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module 5 communication, homeostasis and energy > 5.2 excretion > Flashcards

5.2 excretion Flashcards

1
Q

Excretion

A

The removal of metabolic waste from the body

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2
Q

Metabolic Waste

A

Substance that’s produced in excess by the metabolic processes in the cells
It may become toxic

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3
Q

What products must be excreted

A

Carbon dioxide
Nitrogenous compounds
Bile

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4
Q

name and explain the role of the excretory organs

A

Lungs - carbon dioxide produced by respiration diffuses into the alveoli to be excreted
Liver - converts excess amino acids to urea , substances produced are passed into the bile to be excreted
Kidneys - kidneys remove urea from the blood to be excreted by the urethra
Skin - sweat contains range of substances (urea, uric acid, ammonia)

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5
Q

Importance of excretion

A

products of metabolism if they are left to build up can become harmful
(CO2 and ammonia are toxic)
Interfere with cell processes by altering the pH - so metabolism is prevented
Other metabolic products - act as inhibitors reduce enzyme activity

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6
Q

Importance of removing CO2

A

CO2 is transported as hydrogencarbonate ions which dissociates into H+ (and HCO3-)
H+ = affect pH = interferes with bonds in the haemoglobin = changes tertiary structure = reduces affinity for oxygen
H+ can also bind to Hb = haemoglobinic acid
CO2 can bind to Hb = carbaminohaemoglobin acid
both reduces oxygen transport

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7
Q

Importance of removing nitrogenous compounds

A

Body can’t store excess amino acids
Transported to the liver and the potentially toxic amino acid group is removed (deamination )
Initially forms ammonia and keto acid (toxic)
Converted to less soluble and toxic urea - taken to kidneys to be excreted
Keto acid can be used in respiration or converted to fat/ carbohydrate

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8
Q

name the components of the liver

A

hepatic artery
hepatic portal vein
hepatic vein
hepatocyte cells
lobules
kupffer cells
sinusoid
bile canaliculas
bile duct

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9
Q

desribe the role of the hepatic artery and the hepatic portal vein

A

h. artery = oxygenated blood from the heart travels from the aorta via the hepatic artery into the liver - liver cells are very active so lots of oxygen used in respiration
h.p. vein = deoxygenated blood from the digestive system that contains lots of nutrients, may also contain toxic compounds which can be removed by liver

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10
Q

describe the role of the hepatic vein

A

blood is removed from the liver by the hepatic vein, it rejoins the vena cava and the blood returns the body to bodys normal circulation

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11
Q

describe the role of the bile duct and the bile canaliculus

A

bile is made in the liver, released into the bile canaliculus, this joins to the bile duct where it transports thebile to the ball bladder

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12
Q

what are liver cells called

A

hepatocytes

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13
Q

what is the liver made up of/ split into

A

hepatocytes
liver is spilt into lobes which is further split into hexagonal lobules

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14
Q

what are inter lobular vessels

A

the hepatic artery and hepatic portal vein splits into smaller vessels - which run between and parallel to the lobules

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15
Q

what is a sinosoid and the role

A

wide capillary that blood passes through large hepatocyte lined spaces
the blood from the h.a and h.p.v mixes and passes along - as blood passes through the oxygen and nutrients can be removed by the hepatocyte cells

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16
Q

what is a kupffer cell

A

macrophage that moves about within the sinusoid and breaksdown and recyles rbc

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17
Q

Main functions of the liver

A

Storage of glycogen
Detoxification
Deamination/ formation of urea

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18
Q

Other functions of the liver

A

Controls blood glucose levels/ amino acid levels / lipid levels
Synthesis of bile/ plasma proteins/ cholesterol
Synthesis of red blood cells in the foetus
Breakdown of hormones
Destruction of red blood cells

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19
Q

Explain the role of liver in storing glycogen

A

storage of glycogen makes up about 8% of the weight
Glycogen forms granules in the cytoplasm of the hepatocytes
Can be broken down into blood

