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OCR BIOLOGY (MODULE 5) > EXCRETION > Flashcards

EXCRETION Flashcards

1
Q

Define excretion

A

Removal of waste products of metabolism from the body

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2
Q

Examples of excretory substances

A

CO2- from aerobic respiration

Urea- produced from deamination of excess ammonia acids

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3
Q

What is respiratory acidosis

A

Blood pH drops below 7.35 (becoming acidic- enzymes denature)
Reduces ventilation causing increased blood CO2 concentration + reduces pH

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4
Q

Causes of respiratory acidosis

A

Blockage of airways
Chronic bronchitis
Asthma
Severe pneumonia

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5
Q

Symptoms of respiratory acidosis

A

Slow/difficulty breathing
Headache
Drowsiness
Confusion

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6
Q

The liver

A

Largest organ in body

Almost 30% blood pumped with each heartbeat flows through liver

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7
Q

Hepatic artery

From, to, contains

A

Aorta
Liver
Blood, O2 needed for aerobic respiration

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8
Q

Hepatic portal vein

From, to, contains

A

Small intestine
Liver
Blood, products of digestion (e.g. glucose, amino acids)

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9
Q

Hepatic vein

From, to, contains

A

Liver
Vena cava
Blood- CO2- waste product of respiration

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10
Q

Bile duct

From, to, contains

A

Liver
Gall bladder
Bile- produced by hepatocytes (emulsify fats)

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11
Q

Why is the hepatic portal vein an unusual blood vessel

A

Has capillaries on both ends of the vessel

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12
Q

Liver lobules

A

Liver made up of lobules (hexagons)
In centre of each lobule= branch of hepatic vein
Between lobules are branches of hepatic artery + hepatic portal vein, blood flows through here vessels throughout he lobules into the hepatic vein

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13
Q

What is each lobule made up of

A

Liver cells called hepatocytes

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14
Q

What are channels carrying blood between rows of liver cells called

A

Sinusoid

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15
Q

What are channels carrying bile (produced by hepatocytes) called

A

Canaliculus

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16
Q

What are sinusoid cells lined with

A

Kupffer cells (macrophages)

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17
Q

Hepatocytes structure

A

Simple cuboidal shape
Microvilli to increase SA
Many organelles (e.g. ribosomes, mitochondria, etc)

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18
Q

Kupffer cells

A 
Specialised macrophages (phagocytes)
Engluf bacteria
Breakdown old RBC
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19
Q

How are amino acids broken down into ammonia

A

Deamination

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20
Q

Formation of urea

A

Amine group removed forming ammonia
Remainder forms kept acid
-can enter Kerbs cycle (respiration)
-or converted into fats to be stored

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21
Q

The ornithine cycle

A

Series of metabolic reactions converting toxic ammonia to urea
Takes place in mitochondria so needs ATP

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22
Q

Chemical equation for urea

A

CO(NH2)2

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23
Q

Ornithine

A

Amino acid (not used in proteins)

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24
Q

Ammonia

A

Very soluble + toxic (must be removed)

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25
Q

Urea

A

Excretory product

Less soluble + toxic, dissolves in plasma + kidneys remove

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26
Q

Detoxification

A

Conversion of toxic molecules to less toxic molecules
E.g. enzyme catalase breaks down hydrogen peroxide into oxygen + water
Toxins made harmless by oxidation, reduction, etc

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27
Q

Ethanol

A

Drug that depresses nerve activity
Small, lipid soluble molecules
Cross plasma membrane via simple diffusion
Enters bloodstream quickly as it diffuses across stomach walls
Toxic + can damage cells

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28
Q

Detoxification of alcohol

A

Alcohol broken down int he hepatocytes with the use of enzymes
EthanOl dehydrogenase reduces ethanOl to ethanAl
EthanAl dehydrogenase reduces ethanAl to ethanoate
Ethanoate combines with coenzyme A and enters Kerbs cycle

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29
Q

Detoxification of alcohol

How is reduced NAD formed

A

Reduction of hydrogen

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30
Q

What is NAD needed for

A

Breaking down fatty acids for use in respiration

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31
Q

What is cirrhosis

A

Scarring of liver caused by long term liver damage

Prevents liver working properly

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32
Q

Cause of cirrhosis

A

Drinking too much alcohol
Being infected with hepatitis for too long
Severe form of non-alcoholic fatty liver disease (liver becomes inflamed from build up of excess fat)

