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OCR A level Biology > 5.1.2 - Excretion > Flashcards

5.1.2 - Excretion Flashcards

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1
Q

Respiratory acidosis

A

Effect of lowered blood pH (excess CO2)

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2
Q

Why must nitrogenous compounds be removed from the body

A

This is because the body cannot store amino acids, but it would be toxic to excrete them

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3
Q

Deamination

A

Process by which potentially toxic NH2 group is removed from amino acids to produce keto acids and ammonia. The ammonia is then coverted into urea (less toxic)

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4
Q

Where is CO2 from respiring tissues excreted

A

Lungs

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5
Q

Where is water from respiration excreted

A

Lungs
Bladder
Skin

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6
Q

Where is urea from the kidney excreted

A

Bladder/ kidney

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7
Q

Where are poisons excreted

A

Liver

Bladder

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8
Q

Where are drugs excreted

A

Liver

Bladder

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9
Q

Where are bile pigments from liver reactions excreted

A

Rectum (bilirubin in faeces)

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10
Q

Excretion

A

Removing metabolic waste from the body

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11
Q

Hepatic Portal Vein

A

Carries blood loaded with the products of digestion straight from the intestine to the liver (75% of the blood)

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12
Q

Hepatic Artery

A

Supplies liver w/ oxygenated blood (25% of the blood)

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13
Q

Hepatic Vein

A

Connects to inferior vena cava and carries deoxygenated blood back to heart

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14
Q

Sinusoids

A

Run from central vein to portal triads. Mixing increases O2 content of the blood from hepatic portal vein

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15
Q

Kuppfer cells

A

Hepatic macrophages that move within sinusoids
Ingest foreign particles
Recycle old RBC’s

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16
Q

What do hepatocytes do

A

Relatively unspecialised to carry out many functions
Synthesise proteins (enzymes and hormones)
Transform and store carbs (glycogen)
Synthesise cholesterol and bile salts
Form bile and secrete into bile canaliculi
Absorb substances from blood and also secrete products

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17
Q

Shape of hepatocytes

A

Cuboidal w/ many microvilli (increases SA for contact w/ sinusoids)

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18
Q

Organelles in hepatocytes

A

Rough ER
Golgi Apparatus
Mitochondria
Vesicles

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19
Q

Role of the liver in excretion

A

Break down excess amino acids and haemoglobin
Detoxifies alcohol
Produces urea

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20
Q

Basic functional unit of liver

A

Lobule

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21
Q

Protein metabolism in the liver

A

Protein synthesis of plasma proteins
Deamination to form keto acid and NH2
Transamination to make new amino acids

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22
Q

Fate of keto acids

A

Kreb’s cycle (respration)

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23
Q

Portal triads

A

Hepatic Artery
Bile duct
Hepatic Portal Vein

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24
Q

Bile canaliculi

A

Drains bile from hepatacytes to bile duct

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25
Q

Where does deamination occur

A

In hepatocytes

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26
Q

Keto acid

A

An acid with a carboxylic acid group and a ketone group

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27
Q

Equation of deamination

A

Amino acid + oxygen —> keto acid + ammonia

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28
Q

Ornithine cycle

A

2NH3 + ornithine + CO2 (from respiration) —> H2O + urea (circulates in blood until filtered by kidney)

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29
Q

Detoxification of alcohol

A

Alcohol is broken down by hepatocytes by alcohol dehydrogenase to make ethanal which is further dehydrogenated by ethanal dehydrogenase to make ethanoate
NAD is needed to oxidise and breakdown fatty acids

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30
Q

Uses of ethanoate

A

Build up fatty acids

Cellular respiration

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31
Q

Pressures in the glomerulus

A

Hydrostatic pressure
Oncotic pressure
Capsular pressure

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32
Q

Calculating net pressure in the nephron

A

Hp - (Op + Cp)

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33
Q

Where does blood leave from the nephron

A

Efferent arteriole

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34
Q

Whats in the glomerular filtrate

A 
Glucose 
Amino acids 
Ions (sodium, potassim, etc)
Urea
Water
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35
Q

