Hard Stuff Flashcards
(134 cards)
1
Q
What is the definition for osmosis?
A
- Osmosis is the movement of water molecules across a partially permeable membrane from a region of high water concentration to a region of low water concentration.
- Osmosis is a type of diffusion - passive movement of water molecules from an area of high water concentration to an area of low water concentration.
2
Q
What is a partially permeable membrane?
A
-A partially permeable membrane is just one with very small holes in it. So small, in fact, only tiny molecules (like water) can pass through them, and bigger molecules (e.g. sucrose) can’t.
3
Q
Which way do the water molecules pass through the partially permeable me,brand in osmosis?
A
- Water molecules actually pass both ways through the membrane during osmosis this happens because water molecules move about randomly all the time.
- But because there are more water molecules on one side than on the others there’s a steady net flow of water into the region with fewer water molecules, i.e. into the stronger sugar solution.
4
Q
What happens to the stronger sugar solution in osmosis?
A
-The strong sugar solution gets more dilute. The water acts like it’s trying to “even up” the concentration either side of the membrane.
5
Q
Where is osmosis used in the human body?
A
- Water moves into and out of cells by osmosis.
- Tissue fluid surrounds the cells in the body - basically just water with oxygen, glucose and stuff dissolved in it. It’s squeezed out of the blood capillaries to supply the cells with everything they need.
- Tissue fluid will usually have a different concentration to the fluid inside a cell. This means that water will either move into the cell from the tissue fluid, or out of the cell, by osmosis.
6
Q
What will happen if a cell is short of water?
A
- If a cell is short of water, the solution inside it will become quite concentrated (so has a lower water concentration).
- Usually means the solution outside is more dilute (so has a higher water concentration), and so water will move into the cell by osmosis.
7
Q
What happens if a cell has lots of water in it?
A
-If a cell has lots of water, solution inside will be more dilute (so will have a higher water concentration), and water will be drawn out of the cell and into the fluid outside by osmosis.
8
Q
What is an experiment you can do to show osmosis at work?
A
- Cut potato into cylinders, and get some beakers with different sugar solutions in them. One should be pure water, another should be a very concentrated sugar solution. Then you can have a few others with concentrations in between.
- Measure the length of the cylinders, (made of potatoes) then leave a few cylinders in each beaker for half an hour or so.
- Then you take them out and measure their lengths again.
- If the cylinders have drawn in water by osmosis, they’ll be a bit longer.
- If water has been drawn out, they’ll have shrunk a bit.
9
Q
What are the different variables in the potato cylinder osmosis experiment?
A
- The dependant variable is the chip length.
- The independent variable is the concentration of the sugar solution.
- All other variables (volume of solution, temperature, time, type of sugar used, etc.) must be kept the same in each case (control variables) or the experiment won’t be a fair test.
10
Q
What are the 3 ways substances move?
A
- Diffusion.
- Osmosis.
- And Active Transport.
11
Q
In life processes what must the gases and dissolved substances move through?
A
-Some sort of exchange surface. The exchange. The exchange surface have to allow enough of the necessary substances to pass through.
12
Q
How are exchange surfaces adapted to maximise effectiveness?
A
- They are thin, so substances only have a short distance to diffuse.
- They have a large surface area so lots of a substance can diffuse at once.
- Exchange surfaces in animals have lots of blood vessels, to get stuff into and out of the blood quickly.
- Gas exchange surfaces in animals (e.g. alveoli) are often ventilated too - air moves in and out.
13
Q
Why does exchanging substances get more difficult in bigger and more complex organisms?
A
-The place where the substances are needed (or the waste is made) ends up being a long way away from exchange surfaces.
14
Q
How is the structure of leaves adapted for letting gases diffuse in and out of cells?
A
-Carbon dioxide diffuses into the air spaces within the leaf, then it diffuses into the cells where photosynthesis happens. Leaf’s structure is adapted so that this can happen easily.
-Underneath of a leaf = an exchange surface. It’s covered in biddy little holes called stomata - carbon dioxide diffuses through them.
-Oxygen (produced in photosynthesis)/water vapour diffuse out through the stomata (water vapour lost over surface of leaf too, but most lost through stomata).
-Size of stomata controlled by guard cells. These
close stomata if plant is losing water faster than it is being replaced by the roots. Without these guard cells, plant would soon wilt.
15
Q
How is the structure of a plant leaf adapted to being an exchange surface?
A
- Flattened shape of the leaf increases surface area of exchange surface so that’s more effective.
