B5f: Waste Disposal

Our bodies produce waste, which is often toxic. To avoid poisoning ourselves, we must get rid of this waste. What role do our kidneys, skin and lungs play in this process? Researching methods of respiratory and kidney failure can be used to illustrate contemporary scientific and technological developments.

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What is excretion?
The removal of waste products from the body.
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What is egestion?
The removal of undigested semi-solid waste (faeces) from your ****.
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What are the three main organs involved in excretion?
The lungs, kidneys and skin.
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What three things to the kidneys excrete in urine?
Salt, Urea and Water.
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What three things is the concentration of urine affected by?
Exercise, temperature and water intake.
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How is carbon dioxide produced by the body? How is it removed?
Produced = respiration, removed = lungs
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Why is it important to maintain a constant concentration of water molecules in the plasma?
Too much water would make the plasma too dilute - causing blood cells to swell and burst but too little water would make the plasma too concentrated - causing blood cells to shrink and stop working
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Name the five structures of a kidney.
Medulla, cortex, ureter, renal vein and renal artery.
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How do the kidneys work?
Blood is filtered at high pressure to remove glucose, water, salts and urea, and ll the glucose, and some water and salts, are reabsorbed back into the blood but UREA IS NOT REABSORBED
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Talk about the production of urea and how it is excreted.
Proteins in the diet are digested to form amino acids. Excess amino acids are broken down in the liver to form ammonia. The liver converts the ammonia into urea. This is less toxic than ammonia, but must still be excreted from the body.
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Why does heat affect the concentration of urine? (small amount of concentrated urine)
When it's hot you sweat,which contains water so it causes water loss.This causes the release of ADH into the blood so the kidneys will reabsorb more water.This leaves only a small amount of excess water that needs to be got rid of.
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Why does exercise affect the concentration of urine?
Exercise makes you hot, so you swear to cool down. This produces the same effect as heat - a concentrated, small volume of urine.
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Why does water intake affect the concentration of urine?
Not drinking enough water will produce concentrated urine (since there'll be little excess water to 'dilute' to other wastes) Drinking lots of water will produce lots of dilute urine.
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Talk about Carbon Dioxide in the body and why/how it needs to be excreted.
CO2 dissolves in blood plasma,making it more acidic.Excess CO2 must be removed from body to stop it reaching toxic levels.As blood flows through lungs,excess CO2 passes out of blood&into alveoli by diffusion.Its then removed from lungs when we exhale
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Explain how the structure of the kidney tubule (nephrons) is related to filtration of the blood and formation of urine.
Each nephron has a filtering unit called the glomerulus - which is inside a capsule,a region where selective reabsorption of useful substances happens and a region where the amount of water and salt is regulated.
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What two things aren't filtered out in the glomerulus and capsule?
Big molecules like proteins and blood cells.
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Which useful substances are selectively reabsorbed? Explain.
All the sugar is reabsorbed and sufficient salt which both involve active transport and sufficient water is reabsorbed.
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What happens to the substances that are not reabsorbed?
They continue out of the nephron into the ureter and down to the bladder as urine.
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Why might a kidney dialysis machine be used?
The kidneys in some people may stop working properly. If such kidney failure happens, the patient may receive treatment with a dialysis machine.
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What does the dialysis machine do?
Removes urea from the blood and maintains correct levels of glucose and sodium ions in the blood.
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How does a kidney dialysis machine work? (SP = semi-permeable, DF = dialysis fluid and B = blood)
B from patient passes through tubes&a SP membrane separates B from DF.Urea,glucose&Na're small enough 2 diffuse from B in2 DF.Concentration of glucose&Na ions in DF are adjusted so levels in ‘cleaned’ B leaving machine is correct
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Which hormone is the concentration of our urine is controlled by? Where is it produced.
Anti-diuretic hormone or ADH. This hormone is produced by the pituitary gland in the brain.
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What does the pituitary gland monitor?
The concentration of the blood plasma. It releases ADH into the bloodstream, which travels in the blood to the kidneys. ADH increases the permeability of the kidney tubules (nephrons), causing them to reabsorb more water.
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Talk about what happens when the blood plasma is too concentrated - linked to ADH.
More ADH is released, which makes the nephrons more permeable reabsorb more water - keeping more water in the body and producing more concentrated urine.
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Talk about what happens when the blood plasma is too dilute - linked to ADH.
Less ADH is released. This makes the nephrons less permeable - reabsorb less water - making more water leave the body and producing more dilute urine.
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What is the production of ADH an example of?
A negative feedback mechanism.
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Talk about what happens if the brain detects there is too much carbon dioxide in the blood.
The brain detects increased levels of carbon dioxide in the blood. If levels are raised, it sends signals to increase the breathing rate. This means that carbon dioxide is removed from the blood more quickly, lowering the levels back to normal.
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Other cards in this set

Card 2

Front

What is egestion?

Back

The removal of undigested semi-solid waste (faeces) from your ****.

Card 3

Front

What are the three main organs involved in excretion?

Back

Preview of the front of card 3

Card 4

Front

What three things to the kidneys excrete in urine?

Back

Preview of the front of card 4

Card 5

Front

What three things is the concentration of urine affected by?

Back

Preview of the front of card 5
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