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IP Secondary 4 Biology > Chapter 1 - Excretion > Flashcards

Chapter 1 - Excretion Flashcards

1
Q

The chemical reactions that take place in living cells can be categorised into ________ and ________ reactions

A

anabolic

catabolic

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2
Q

What are anabolic reactions?

A

Reactions that build up complex molecules

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3
Q

What are catabolic reactions?

A

Reactions that break down complex

molecules

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4
Q

Examples of anabolism

A
  • Photosynthesis: synthesis of glucose using carbon dioxide and water
  • Formation of glycogen from glucose molecules
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5
Q

Examples of catabolism

A
  • Oxidation of glucose during respiration to form carbon dioxide and water
  • Deamination of proteins and amino acids to form urea
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6
Q

What is metabolism?

A

The sum of all the chemical reactions within the body of an organism
(anabolism + catabolism = metabolism)

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7
Q

What do metabolic reactions produce?

A

Waste products that can harm the body if they accumulate (need to be removed)

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8
Q

What is excretion?

A

The process by which metabolic waste products and toxic substances are removed from the body

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9
Q

Most unicellular organisms excrete waste products via ________

A

simple diffusion

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10
Q

Multicellular organisms have ________ for excretion

A

excretory organs

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11
Q

What are the waste products excreted by the skin and in what form are they excreted?

A

urea, excess water, excess mineral salts
in sweat

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12
Q

What are the waste products excreted by the lungs and in what form are they excreted?

A

carbon dioxide, excess water (as water vapour)

in expired air

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13
Q

What are the waste products excreted by the liver and in what form are they excreted?

A

bile pigments

in faeces through the intestines

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14
Q

What are the waste products excreted by the kidneys and in what form are they excreted?

A

urea, excess water, excess mineral salts

in urine

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15
Q

How can carbon dioxide be excreted?

A

By the lungs, in expired air

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16
Q

How can urea and excess mineral salts be excreted?

A

By the kidney, in urine

By the skin, in sweat

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17
Q

How can excess water be excreted?

A

By the kidney, in urine
By the skin, in sweat
By the lungs, in expired air (as water vapour)

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18
Q

How can bile pigments (from breakdown of haemoglobin) be excreted?

A

By the liver, in faeces via the intestines

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19
Q

What are the components of the human urinary system?

A

kidneys, ureters, bladder, urethra, hilus, sphincter muscle

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20
Q

Function of kidney

A

Produce urine

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21
Q

Function of ureters

A

Connect the kidneys to the bladder

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22
Q

Function of bladder

A

Stores urine temporarily

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23
Q

Function of urethra

A

Passage through which urine is discharged from the bladder

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24
Q

Function of hilus

A

A concave depression where the blood vessels are connected to the kidney

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25
Q

Function of sphincter muscle

A

Controls the exit of urine from the bladder (When the muscle relaxes, it allows urine to flow into the urethra)

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26
Q

Kidney structure: consists of an outer ________ and an inner ________

A

cortex

medulla

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27
Q

Kidney structure: cortex

A

The outer dark red region that is surrounded by a fibrous capsule

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28
Q

Kidney structure: medulla

A

The inner pale red region that contains 12-16 medulla pyramids

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29
Q

Kidney structure: medulla pyramids

A

Conical structures that contain a large number of kidney tubules

30
Q

Kidney structure: kidney tubules

A

Narrow tubules that are richly supplied with blood vessels. Urine is formed in here.

31
Q

Kidney structure: renal pelvis

A

The enlarged portion of the ureter inside the kidney. The pyramids project into this funnel-like space.

32
Q

Kidney structure: Bowman’s capsule

A

A cup-like structure found at the beginning of the kidney tubule

33
Q

Kidney structure: proximal convoluted tubule

A

A short, coiled tubule that straightens out as it enters the medulla

34
Q

Kidney structure: loop of Henle

A

The U-shaped portion of the tubule in the medulla

35
Q

Kidney structure: distal convoluted tubule

A

As the tubule re-enters the cortex, it coils again to form the distal convoluted tubule

36
Q

Kidney structure: collecting duct

A

The tubule opens into a collecting duct which passes through the medulla and opens into the renal pelvis

37
Q

Blood circulation at the kidney tubule (7 steps)

A
  1. Blood enters the kidney via the renal artery
  2. Renal artery branches into many arterioles
  3. Arterioles branch into a mass of blood capillaries (glomerulus)
  4. Blood leaves glomerulus and enters blood capillaries surrounding the kidney tubule
  5. Blood capillaries unite to form venules
  6. Venules join to form renal vein
  7. Blood exits the kidney via the renal vein
38
Q

What are the 2 main processes involved in urine formation and where do they occur?

A
  1. Ultrafiltration (occurs at the renal corpuscle)

2. Selective reabsoprtion (occurs at the renal tubule)

39
Q

What is ultrafiltration?

A

The mechanical filtration that occurs at the renal corpuscle

40
Q

Why does ultrafiltration occur?

