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IP Secondary 4 Biology > Chapter 1 - Excretion > Flashcards

Chapter 1 - Excretion Flashcards

(72 cards)

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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
Function of sphincter muscle
Controls the exit of urine from the bladder (When the muscle relaxes, it allows urine to flow into the urethra)
26
Kidney structure: consists of an outer ________ and an inner ________
cortex | medulla
27
Kidney structure: cortex
The outer dark red region that is surrounded by a fibrous capsule
28
Kidney structure: medulla
The inner pale red region that contains 12-16 medulla pyramids
29
Kidney structure: medulla pyramids
Conical structures that contain a large number of kidney tubules
30
Kidney structure: kidney tubules
Narrow tubules that are richly supplied with blood vessels. Urine is formed in here.
31
Kidney structure: renal pelvis
The enlarged portion of the ureter inside the kidney. The pyramids project into this funnel-like space.
32
Kidney structure: Bowman's capsule
A cup-like structure found at the beginning of the kidney tubule
33
Kidney structure: proximal convoluted tubule
A short, coiled tubule that straightens out as it enters the medulla
34
Kidney structure: loop of Henle
The U-shaped portion of the tubule in the medulla
35
Kidney structure: distal convoluted tubule
As the tubule re-enters the cortex, it coils again to form the distal convoluted tubule
36
Kidney structure: collecting duct
The tubule opens into a collecting duct which passes through the medulla and opens into the renal pelvis
37
Blood circulation at the kidney tubule (7 steps)
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
What are the 2 main processes involved in urine formation and where do they occur?
1. Ultrafiltration (occurs at the renal corpuscle) | 2. Selective reabsoprtion (occurs at the renal tubule)
39
What is ultrafiltration?
The mechanical filtration that occurs at the renal corpuscle
40
Why does ultrafiltration occur?
- There is a high hydrostatic blood pressure at the glomerulus - The basement membrane around the glomerular capillaries is like a fine filter
41
What are the 2 conditions required for ultrafiltration to take place?
1. Force: high hydrostatic pressure | 2. Filter: basement membrane around glomerular blood capillaries is partially permeable and acts as a filter
42
Ultrafiltration: What is in the filtrate?
- Water | - Small molecules such as glucose, amino acids, mineral salts, urea
43
Ultrafiltration: What is not filtered out?
Large molecules such as plasma proteins and red blood cells
44
What is selective reabsorption?
- Allows useful substances to be reabsorbed | - > 80% of the filtrate is reabsorbed at the proximal convoluted tubule
45
What is the type of transport used for selective reabsorption of glucose, amino acids and salts?
Via diffusion and active transport
46
What is the type of transport used for selective reabsorption of water?
Via osmosis
47
How are glucose, amino acids and salts reabsorbed?
1. Diffuse into the cells lining the proximal convoluted tubule 2. Actively transported into the interstitial fluid 3. Diffuse into the blood capillaries
48
How are water and salts reabsorbed?
- 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
The water potential of blood plasma needs to be ________
kept relatively constant
50
What will happen if the blood plasma | is too concentrated?
The red blood cells would dehydrate and undergo crenation
51
What will happen if the blood plasma | is too dilute?
The red blood cells would absorb water, expand and burst
52
What is osmoregulation?
The regulation of the water potential of blood plasma
53
What is the function of osmoregulation?
To maintain the water potential and concentration of salts within an organism
54
Osmoregulation is a type of ________
homeostasis
55
What does the water potential of blood plasma depend on?
The amount of water and solutes in the plasma
56
What controls the water potential of blood plasma?
Anti-diuretic hormone (ADH)
57
As blood volume is controlled by osmoregulation, ________ is also indirectly regulated
blood pressure
58
What would high blood pressure cause?
Can cause blood vessels in the brain to burst, resulting in a stroke
59
Anti-diuretic hormone (ADH) is produced by the ________
hypothalamus
60
Anti-diuretic hormone (ADH) is released by the ________
pituitary gland
61
What does anti-diuretic hormone (ADH) do?
Controls the amount of water reabsorbed by the kidney tubules (blood volume is controlled by removing excess salts and water)
62
What does ADH secretion by the pituitary gland depend on?
‘Instructions’ from the hypothalamus (has receptors that detect changes in blood water potential)
63
What happens if there is excess water in the blood?
Less ADH is secreted | Less water is reabsorbed and the urine excreted is more dilute
64
What happens if the body is dehydrated?
More ADH is secreted | More water is reabsorbed and the urine excreted is more concentrated
65
Describe the entire process of osmoregulation (excess water)
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
Describe the entire process of osmoregulation (dehydration)
1. Loss of water through sweating 2. Water potential of plasma decreases 3. This stimulates the hypothalamus → pituitary gland secretes more ADH 4. Kidney tubules reabsorb more water 5. Water potential of plasma returns to normal level
67
Kidneys are ________ and ________
excretory organs | osmoregulators
68
What is required if both kidneys fail?
A kidney transplant or dialysis
69
Describe the entire process of dialysis
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
A dialysis machine mimics ________
the function of a kidney
71
What is the composition of dialysis fluid?
It has the same composition as blood but it lacks the nitrogenous waste
72
Describe the entire process of how dialysis fluid works
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

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