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Module 5.2 Flashcards

excretion

1
Q

What is excretion

A

The removal of metabolic waste from the body

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2
Q

Why is excretion important

A

almost all products that are formed in excess by chemical processes must be removed so they do not build up and become toxic or inhibit enzyme activity

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3
Q

why must carbon dioxide be excreted

A

if it builds up in the blood it makes the blood acidic which denatures enzymes
excreted through the lungs

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4
Q

Why must nitrogenous wate be excreted

A

excess amino acids cannot be stored but as they contain a lot of energy the whole molecule should not be excreted
the amino group is removed and excreted as it is toxic while the rest is used for energy

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5
Q

how is the liver supplied with blood

A

hepatic artery
hepatic portal vein

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6
Q

role of the hepatic artery

A

oxygenated blood from the heart supplies oxygen to the very active liver cells for aerobic respiration

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7
Q

role of the hepatic portal vein

A

deoxygenated blood from the digestive system
rich in products of digestion at uncontrolled concentrations go to liver to be controlled

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8
Q

how blood leaves the liver

A

hepatic vein

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9
Q

role of the bile duct

A

carries bile which is a secretion from the liver which has functions in digestion and excretion
from the bile duct it is stored in the gallbladder

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10
Q

how is the liver divided

A

lobes which are further divided into lobules
to ensure the greatest possible contact between the blood and the liver cells

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11
Q

what happens to the blood as it enters the liver

A

as the hepatic artery and hepatic portal vein run into the liver they split into smaller vessels and run between and parallel to the lobules.
The blood from the 2 vessels mixes and pass along a sinusoid

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12
Q

role of the sinusoid

A

lined with liver cells so as blood flows along it it is in close contact with liver cells and the cells can remove substances from the blood and return other substances to the blood

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13
Q

what are kupffer cells

A

move about within sinusoids to break down and recycle old blood cells

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14
Q

what is one of the products of haemoglobin breakdown

A

bilirubin

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15
Q

where is bile released in the liver

A

into the bile canaliculi which join together to form the bile duct

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16
Q

what do the sinusoids empty into

A

branches of the hepatic vein at the centre of each lobule

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17
Q

inter-lobular vessels

A

hepatic artery
hepatic portal vein

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18
Q

intra-lobular vessel

A

hepatic vein

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19
Q

what are liver cells called

A

hepatocytes

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20
Q

specialisation of hepatocytes

A

many micro villi on the surface
dense cytoplasm for the many metabolic functions
many mitochondria

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21
Q

roles of the liver

A

storage of glycogen
detoxification
formation of urea

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22
Q

how the liver stores glycogen

A

glycogen forms granules in the cytoplasm of hepatocytes
able to store 100-120g of glycogen
glycogen can be broken down to release glucose as required

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23
Q

why does alcohol need to be detoxified

A

depresses nerve activity and contains chemical potential energy which can be used for respiration

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24
Q

first step of alcohol break down

A

ethanol dehydrogenase breaks ethanol into ethanal releasing hydrogen which combines with NAD to form reduced NAD

