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Biology > Topic 5 - Homeostasis > Flashcards

Topic 5 - Homeostasis Flashcards

1
Q

What is Homeostasis?

A

It is the regulation of internal conditions of a cell or organism to maintain optimum conditions for functions in response to internal and external changes.

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2
Q

How is Homeostasis shown when exercising?

A

Exercise causes a demand on the body, the blood glucose levels fall, and our body temperature rises, and we loose water by sweating which requires energy, so our body temp will decline.

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3
Q

What does an Automatic Control System consist of?

A

Hormones and our nervous system.

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4
Q

What do our receptor cells do?

A

They detect a change in environment (stimulus).

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5
Q

What does our coordination centre do and what are some examples?

A

Our coordination centre processes and receives the information from the receptor cells, examples including out brain, spine and pancreas (and more!)

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6
Q

What is an effector, and what are two examples?

A

An effector carries out a response to the stimulus to return to optimum level. Examples including our glands and muscle.

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7
Q

What does our nervous system consist of?

A

Our nervous system consists of a central nervous system and a automatic nervous system, our central being important (brain and spine)

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8
Q

What happens when we touch a hot candle (to demonstrate reflex arc)?

A

1) The stimulus (heat) is detected by receptor cells.
2) This sends electrical impulses along a sensory neurone, which it meets a junction called a synapse and a chemical is released, which diffuses across to a relay neurone.
3) Our relay neurone meets our CNS which triggers an electrical impulse which moves along and meets another synapse.
4) The impulse then passes down the motor neurone to the effector, which responds by contraction of muscle to remove it away from heat.

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9
Q

Does our brain control our reflexes, explain?

A

Our reflexes are NOT controlled by the conscious part of our brain, as there is no decision making which makes them automatic and rapid which protects us from danger.

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10
Q

Describe the method to test reaction time (6 marker)?

A

1) Work with a partner.
2) Person A holds out their hand with a gap between their thumb and first finger.
3) Person B holds the ruler with the zero at the top of person A’s thumb
4) Person B drops the ruler without telling Person A and they must catch it.
5) The number level with the top of person A’s thumb is recorded in a suitable table. Repeat this ten times.
6) Swap places, and record another ten attempts.
7) You can use the conversion table to help convert your ruler measurements into reaction time or just record the catch distance in cm.

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11
Q

In the reaction time experiment, what are our variables?

A

Dependent Variable - Reaction Time
Control Variable - Starting distance, measure from top of thumb, environment in room
Independent Variable - We can change many, person having the reaction time tested, practise, hand catching the ruler, or caffeine effect on reaction time.

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12
Q

What are the three parts of our brain?

A

Cerebral Cortex, Cerebellum and Medulla.

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13
Q

What behaviour is our cerebellum responsible for?

A

Balance and Movement

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14
Q

What behaviour is our medulla responsible for?

A

Breathing and heart rate.

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15
Q

What behaviour is our cerebral cortex responsible for?

A

Language, Memory and Conciousnes

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16
Q

Why is our brain difficult to operate?

A

It has many complex structures, easy to damage and is protected by our skull.

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17
Q

How do scientist test/develop understanding of our brain?

A

1) Look with patients who suffer from brain damage and their behaviour, link this to where it is in our brain and what function.
2) Electrically stimulate certain areas of our brain, and look at certain behaviours.
3) MRI scanning when producing different cognitive abilities, and then match with area to function, e.g (image processing)

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18
Q

What is the function of our Cornea, Iris and Pupil?

A

Cornea - Focusing on light rays.
Iris - Our coloured part, controls the size of pupil.
Pupil - Space in centre of iris where light passes through.

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19
Q

What is the function of our lens, retina and optic nerve?

A

Lens - Focus light rays on back of the eye, can change shape based on environment.
Retina - Contains receptor cells for light, colour and light intensity.
Optic Nerve - Receptor Cells send electrical impulses down to the optic nerve into the brain.

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20
Q

What is the function of our sclera, ciliary muscle and suspensory ligaments?

A

Sclera - Protects the eye
Ciliary Muscle + Suspensory Ligaments - Focus on distant or near objects.

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21
Q

How does our eye respond to a dark room?

A

As there is low light, our light receptors sense this in our retina which send electrical impulses to our brain.
Our brain sends in pulses to specific muscles in the iris.
These contract, allowing for pupil to become larger, which allows for more light to pass through, which is a reflex action.

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22
Q

What happens to our pupil size when we are in a bright room?