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33
Q

Symptoms of cirrhosis

A

Fatigue, nausea, loss of appetite, weight loss

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34
Q

Treatment of cirrhosis

A

No cure, but its manageable
1. treat problem leading to cirrhosis (e.g. anti-viral medication to treat hepatitis)
2. cut down on alcohol intake
3, lose weight

35
Q

Prevention of cirrhosis

A

Limit alcohol intake
Protect yourself from hepatitis
Aim for healthy weight

36
Q

Role of kidneys

A

Remove waste from blood + produce urine

37
Q

Cortex

A

Outer membrane of kidney (lighter colour)

38
Q

Medulla

A

Inner membrane (darker colour)

39
Q

Role of branch of renal vein

A

Returns blood to heart

40
Q

Role of renal artery

A

Supplies kidney with blood

41
Q

Nephrons: process

A
  1. blood enters kidney through renal artery
  2. branches into arterioles called afferent arterioles + enter renal capsule of nephron
  3. divides into glomerulus
  4. merge to form efferent arteriole, which forms renal vein
42
Q

Define ultrafiltration

A

Filtration on micro-scale

43
Q

Blood vessels in Bownmans capsule

A

Afferent arteriole- enters

Effecerent arteriole- exits

44
Q

Adaptions for ultrafiltration (bowman’s capsule): basement membrane

A

Acts as filter
Any molecule up to 69,000 relative molecular mass forced out of capillary into filtrate
E.g. water, glucose, mineral ions

45
Q

Adaptions for ultrafiltration (bowman’s capsule): diameter of blood vessels

A

Afferent= greater than efferent

Builds up hydrostatic pressure in glomerulus, forcing fluid into bowman’s capsule

46
Q

Adaptions for ultrafiltration (bowman’s capsule): podocytes

A

Specialised cells with projections

Filtrate passes between rather than through

47
Q

Adaptions for ultrafiltration (bowman’s capsule): capillary endothelium

A

Fluid passes between cells rather than through

48
Q

Filtrate composition

A

Same as blood plasma except plasma proteins (too large to pass across basement membrane)

49
Q

Selective reabsorption

A

In proximal convoluted tubule, nearly 65% reabsorbed into blood

50
Q

Proximal convoluted tubule

A

Cuboidal epithelial cells
Microvilli increases SA
Mitochondria (ATP)
Blood capillaries lie closely to cells

51
Q

Stages on selective reabsorption

A
  1. Na+/K+ pump AT 3Na+ out of PCT cell
  2. decreases conc of Na+ inside PCT cell, causes Na+ to enter from filtrate via FD. Glucose +amino acids transported with Na+ through cotransporter proteins
  3. increased WP of filtrate as solutes in PCT
  4. water moves WP gradient (osmosis) through PCT into blood
  5. urea enters PCT cells via SD
  6. any large molecules reabsorbed by endocytosis
52
Q

Reabsorption of water- loop of Henle

A

Hair pin shaped tubule, into medulla
Reabsorbs water from collecting duct
Filtrate enters descending limb from PCT

53
Q

Reabsorbing water- descending limb

A

Narrow
Thin walls
Highly permeable to water- more aquaporins

54
Q

Reabsorbing water- ascending limb

A

Wider
Thick walls
Impermeable to water

55
Q

Reabsorbing water- stages

A

Na+ + Cl- AT out ascending limb into medulla
Reduces WP in interstitial region (water can’t leave A-limb as impermeable)
Water leaves D-limb by osmosis, enters interstitial region+ enters blood capillaries
Lowest WP in tip
Na+ + Cl- diffuse out of A-limb into medulla, reduces WP
WP gradient forms
Collecting duct permeable to water (osmosis) water enters capillaries
As water leaves collecting duct, WP decreases in interstitial region, water continues to leave collecting duct via osmosis

56
Q

Distal convoluted tubule- structure

A

Microvilli

Mitochondria

57
Q

Distal convoluted tubule- function

A

Controls pH + salts under influence of hormones

58
Q

Collecting tubule

A

Contains lots of water (high WP)
As tubule fluid passes down collecting duct, water moves by osmosis into medulla (reduces WP)
Water enters capillaries by osmosis + taken away

