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A Level Biology > Module 5.1.2 Excretion As An Example Of Homeostatic Control > Flashcards

Module 5.1.2 Excretion As An Example Of Homeostatic Control Flashcards

1
Q

What are the different organs involved with the liver?

A

gallbladder
bile duct
duodenum
small intestine
pancreas
hepatic portal vein
hepatic artery
hepatic vein
aorta
posterior vena cava

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2
Q

What is the function of the gallbladder?

A

produces bile

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3
Q

What is the duodenum?

A

The point which the bile duct meets the small intestine

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4
Q

What is a hepatocyte?

A

A liver cell

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5
Q

What is the structure of a hepatocyte?

A

large nuclei
prominent Golgi apparatus
lots of mitochondria
divide & replicate frequently

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6
Q

Why do hepatocytes have prominent Golgi apparatus?

A

The liver is involved in metabolic processes meaning it has to do a lot of packaging lipids & extracellular proteins

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7
Q

Why do hepatocytes have lots of mitochondria?

A

The liver is a very large & metabolically active organ so it requires lots of energy (ATP)

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8
Q

Why do hepatocytes need to divide & replicate frequently?

A

Damage

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9
Q

What are the 2 main blood vessels that enter the liver?

A

The hepatic artery
The hepatic portal vein

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10
Q

What is the function of the hepatic artery?

A

Carries oxygenated blood from the heart to the liver via the aorta

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11
Q

What is the function of the hepatic portal vein?

A

Takes deoxygenated blood rich in the products of digestion from the intestines to the liver?

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12
Q

What is the structure of the hepatic artery?

A

narrow & unbranched

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13
Q

What is the structure of the hepatic portal vein?

A

wider & branched

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14
Q

What is the main blood vessel that exits the liver?

A

The hepatic vein

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15
Q

What is the function of the hepatic vein?

A

Re-joins the vena cava taking the products of liver metabolism away

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16
Q

What is a lobule?

A

A 6 sided structure made up of hepatocytes

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17
Q

What is the structure of a lobule?

A

Arranged in irregular branching & interconnected plates around a central vein (hepatic vein)

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18
Q

How does blood flow from the hepatic artery & hepatic portal vein to the hepatic vein?

A

Blood passes through sinusoids

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19
Q

What are sinusoids?

A

Large endothelium lined spaces where blood flows from the hepatic artery & hepatic portal vein to the hepatic vein

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20
Q

What is a Kupffer cell?

A

A specialised macrophage (A white blood cell)

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21
Q

What is the role of a Kupffer cell?

A

Destroy worn out red or white blood cells, bacteria & foreign matter arriving from the digestive tract as well as breaking haemoglobin down into bilirubin (brown pigment in faeces)

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22
Q

What is excretion?

A

The removal of metabolic waste, by-products or unwanted substances from normal cellular processes

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23
Q

How does excretion differ to secretion or egestion

A

secretion: internal process of producing useful products e.g. sweating
egestion: discharge of undigested by-products e.g. vomiting

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24
Q

What are the main excretory organs?

A

Lungs
Kidneys
Ureter
Bladder
Urethra

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25
Q

What are the main substances that need removing?

A

CO2 (cellular respiration)
Urea (excess amino acids)

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26
Q

How is CO2 & Urea excreted from the body?

A

Taken to their excretory organ via the bloodstream

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27
Q

How is CO2 transported in the body?

A

85% transported as HCO3- ions
10% transported as carboaminohaemoglobin
5% transported in the plasma as carbonic acid

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28
Q

What is the formula equation for the production of carbonic acid in the blood?

A

CO2 + H20 —> H2CO3

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29
Q

What is the formula equation for the dissociation of carbonic acid?

A

H2CO3 —> H+ + HCO3-

30
Q

What happens if there is too high blood CO2 levels?

A

the pH of the blood decreases & you can get respiratory acidosis

31
Q

What are the complications of respiratory acidosis?

A

slow/difficulty breathing, headache, drowsiness, tremors, confusion etc.

32
Q

What are the functions of the liver?

A

bile production
removal of excess amino acids
detoxification

33
Q

What is the function of bile?

A

emulsifies fats (breaks them down so their surface area is larger)
neutralisation of stomach acid

34
Q

What 2 processes remove excess amino acids?

A

Deamination
The ornithine cycle

35
Q

What happens during deamination?

A

The toxic amine group is turned into ammonia in the liver

36
Q

What is the word equation for deamination?

A

Amino acid + oxygen —> Keto acid + Ammonia

37
Q

What happens during the ornithine cycle?

A

Ammonia is reacted with CO2 to form urea

38
Q

Does the ornithine cycle require ATP?