A

Reflex causes smaller pupil, which protects our eye from damage.

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23
Q

What is accommodation?

A

It is where our lens allows us to focus on distant or nearer objects by changing shape.

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24
Q

How does our eye respond to distant objects?

A

Light needs to be focused only a small amount, are ciliary muscle relaxes and so our suspensory ligaments are pulled tight, so our lens is thin and only slightly refracts our light rays, the light rays our focused on a point of our retina.

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25
How does our eye respond to near objects?
Light needs to be focused a large amount, so our ciliary muscle contracts, and our suspensory ligaments loosen, so our lens is thicker and refracts light rays more strongly, this being focused on a point of our retina.
26
What is hyperopia and how can it be treated?
Hyperopia is where long sighted people cannot focus on nearby objects as our eyeball is too short, so our lens become less elastic and cannot become thick enough, it can be treated by glasses with convex lenses, which partially focus light before it enters our eye.
27
What is myopia and how can it be treated?
Myopia is where short sighted people cannot focus on distant objects, as our eyeball is too long, so light focused on point in front of retina, our lens is too thick. Glasses with concave lenses to unfocused light before it enters the eye
28
What are some other treatment to fix myopia and hyperopia and explain what they do?
Contact lenses which sit on eyeball, which refract light. Laser Surgery, which changes the shape of the cornea, which refracts the light. Artificial Lenses can also be used.
29
Which part of the brain monitors our body temperature and what does it contain?
Thermoregulation centre, which contains receptors sensitive to temperature of blood.
30
Does our skin contain temperature receptors and if so, what do they do? (Electrical….)
Yes it does, and it send electrical impulses down sensory neurones to the thermoregulation centre.
31
How does sweating decrease our body temp when it is too high?
Sweat glands release sweat on skin surface, and our sweat evaporates which takes energy from body cooling us down.
32
How does flushing cool us down when our body temp is too high?
Under our skin we have blood capillaries, supplied with blood via vessels, these become dilute and get wider (vasodilation) so more blood so heat can transfer out of our body, reducing temperature.
33
How does vasoconstriction heat us up when body temp is too low?
Our blood vessels supplying the blood to our capillaries start to become narrow, so less blood flows via our capillaries, and so less heat is lost from body.
34
How does shivering heat us up when body temp is low?
Our skeletal muscles contract, to generate energy for this process, muscle cells increase in respiration rate, which releases heat and warms us up.
35
How does our human endocrine system work and what does it consist of?
It consists of number of glands, which secrete hormones directly into our blood stream, an our blood carries hormones around the body,
36
What are the differences between our nervous system and endocrine system.
Our nervous system uses electrical impulses which travel down neurones, it is extremely fast and is short lasting, whereas our endocrine system has hormones which are chemicals carried in the blood, much slower effect but longer lasting.
37
38
What are the three glands and what is the function of hormones released in them?
1) Thyroid Gland produces hormones in growth and repair. 2) Adrenal Gland produces adrenaline in times of fear or being scared. 3) Pituitary Gland releases a number of different hormones into blood which interact with other glands and cause other hormones to be released, so can trigger a wide range of effects.
39
What does our pancreas hormones control?
It controls our concentration of blood glucose.
40
Where is our blood glucose monitored and what does it produce if it rises?
Our glucose is monitored by the pancreas, after a meal which is high in carbohydrates our pancreas detects this and produces insulin.
41
Where does insulin travel and what does it trigger?
Our insulin travels in the blood stream all around the body, triggers body cells to take up glucose from the blood.
42
What do liver and muscle cells store excess glucose as?
Glycogen
43
What happens in type 1 diabetes and how is treated?
Pancreas does not produce enough insulin, so blood glucose stays at high level, it is treated by people with this injecting themselves with insulin if our blood glucose levels is too high.
44
What is type 2 diabetes and how is it treated?
Type 2 diabetes is where our body cells stop responding to insulin, and our blood glucose levels go too high. Treated by a diet controlled with levels of carbohydrates and advised to take excerise, risk factor is obesity.
45
How does blood glucose concentration show negative feedback?
If blood glucose levels are too low, pancreas releases glucagon which triggers liver cells to convert glycogen to glucose, and levels return to normal, glucagon and insulin have opposite effects so providing a negative feedback cycle.
46
What are the three ways water can leave our body?