59
Q

Kangaroo rat adaptions

A

Long loops of Henle- produce concentrated urine
Bet adaption- no sweat
Produce dry faeces

60
Q

Camelids adaptions

A

Long large intestine for reabsorbing water

Fat filled hump (breaks down to supple energy- survive long desert treks)

61
Q

Jerboa adaptions

A

Dwarfed by long ears

62
Q

Define osmoregulation

A

Control of water + salt levels

63
Q

How to gain water

A

Drinking
Food
Respiration

64
Q

How to lose water

A

Sweating
Urinating
Faeces

65
Q

Osmoreceptors

A

In hypothalamus, sensitive to changes in WP

Reduced WP= water leaves cells via osmosis, causing cells to shrink

66
Q

Neurosecretary cells

A

In hypothalamus, stimulates production of ADH
Once stimulated- send AP down axon, secreting ADH into capillaries in posterior pituitary gland
Target cells for ADH in collecting duct

67
Q

How ADH effects permeability of collecting ducts

A

ADH binds with receptors on membrane of cells of collecting duct
Activates adrenaline cyclase, causes vesicle in cells to fuse with cell surface membrane
Vesicles contain aquaporins= increased permeability
Increased water in collecting duct, increases reabsorption into blood
Reduced ADH- cell membrane folds inwards forming vesicles (containing aquaporins)- reduces permeability of membrane

68
Q

Aquaporins

A

Narrow

+ve charge in centre, repels ions

69
Q

Response to dehydration

A

Reduced WP in blood
Osmoreceptors in hypothalamus reduce water
Neurosecretary cells stimulated in hypothalamus
Increases ADH production in posterior pituitary gland
ADH transported in blood plasma
ADH arrives at collecting duct
Collecting duct increases permeability
Reduces water leaving body, urine= more concentrated

70
Q

Kidney failure

A

Happens when kidneys are unable to regulate water levels of water + electrolytes, or to remove waste products

71
Q

Causes of kidney failure

A

Diabetes
Miletus
High blood pressure

72
Q

Glomerular rate

A

An estimate of how much fluid passes into nephrons each minute
Normal- 90-120 cm3/min

73
Q

Treatment- dialysis

A

Waste products/excess fluid removed from passing over partially permeable membrane of dialysis machine
With dialysis fluid on other side
Any excess will diffuse out of blood in dialysis fluid

74
Q

Haemodialysis

A

In hospital
Blood leaves Px arteries into machine
Flows between partially permeable dialysis membrane
Excess fluid leaves blood

75
Q

Peritoneal dialysis

A 
At home (in body)
Dialysis enters abdomen using catheter- left for several hours 
Dialysis takes place across peritoneal membrane (excess products in blood diffuses into peritoneal membrane- dialysis fluid)
Fluid drained + discarded
76
Q

Transplant

A

Blood vessels joined + uretar of new kidney inserted into bladder
Main problem= rejection

77
Q

Advantages of transplants

A

Less expensive than long term dialysis

Free from restrictions

78
Q

Disadvantages of transplants

A

Long waiting list

79
Q

Pregnancy testing

A

Once human embryo implants into uterus using it produces HCG hormones
HCG- small glycoprotein (passes through basement membrane into nephron) + excited in urine

80
Q

How pregnancy tests work

A
  1. urine poured onto stick
  2. HCG binds to mobile monoclonal antibody attached to blue beads
  3. HCG antibody complex binds to immobilised monoclonal antibodies in strip- blue line forms at 1st window
  4. free antibodies with no HCG attached will bind to immobilised monoclonal antibodies in 2nd window - control to show test has worked
81
Q

Effects on anabolic steroids

A

Increased muscle mass
Improved athletic performance
Mimic effect of testosterone

82
Q

Side effects of anabolic steroids

A

Physical- reduces sperm count, infertility, breast development
Medical- heart attacks, stroke, blood clots, increase blood pressure
Psychological- mood swings, aggression

83
Q

How are anabolic steroids tested

A

Drug screening

Urine sample

OCR BIOLOGY (MODULE 5) (7 decks)

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