
41
What is accommodation (eyes)?
Accommodation is the process of changing lens shape in order to focus on an object as its distance from the eye changes.
42
What does the receptors in the thermoregulatory centre of our brain (hypothalamus) monitor?
The internal body temperature as blood flows through the brain
43
What do receptors on the surface of the skin monitor?
It monitors the temperature of the surface of the body.
44
What happens to our body if we are too cold?
- Muscle contraction increase, causing shivering
- Hairs stand on end
- Blood vessels constrict to reduce blood flow in capillaries (vasoconstriction)
45
What happens to our body when we are too hot?
- Sweat is released from sweat glands under the skin
- Hairs lie flat
- Blood vessels dilate to allow more blood to enter capillaries that pass close to the skin surface (vasodilation)
46
What happens when we shiver?
- Our muscles contract automatically, making us shiver.
- This process required energy which is generated through respiration.
- Respiration produces heat, warming us up.
47
What happens when we sweat?
- Sweat glands release water, which covers the skin.
- Heat energy from the body is transferred to the water, and evaporates when it has enough energy.
- As it evaporates, it takes heat energy with it, lowering the average temperature of the body.
48
What is the endocrine system?
The endocrine system coordinates the body's message to changes in the environment using chemical messengers (hormones).
49
Where are hormones released?
Hormones are released by glands into the bloodstream, where they travel to target organs.
50
What are the different endocrine glands?
- Ovaries (female only)
- Pituitary gland
- Testes (male only)
- Thyroid gland
- Pancreas
- Adrenal glands
51
What do the ovaries produce?
Ovaries produce oestrogen, which controls puberty and is one of the main hormones in the regulation of the menstrual cycle.
52
What is the pituitary gland?
The pituitary gland is the main endocrine gland or "master gland". It releases hormones in response to changes detected by the hypothalamus. Lots of these hormones trigger other glands to release more hormones.
53
What do the testes produce?
The testes produce testosterone, which controls puberty and sperm production.
54
What does the thyroid gland release?
It releases thyroxine, which regulates our metabolism, heart rate and temperature.
55
What does the pancreas produce?
The pancreas produces insulin and glucagon, which are involved in regulating blood glucose levels.
56
What are the adrenal glands?
The adrenal glands are placed above each kidney, and produce adrenaline.
57
How is the nervous system different to the endocrine system?
Endocrine system:
- Slower response
- Uses chemical messengers carried by blood
- Response can be long lasting
- Can act on large areas of the body
58
What mechanism regulates the production of thyroxine?
Negative feedback
59
What happens if there is too little thyroxine in the body?
TSH is produced
Negative feedback is in action
60
What happens if there is too little glucose?
An organism cannot produce enough energy as glucose is important for respiration.
61
What happens if there is too much glucose?
This could have a negative impact on osmosis by affecting concentration gradients.
62
What is released if there is too much/too little glucose?
Too much - insulin
Too little - glucagon
63
What organ helps to restore glucose levels to normal when they fluctuate?
The liver
64
What is type 1 diabetes?
Suffered are unable to produce enough insulin
65
What is type 2 diabetes?
Sufferers can still produce insulin, but the body doesn't respond to it.
66
How does type 1 diabetes start?
Type 1 diabetes develops during childhood.
The cause of type 1 diabetes is unknown, but is thought of that the body's immune system attacks pancreas cells.
67
How can type 1 diabetes be treated?
The main treatment is to inject insulin when blood glucose levels rise too high.
Sufferers can also manage their diet and exercise on a regular basis to keep levels as steady as possible.
68
How does type 2 diabetes start?
Type 2 diabetes usually develops later in life.
Being overweight and of old age are recognised as 2 primary factors.
69
How could type 2 diabetes be treated?
Injecting insulin will not help, sufferers must manage their diet and exercise regularly to keep blood glucose levels steady.
70
Why must water levels in the body be kept at a relative constant?
To control the amount of water and ions diffusing into and out of cells.
71
What factors could disrput the balance of water levels?
- Eating too much salt (blood ion concentration too high).
- Illness (fever, vomiting or diarrhoea could result in dehydration, which makes the blood's water concentration too low)
- Sweating (water, ions and urea are all lost in sweat).
- Exhalation (water in lungs leaves the body by breath).
72
Why are kidneys important for homeostasis?
They control the water and ion levels in the blood.
73
What happens when there is too much urea in the bloodstream?
Because urea is toxic, this may cause harm to cells and tissues.
74
How is urea formed?
Urea is formed when the digestion of protein results in an excess of amino acids which cannot be stored in the body.
75
What happens to excess amino acids from proteins in the body?
The amino acids undergo delamination in the liver, the waste product being ammonia.
76
What happens to ammonia after deamination?
The ammonia is then converted into urea and must be excreted from the body as urine.
77
What are the two stages of the process of urine production?
- Ultrafiltration
- Selective Reabsorption
78
What is ultrafiltration?
Where the blood is filtered and all water, urea and salts move into the nephron tubule.
Proteins and blood cells remain in the bloods and they are too big to move across the capillary walls.