- Walls of the cells inside the leaf form another exchange surface. The air spaces inside the leaf increase the area of this surface so there’s more chance for carbon dioxide to get into the cells (for photosynthesis).
16
Q
How does water leave the cells inside a leaf?
A
-The water vapour evaporates from the cells inside the leaf. Then it escapes by diffusion because there’s a lot of it inside the leaf and loss of it in the air outside.
17
Q
When is evaporation quickest?
A
-Evaporation is quickest in hot, dry, windy conditions.
18
Q
What is the thorax?
A
-The thorax is the top part of the body.
19
Q
What is the thorax separated from the lower part of the body (the abdomen) by?
A
-The diaphragm.
20
Q
What are the lungs protected by?
A
-The ribs.
21
Q
Describe the path which air travels (from the mouth to the alveoli).
A
- Air you breathe goes through the trachea.
- This splits into two tubes called ‘bronchi’ (each one is ‘a bronchus’), one going to each lung.
- The bronchi split into progressively smaller tubes called bronchioles.
- The bronchioles finally end at small bags called alveoli where the gas exchange takes place.
22
Q
What is ventilation?
A
-Breathing in and out.
23
Q
What happens to the thorax when we breathe in?
A
- Intercostal muscles and diaphragm contract.
- Thorax volume increases.
- This decreases the pressure, drawing air in via the mouth (to balance the pressure in the thorax).
24
Q
What happens to the thorax when we breathe out?
A
- Intercostal muscles and diaphragm relax.
- Thorax volume decreases.
- This increases pressure, so air is forced out via the mouth (to balance the pressure in the thorax).
25
What do artificial ventilators do?
- Ventilators are machines that move air (often with extra oxygen) into or out of the lungs.
- They help people who can't breathe themselves, e.g. if they're under general anaesthetic, or have a lung injury or disease.
26
What were old artificial ventilators like?
- They used to be a giant case (an 'iron lung') from the neck to the abdomen, with only the patient's head poking out.
- Air was pumped out of the case, pressure dropped, the lungs expanded and so air was drawn into the lungs. Air pumped into the case had the opposite effect, forcing air out of the lungs.
- However, they could interfere with blood flow to the lower body.
27
What are artificial ventilators like nowadays?
- Nowadays, most ventilators work by pumping air into the lungs.
- This expands the ribcage - when they stop pumping, the ribcage relaxes and pushes air back out of the lungs.
- This doesn't interfere with blood flow, but it can occasionally cause damage (e.g. burst alveoli) if the lungs can't cope with the artificial air flow.
28
What is the job of the lungs and how do they do this job?
- The job of the lungs is to transfer oxygen to the blood and to remove waste carbon dioxide from it.
- To do this the lungs contain millions of little air sacs called alveoli where gas exchange takes place.
29
How are the alveoli specialised to maximise the diffusion of oxygen and CO2?
- They have an enormous surface area (about 75m^2 in humans).
- They have a moist lining for dissolving gases.
- They have very thin walls (shorter diffusion paths).
- They have a good blood supply.
30
Where are the villi and what do they do?
- The inside of the small intestine is covered in millions and millions of these tiny projections called villi.
- They increase the surface area in a big way so that digested food is absorbed much more quickly into the blood.
31
How are villi specialised for maximising food absorption?
- They have a single layer of surface cells (shorter diffusion/active transport path).
- A very good supply to assist quick absorption.
- Big surface area - maximise diffusion/active transport.
32
How does digested food move into the blood?
- Diffusion.
| - Active Transport.
33
What are root hairs specialised for?
-Absorbing water and minerals.
34
How are root hairs specialised for absorbing eater and minerals?
- The cells on the surface of plant roots grow into long "hairs" which stick out into the soil.
- This gives the plant a big surface area for absorbing water and mineral ions from the soil.
- Most of the water and mineral ions that get into a plant are absorbed by the root hair cells.
35
How do root hairs take in minerals and why do they use this method?
-Active Transport - the concentration is usually higher in the root hair cell than in the soil around it, so minerals are taken up into the root hair cell by active transport as it goes against the concentration gradient, whereas diffusion is along the concentration, so would not explain why/how minerals are taken up into the root hair cell.
36
What is active transport?
- The movement of substances against a concentration gradient, so from an area of low concentration to an area of a high concentration.
- Active Transport needs energy from respiration to make it work.
- Active Transport also happens in humans, for example in taking glucose from the gut and from kidney tubules.
37
What is Active Transport used for in the human body?
- We need Active Transport to stop us starving.
- When there's a higher concentration of glucose/amino acids in the gut they diffuse naturally into the blood.