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25
second step of alcohol break down
ethanal dehydrogenase breaks ethanal into ethanoic acids releasing hydrogen which combines with NAD to form reduced NAD
26
final product of alcohol break down
acetyl coenzyme a which is used in respiration
27
why is the liver detoxifying too much alcohol bad
NAD is required to break down fatty acids for use in respiration If too much alcohol is detoxified the stores of NAD are used up and cannot be used for fatty acids the fatty acids are then stored as fat in the hepatocytes making the liver enlarged
28
process of deamination
removes the amino group from the amino acid producing ammonia and keto acid
29
the ornithine cycle
ammonia is soluble and toxic so must be converted to a less toxic form quickly ammonia is reacted with carbon dioxide to produce urea urea is less soluble and less toxic
30
functions of the kidney
remove waste products from the blood and produce urine
31
how are the kidneys supplied with blood
renal artery
32
regions of the kidney from outside to inside
pelvis medulla cortex capsule
33
what makes up the kidney
nephrons
34
structure of nephrons
bowman's capsule proximal convoluted tubule loop of Henle distal convoluted tubule collecting duct
35
how does blood supply the nephrons
the renal artery splits into many arterioles afferent arterioles lead into the glomerulus and efferent arterioles lead away from the glomerulus
36
what is the glomerulus
a knot of capillaries inside the Bowman's capsule
37
what is ultrafiltration
filtration of the blood at a molecular level under pressure
38
where does ultrafiltration occur
the glomerulus and Bowman's capsule
39
what are the different barriers in ultrafiltration
endothelium of the capillary basement membrane epithelial cells of the Bowman's capsule
40
how the endothelium of the capillary enables ultrafiltration
gaps between the endothelial cells the cells contain pores (fenestrations) allows plasma and the substances dissolved in it to pass out of the capillary
41
How the basement membrane enables ultrafiltration
Membrane consists of a fine mesh of collagen fibres and glycoprotein molecules with relative molecular mass over 69000 cannot pass through the mesh (most proteins and blood cells)
42
How the epithelial cells of the Bowman's capsule enable ultrafiltration
the cells (podocytes) have finger-like projections that hold the cells away from the endothelium of the capillary so the fluid from the blood in the glomerulus can pass between these cells into the lumen of the Bowman's capsule
43
how is the high pressure created in ultrafiltration
the afferent arteriole is wider than the efferent arteriole
44
what is filtered out of the blood in ultrafiltration
water amino acids glucose urea inorganic ion (sodium chloride, potassium)
45
where does selective reabsorption happen
proximal convoluted tubule
46
how selective reabsorption occurs
sodium ions are actively pumped out of the cells lining the PCT cell cytoplasm sodium ion concentration decreases sodium ions diffuse into cell in cotransporter protein carrying glucose or an amino acid at the same time water moves into cells by osmosis glucose and amino acids diffuse into blood and water follows by osmosis
47
descending limb of the loop of henle
diffusion of sodium and chloride ions into the descending limb water moves out of the limb by osmosis and enters capillaries
48
ascending limb of the loop of henle
active removal of sodium and chloride ions as the
49
function of the loop of henle
Increase the concentration of mineral ions in the tubule fluid of the descending limb and decrease the mineral ion concentration in the ascending limb creates water potential gradient in the medulla which gets steeper as it goes towards the pelvis so water can move out of the collecting duct
50
role of adh
adh binds to membrane bound receptors in the plasma membrane of collecting duct cells this causes a chain of enzyme controlled reactions resulting in vesicles containing water permeable channels (aquaporins) to fuse with the cell surface membrane making the collecting duct walls more permeable to water
51
what happens when there is a lot of adh in the blood
more water-permeable channels are inserted so more water can be reabsorbed into the blood less urine is produced and the urine has a lower water potential
52
what happens when adh levels fall
the cell surface membrane folds in on itself to create a new vesicles that removes the water-permeable channels from the membrane make the walls less permeable so less water is reabsorbed into the blood more urine is formed that has a higher water potential
53
role of osmoreceptors in the hypothalamus
monitor the water potential of the blood
54
what do osmoreceptors do when blood water potential is low
osmoreceptor cells loose water and shrink which stimulates neurosecretory cells in the hypothalamus to release ADH
55
how neurosecretory cells work
ADH is manufactured in the cells body in the hypothalamus adh moves down the axon to the terminal bulb in the posterior pituitary gland where it is stored in vesicles when stimulated the action potential is carried down the axon and adh is released by exocytosis
56
how does adh enter the blood
enters the capillaries running through the posterior pituitary gland
57
causes of kidney failure
diabetes heart disease hypertension infection
58
what is glomerular filtration rate
measure of how much fluid passes into the nephrons each minutes
59
effect of kidney failure
unable to regulate the levels of water and electrolytes in the body unable to remove waste products from the blood lower glomerular filtration rate
60
what treatments are there for kidney failure
renal dialysis (haemodialysis) transplant
61
what is dialysis fluid
contains the correct concentrations of mineral ions urea water and other substances found in the blood plasma
62
how does dialysis work
blood is passed over a partially permeable dialysis membrane that allows the exchange of substances between the blood and dialysis fluid substances in excess in the blood pass into the dialysis fluid and substances too low in the blood pass into the blood from the dialysis fluid
63
how haemodialysis works
blood from an artery or vein is passed into a machine with a dialysis membrane shaped with many capillaries to increase surface area heparin is used to prevent clotting dialysis fluid flows in the opposite direction to the blood
64
what happens in a kidney transplant
new kidney is implanted into the lower abdomen and attached to the blood supply and the bladder
65
advantages of transplant
dialysis is time consuming feel physically fitter improved quality of life (can travel)
66
disadvantages of transplant
immunosuppressant drugs major surgery under anaesthetic regular checks for rejection side effects of immunosuppressants
67
how urine analysis is used in diagnostics
any metabolic product with a relative molecular mass under 69000 can enter the nephron and if not reabsorbed can be detected in the urine e.g. glucose for diabetes, alcohol and drugs, hCG in pregnancy
68
how pregnancy testing works
hCG is a hormone that can be found in urine as early as 6 days after conception relative molecular mass less than 69000 so is found in urine monoclonal antibodies bind to hCG in urine in pregnancy test kits
69
how are anabolic steroids tested for
they are relatively small molecules and can enter the nephron urine samples are analysed using ga chromatography

Biology (25 decks)

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