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A2 Biology > Module 2- Excretion > Flashcards

Module 2- Excretion Flashcards

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1
Q

What is excretion?

A

Process by which an organism gets rid of waste metabolic products, such as nitrogenous waste from amino acid metabolism and carbon dioxide from respiration. These products are harmful or toxic and would damage cells if allowed to accumulate.

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2
Q

What is the liver and what are the cells called?

A

Largest internal organ. Hepatocytes.

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3
Q

How are the cells in the liver arranged?

A

Hexagonal groups called lobules.

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4
Q

How many blood supplies does the liver have and what are they called?

A

2.

Hepatic portal vein and hepatic artery.

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5
Q

Carbohydrate metabolism

A

Glucose is converted into glycogen by the hormone insulin. Glucagon also triggers the conversion of glycogen into glucose.

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6
Q

Protein metabolism

A

Amino acids are deaminated into ammonia and keto acid. The ammonia is eventually converted into urea by the ornithine cycle.

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7
Q

Storage

A

Hepatocytes are able to store vitamins and inorganic ions.

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8
Q

Detoxification

A

The liver can convert toxins into harmless compounds. The liver can detoxify alcohol, nicotine, pathogens and a variety of drugs.

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9
Q

Breakdown of erythrocytes

A

Dead erythrocytes are broken down into a brown pigment called bilirubin.

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10
Q

Production of bile

A

Hepatocytes manufacture bile and transport bile to the gall bladder via the bile canaliculi and bile duct.

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11
Q

Lipid metabolism

A

Excess glucose is converted into fatty acids. Hepatocytes can also remove certain lipids from the blood, such as cholesterol.

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12
Q

Breakdown of hormones

A

Testosterone is a hormone that is broken down very quickly by the liver, whereas insulin is broken down more slowly.

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13
Q

What are the two processes in the liver into making urea?

A

Deamination and ornithine cycle

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14
Q

What happens in deamination and give the equation.

A

Amino group is removed from the amino acid.

amino acid + oxygen= ammonia + keto acid

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15
Q

What happens in the ornithine cycle and give the equation.

A

Ammonia is converted into urea.
Ammonia + carbon dioxide + ornithine = citrulline + water
Citrulline + ammonia = arginine + water
Arginine + water = urea + water

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16
Q

What is the function of the kidney?

A

To filter blood of unwanted waste products.

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17
Q

What the parts of the nephron?

A
  • Bowman’s capsule
  • Proximal convoluted tubule (PCT)
  • Loop of Henlé
  • Distal convoluted tubule (DCT)
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18
Q

What is in urine?

A
  • Water
  • Urea
  • Inorganic ions
  • Hormones
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19
Q

What is the fluid found in the glomerulus?

A

Blood

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20
Q

What is the fluid found in the Bowman’s capsule?

A

Glomerular filtrate

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21
Q

What is the fluid found in the collecting duct?

A

Urine

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22
Q

What is ultrafiltration?

A

The filtration of molecules across a partially- permeable membrane.

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23
Q

What is selective reabsorption?

A

The absorption of certain molecules from the fluid inside the nephron, back into the blood.

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24
Q

What are the structural barriers in ultrafiltration?

A
  1. Endothelial cells of the capillaries
  2. Bastment membranes
  3. Foot process of podocyte
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25
Q

What part of the nephron does ultrafiltration occur?

A

From the glomerulus to the Bowman’s capsule.

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26
Q

What part of the nephron does selective absorption occur?

A

From Bowman’s capsule to the proximal convoluted tubule.

27
Q

What do the cells lining the PCT possess?

A

Microvilli- increase surface area of membrane.

28
Q

What is the role of the loop of Henlé?

A

To establish a very low negative water potential in the renal medulla.

29
Q

What happens to the water potential when the filtrate enters the descending limb and why?(2)

A

Water potential decreases.

  • Entrance of Na+ and Cl- by facilitated diffusion
  • The walls of the descending limb are also permeable to water, so molecules of water are able to move down the water potential gradient into the interstitial fluid.
30
Q

What happens to the water potential as the filtrate moves into the ascending limb and why? (3)

A

Water potential increases.

  • Walls are impermeable to water molecules.
  • Na+ are actively transported out of the descending limb and Cl- follow by diffusion.
  • Decreases water potential of the interstitial fluid.
31
Q

What happens to the filtrate when going through the DCT and the collecting duct? (4)

A
  • Collecting duct carriers the tubular fluid deep into the kidney medulla.
  • The active pumping of ions by the loop of Henlé creates a steep water potential gradient between the filtrate and the interstitial fluid.
  • This difference in water potential causes water to leave the collecting duct by osmosis.
  • The tubular fluid now has a very low water potential and contains a small amount of water, urea, inorganic ions and small hormones. Urine has been formed.
32
Q

What are the specialised cells surrounding the glomerulus called?

A

Podocytes

33
Q

What is osmoregulation?