- But - sometimes there's a lower concentration of nutrients in the gut than there is in the blood.
- This means that the concentration gradient is the wrong way.
- So Active Transport allows nutrients to be taken into the blood as concentration gradient is other way around.
- Same process is used in plant roots - "Active transport".
38
What are phloem tubes?
- Made of columns of living cells with small holes in the ends to allow stuff through.
- Transport food substances (mainly dissolved sugars) made in leaves to growing regions (e.g. new shoots) and storage organs (e.g. root tubers) of the plant.
- Transport goes in both directions.
39
What are xylem tubes?
- Xylem tubes take water up.
- Made of dead cells joined end to end with no end walls between them and a hole down the middle (so they are hollow).
- They carry water and minerals from the roots to the stem and leaves in the transpiration stream.
40
What is transpiration?
- Transpiration is the loss of water from the plant.
- Transpiration is caused by the evaporation and diffusion of water from inside the leaves.
- Transpiration = a side effect of the way leaves are adapted for photosynthesis. They have to have stomata in them so that gases can be exchanged easily. Because there's more water inside the plant than in the air outside (from photosynthesis), the water escapes from the leaves through the stomata.
41
What is the transpiration stream?
- Water is lost from the leaves through evaporation and diffusion inside the leaves.
- This creates a slight shortage of water in the leaf, and so more water is drawn up from the rest of the plant through the xylem vessels to replace it.
- This in turn means more water is drawn up from the roots, and so there's a constant transpiration stream of water through the plant.
42
What type of circulatory system do humans have?
-Double circulatory system.
43
What do the two circuits in the human double circulatory system do?
- The first one pumps deoxygenated blood (blood without oxygen) to the lungs to take in oxygen. The blood then returns to the heart.
- The second one pumps oxygenated blood around all the other organs of the body. The blood gives up its oxygen at the body cells and the deoxygenated blood returns to the heart to be pumped out to the lungs again (to gain oxygen again and become oxygenated).
44
Describe the structure of the heart.
- The heart is a pumping organ that keeps the blood flowing around the body. The walls of the heart are made of muscle tissue.
- The heart has valves to make sure that blood goes in the right direction - they prevent it flowing backwards.
- It is made of four chambers (right atrium, right ventricle, left atrium and left ventricle) to pump blood around.
- It's left and right side are the opposite way around (so the left side of the heart appears on our right side and vice versa).
45
How does the heart use its four chambers (right atrium, right ventricle, left atrium and left ventricle) to pump blood around?
- Blood flows into the two atria (right atrium or left atrium) from the vena carva and the pulmonary vein.
- The atria contract, pushing the blood into the ventricles.
- The ventricles contract, forcing the blood into the pulmonary artery and the aorta, and out of the heart.
- The blood then flows to the organs through arteries, and returns through veins.
- The atria fill again and the whole cycle starts over.
46
What are the three types of blood vessels?
- Arteries - these carry blood away from the heart.
- Capillaries - these are involved in the exchange of materials at the tissues.
- Veins - these carry the blood to the heart.
47
Describe the structure of an artery and why it is like this?
- The heart pumps blood out at high pressure so the artery walls are strong/elastic to withstand these high pressures.
- Walls are think compared to size of the hole down the middle (the "lumen").
- They contain thick layers of muscle to make them strong, and elastic fibres to allow them to stretch and spring back.
48
Describe the structure of a capillary and why it is like this?
- Arteries branch into capillaries.
- Capillaries are really tiny (too small to see).
- They carry the blood really close to every cell in the body to exchange substances with them.
- They have permeable walls, so substances can diffuse in and out.
- They supply food and oxygen, and take away waste like CO2.
- Their walls are usually only one cell thick. This increases the rate of diffusion by decreasing the distance over which it occurs.
49
Describe the structure of a vein and why it is like this?
- Capillaries eventually join up to form veins.
- Blood is at a lower pressure in the veins so the walls don't need to be as thick as artery walls.
- They have a bigger lumen (hole in the middle) than arteries to help the blood flow despite the lower pressure.
- They also have valves to help keep the blood flowing in the right direction.
50
What are the four main components in the blood?
- Red Blood Cells.
- White Blood Cells.
- Platelets.
- Blood Plasma.
51
What are red blood cells and how are they adapted to maximise their function?
- The job of red blood cells is to carry oxygen from the lungs to all the cells in the body.
- They have a doughnut shape to give a large surface area for absorbing oxygen.
- They don't have a nucleus - this allows more room to carry oxygen/more room for more of the pigment haemoglobin.
