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Biology > 5.2 Excretion > Flashcards

5.2 Excretion Flashcards

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1
Q

What is excretion?

A

The removal of waste products made from metabolic reactions, from the body.

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2
Q

What does excretion maintain!

A

normal metabolism and homeostasis

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3
Q

What are the key metabolic wastes?

A
  • Co2 from aerobic respiration
  • Nitrogenous waste from excess amino acids.
  • bile
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4
Q

What is the structure of the liver + Draw it.

A

Large lobed organ!
Hepatic artery- blood supplied to liver from heart (thick walls small lumen)
Hepatic vein - blood leaves liver (flatter and has wider lumen and thinner walls)
Hepatic portal vein- blood from small intestines to liver
Also Bile duct carrying bike from liver to hall bladder where it’s stored

Check book for drawing.

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5
Q

What are liver cells called and what are there adaptations?

A

Hepatocytes
Have lots of mitochondria large nucleus and big golgi all allowing for high metabolic rate

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6
Q

Describe the structure of lobules.

A

Little hexagon cylinders.

Made of hepatocytes and kupffer cells.

Hepatic portal vein and hepatic artery being blood and this travels by sinusoids into central vein in middle.

Bile travels down bile canalices from hepatocytes to bile duct.

Also kupffer cells on walls of sinusoids act as macrophages and engulf pathogens.

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7
Q

What are the functions of the liver

A
  • Glycogen storage
  • Detoxification of harmful substances like alcohol, paracetamol and insulin.
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8
Q

Describe Urea production stages.

A
  1. Deamination ( break down of amino acids to remove nitrogen containing amino groups into ammonia and organic acids)
  2. Ornithine cycle ( produces urea from ammonia)
    - Ammonia (NH3) binds with CO2 to make Citruline. Then Arginine and then ornithine. Atp is used twice and H20 is produced.
    - Urea is also produced and then released from liver in blood
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9
Q

Why does the ornithine cycle happen?

A

To convert ammonia into urea as it is highly toxic!

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10
Q

Why does deamination happen?

A

To make ammonia for the ornithine cycle and get rid of the excess amino acids

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11
Q

What is the structure of the kidney?

A

2 kidneys
Blood brought from aorta enters through renal artery.
Blood taken away by vena cava leaves kidneys via renal vein.
ureters lead from kidney to ureter and then ureter goes to bladder. Muscle urethra releases urine.

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12
Q

What is the inside of a kidney like? (colour wise)

A

Outside capsule (smooth membrane) is transparent.
Then the Renal cortex (brown)
Then medulla (deep red)
Renal pelvis (cream)
Ureter and renal vein and renal artery

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13
Q

What is detoxification?

A

Where harmful substances like alcohol drugs and unwanted hormones are broken down into less harmful substances that can be excreted from the body.

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14
Q

What harmful products can the liver break down and what are they broken down into?

A
  1. Alcohol broken down into ethanal then acetic acid.
  2. Paracetamol
  3. Insulin
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15
Q

How and where is glucose stored?

A
  • Gluocse is converted into glycogen in glycogenesis.
  • Glycogen then stored as granules in liver cells until needed.
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16
Q

What is it called when glucose is made into glycogen?

A

Glycogenolysis

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17
Q

What is it called when glycogen is made into glucose?

A

Glycogenisis

18
Q

What are nephrons?

A

Long tubules with capillaries where the blood is filtered. Found in kidneys.

19
Q

Draw out and label the nephrons with the cortex and medulla boundary and the different parts.

A

Check book.

20
Q

Where does ultrafiltration happen?

A

In the Bowman’s capsule and the Glomerulus. Located in the Cortex

21
Q

What is the arterys called that takes blood to the glomerulus and away?

A

Too = afferent arteriole
From = efferent arteriole

22
Q

What arteriole has a wider diameter and why is this important

A
  • Afferent arteriole has a wider diameter
  • This allows blood in glomerulus to be under high hydrostatic pressures which helps to force liquid and small molecules out of blood and into the Bowman’s capsule.
23
Q

What does Ultrafiltration produce?