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20
Q

Explain what detoxification is and how it works

A

Detoxification of substances that may cause harm
Toxins broken down by oxidation, reduction, methylation or combination with other molecules
Enzymes
- catalase breaks down hydrogen peroxide
- cytochrome P450 breaks down drugs

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21
Q

Detoxification of alcohol

A

Broken down in hepatocytes by enzymes
Ethanol - ethanol dehydrogenase -> forms ethanal + H+
NAD takes H away
Ethanol - ethanal dehydrogenase -> ethanoic acid + H+
NAD takes H away
bonds with coenzyme A = acetyl coenzyme A used in respiration

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22
Q

Explain how urea is formed

A

Excess amino acids need to be converted and excreted
1. Deamination - amine group is removed from the amino acid, produces ammonia (rest of amino acid is a keto group - used in respiration)
2. The ornithine cycle - ammonia broken down to urea

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23
Q

Explain what happens in the orinthine cycle

A

Ammonia + CO2 = citrulline + H20
Citrulline + ammonia = arginine + H20
Arginine + H20 = urea + ornithine (recycled and used again)

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24
Q

overall word equation of ornithine cycle

A

ammonia + CO2 -> urea + H20

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25
name the structures of the kidney
capsule cortex medulla pelvis ureter renal artery renal vein nephrons
26
what are nephrons
functional unit of the kidney and is tiny tubules
27
name the features of a nephron (in order)
bowmans capsule glomerulus proximal convoluted tubule loop of henle -descending limb -ascending limb distal convoluted tubule collecting duct pelvis
28
what is the bowmans capsules and glomerulus
surround the glomerulus and fluid is pushed into this by ultrafiltration a knot of capillaries formed from the renal artery
29
define ultrafiltration
filtration of the blood under pressure and fluid gets pushed and filtered into the bowmans capsule
30
name the 3 layers of ultrafiltration
the endothelium of the capillary the basement membrane the epithelial cells of the bowmans capsule
31
desribe the role of the endothelium of the capillary
narrow gaps between cells of the endothelium of the capillary walls gaps/pores allow blood plasma and dissolved substances to pass out of the capillary
32
describe the role of the basement membrane
fine mesh of collagen fibres and glycoproteins acts as a filter to prevent the passage of molecules with mass greater then 69000 or large molecules proteins get held in the capillaries
33
describe the role of the epithelial cells of the bowmans capsule
cells called podocytes that have specialised shape - finger like projections creates gaps between cells so fluid from the blood in the glomerulus can pass between the cells
34
what is filtered out of the blood
water amino acids glucose urea ions
35
what is left in the capillary during ultrafiltration
blood cells and proteins
36
define selective reabsorbtion
reabsorbing molecules using active transport and cotransport
37
function of a nephron
to reabsorb about 85% of fluid in selective reabsorption leaves product of urine which has low water potential and a high concentration of solutes
38
what part of the nephron is used for selective reabsorption
proximal convoluted tubule
39
specialised features of the PCT cells for selective reabsorption
cell surface membrane is highly folded = microvilli = increases surface area for reabsorption contains cotransporter proteins that transport glucose or amino acids from the tubule into the cell Na K pumps in membrane many mitochondria = produce lots of ATP
40
mechanism of reabsorption
1. Na ions are actively pumped out of the cells lining tubule into the blood 2. concentration of Na decreases inside 3. creates conc. gradient and Na ions diffuse back into cell by a cotransport protein bringing glucose or an amino acid 4. causes water to move in by osmosis 5. glucose and amino acids diffuse into the blood
41
role of the loop of henle
reabsorption of water decreases water potential in the tissue fluid of the medulla (make more salty) descending limb is permeable to water ascending limb is not permeable to water and uses active transport to remove ions from filtrate water potential surrounding collecting duct is lower so water removed from collecting duct
42
name the components of the loop of henle
proximal convoluted tubule descending limb ascending limb distal convoluted tubule collecting duct
43
how are water and ions reabsorbed in the loop of henle