- Contain red pigment called haemoglobin.
- In the lungs, haemoglobin combines with oxygen to become oxyhaemoglobin. In body tissues, the revers happens - oxyhaemoglobin splits up into haemoglobin and oxygen, to release oxygen to the cells.
52
What are white blood cells and how are they adapted to maximise their function?
- They can change shape to engulf unwelcome/foreign microorganisms.
- They produce antibodies to fight microorganisms, as well as antitoxins to neutralise any toxins produced by the microorganisms.
- Unlike red blood cells, they do have a nucleus.
53
What are platelets and what do they do?
- They are small fragments of cells. They have no nucleus.
| - These help the blood to clot at a wound - to stop all your blood pouring out and to stop microorganisms getting in.
54
What does lack of platelets cause?
-Lack of platelets can cause excessive bleeding and bruising.
55
What is blood plasma and what does it look like?
- One of the four components of blood.
| - A pale straw-coloured liquid which carries just about everything.
56
What does the blood plasma carry (the different substances 9-10 ones)?
- Red/white blood cells and platelets.
- Nutrients like glucose and amino acids. (These are soluble products of digestion which are absorbed from the gut and are taken to the cells of the body).
- Carbon dioxide from the organs to the lungs.
- Urea from the liver to the kidneys.
- Hormones.
- Antibodies and antitoxins produced by the white blood cells.
57
What is artificial blood?
- A blood substitute, e.g. a salt solution ("saline") which is used to replace the lost volume of blood.
- It's safe (if no air bubbles get into the blood) and can keep people alive even if they lose 2/3 of heir red blood cells.
- This may give the patient enough time to produce new blood cells. If not, that patient will need a blood transfusion.
58
What are the two options when someone loses a lot of blood?
- Artificial blood as a blood substitute, e.g. a salt solution ("saline") used to replace lost volume of blood.
- Blood transfusion.
59
What is the most ideal treatment when someone loses a lot of blood?
-Ideally, an artificial blood product would replace the function of the red blood cells, so that there's no need for a blood transfusion. These are being developed but currently have problems with side-effects.
60
What are artificial hearts?
-Artificial hearts are mechanical devices that are put into a person to pump blood if their heart fails. They're usually used as a temporary fix, to keep a person alive until a donor heart can be found. In some cases, they're used as a permanent fix, which reduces the need for a donor heart.
61
What is the main advantage of using artificial hearts?
-They're less likely to be rejected by the body's immune system than donor hearts. This is because they're made from metals or plastics, so the body doesn't recognise them as 'foreign' and attack them in the same way as it does with living tissue.
62
What are the disadvantages to artificial hearts?
- Surgery to fit an artificial heart can lead to bleeding and infection.
- Also, artificial hearts don't work as well as healthy ones - parts of the heart could wear out or the electric motor could fail.
- Blood doesn't flow through artificial hearts as smoothly, which can cause blood clots and lead to strokes.
- The patient has to take drugs to thin their blood and make sure clotting doesn't happen ^^^, which can cause problems with bleeding if they're hurt in an accident.
63
What is the treatment if it's just the heart valves that are defective?
- If it's just the heart valves that are defective, they can be replaced with mechanical valves.
- Replacing a valve is a much less drastic procedure than a whole heart transplant. But fitting artificial valves is still major surgery and there can still be problems with blood clots.
64
What is Coronary heart disease?
-Coronary heart disease is when the arteries that supply the blood to the muscle of the heart get blocked by fatty deposits. This causes the arteries to become narrow and blood flow is restricted - this can result in a heart attack.
65
What are stents?
- Stents are hollow metal tubes that are inserted inside arteries. They keep them open, making sure blood can pass through to the heart muscles. This keeps the person's heart beating (and the person alive).
- Stents are a way of lowering the risk of a heart attack in people with coronary heart disease.
66
What are the disadvantages to using stents to treat Coronary heart disease?
- But over time, the artery can narrow again as stents can irritate the artery and make scar tissue grow.
- The patient also has to take drugs to stop blood clotting on the stent.
67
What is homeostasis?
-Homeostasis is the maintenance of a constant internal environment.
68
What are the six main things that need to be controlled in the human baby?
- First four are all things you need, but at just the right level - not too much/too little:
- The body temperature can't get too hot or too cold.
- Water content mustn't get too high or too low, or too much water could move into or out of cells and damage them.
- Ion content, same as above ^^^.
- The blood sugar levels need to stay within certain limits.