1) Lungs when we exhale, this is not controlled 2) When we sweat, this is not controlled 3) When we urinate, this can be controlled.
47
What do kidneys do if our blood is to dilute?
Kidneys remove the excess water with urine, as well as urea and excess ions.
48
How do the kidneys work/operate to ensure we get enough of everything?
Blood enters our arteries with urea, kidneys remove the water (some of it) and ions (which are in excess), and this is stored in our bladder before urinating, so our blood leaves with no urea. The idea is that they get passed into the tubules and re enter the blood if needed, this is called selective absorption.
49
Overall, how much do our kidneys remove of glucose, ions, water and urea?
Our glucose remains constant, our ions our removed a little if in excess, some of the water gets removed, and urea looses al concentration. This showing homeostasis.
50
How does our liver interact with amino acids?
Our liver breaks down excess amino acids and they are converted into ammonia, ammonia is then considered toxic and converted into urea which leaves via our kidneys, so excess amino acids are removed via urinating.
51
When is ADH produced and what does it cause?
ADH is produced by our pituitary gland if our level of water in blood falls, (exercising on a hot day). ADH causes the tubules in the kidneys to become more permeable to water, so more water can pass out to the tubules and can be reabsorbed into our blood stream, so our urine contains less water and our levels can rise.
52
What happens if our blood becomes more concentrated with water?
ADH is stopped being released and our kidneys re absorb less water so more urine produced with a higher concentration of water, so our blood levels return to normal/decrease, this again showing a negative feedback cycle.
53
What happens if our kidneys fail? (what happens to our kidneys?)
You get placed on dialysis, as our blood contains more water ions and urea, so our blood becomes more concentrated in this these.
54
How does dialysis work?
When being placed on a dialysis machine, dialysis fluid enters our body, this fluid contains a normal concentration of water and ions, and ZERO urea. This allows for a steep concentration gradient for urea to diffuse across from the blood into the fluid.
55
Why is dialysis fluid being constantly refreshed?
To ensure a large concentration gradient for the urea, and so our ions/water levels can continue diffusing in a little rate, which causes our kidneys to work/
56
What our the advantages/disadvantages with a kidney transplant or dialysis?
Kidney Transplant. 1) Shortage of doners (disadvantage) 2) Can lead to a normal life when given a new kidney (advantage) 3) Only expensive at the start (advantage) 4) Possible rejection, and take anti rejection drugs for life (disadvantage) Dialysis 1) No shortage of machines (advantage) 2) Frequent treatment, have to visit hospital very often and a controlled diet, alongside expensive for long term (disadvantage)
57
What is the role of the reproductive organs during puberty?
Causes secondary sexual characteristics, for example pubic hair.
58
What do our testes produce, and what does the product produced stimulate?
Our testes produce testosterone which stimulates our testes to produce sperm.
59
What do our ovaries produce and what is the function of what is produced?
Ovaries produce oestrogen, and once puberty begins, eggs in ovaries mature every 18 days and egg is released, this being called ovulation and being part of the menstrual cycle!
60
What are the main stages in the menstrual cycle?
1) Ovulation takes place, in preparation uterus lining becomes thick and spongy. 2) Egg makes it way to the uterus, and if sperm is present the egg can be fertilised 3) If fertilised egg implants in the uterus wall and develops into a baby. 4) If no sperm is present, both egg and the uterus lining is released, this causing a period.
61
What is FSH, function of FSH, and how does it interact in the cycle?
FSH is follide stimulating hormone, and it causes our egg to mature. FSH is released by our pituitary gland and travels in the blood to ovaries which causes our eggs to mature. FSH triggers ovaries to make oestrogen.
62
What is LH, function of LH, and how does it interact with the cycle?
LH is luteinising hormone and it causes ovulation (egg to be released). LH is released by our pituitary gland, it triggers ovulation and our ovary produces progesterone once released.
63
What is the role of progesterone in the cycle? What happens if there is no fertilisation?
Progesterone stops the pituitary gland releasing FSH and LH, it prevents more eggs being released, keeps our lining of uterus thick and if no fertilisation our progesterone levels fall.
64
What is the role of oestrogen in the cycle?
Oestrogen stops our pituitary gland releasing FSH, and keeps our lining of the uterus wall thick.
65
What is the oral contraceptive pills? What is the function of them? What are the advantages/disadvantages?
The oral contraceptive pill prevents our body from producing FSH so egg cannot mature, the advantage being that it is highly effective if taken correctly, the disadvantages being it must be taken every day or pregnancy can occur, possible side effects like blood clots.
66
How does our implant/skin patch/injection act as contraception, what is the function, and what are the advantages/disadvantages?