Where does ultrafiltration occur

A

Bowman’s Capsule

36
Q

Process of ultrafiltration

A

Blood flows through fenestrations in endothelium then basement membrane then podocytes (3 layers)
Basement membrane consists of fine mesh of collagen fibres and glycoproteins, preventing proteins and rbc’s leaving
Podocytes have projecting fingers that wrap around capillaries
Tiny slits are left between interlocked podocytes

37
Q

How does blood reach Bowman’s capsule

A

Diameter of afferent arteriole > diameter of efferent arteriole
Build up of hydrostatic pressure in glomerulus capillaries so blood is forced through slits of podocytes into Bowman’s Capsule

38
Q

Components of nephron

A 
Glomerulus 
Bowman's capsule
Loop of Henle
Proximal convoluted tubule
Distal convoluted tubule
Collecting duct
39
Q

Glomerulus

A

High hydrostatic pressure mass of capillaries that filters blood

40
Q

Function of proximal convoluted tubule

A

Selective reabsorption

41
Q

Function of the Loop of Henle

A

Osmoregulation - creates a high conc. of Na+ and Cl- in the tissue fluid of the medulla to allow water to be reabsorbed in the collecting duct
Hairpin counter current multiplier

42
Q

Collecting ducts

A

Where several tubules join to collect the filtrate and final sodium regulation takes place in the ureter

43
Q

Features of proximal convoluted tubule

A 
Form microvilli (increases SA for 
reabsorption)
Many mitochondria 
Sodium/ potassium pump
RER to synthesise proteins 
Co transporter proteins 
Vesicles to transport substances across cell 
Tight junction between cells to prevent filtrate passing between cells
44
Q

Selective reabsorption

A

All glucose, amino acids, hormones, vitamins, and 65% Na+ and Cl- and some water are reabsorbed back into the blood
Na gets actively transported out of cytoplasm of PCT cells (Na/K pump in outer membrane)
Glucose or amino acids enter cells with Na+ by facilitated diffusion (co transporter proteins)
Water and Cl- diffuse down conc gradient as wp has increased
Blood now flowing is isotonic to tissue fluid and glomerular filtrate
All diffuse into extensive network of capillaries

45
Q

Survival advantage of Loop of Henle

A

V. concentrated urine can be produced

Conserves water and prevents dehydration

46
Q

Descending limb of Loop of Henle

A

Water moves down conc. gradient from nephron and into surrounding fluid (high salt conc.)

47
Q

Ascending limb of Loop of Henle

A

In the lower part, fluid is v. concentrated and Na+ and Cl- diffuse out into surrounding tisues
In the upper part, there is active transport of Na+ and Cl- out of the nephron. Increases water potential of fluid inside nephron (water moves out)

48
Q

Functional unit of kidney

A

Nephron

49
Q

Why do we call the processes in the Loop of Henle ‘counter current multiplication’

A

Multiplies effect of gradient

50
Q

Osmoregulation

A

Process by which organisms regulate water content of the body

51
Q

What happens a when the water potential of the blood rises above normal

A

Change detected by osmoreceptors in hypothalamus
Posterior pituitary gland releases less ADH
Decrease in permeability of collecting ducts
Dilute urine

52
Q

What happens if the water potential of the blood falls below normal levels

A

Change detected by osmoreceptors in hypothalamus
Posterior pituitary gland releases more ADH
ADH increases permeability of collecting ducts
Concentrated urine

53
Q

Osmoregulation at the collecting duct

A

ADH released by posterior pituitary gland diffuses out of the capillaries
ADH detected by cell surface receptors on the cells of the collecting ducts
Cascade of enzyme reactions triggered by cAMP
Vesicles containing aquaporins fuse to membranes of cells that line CD
More H2O absorbed in the blood

54
Q

Aquaporins

A

Channel proteins for H2O

55
Q

GFR < 60

A

Chronic kidney disease

56
Q

GFR < 15

A

Kidney failure

57
Q

Treatment for kidney failure

A

Haemdialysis
Peritoneal dialysis
Transplant

58
Q

What does dialysate contain

A

Correct conc for body (same conc as normal blood)
Includes water, glucose, salts and electrolytes
No urea