- The last two are waste products - they're constantly produced in the body and you need to get rid of them:
- Carbon Dioxide is a product of respiration. It's toxic in high qualities so it's got to be removed. It leaves the body by the lungs when you breathe out.
- Urea is a waste product made from excess amino acids.
69
Why must the body temperature be carefully monitored and at what temperature?
- All enzymes work best at certain temperatures. The enzymes within the human body work best at about 37degrees.
- If the body gets too hot or too cold, the enzymes won't work properly (will be denatured if it gets too hot) and some really important reactions could be disrupted.
- In extreme cases, this can even lead to death.
70
How is the body's temperature controlled at about 37degrees?
- Thermoregulatory centre in the brain - personal thermostat.
- Contains receptors that are sensitive to the temperature of the blood flowing through the brain.
- The thermoregulatory centre also receives impulses from the skin, giving information about skin temperature.
71
How does your body respond if you're getting too hot?
- Hairs lie flat (decrease surface area/heat transfer).
- Sweat is produced by sweat glands and evaporates from the skin, which removes heat (when sweat evaporates, it takes its heat energy with it, decreasing the body temperature).
- The blood vessels supplying the skin dilate so more blood flows close to the surface of the skin. This makes it easier for heat to be transferred from the blood to the environment (therefore, decreasing the body temperature).
72
What does your body do if you're getting too cold?
- Hairs stand up to trap an insulating layer of air.
- No sweat is produced by the sweat glands.
- Blood vessels supplying skin capillaries contract to close off the skin's blood supply (to limit amount of heat transfer/loss from blood to the environment).
- When you're cold you shiver too (your muscles contract automatically/spasm). This needs respiration, which releases some energy to warm the body.
73
What are the three main jobs of the kidney?
- Remove urea from the blood.
- Adjustment of ions in the blood.
- Adjustment of water content of the blood.
74
How and why do kidneys remove urea from the blood?
- Proteins can't be stored by the body - so any excess amino acids are converted into fats and carbohydrates, which can be stored.
- This process occurs in the liver. Urea is produced as a waste product from these reactions.
- Urea is poisonous. It's released into the bloodstream by the liver. The kidneys then filter it out of the blood. It's temporarily stored in the bladder in urine and excreted from the body.
75
How and why do the kidneys adjust ion content in the blood?
- Ions such as sodium are taken into the body in food, and then absorbed into the blood.
- If the ion (or water) content of the body is wrong, could upset the balance between ions + water, meaning too much or too little water is drawn into the cells by osmosis. Having the wrong amount of water can damage cells or mean they don't work as well as normal.
- Excess ions are removed from the kidneys. For example, a salty meal = far too much sodium, so kidneys will remove the excess sodium ions from the blood.
- Some ions are also lost in sweat.
- Balance is always maintained by the kidneys.
76
How and why do the kidneys adjust the water content of the blood?
- Water is taken into the body as food and drink and is lost from the body in three main ways:
1) In urine. 2) In sweat. 3) In the air we breathe out.
- Body has to constantly balance the water coming in against the water going out. Our bodies can't control how much we lose in our breath, but we do control the other factors. This means the water balance is between:
1) Liquids consumed. 2) Amount sweated out. 3) Amount excreted but the kidneys in the urine.
77
What will happen on a cold day to our urine volume and colour?
-On a cold day, if you don't sweat, you'll produce more urine which will be pale and dilute (as there will be more water).
78
What will happen on a hot day to our urine volume and colour?
- On a hot day, you sweat a lot, and you'll produce less urine which will be dark-coloured and concentrated.
- Th water lost when it is hot has to be replaced with water from food and drink to restore the balance.
79
What do sports drinks do?
- Sports drinks (which usually contain water, sugar and ions) can help keep things in order.
- The water and ions (e.g. sodium) replace those lost in sweat, while the sugar can replace the sugar that's used up by muscles during exercise.
80
What do some sport drink manufacturers claim and how can you test this claim?
- Some sport drink manufacturers claim that their products will rehydrate you faster than plain water/improve your endurance (how long you stay exercising for).
- To judge if you can believe claims like this or not, you need to watch out for:
- Is the report a scientific study, published in a reputable journal?
- Written by a qualified person (not connected wth people selling it - independent company).
- Sample of people asked/tested large enough to give reliable results?
- Have there been other studies which found similar results?
81
What are nephrons?
-Nephrons are the filtration units in the kidneys.
82
How do kidneys function (what order does it go in)?
- Ultrafiltration.
- Reabsorption.
- Release of wastes.
83
What is ultrafiltration (what happens at this stage)?