They contain progesterone which stops the egg releasing, the advantage being it is more convenient and lasts longer before having to re-apply. Disadvantages being the possible side effects, does not protect against an STI.
67
Examples of barrier methods, what are the function, what are the advantages/disadvantages?
Examples being condom and diaphragm, they prevent the sperm getting to the egg, the advantage being they do not have side effects and do not contain hormones, the disadvantage being that they can break/fall off, a gel can be used which will kill the sperm incase.
68
What are Intrauterine devices/coils function, and what are the disadvantages/advantages?
They prevent the embryo from planting, some release hormones which prevent fertilisation, the advantages being that they do not have side effects, but they do not protect from STIs.
69
What our surgical methods for contraception, what are the disadvantages/advantages.
Surgical methods cause sterilisation, which prevents the egg from reaching the uterus, or prevent sperm from leaving the penis, the advantage is that they are effective but difficult to reverse and does not protect from STIs.
70
What is abstinence?
Abstinence is not taking part in sexual activities, but does not protect from STIs, we call this a natural form.
71
What are the ethical concerns with contraception?
Ethical concerns consist of the catholic church may not agree with these methods apart from natural forms, but people also have a choice with their bodies.
72
What does the 'fertility drug' consist of and the function of this?
They contain FSH and LH and this allows for ovulation to occur so an increase chance in pregnancy.
73
What is the process of IFV
1) FSH and LH are injected, so eggs can mature, mutiple of them. 2) The sperm is collected from the father, and the eggs are collected from the mother. 3) These are then fertilised in a lab. 4) They develop into embryos and then inserted via the mothers uterus into the womb and develop into a baby!
74
What are the benefits of IFV, what are the problems, and what are the ethical concerns?
Benefits of IFV mean you can have your own baby if you were having difficulty to conceive. The problems with IFV is they have a low success rate, and can cause emotional stress for the family. It is physically demanding and you may have mutiple births. The ethical concerns are not all embryos will be transferred, so some embryos will be destroyed, it is also very expensive this money could go to treating cancer etc,
75
Where is the adrenal gland, what does it release and what does the product released do to our body?
Our adrenal gland is located in the top of our kidneys, during stress it produces adrenaline, the adrenaline is released into our blood, causing an increase in heart rate and an increase in aerobic respiration, preparing us for fight of flight.
76
What is negative feedback, and how does it work? (Example in answer is using thyroxine!)
Level of thyroxine is monitored by our brain, when this drops our pituitary gland releases TSH into our blood stream, and triggers our thyroid gland to produce more thyroxine. If it increases too much, our brain monitors this, our pituitary gland stops releasing TSH, and hence a negative feedback cycle.
77
Why do plants produce hormones?
Plants produce hormones in order to coordinate and control growth responses.
78
What effect does auxin have on cells in the shoots of plants?
Auxin stimulates cell elongation in plant shoots
79
How does auxin distribution in response to light lead to phototropism?
Auxin accumulation on the shaded side of a shoot causes cells on the shady side to elongate at a faster rate than cells on the light side; this leads to bending of the shoot towards the light.
80
What role do gibberellins have in seeds?
Initiate seed germination.
81
What is the role of ethene in plants?
They control cell division, and also ripening of fruits/plants.
82
What is the method for required practical 8?
1. Put cotton wool into three petri dishes, and add the same volume of water to each dish. 2. Add ten seeds to each dish and place them in a warm place where they won’t be disturbed. 3. Allow the seeds to germinate, and add more water if the cotton wool dries out. 4. Once the seeds have germinated, ensure the petri dishes each contain the same number of seeds, and remove any extra seeds if necessary. 5. One petri dish will sit in full light on a windowsill, the second will be in a dark cupboard, and the final dish will be placed in partial light. 6. Every day for one week, measure the height of each seedling and record the results in a table. You must record the height of the individual seedlings on each day. 7. Calculate the mean of the seedlings each day, and compare the mean heights in the three different locations.
83
What are the uses of auxins?
Auxins are used as weedkillers, rooting powders, in tissue culture and in growth.
84
What are the use of gibberellins?
End seed dormancy (germinate earlier) and ensure plants flower alongside fruits growing larger.
85
What is the uses of ethene?
Ethene triggers a ripening in fruits just before being stocked, allowing for the most ripe fruit for the consumer.

Biology (5 decks)

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