filtrate passes from PCT to the descending limb of loop of henle water moves out of the d.l by osmosis into the tissue fluid/medulla at the bottom of the limb = high concentration of urea + ions as water has left enters ascending limb = impermeable to water left in, permeable to ions ions move out by facilitated diffusion and active transport as cotransport proteins become saturated/ conc will even out but ions still need to be removed urea is left in the filtrate filtrate enters collecting duct water moves out of collecting duct urine passes down c.d to the pelvis
44
what happens to the water potential as you travel down the loop of henle
decreases more as you go deeper (down collecting duct and descending limb)
45
explain the concentration changes in the tubule fluid
glucose decreases in conc. as its selectively reabsorbed from the PCT Na+ actively transported out of the ascending limb = conc falls urea conc increases as water moves out adn urea actively moved in conc of Na+ increases as water removed in collecting duct
46
define osmoregulation
the control of water potential in the body and salt levels
47
when does osmoregulation happen
kidneys alter the volume of urine produced walls of collectind duct can be made more or less permeable conserve less water - walls of CD become less permeable = less water is reabsorbed = more urine produced conserve more water - walls of CD become more permeable = more water is reabsorbed = smaller volume of urine
48
how does ADH alter the permeabilitly of the collecting duct
ADH level increases in the blood = detected by receptors in DCT and CD = causes aquaporins to be inserted/ water permeable channels = allows more water to be reabsorbed ADH level decreases in the blood = cell surface membrane folds inwards = creates new vesicles that remove water permeable channels from membrane = more water passes down CD = more urine which is more dilute
49
ADH
antidiuretic hormone that controls the permeability of the CD
50
how is the concentration of ADH adjusted in the blood
osmoreceptors in the hypothalamus - detect water potential in the blood stimulates neurosecretory cells in the hypothalamus - release ADH store it in the postierior pituitary where it then gets secreted into the blood
51
negative feedback to control water potential
increase in water potential detected by osmoreceptors in the hypothalamus less ADH released from posterior pituitary CD walls less permeable less water reabsorbed into blood / more urine produced decrease in water potential detected by osmoreceptors in the hypothalamus more ADH released from posterioir pituitary CD walls are more permeable more water reabsorbed into blood/ less urine produced
52
what will kidney failure cause
death as watse products accumlate (urea)
53
how can kidney failure be assessed
glomerular filtration rate - the rate at which fluid enters the nephron analysing the urine for substances eg. proteins
54
causes of kidney failure
diabetes heart disease hypertension infection
55
name the treatments for kidney failure
dialysis - haemodialysis - peritoneal dialysis transplant
56
describe how dialysis works
wate products and excess fluids are removed by passing it over a partially permeable membrane dialysis fluid contains the correct amount of substances countercurrent flow allows the substances to move down the concentration gradients
57
describe the difference between haemogdialysis and peritonal dialysis
haemogdialysis - blood from an artery and passed into a machine, contaons dialysis fluid, heparin added to prevent blood clotting, air bubbles removed before returned to the blood, performed 2-3 times a week - has countercurrent flow peritoneal - dialysis membrane is the bodys abdominal perionel membrane, tube implanted into abdomen, dialysis fluid fills membrane that surrounds the organs, solution drained after several hours - no countercurrent flow
58
adavnatges of kidney transplant
freedom from time consuming dialysis feel physically fitter improved quality of life improved self image no longer chronically ill
59
disadvantages of kidney transplant
need to take immunosuppressants need for surgery/ general anaesthetic need for regualr checks for signs of rejection side effects of immunosuppressants
60
how does a pregnancy test work
Hormone (HCG) binds to free monoclonal antibodies complementary shape forms antigen antibody complex this attaches to immobilised monoclonal antibody so coloured pattern form a line test zone and control zone
61
testing for anabolic steroids
anabolic steriods increase protein synthesis gas chromotography can be used sample vapourised and passed down tube with absorbant lining substances dissolve differently in the gas and have a different retention time creates chromatogram compared to normal chromatograms

module 5 communication, homeostasis and energy (7 decks)

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