79
What is selective reabsorption?
Useful substances like water are reabsorbed from the tubule back into the bloodstream, leaving urea, excess salts and water in the tubule.
This mixture forms urine which is collected by the kidneys and travels to the bladder.
80
Where does urine production take place?
In the nephron
81
What happens if there is too little water in the blood?
The hypothalamus triggers the pituitary gland to release anti-diuretic hormone (ADH). This increases the permeability of the kidney tubules. This means that more water is reabsorbed back into the bloodstream. Resulting in a small volume of concentrated urine.
82
What happens if there is too much water in the blood?
The hypothalamus triggers the pituitary gland to stop the release of anti-diuretic hormone (ADH). This reduces the permeability of the kidney tubules, so that less water is reabsorbed back into the bloodstream. This results in a large volume of dilute urine.
83
What is dialysis used for?
Dialysis is a possible treatment for kidney failure. It is an essential treatment for people whose kidneys cannot keep the concentrations of urea and salt at an optimum level to ensure tissue damage doesn't occur.
84
How does the dialysis machine work?
The patient is linked to the dialysis machine, with their blood flowing into the machine. The machine contains a fluid which is designed to have optimum concentrations of salt and glucose.
85
How does the dialysis fluid work?
The patient's blood passes over a partially permeable membrane in the machine, designed to replicate the kidney tubules. The dialysis fluid is on the other side of the membrane, where a concentration gradient is established which allows excess ions and urea to diffuse.
86
What are the advantages of using a dialysis?
- Dialysis can be used for life saving processes.
- It gives a patient more time to find a kidney donor.
87
What are the disadvantages of using a dialysis?
- Lasts 3-4 hours and needed 3 times a week.
- Expensive process
- Increases risk of blood clots and infections.
88
Why might having a close relative donate a kidney be useful?
Closer relatives have a higher chance of being a tissue match.
89
Why are immunosupressants be useful after a kidney transplant?
Patients may have to take immunosuppressants for the rest of their lives as it suppresses the immune system to prevent it from attempting to destroy the foreign cells of the transplanted kidney.
90
What are the advantages of a kidney transplant?
- The patient does not need to have dialysis treatment (time-consuming).
- Cheaper than dialysis in the long run.
91
What are the disadvantages of a kidney transplant?
- Kidney may be rejected by the body.
- There may be a long waiting list for transplants.
- Patient often has to take immunosuppressant drugs, making the patient prone to other infections.
92
What happens in puberty for women?
- Oestrogen rises and triggers the menstrual cycle.
- Underarm and pubic hair grow.
- Breasts enlarge.
93
What happens in puberty for men?
- Testosterone rises, stimulating sperm production.
- Voice deepens.
- Underarm, facial and pubic hair grow.
94
What four hormones in the menstrual cycle are from the endocrine system?
- Follicle stimulating hormone (FSH)
- Oestrogen
- Progesterone
- Luteinising Hormone (LH)
95
What is FSH?
It is released from the pituitary glands, which causes an egg in the ovary to mature. It also stimulates the production of oestrogen.
96
What is oestrogen?
It is produced in the ovaries and causes the development of the thick, uterus lining. It stimulates the production of LH and stops the production of FSH.
97
What is LH?
It is produced from the pituitary gland and stimulates the release of a mature egg on day 14 of the menstrual cycle (ovulation).
98
What is progesterone?
Is produced in the ovaries after ovulation and is responsible for maintaining the uterus lining from days 14-28.
When progesterone levels drop, it triggers the breakdown of the lining, starting the menstrual cycle. It stops the release of LH and FSH.
99
What is the progesterone-only pill?
- Stimulates the production of thick, sticky mucus, making it difficult for sperm to penetrate. Inhibits the release of FSH, so the eggs don't mature. Contains fewer side effects than combined pill.
100
What is the combined pill?
Contains both oestrogen and progesterone. If taken everyday, enough oestrogen builds up so it stops the production of FSH, so no eggs mature.
101
What is the contraceptive patch?
Steadily releases progesterone, and should change the patch on the skin weekly.
102
What is a contraseptive implant?
A contraceptive implant can last for 3 years. It is inserted under the skin (normally an arm) and continuously releases a small amount of progesterone.
103
What is the contraceptive injection?
The contraceptive injection contains progesterone and lasts up to 3 months.
104
What is a diaphragm (contraceptive)?
It is a shallow plastic cup inserted into the vagina prior to sexual intercourse, sitting at the entrance of the uterus. It prevents sperm reaching the egg. It is also covered in spermicide to kill sperm.
105
What is an intrauterine device (IUD)?
A small t-shaped device inserted into the uterus. It works by preventing implantation of an embryo. Some IUDs release progesterone.
106
What is ethene?
Ethane is a gas that controls cell division and the ripening of fruits.
107
What are auxins?
Auxins change the growth pattern to allow roots and shoots to move either towards or away from a stimulus. Responses to stimuli that involve directional growth are called tropisms.
108
What are gibberellins?
Gibberellins are important in starting off seed germination.
109
What are the two types of tropisms?
- Phototropism
- Gravitropism
