Body temp, kidneys and waste B12

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Why is it important that the body keeps the level of water in the blood as constant as possible?
If the blood becomes too dilute, water moves into cells via osmosis
If the blood becomes too concentrated, water moves out of cells via osmosis
If body cells gain/lose too much water, they work less efficiently
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What are the three ways that the body loses water?
-Via the lungs during exhalation
-When we sweat we lose water, ions and urea through skin
-Via kidneys in urine
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Which type of water loss can we control and which type can we not control?
We cannot control exhalation and sweat
We can control urine
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How do the kidneys control water loss via urine?
If blood becomes too dilute, kidneys remove excess water by producing ↑ vol of urine (urea and excess ions are also removed in urine)
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How do the kidneys remove urea and adjust the level of water and ions?
Blood, which contains urea, enters the kidney via artery. Kidney removes urea + excess water/ions. These leave kidney as urine, and are stored in bladder. Blood contains no urea, then leaves kidney through vein
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How do kidneys produce urine?
The kidneys produce urine by filtration of the blood and selective reabsorption of useful substances such as glucose, some ions and water.
The kidneys are carrying out homeostasis
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How do kidneys produce urine?
Explain in more depth
Blood passes through capillaries. Small molecules (eg urea, ions, water, glucose) are filtered out of blood. These pass into tubule where all of the glucose+some of the water/ions is reabsorbed into blood. Urea + excess ions/water are released as urine
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What hormone controls the water level in the body?
ADH
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How does ADH control water level in the body if blood becomes too concentrated?
If blood becomes too concentrated, pituitary gland releases ADH into bloodstream. ADH travels to kidneys which causes kidney tubules to become ↑ permeable to water, so ↑ water can pass out of tubules, so ↑ water is reabsorbed into blood. Less urine produc
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What happens to ADH after the blood water levels return to normal? What is this called?
The pituitary gland stops releasing ADH. This is a negative feedback cycle.
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What happens if blood becomes too dilute?
The pituitary gland stops releasing ADH. Kidneys reabsorb less water back into blood, and produce more urine. Conc of water in blood returns to normal.
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What is deamination?
When a person eats more protein than they need, the liver breaks down amino acids and produces ammonia.
Ammonia is very toxic so the liver immediately converts it to urea, which is then excreted via kidneys
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What is kidney dialysis?
Some peoples kidneys fail, so their levels of water, ions and urea must be adjusted by a machine
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How does kidney dialysis work?
When kidney fails, blood contains higher conc of water, ions+urea than it should. In kidney dialysis, patients blood passes over semi-permeable membrane. This allows urea, water, ions through but does not allow larger molecules eg blood through
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How does kidney dialysis work? cont.
On other side of membrane, there is dialysis fluid, which contains normal conc of water/ions, but no urea. There is conc gradient for urea so urea diffuses from blood into fluid. As the fluid contains normal conc of water/ions, some water/ion diffuse into
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How is the concentration gradient for urea maintained?
The dialysis fluid is constantly refreshed
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What is an alternative to kidney dialysis and how does it work?
Kidney transplant
The diseased kidney is replaced with a healthy one from a donor
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Advantages of kidney dialysis
-No shortage of dialysis machines
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Disadvantages of kidney dialysis
-Patients have to visit hospital a few times a week
-Patient must eat controlled diet
-Expensive longterm
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Advantages of kidney transplant
-Allows patient to live a normal life
-Only expensive initially
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Disadvantages of kidney transplant
-Donor's kidney may be rejected by immune system so must take immunosuppressants for the rest of their life
-Shortage of kidney donors
-Dangerous operation, long recovery
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What is body temperature monitored and controlled by?
The thermoregulatory centre in the brain.
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How does the thermoregulatory centre in the brain monitor and control body temp?
The thermoregulatory centre contains receptors which are sensitive to the temp of the blood. The skin also contains temperature receptors and sends electrical impulses down sensory neurones to the thermoregulatory centre.
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How does the body respond to restore normal body temp if the body temp gets too high?
Sweat glands release sweat onto skin surface- it evaporates, taking energy from body+ cooling it.
Blood vessels dilate, so more blood flows through capillaries near skin. More radiation of heat from skins surface
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What is the word for when blood vessels dilate?
Vasodilation
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How does the body respond to restore normal body temp if the body temp gets too low?
Blood vessels constrict, so less blood flows near skins surface + hairs rise (insulating layer of air trapped)
We shiver so our skeletal muscles contract. To generate energy for this, muscle cells ↑ rate of respiration. This releases energy
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What is the word for when blood vessels constrict?
Vasoconstriction
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Other cards in this set

Card 2

Front

What are the three ways that the body loses water?

Back

-Via the lungs during exhalation
-When we sweat we lose water, ions and urea through skin
-Via kidneys in urine

Card 3

Front

Which type of water loss can we control and which type can we not control?

Back

Preview of the front of card 3

Card 4

Front

How do the kidneys control water loss via urine?

Back

Preview of the front of card 4

Card 5

Front

How do the kidneys remove urea and adjust the level of water and ions?

Back

Preview of the front of card 5
View more cards

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