- A high pressure is built up which squeezes water, urea, ions and sugar out of the blood and into the Bowman's capsule.
- The membranes between the blood vessels + the Bowman's capsule act like filters, so big molecules like proteins and blood cells are not squeezed out. They stay in the blood.
84
What is reabsorption (what happens at this stage of the kidney function)?
- As the liquid flows along the nephron, useful substances are reabsorbed back into the blood:
- All the sugar is reabsorbed. This involves the process of active transport against the concentration gradient.
- Sufficient ions are reabsorbed. Excess ions are not. Active transport is needed.
- Sufficient water is reabsorbed.
85
What is release of wastes (what happens at his stage of the kidney function)?
-The remaining substances (including urea) continue out of the nephron, into the ureter and down to the bladder as urine then released as urine/we out of the body.
86
What substances are and aren't absorbed by the kidney from the blood into the nephron/Bowman's capsule?
- Are - Water, urea, ions and sugar.
| - Aren't - Big molecules, like proteins and blood cells.
87
Which substances are and aren't reabsorbed by the blood from the nephrons in the kidneys?
- Are - All the sugar is reabsorbed - by active transport (against concentration gradient).
- Are - Sufficient ions are reabsorbed. Active transport is needed (against concentration gradient).
- Aren't - Excess ions are not reabsorbed.
- Are - Sufficient water is reabsorbed.
- Aren't - Excess water is not reabsorbed.
- Aren't - Urea is not reabsorbed at all.
88
What happens if the kidneys don't work properly?
-Waste substances build up in the blood and you lose your a I,it's to control the levels of ions and water in your body. Eventually this results in death.
89
What are two options for people with kidney failure?
- Can be kept alive by having dialysis treatment - where machines do the job of the kidneys.
- Or they can have a kidney transplant.
90
What are dialysis machines and how do they work?
- Has to be done regularly to keep concentrations of dissolved substances in the blood at normal levels, and to remove waste substances.
- In dialysis machine the person's blood flows alongside a selectively permeable barrier, surrounded by dialysis fluid. Permeable to things like ions and waste substances, but not big molecules like proteins (just like the membranes in the kidney).
- Dialysis fluid has the same concentration of dissolved ions and glucose as healthy blood.
- Means that useful dissolved ions and glucose won't be lost from the blood during dialysis.
- Only waste substances (such as urea) and excess ions and water diffuse across the barrier.
91
What are disadvantages to dialysis machines as a treatment for kidney failure?
- Many patients with kidney failure have to have a dialysis session three times a week. Each session takes 3-4 hours - interferes with everyday plans is an inconvenience for people with kidney failure/dialysis sessions.
- Dialysis may cause blood clots or infections.
92
What is the only cure at the moment for kidney disease?
-Kidney transplants.
93
How are people treated with a kidney transplant?
-Healthy kidneys are usually transplanted from people who have died suddenly, say in a car accident, and who are on the organ donor register or carry a donor card (provided the relatives give the go-ahead). But kidneys can also be transplanted from people who are still alive - most of us have two of them which is kind of unnecessary - we can live with just one.
94
What are disadvantages to kidney transplants as a treatment for kidney diseases?
-Donor kidney can be rejected but the patient's immune system - foreign antigens on donor kidney are attacked by the patient's antibodies.
95
How is organ rejection kept to a minimum or prevented?
- A donor with a tissue type that closely matches the patient is chosen. Tissue type is based on antigens - proteins on surface of most cells.
- Patient is treated with drugs that suppress the immune system, so that their immune system won't attack the transplanted kidney.
96
What are the two hormones that control the glucose levels in the blood?
- Glucagon.
| - Insulin.
97
What happens if the kidneys don't work properly?
-Waste substances build up in the blood and you lose your a I,it's to control the levels of ions and water in your body. Eventually this results in death.
98
What are two options for people with kidney failure?
- Can be kept alive by having dialysis treatment - where machines do the job of the kidneys.
- Or they can have a kidney transplant.
99
What are dialysis machines and how do they work?
- Has to be done regularly to keep concentrations of dissolved substances in the blood at normal levels, and to remove waste substances.
- In dialysis machine the person's blood flows alongside a selectively permeable barrier, surrounded by dialysis fluid. Permeable to things like ions and waste substances, but not big molecules like proteins (just like the membranes in the kidney).
- Dialysis fluid has the same concentration of dissolved ions and glucose as healthy blood.
- Means that useful dissolved ions and glucose won't be lost from the blood during dialysis.
- Only waste substances (such as urea) and excess ions and water diffuse across the barrier.