A
  • There is a high hydrostatic blood pressure at the glomerulus
  • The basement membrane around the glomerular capillaries is like a fine filter
41
Q

What are the 2 conditions required for ultrafiltration to take place?

A
  1. Force: high hydrostatic pressure

2. Filter: basement membrane around glomerular blood capillaries is partially permeable and acts as a filter

42
Q

Ultrafiltration: What is in the filtrate?

A
  • Water

- Small molecules such as glucose, amino acids, mineral salts, urea

43
Q

Ultrafiltration: What is not filtered out?

A

Large molecules such as plasma proteins and red blood cells

44
Q

What is selective reabsorption?

A
  • Allows useful substances to be reabsorbed

- > 80% of the filtrate is reabsorbed at the proximal convoluted tubule

45
Q

What is the type of transport used for selective reabsorption of glucose, amino acids and salts?

A

Via diffusion and active transport

46
Q

What is the type of transport used for selective reabsorption of water?

A

Via osmosis

47
Q

How are glucose, amino acids and salts reabsorbed?

A
  1. Diffuse into the cells lining the proximal convoluted tubule
  2. Actively transported into the interstitial fluid
  3. Diffuse into the blood capillaries
48
Q

How are water and salts reabsorbed?

A
  • At the loop of Henle, some water is reabsorbed from the filtrate in the tubule
  • At the distal convoluted tubule, some salts are reabsorbed
  • At the collecting duct, some water is reabsorbed
  • The remaining fluid in the tubule passes out of the collecting duct into the renal pelvis to form urine
49
Q

The water potential of blood plasma needs to be ________

A

kept relatively constant

50
Q

What will happen if the blood plasma

is too concentrated?

A

The red blood cells would dehydrate and undergo crenation

51
Q

What will happen if the blood plasma

is too dilute?

A

The red blood cells would absorb water, expand and burst

52
Q

What is osmoregulation?

A

The regulation of the water potential of blood plasma

53
Q

What is the function of osmoregulation?

A

To maintain the water potential and concentration of salts within an organism

54
Q

Osmoregulation is a type of ________

A

homeostasis

55
Q

What does the water potential of blood plasma depend on?

A

The amount of water and solutes in the plasma

56
Q

What controls the water potential of blood plasma?

A

Anti-diuretic hormone (ADH)

57
Q

As blood volume is controlled by osmoregulation, ________ is also indirectly regulated

A

blood pressure

58
Q

What would high blood pressure cause?

A

Can cause blood vessels in the brain to burst, resulting in a stroke

59
Q

Anti-diuretic hormone (ADH) is produced by the ________

A

hypothalamus

60
Q

Anti-diuretic hormone (ADH) is released by the ________

A

pituitary gland

61
Q

What does anti-diuretic hormone (ADH) do?

A

Controls the amount of water reabsorbed by the kidney tubules
(blood volume is controlled by removing excess salts and water)

62
Q

What does ADH secretion by the pituitary gland depend on?

A

‘Instructions’ from the hypothalamus (has receptors that detect changes in blood water potential)

63
Q

What happens if there is excess water in the blood?

A

Less ADH is secreted

Less water is reabsorbed and the urine excreted is more dilute

64
Q

What happens if the body is dehydrated?

A

More ADH is secreted

More water is reabsorbed and the urine excreted is more concentrated

65
Q

Describe the entire process of osmoregulation (excess water)

A
  1. Large intake of water (e.g. drinking)
  2. Water potential of plasma increases
  3. This stimulates the hypothalamus → pituitary gland secretes less ADH
  4. Kidney tubules reabsorb less water
  5. Water potential of plasma returns to normal level
66
Q

Describe the entire process of osmoregulation (dehydration)

A
  1. Loss of water through sweating
  2. Water potential of plasma decreases 3. This stimulates the hypothalamus → pituitary gland secretes more ADH
  3. Kidney tubules reabsorb more water
  4. Water potential of plasma returns to normal level
67
Q

Kidneys are ________ and ________

A

excretory organs

osmoregulators

68
Q

What is required if both kidneys fail?

A

A kidney transplant or dialysis

69
Q

Describe the entire process of dialysis

A
  1. Blood is drawn from a vein in the patient’s arm
  2. Blood is pumped into the dialysis machine through a tubing
  3. The tubing is bathed in a dialysis fluid and the tubing is semi-permeable
  4. Small molecules (e.g. urea) and metabolic waste products diffuse out of the tubing
  5. Larger molecules (e.g. platelets and blood cells) remain in the tubing
  6. The filtered blood is returned to a vein in the patient’s arm
70
Q

A dialysis machine mimics ________

A

the function of a kidney

71
Q

What is the composition of dialysis fluid?

A

It has the same composition as blood but it lacks the nitrogenous waste

72
Q

Describe the entire process of how dialysis fluid works

A
  1. Patient’s blood enters dialysis machine
  2. Blood flows in the direction opposite to the flow of the dialysis fluid
  3. A concentration gradient is set up between dialysis fluid and the blood
  4. Removal of metabolic waste products from the blood
  5. Filtered blood is returned to the patient

IP Secondary 4 Biology (6 decks)

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