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Biology > 5.1.2 Excretion > Flashcards

5.1.2 Excretion Flashcards

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1
Q

What is excretion?

A

Removal of metabolic waste from the body

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2
Q

What are the main metabolic waste products?

A
  • CO2 from cellular respiration
  • Bile pigment- from breakdown of haemoglobin
  • Nitrogenous urea- from the breAKDOWN OF EXCESS AMINO ACIDS
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3
Q

Why is ammonia converted to urea?

A

Urea is less toxic and less soluble

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4
Q

What is the renal capsule?

A

Tough fibrous outer layer of kidneys

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5
Q

What is the medulla in the kidneys?

A

The middle sections in the cortex

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6
Q

What is the renal pelvis?

A

The tubes that connect the ureter and nephrons

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7
Q

What is the role of the kidney?

A

To remove waste products from blood and produce urine

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8
Q

What process takes place at the bowman’s capsule?

A

Ultrafiltration

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9
Q

What are the three layers between the glomerulus and bowman’s capsule and what is their functions?

A
  1. Endothelium of capillary- Narrow gaps
  2. Basement membrane- Acts as filter
  3. Epithelial podocytes- Have finger ike protrusions ensuring gaps so fluid can flow through
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10
Q

What feature does the glomerulus have?

A

A high hydrostatic pressure so fluid is forced out

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11
Q

What are the only components present in the filtrate at the bowman’s capsule compared tot he blood?

A

Glucose
Amino acids
Water
Ions

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12
Q

Why are large plasma proteins not found in the bowman’s capsule filtrate?

A

Because they cannot fit through the gaps in the endothelium

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13
Q

What is selective reabsorption at the PCT?

A

Where all glucose and amino acids, sone salts and some water is reabsorbed

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14
Q

What does PCT stand for?

A

Proximal convoluted tubule

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15
Q

How are cells lining PCT adapted for absorption?

A

Microvilli- Increases surface area
Co-transporter proteins- transports glucose and amino acids in conjunction with Na+
Sodium potassium pump- Pumps NA+ out of cells and K+ into cells
Many mitochondria- supply ATP

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16
Q

What are the steps of selective reabsorption?

A
  1. Na/K pump establishes steep concentration gradient
  2. Na+ diffuse back into cells in conjunction with glucose/amino acids
  3. Glucose/ amino acids diffuse into capillaries
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17
Q

How the walls of the PCT adapted to aid reabsorption?

A

They are folded to increase rate of diffusion as there is a larger surface area so more diffusion can occur at one time

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18
Q

What is the role of the loop of Henle?

A

To reabsorb as much water as possible from the collecting duct

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19
Q

How does the loop of henle work?

A

BY creating a low water potential in the tissues of the medulla

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20
Q

What are the steps of water reabsorption in the loop of henle?

A
  1. Water leaves the permeable part of the collecting duct via osmosis
  2. Fluid remaining becomes very concentrated
  3. Na+ and Cl- diffuse out
  4. Na+/Cl- are actively transported out
  5. Very high conc of Na+/Cl- in medulla
  6. Solution becomes increasingly dilute
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21
Q

What is a counter current multiplier?

A

Using energy to maintain a concentration gradient

22
Q

What is osmoregulation?

A

The balancing and control of the water potential of the blood

23
Q

What is the role of the kidney in relation to homeostatic control of water?

A
  • The distal convoluted tubule and the collecting duct are influenced by body fluid composition y acting in signals from the posterior lobe of the pituitary gland sent by osmoreceptors.
24
Q

How do osmoreceptors work?

A

-Monitor the amount of water in the blood
- When water content is low water is lost from receptor cells via osmosis,which reduces cell volume and triggers an action potential
- Action potential causes ADH to be released into blood capillaries
- ADH acts on membranes in collecting duct making them more permeable to water
Causing concentrated urine

25
Q

How does ADH increase water absorption?

A
  1. Binds to cell surface membranes in collecting duct
  2. Causes series of enzyme controlled reactions forming active phosphorylase enzyme
  3. Phosphorylase causes vesicles with water permeable channels to move to the cell surface membrane
  4. Vesicles fuse with membrane
  5. Water can now move freely through the membrane
26
Q

How can kidney failure be triggered?

A

-kidney infections which may damage nephrons
- COntinuous high blood pressure which may damage capillaries at glomerulus

27
Q

What are the consequences of kidney failure?

A
  • Build up of toxic waste
  • FLuid accumulation
  • Disruption of balance of ions
  • More brittle bones
28
Q

What are the features of haemodialysis?

A

Takes blood from body and runs it through machine in counter current flow
Waste diffuses into dialysis fluid

29
Q

What are the features of peritoneal dialysis?

A

A tube is put through the membranes of the peritoneum which act as a filter and exchange happens across fluids

30
Q

What are the advantages and disadvantages with kidney transplants?

A

Advantages- Life saving, no longer need dialysis
Disadvantages- Need a suitable donor, have to take immunosuppressants, only usually last around ten years

31
Q

Why can pregnancy be tested for in urine?

A

Because human embryo secretes a hormone called hCG which is detected in urine

32
Q

How are substances in urine tested for?

A

By using mobile monoclonal antibodies with dyes attached so that they will bind to hormone/protein and then move up the strip along with the urine to immobilised antibodies

33
Q

What are anabolic steroids?

A

Small molecules which increase protein synthesis in cells

34
Q

What are the steps for gas chromatography?

A
  1. Sample vapourised
  2. Sample passed down tube lined with absorption agent
  3. Each substance dissolves differently in gas in different lengths of time
  4. Substances eventually absorbed in lining
35
Q

What is the name of cells in the liver and what processes do they carry out?

A
  • Hepatocytes arranged in lobules
  • Metabolic process e.g. protein synthesis,detoxification and deamination
36
Q

What is the hepatic artery?

A

Supplies oxygenated blood

37
Q

What is the purpose of the hepatic portal vein?

A
  • Supplies blood rich in nutrients from digestive system
38
Q

What is the purpose of the hepatic vein?

A

Removes deoxygenated blood from liver

39
Q

What is the purpose of the branch of the bile duct?

A

Carries bile to gall bladder to be stored

40
Q

What is the structure of a sinusoid?

A

Rows of cells with a lumen so blood can flow through

41
Q

What is the bile cannaliculus?

A

Channel for bile

42
Q

What direction does blood and bile flow in?

A

Blood= outside in
Bile= inside out

43
Q

What are the roles of kupfer cells?

A
  • Type of white blood cell
  • Help break down of old red blood cell
44
Q

Which vessel is found at the centre of a lobule?

A
  • Central vein which carries blood straight to heart
45
Q

How is CO2 removed?

A

Travels around body mainly as HCO3- or carbaminohaemoglobin
Turned back into CO2 at lungs where it is excreted

46
Q

What is respiratory acidosis?

A

Where an increase in H+ ions decreases blood PH which is then detected by respiratory centre in medulla oblongata

47
Q

Why are nitrogenous compounds formed?

A

Because body cannot store proteins/amino acids

48
Q

What is the definition of deamination?

A

Removal of amine groups from amino acids to produce ammonia

49
Q

What are the two equations in production of urea?

A

amino acid + oxygen -> ketone acid + ammonia
ammonia + CO2 -> urea + water

50
Q

NOT COMPLETE I LOST THE WILL TO LIVE

A

Biology (26 decks)

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