A

Homeostatic response that helps to maintain the water potential of the blood plasma at the set point.

34
Q

What does ADH stand for?

A

Anti-diaretic hormone

35
Q

Where is ADH synthesised?

A

By the neurosecretory cells in the hypothalamus

36
Q

Where is ADH released?

A

From vesicles in the synaptic knobs of the posterior pituitary gland.

37
Q

What are the receptors for ADH called?

A

Osmoreceptors

38
Q

What is the knock on effect of drinking water?

A
  • Increase in water potential of the blood.
  • Less ADH produced
  • Collecting ducts become less permeable
  • Large volume of urine produced
  • More dilute urine produced (less conc)
39
Q

What is the knock on effect of sweating after exercise?

A
  • Decrease in water potential of the blood
  • More ADH produced
  • Collecting ducts become more permeable
  • Decreased in volume of urine produced
  • More concentrated urine.
40
Q

What conditions/illnesses are diagnosed through urine testing? (7)

A
  • Pregnancy
  • Performance enhancing drugs
  • Infections (UTI and STI)
  • Presence of kidney stones
  • Kidney failure
  • Diabetes
  • Bladder cancer
41
Q

What is the effect of erythropoietin?

A

Enhances red blood cell formation

42
Q

What is the effect of testosterone/nandrolone/creatine?

A

Enhances protein synthesis in muscle cells

43
Q

Arguments for doping in sport (3)

A
  • Athletes should have the right to choose whether to take performance-enhancing drugs or not.
  • Some athletes may have medical requirements for certain drugs.
  • Athletes are under continuous pressure to succeed.
44
Q

Arguments against doping in sport (3)

A
  • Athletes are role models for young, impressionable people.
  • Sponsors and coaches have a duty to look after the health and well-being of their athletes.
  • Athletes have the right to a fair competition.
45
Q

What hormone is detected in a pregnancy test and where is it produced?

A

Human Chorionic Gonadotropin (hCG)

  • Small hormone secreted by the early placenta cells following implantation.
  • The quantity of hCG in the blood doubles everyday.
46
Q

What method is used in a pregnancy test to detect a pregnancy?

A

Paper chromatography

47
Q

What is the stationary phase in a pregnancy test?

A

The paper

48
Q

What is the mobile phase in a pregnancy test?

A

Urine

49
Q

What is the first step in a pregnancy test?

A

The hCG molecules bind to complementary-shaped monoclonal antibodies to form hCG-antibody complexes.

50
Q

What is the second step in a pregnancy test?

A

As the urine soaks up the absorbent paper, the hCG-antibody complexes are carried to a line of immobilised antibodies, to which they bind.

51
Q

What is the third step in a pregnancy test?

A

The dye molecules found in association with the hcg-antibody complexes form a second line. This is a positive result for pregnancy.

52
Q

What are the 2 types of kidney failure?

A

Acute and Chronic

53
Q

What are 3 examples of acute kidney failure?

A
  • Loss of blood supply (accident or heart failure)
  • Severe bacterial infections
  • Obstruction of the ureter, bladder or urethra.
54
Q

What are 5 examples of chronic kidney failure?

A
  • Infection (e.g Nephritis)
  • High blood pressure (hypertension)
  • Diabetes mellitus
  • Atherosclerosis
  • Obstruction of the ureter, bladder or urethra.
55
Q

What are some possible symptoms of kidney failure?

A
  • Dehydration
  • Dilute/conc urine
  • Hypertension
  • coma and convulsions
  • salt imbalance
  • fatigue
56
Q

What is the treatment for kidney failure?

A

Dialysis or a transplant

57
Q

What are the two types of dialysis?

A

Haemodialysis and peritoneal dialysis

58
Q

What does dialysis do?

A

Removes metabolic waste, excess fluids and salt from the blood over a dialysis membrane. This membrane is partially permeable. Dialysis fluid contains the correct concentrations of urea, water, salts and other substances found in blood plasma.

59
Q

What only happens in haemodialysis?

A
  • Blood from a vein is passed into a machine

- This process is performed at a health clinic, 3-4 times per week.

60
Q

What only happens in peritoneal dialysis?

A
  • The abdominal membrane is used as the partially- permeable membrane.
  • This procedure can occur at home.
61
Q

What happens in both types of dialysis?

A
  • Each session takes several hours.

- A dialysis fluid withe correct concentrations of salts, water and waste is used.

62
Q

What are the advantages of transplants? (3)

A
  • Freedom from time consuming dialysis
  • Diet is less limited.
  • A better quality of life.
63
Q

What are the disadvantages of transplants? (5)

A
  • There are side-effects (fluid retention and hypertension)
  • Major surgery with general anaesthetic is required.
  • Frequent health checks are needed for signs of immune response.
  • Surgery carries a risk of infection and damage to other organs.
  • Immunosuppressant drugs must be taken.

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