100
What are disadvantages to dialysis machines as a treatment for kidney failure?
- Many patients with kidney failure have to have a dialysis session three times a week. Each session takes 3-4 hours - interferes with everyday plans is an inconvenience for people with kidney failure/dialysis sessions.
- Dialysis may cause blood clots or infections.
101
What is the only cure at the moment for kidney disease?
-Kidney transplants.
102
How are people treated with a kidney transplant?
-Healthy kidneys are usually transplanted from people who have died suddenly, say in a car accident, and who are on the organ donor register or carry a donor card (provided the relatives give the go-ahead). But kidneys can also be transplanted from people who are still alive - most of us have two of them which is kind of unnecessary - we can live with just one.
103
What are disadvantages to kidney transplants as a treatment for kidney diseases?
-Donor kidney can be rejected but the patient's immune system - foreign antigens on donor kidney are attacked by the patient's antibodies.
104
How is organ rejection kept to a minimum or prevented?
- A donor with a tissue type that closely matches the patient is chosen. Tissue type is based on antigens - proteins on surface of most cells.
- Patient is treated with drugs that suppress the immune system, so that their immune system won't attack the transplanted kidney.
105
What are the two hormones that control the glucose levels in the blood?
- Glucagon.
| - Insulin.
106
What type of foods puts glucose into the blood from the gut?
-Carbohydrate puts glucose (type of sugar) unit the blood from the gut.
107
What happens when the blood glucose level is too high?
- Insulin is added.
- Blood has too much glucose.
- Insulin is secreted by the pancreas. So therefore there is too much glucose but also insulin in the blood.
- Insulin and glucose are removed by the liver.
- Insulin makes liver turn glucose into glycogen (stored glucose).
- So blood glucose levels are then reduced.
108
What happens when blood glucose levels are too low?
- Glucagon is added.
- Blood has too little glucose.
- Glucagon is secreted by the pancreas.
- So the blood now has too little glucose but also glucagon.
- Glucagon is absorbed by the liver.
- Glucagon makes the liver turn glycogen into glucose.
- Glucose is added to the blood by the liver.
- Blood glucose levels are then increased.
109
What is type 1 diabetes caused by?
- Lack of insulin.
- Type one diabetes is a condition where the pancreas produces little to no insulin. The result is that a person's blood glucose can rise to a level that can kill them.
110
List 3 ways Type 1 diabetes can be treated.
- Limiting the intake of foods rich in simple carbohydrates, I.e. Sugars (cause blood glucose levels to rise rapidly).
- Regular exercise - helps to lower the blood glucose level.
- Insulin therapy - involves injecting insulin into the blood. People with type 1 diabetes usually have several injections of insulin throughout the day, which are likely to be at mealtimes. This makes sure that glucose is removed from the blood quickly once the food has been digested. Stops the level of glucose in the blood from getting too high and is a very effective treatment.
111
What does the amount of insulin that needs to be injected depend on?
-The person's diet and how active they are.
112
Howard insulin injections different now from how. Used to be?
- Insulin used to be extracted from the pancreases of pigs or cows, but now human insulin is made by genetic engineering.
- Human insulin doesn't cause adverse reactions in patients, like animal insulin did.
113
What are the disadvantages to insulin injections?
-Although insulin injections help to control a person's blood glucose level, they can't be controlled as accurately as having a normal working pancreas, so may still have long-term health problems.
114
What is a possible treatment for diabetic So?
-A pancreas transplant.
115
What are the advantages and disadvantages to having a pancreas transplant for a diabetic?
+A successful operation means they won't have to inject themselves with insulin again.
-With any organ transplant, your body can reject the tissue.
-If the organ is rejected you have to take costly immunosuppressive drugs, which often have serious side-effects.
+Modern research into artificial pancreases and stem cell research may mean the elimination of organ rejection, but there's a long way to go yet.
116
Why is our population of the world rapidly increasing?
-Modern medicine and farming methods, which have reduced the number of people dying from dying from disease and hunger.
117
What effects has the rising population on Earth had on the Environment?
- Our increasing population outs pressure on the environment, as we take the resources we need to survive.
- People around the world are demanding a higher standard of living (demand luxuries to make life comfortable - cars, computers, etc). So we use more raw materials (e.g. oil to make plastics), but we also use more energy for the processes. So, we're taking more and more resources from the environment quickly.
- Many raw materials are being used up quicker than they're being replaced. So if we carry on like we are, one day we're going to run out.
118
What are we more likely to do as we produce more?
