EXCRETION Flashcards
(83 cards)
1
Q
Define excretion
A
Removal of waste products of metabolism from the body
2
Q
Examples of excretory substances
A
CO2- from aerobic respiration
Urea- produced from deamination of excess ammonia acids
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
4
Q
Causes of respiratory acidosis
A
Blockage of airways
Chronic bronchitis
Asthma
Severe pneumonia
5
Q
Symptoms of respiratory acidosis
A
Slow/difficulty breathing
Headache
Drowsiness
Confusion
6
Q
The liver
A
Largest organ in body
Almost 30% blood pumped with each heartbeat flows through liver
7
Q
Hepatic artery
From, to, contains
A
Aorta
Liver
Blood, O2 needed for aerobic respiration
8
Q
Hepatic portal vein
From, to, contains
A
Small intestine
Liver
Blood, products of digestion (e.g. glucose, amino acids)
9
Q
Hepatic vein
From, to, contains
A
Liver
Vena cava
Blood- CO2- waste product of respiration
10
Q
Bile duct
From, to, contains
A
Liver
Gall bladder
Bile- produced by hepatocytes (emulsify fats)
11
Q
Why is the hepatic portal vein an unusual blood vessel
A
Has capillaries on both ends of the vessel
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
13
Q
What is each lobule made up of
A
Liver cells called hepatocytes
14
Q
What are channels carrying blood between rows of liver cells called
A
Sinusoid
15
Q
What are channels carrying bile (produced by hepatocytes) called
A
Canaliculus
16
Q
What are sinusoid cells lined with
A
Kupffer cells (macrophages)
17
Q
Hepatocytes structure
A
Simple cuboidal shape
Microvilli to increase SA
Many organelles (e.g. ribosomes, mitochondria, etc)
18
Q
Kupffer cells
A
Specialised macrophages (phagocytes) Engluf bacteria Breakdown old RBC
19
Q
How are amino acids broken down into ammonia
A
Deamination
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
21
Q
The ornithine cycle
A
Series of metabolic reactions converting toxic ammonia to urea
Takes place in mitochondria so needs ATP
22
Q
Chemical equation for urea
A
CO(NH2)2
23
Q
Ornithine
A
Amino acid (not used in proteins)
24
Q
Ammonia
A
Very soluble + toxic (must be removed)
25
Urea
Excretory product
| Less soluble + toxic, dissolves in plasma + kidneys remove
26
Detoxification
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
27
Ethanol
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
28
Detoxification of alcohol
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
29
Detoxification of alcohol
| How is reduced NAD formed
Reduction of hydrogen
30
What is NAD needed for
Breaking down fatty acids for use in respiration
31
What is cirrhosis
Scarring of liver caused by long term liver damage
| Prevents liver working properly
32
Cause of cirrhosis
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)
33
Symptoms of cirrhosis
Fatigue, nausea, loss of appetite, weight loss
34
Treatment of cirrhosis
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
Prevention of cirrhosis
Limit alcohol intake
Protect yourself from hepatitis
Aim for healthy weight
36
Role of kidneys
Remove waste from blood + produce urine
37
Cortex
Outer membrane of kidney (lighter colour)
38
Medulla
Inner membrane (darker colour)
39
Role of branch of renal vein
Returns blood to heart
40
Role of renal artery
Supplies kidney with blood
41
Nephrons: process
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
Define ultrafiltration
Filtration on micro-scale
43
Blood vessels in Bownmans capsule
Afferent arteriole- enters
| Effecerent arteriole- exits
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Adaptions for ultrafiltration (bowman's capsule): basement membrane
Acts as filter
Any molecule up to 69,000 relative molecular mass forced out of capillary into filtrate
E.g. water, glucose, mineral ions
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Adaptions for ultrafiltration (bowman's capsule): diameter of blood vessels
Afferent= greater than efferent
| Builds up hydrostatic pressure in glomerulus, forcing fluid into bowman's capsule
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Adaptions for ultrafiltration (bowman's capsule): podocytes
Specialised cells with projections
| Filtrate passes between rather than through
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Adaptions for ultrafiltration (bowman's capsule): capillary endothelium
Fluid passes between cells rather than through
48
Filtrate composition
Same as blood plasma except plasma proteins (too large to pass across basement membrane)
49
Selective reabsorption
In proximal convoluted tubule, nearly 65% reabsorbed into blood
50
Proximal convoluted tubule
Cuboidal epithelial cells
Microvilli increases SA
Mitochondria (ATP)
Blood capillaries lie closely to cells
51
Stages on selective reabsorption
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
Reabsorption of water- loop of Henle
Hair pin shaped tubule, into medulla
Reabsorbs water from collecting duct
Filtrate enters descending limb from PCT
53
Reabsorbing water- descending limb
Narrow
Thin walls
Highly permeable to water- more aquaporins
54
Reabsorbing water- ascending limb
Wider
Thick walls
Impermeable to water
55
Reabsorbing water- stages
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
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Distal convoluted tubule- structure
Microvilli
| Mitochondria
57
Distal convoluted tubule- function
Controls pH + salts under influence of hormones
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Collecting tubule
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
Kangaroo rat adaptions
Long loops of Henle- produce concentrated urine
Bet adaption- no sweat
Produce dry faeces
60
Camelids adaptions
Long large intestine for reabsorbing water
| Fat filled hump (breaks down to supple energy- survive long desert treks)
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Jerboa adaptions
Dwarfed by long ears
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Define osmoregulation
Control of water + salt levels
63
How to gain water
Drinking
Food
Respiration
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How to lose water
Sweating
Urinating
Faeces
65
Osmoreceptors
In hypothalamus, sensitive to changes in WP
| Reduced WP= water leaves cells via osmosis, causing cells to shrink
66
Neurosecretary cells
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
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How ADH effects permeability of collecting ducts
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
Aquaporins
Narrow
| +ve charge in centre, repels ions
69
Response to dehydration
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
Kidney failure
Happens when kidneys are unable to regulate water levels of water + electrolytes, or to remove waste products
71
Causes of kidney failure
Diabetes
Miletus
High blood pressure
72
Glomerular rate
An estimate of how much fluid passes into nephrons each minute
Normal- 90-120 cm3/min
73
Treatment- dialysis
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
Haemodialysis
In hospital
Blood leaves Px arteries into machine
Flows between partially permeable dialysis membrane
Excess fluid leaves blood
75
Peritoneal dialysis
```
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
Transplant
Blood vessels joined + uretar of new kidney inserted into bladder
Main problem= rejection
77
Advantages of transplants
Less expensive than long term dialysis
| Free from restrictions
78
Disadvantages of transplants
Long waiting list
79
Pregnancy testing
Once human embryo implants into uterus using it produces HCG hormones
HCG- small glycoprotein (passes through basement membrane into nephron) + excited in urine
80
How pregnancy tests work
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
Effects on anabolic steroids
Increased muscle mass
Improved athletic performance
Mimic effect of testosterone
82
Side effects of anabolic steroids
Physical- reduces sperm count, infertility, breast development
Medical- heart attacks, stroke, blood clots, increase blood pressure
Psychological- mood swings, aggression
83
How are anabolic steroids tested
Drug screening
| Urine sample