A

Glomerulus filtrate

24
Q

What molecules will get forced out of the blood in ultrafiltration?

A

• Small molecules with a molecular mass of less than 6900
eg H20, glucose, amino acids, urea, ions.

25
Q

What molecules can’t pass out the blood during ultrafiltration?

A

Large proteins
Blood cells

26
Q

Describe how the molecules pass from the blood in the glomerulus into the bowman’s capsule (layers).

A

Due to the high hydrostatic pressure of blood.

  1. First through the squamous epithelium of the capillaries pores
  2. Then through the basement membrane
  3. Then through split pores of the podocytes of the inner wall of the bowman’s capsule wall
27
Q

Where does selective reabsorption happen?

A

In the PCT in the cortex

28
Q

What does selective reabsorption do?

A

Reabsorbs the useful substances like glucose vitamins and salts by active transport and facilitated diffusion

29
Q

What happens in Selective Reabsortbtion in the PCT?

A
  1. NA+ ions move into the blood and K+ ions move into the PCT cell through a sodium potassium pump. Needs ATP. This lowers the concentration gradient of NA+ ions in the PCT cell.

2 Due to the low concentration gradient of NA+ in the PCT cell NA+ ions diffuse through the membrane from the lumen into the PCT cells by a co transport protein and they bring amino acids and glucose with them.

  1. This increases the concentration gradient of amino acids in the PCT cell compared to the blood so amino acids then move out of the PCT cell into the blood down there concentration gradient via facilitated diffusion and channel proteins.
  2. This lowers the water potential in the blood so water enters the PCT cell from the lumen by osmosis and then into the blood down its water potential gradient by osmosis.
30
Q

What adaptation do the cells of walls of the PCT have?

A
  • They have microvilli to increase surface area for reabsorption of useful materials.
31
Q

What is osmoregulation?

A

The process of regulating water potential.

32
Q

Where does osmoregualtion occur?

A

In the Loop of Henle, The DCT and the collecting duct.

33
Q

What controls the water potential?

A

The osmoreceptors in the hypothalamus. They detect the water potential and send impulses to the pituitary gland to release ADH or stop releasing ADH

34
Q

What is the hormone that controls water potential?

A

ADH (anti diuretic hormone)

35
Q

What is special about the Loop of Henle?

A

It has a counter current system with the accenting and descending limb.
(HAIRPIN COUNTERCURRENT MULTIPLIER)

36
Q

Explain the steps in Osmoregualtion near the loop of henle.

A
  1. At the top of the accenting limb NA+ ions and Cl- ions are actively pumped out into the medulla using ATP. But it’s impermeable so no water leaves and this creates a low water potential in the medulla.
  2. Due to the low water potential in the medulla at the descending limb part of the Loop of henle the walls are permeable and so H20 leaves via osmosis down its water potential gradient. The walls here are impermeable to ions so no ions diffuse out and so ion conc increases in the Loop of henle.
  3. NA+ and CL- ions then are passively diffuses out of the Loop of Henle near the bottom as the walls here are permeable to ions but not to water.
  4. After this the Water potential in the medulla is lowered and so the next part is the collecting duct.
37
Q

What happens if the Loop of Henle is longer?

A

The longer the loop of henle the more water an animal can reabsorb from the filtrate.

38
Q

What animals need a long Loop of Henle?

A

Animals with water scarecity eg desert animals.

39
Q

How does regulation of water potential in the DCT and the collecting duct work?

A
  1. ADH molecules bind to receptors on the plasma membrane of cells in the DCT and the collecting duct. This causes aquaporins to be transported in vesicles to the membrane and the vesicles fuse with the membrane and this creates protein channels in which water can pass through via osmosis.
  2. This increases the permeability of the collecting duct and PCT walls to water.
40
Q

What is kidney failure?

A

When the kidneys can’t carry out there normal functions because they don’t work properly.

41
Q

How can you detect Kidney failure?

A

By measuring the GFR ( glomerular filtration rate)
If the rate is below normal is suggests kidney failure ?

42
Q

What are the methods of treating Kindey failure?

A
  1. Kidney transplant
  2. Renal dialysis

Biology (25 decks)

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