-As we produce more things we produce more waste. Unless this is handled, more harmful pollution will be caused.
119
What three things does pollution affect?
- Water.
- Land.
- Air.
120
How is water affected by pollution?
- Sewage/toxins chemicals from industry can pollute lakes, rivers and oceans, affecting the plants and animals that rely on them for survival (including humans).
- The chemicals used on land (e.g. fertilisers) can be washed into water.
121
How is the land affected by pollution?
- Use toxic chemicals for farming (e.g. pesticides and herbicides).
- We also bury nuclear waste underground, and we dump a lot of household waste in landfill sites.
122
How is the air affected by pollution?
-Smoke/gases released into the atmosphere can pollute the air, e.g. sulfur dioxide can cause acid rain.
123
What are the four ways humans are reducing the amount of land and resources available to other animals and plants?
- Building.
- Farming.
- Dumping waste.
- Quarrying for metal ores.
124
What are the 3 ways carbon dioxide can be sequestered ('locked up') in natural stores?
- Oceans, lakes and ponds.
- Green plants, where it's stored as carbon compounds. Green plants remove CO2 from the atmosphere during photosynthesis.
- Peat bogs.
- Storing in these ways is really important as it means CO2 is removed from the atmosphere.
125
What are the two gases that trap the heat from the Sun?
- Carbon dioxide.
| - Methane.
126
What is the temperature on the Earth a balance between?
-Temperature on Earth is a balance between the heat it gets from the Sun and the heat it radiates back out into space.
127
What do gases in the atmosphere act like?
- Gases in the atmosphere act like an insulating layer. They absorb most of the heat that would normally be radiated out into space, and re-radiate it in all directions (including back towards the Earth) (the greenhouse effect).
- If this didn't happen, then at night there'd be nothing to keep any heat in, and we'd quickly get very cold.
128
What are "greenhouse gases"?
-There are several different gases in the atmosphere which help keep heat in. They're called "greenhouse gases". The main ones we have to worry about are carbon dioxide and methane - because levels of these are rising quite quickly.
129
What is global warming?
-The Earth is gradually heating up because of the increasing levels of greenhouse gases - this is global warming. Global warming is a type of climate change and causes other types of climate change, e.g. changing rainfall patterns.
130
What is deforestation?
-Cutting down of forests. Causes problems when it's done on a large-scale, such as cutting down rainforests.
131
Why is deforestation done?
- Done for various reasons:
- To provide timber to use as building material.
- To clear more land for farming, which is important to : provide more food, e.g. From more rice fields or farming more cattle, or, grow crops from which biofuels based on ethanol can be produced.
- To produce paper from wood.
132
What are the four main problems that deforestation leads to?
- More methane in the atmosphere: Rice is grown in warm, waterlogged conditions - ideal for decomposes. These organisms produce methane, so more is released into the atmosphere. Cattle produce methane and rearing cattle means that more methane is produced.
- More carbon dioxide in the atmosphere: Carbon dioxide = released when the trees are burnt to clear land (carbon in wood doesn't contribute to atmospheric pollution until it's released by burning). Microorganisms feeding on bits of dead wood release carbon dioxide as a waste product of respiration.
- Less carbon dioxide taken in: Cutting down loads of trees means that the amount of carbon dioxide removed from the atmosphere during photosynthesis is reduced.
- Less biodiversity: Biodiversity is the variety of different species in a habitat - the more species, greater the biodiversity. Habitats like rainforests can contain a huge number of different species, so when they are destroyed there is a danger of many species becoming extinct - biodiversity is reduced. This causes a number of lost opportunities, e.g. there are probably loads of useful products that we will never know about because the organisms that produced them have become extinct. Newly discovered plants/animals are a great source of new foods, new fibres for clothing and new medicines.
133
What does destroying peat bogs do to the atmosphere?
- Bogs are areas of land that are acidic and waterlogged. Plants that live in bogs don't fully decay when they die, because there's not enough oxygen. The partly-rotted plants gradually build up to form peat.
- So the carbon in the plants is stored as peat instead of being released into the atmosphere.
- However, peat bogs are often drained so that the area can be used as farmland, or the peat is cut up and drained to use as fuel. Peat is also sold to gardeners as compost.
- Peat starts to decompose when the bogs are drained, so carbon dioxide is released. If we continue to destroy peat bogs, more carbon dioxide will be released, adding to the greenhouse effect.
134
What is the one way people can reduce the demand for peat?
-So one way people can do their bit is by buying peat-free compost for their gardens (e.g. manure, leaf mound or bark chip pings) to reduce the demand for peat.