59
Q

hCG

A

A hormone released by pregnant women which prevents uterus lining from shedding

60
Q

Haemdialysis

A

Short term
Works inside body
Blood from artery flows into dialysis machine w/ blood thinners where it flows through a partially permeable membrane (basement membrane)
Lose excess ions and urea through diffusion
Blood and dialysate flow in opp. directions to maintain countercurrent exchange system (maximise rate of diffusion)
Cleaned blood returns to veins

61
Q

Peritoneal dialysis

A

Short term
Works inside of the body
Abdomen has natural dialysis membrane - peritoneum
Dialysis fluid introduced into abdomen using a catheter - takes place across peritoneum
Urea and excess mineral ions diffuse out of the blood into tissue fluid and out of peritoneal into dialysate
Fluid is then discarded leaving blood balanced

62
Q

Kidney transplants

A 
Long term (8-10 years) 
Works inside the body 
Blood vessels are joined and the ureter of the new kidney inserted into the bladder
Tissue types should be matched to reduce chances of rejection
63
Q

Pros of kidney transplant

A

Long term
Free from dialysis and dietary monitoring
Healthy kidney

64
Q

Cons of kidney transplant

A

Chance of rejection

Always has to take immunosuppressants

65
Q

Pros of peritoneal dialysis

A

Can be done at home

Patients can live relatively normal lives

66
Q

Cons of peritoneal dialysis

A

Needs to be done 4 times a day

High risk of infection

67
Q

Pros of haemdialysis

A

Needs to be done 3/4 times a week

Adds to life expectancy

68
Q

Cons of haemdialysis

A

High risk of infection
Sessions are time consuming
Have to be careful managing diet
Quite expensive

69
Q

Monoclonal antibodies

A

Produced from one plasma cell

70
Q

Relationship between length of Loop of Henle and conc of urine

A

Longer the loop of henle, more ions pass out of ascending limb into medulla
Lowers wp in medulla
More water can be reabsorbed back into blood

71
Q

Why is protein in urine a sign of chronic high blood pressure

A

High bp causes larger substances to force through basement membrane and damage capillaries

72
Q

How do pregnancy sticks work

A

Urine on reaction site travels up and monoclonal antibodies complementary to hCG bind to hCG in urine.
Mobile antibody/hCG complex binds to immobilised antibodies attached to test site
This activates dyes

73
Q

How do you know of a pregnancy test is working

A

Any excess mobile monoclonal antibodies from the reaction site bind to immobile antibodies at the control site

74
Q

What else can urine test for

A

Anabolic steroids

75
Q

Anabolic steroid tests

A

Used to boost muscle growth and strength

Urine can be tested by gas chromatography in which a gaseous solvent separates substances or mass spec

76
Q

Kidney dissection

A

Cut kidney in half (lengthways)
Cortex is lighter than medulla
Medulla contains renal pyramids (striped and cone shaped)

77
Q

Why do the renal pyramids appear stripy

A

Contain sections of the nephron e.g. collecting duct and loop of henle

78
Q

Where does the first part of the ornithine cycle occur

A

Mitochondria

79
Q

Characteristics affecting use of creatinine phosphate levels to estimate GFR

A

Diet - effects levels of cp
Exercise levels - more active patients have a higher conc of cp
Ethnicity/ genetic makeup - Diff alleles affect metabolism of cp
Gender - men and women have diff muscle mass

80
Q

Effects of kidney failure

A

Loss of electrolyte balance
Build up of urea in blood
High bp
Weakened bones - Ca/P balance in blood lost
Pain and stiff joints - abnormal proteins build up in the blood
Anaemia

81
Q

Storage of glycogen

A

Approx. 100-120g

Stored as granules in cytoplasm

82
Q

H2O2

A

Harmful waste product of many metabolic processes

83
Q

Cytochrome P450

A

Group of enzymes used to breakdown drugs and have a role in e- transport in respiration
These two functions can interfere w/ each other

84
Q

What causes fatty liver

A

If hepatocytes detoxify too much alcohol, lipids are stored in hepatocytes causing the liver to become enlarged

85
Q

Which liver cells lead to regeneration of the liver

A

Hepatocytes through cell division (mitosis)

86
Q

Distal convoluted tubule

A

Involved with balancing water and salt levels depending on needs and blood pH
Any reabsorption is done actively as all fluids are isotonic

OCR A level Biology (25 decks)

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