A

Yes

39
Q

What is the word equation for the ornithine cycle?

A

Ammonia + Carbon dioxide —> urea + water

40
Q

What is detoxification?

A

the breakdown of substances that aren’t needed or are toxic by the liver

41
Q

What substances does the liver detoxify?

A

Lactate
Alcohol
Hormones
Medicinal Drugs

42
Q

What different structures make up the gross kidney structure?

A

Nephron
Capsule
Cortex
Medulla
Renal Vein
Renal Artery
Pelvis
Ureter

43
Q

What is the function of the capsule?

A

A protective outer layer

44
Q

What is the the cortex?

A

the outer darker layer of the kidneys

45
Q

What is the medulla?

A

The inner pale layer of the kidneys

46
Q

What is the function of the renal vein?

A

returns deoxygenated blood to the heart via the vena cava

47
Q

What is the function of the renal artery?

A

supplies oxygenated blood to the kidneys via the aorta & carries urea to the kidneys

48
Q

What is the function of the pelvis?

A

funnels the urine that is produced into the ureter

49
Q

What is the function of the ureter?

A

carries urine to the bladder

50
Q

What are the 3 functions of the kidneys?

A

ultrafiltration
selective reabsorption
control of water potential

51
Q

What is a nephron?

A

Part of the kidneys that carry out ultrafiltration of the blood to produced the most concentrated urine possible

52
Q

What are the different structures in the nephrons?

A

The bowman’s capsule
Glomerulus (not apart of the nephron)
The proximal convoluted tubule (PCT)
The loop of Henle
The distal convoluted tubule (DCT)
The collecting duct

53
Q

What is the function of the Bowman’s capsule?

A

The site of ultrafiltration

54
Q

What is ultrafiltration & how does it happen?

A

small molecules e.g. water, urea, amino acids are filtered out of the blood & passed into the nephrons through the 3 part filter

55
Q

What 3 structures make up the three part filter?

A

The endothelium of blood capillaries (glomerulus)
Basement membrane
Epithelium of the renal capusle

56
Q

What is the structure & function of the endothelium of blood capillaries

A

Very thin containing 1000s of pores 10nm in diameter which cover 30% of the capillary wall

Provides a barrier so that cells cannot pass through but plasma proteins can pass through

57
Q

What is the structure & function of the basement membrane?

A

A meshwork of collagen & glycoprotein fibres

Allows water & small molecules to pass through but proteins cannot as they get repelled by the negative charges of the fibres

58
Q

What is the structure & function of the renal capsule?

A

Made of podocytes which are specialised for filtration

59
Q

What relative molecular weight must ions & molecules be under to be able to be filtered?

A

69000 so RBC & WBC cannot

60
Q

What molecules can be filtered & what is this also known as?

A

water, glucose, amino acids, many vitamins & drugs e.g. penicillin

glomerular filtrate

61
Q

What are podocytes?

A

foot like extensions that wrap around capillaries of the glomerulus & interlink with extensions from neighbouring cells. They fit together loosely leaving filtration slits about 25nm wide which fluid passes through during filtration

62
Q

What is the glomerulus?

A

a knot of capillaries where blood is filtered from the bowman’s capsule

63
Q

What blood vessel delivers blood to the glomerulus?

A

the afferent arteriole

64
Q

What blood vessel delivers blood away from the glomerulus?

A

The efferent arteriole

65
Q

Why is the afferent arteriole wider than the efferent arteriole?

A

The pressure rises as blood enters the glomerulus so high hydrostatic pressure is generated to push the blood into the glomerulus

66
Q

What is the proximal convoluted tubule?

A

The tube closest to the Bowman’s capsule where selective reabsorption occurs

67
Q

What is the loop of Henle?

A

A tube that descends into the medulla & connects both PCT & DCT together which adds salt to the urine in order to concentrate it & remove as much water as possible

68
Q

What is the distal convoluted tubule?

A

The tube furthest away from the bowman’s capsule that delivers urine to the collecting duct & removes the salt from the urine

69
Q

What is the collecting duct?

A

a tube that collects all the urine & removes any more water to ensure urine has a low water potential & it is extremely concentrated

70
Q

Where does selective reabsorption occur?

A

The PCT -> the fluid is altered by the reabsoption of all sugars, most salts & some water?

71
Q

Why is absorption selective?

A

Because urea would end up being reabsorbed into the blood

72
Q

How is water potential controlled in the kidneys?

A

Loop of Henle -> adds salt to decrease water potential
DCT -> removes salt to regulate water potential
Collecting duct -> more water removed to further decrease & lower the water potential of urine & making sure it is concentrated

A Level Biology (15 decks)

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