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Biology year 2 > Excretion > Flashcards

Excretion Flashcards

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1
Q

Excretion-

A

removal of metabolic waste from the body eg. lungs excrete CO2

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2
Q

Excretory organs

A

Lungs- excrete CO2
Liver- deamination of amino acids producing NH3 which is converted to urea
Skin- excrete sweat which contains salts, urea, water, amino acids, ammonia
Kidney- excrete urea via urine

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3
Q

CO2 excretion

A

-reacts with water producing carbonic acid
-dissociates to H+ and HCO3-
-this is then transported to lungs

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4
Q

Nitrogenous compounds storage

A

-body can’t store proteins or amino acids
-amino acids contain energy so instead are deaminated in the liver
-this produces ammonia which is converted to urea

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5
Q

Deamination and formation of urea equation

A

amino acid + oxygen -> keto acid + ammonia

ammonia + CO2 -> urea + water

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6
Q

Blood flow to and from the liver

A

-hepatic artery- oxygenated blood travels from aorta via hepatic artery to the liver for aerobic respiration as very metabolically active
-hepatic portal vein- deoxygenated blood from digestive system enters via HPV. Blood is rich in products of digestion. blood from HA mixes with blood from HPV
-hepatic vein- blood leaves via HV and joins to vena cava
-bile duct- secretes bile for digestion and excretion. carries bile from liver to gall bladder, where it is stored

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7
Q

Structure of liver

A

-cells, blood vessels, chambers are arranged to ensure greatest contact between blood and cells
-divided to lobes, which further divide to cylindrical lobules
-HA and HPV split into smaller vessels which run parallel to lobules- inter lobule vessels
-blood from HA and HPV are mixed and pass along sinusoid (chamber), this allows close contact between cells and blood
-when blood reaches end of sinusoid, conc. of many components have been altered
-sinusoid empties into the intra-lobule vessel, which is a branch or the hepatic vein

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8
Q

Kupffer cells

A

-specialised macrophagea
-move within sinusoids
-breakdown and recycle old RBCs

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9
Q

Liver cells

A

-called hepatocytes
-cuboid shape, with microvilli on surface
-dense cytoplasm for metabolic processes

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10
Q

Liver function

A

-control of blood glucose, amino acid and lipid levels
-synthesis of bile, plasma proteins, cholesterol
-synthesis of RBC in fetus
-storage of vitamins A, D, B12, iron, glycogen
-detoxification
-break down of hormones
-destruction of RBCs

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11
Q

Detoxification enzymes

A

-catalase- converts H2O2 to water and oxygen
-cytochrome P450- group of enzymes that break down drugs eg. cocaine

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12
Q

Detoxification of alcohol

A

-ethanol dehydrogenated via ethanol dehydrogenase producing ethanal- this reduces NAD in the process
-ethanal is dehydrogenated via ethanal dehydrogenase producing ethanoate- this reduces NAD in the process
-ethanoate can convert to acetyl CoA for respiration

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13
Q

Formation of urea

A
  1. deamination
  2. ornithine cycle

amino acid -> NH3 + keto acid -> urea

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14
Q

Deamination

A

-removal of amine
-this produces ammonia and keto acid
-ammonia is highly soluble and toxic so quickly converted to urea via ornithine cycle

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15
Q

Ornithine cycle

A

-NH3, CO2 and ornithine react to produce citrulline and water
- citrulline reacts with NH3 to produce arginine and water
-arginine reacts with water to produce urea and ornithine for the cycle to continue

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16
Q

Problems of drinking too much alcohol

A

-detoxification of alcohol uses up NAD stores
-therefore they can’t be used to deal with fatty acids
-fatty acids convert to lipids to be stored as fat
-this causes the the liver to become enlarged

17
Q

kidney structure

A

have to revise in textbook as need diagrams

18
Q

Ultrafiltration

A

-blood enters glomerula knot through afferent arteriole
-this knot increases the pressure
-small molecules leave arteriole through gaps between cells
-basement membrane prevents larger molecules eg. plasma proteins leaving
-podocytes have finger like projections to ensure there’s gaps

19
Q

Selective reabsorption

A

-start with ultrafiltration where everything is removed from blood
-selective reabsorption which is where kidney takes back what it requires and occurs in the proximal convoluted tubule
-finally regulation where the kidney controls how much substance is reabsorbed

20
Q

Proximal convoluted tubule adaptations

A

-microvilli for large SA for absorption
-lots mitochondria for active transport
-membrane has co transporter proteins (Na and glucose/ amino acids)
-opposite membrane, close to capillary, folded to increase SA
-membrane has Na/K pumps

21
Q

How reabsorption occurs

A

-Na+ actively pumped out of cells lining the tubule into the blood
-conc Na+ decreases inside cell
-Na+ diffuse in from proximal tubule through co transporter protein with glucose/ amino acids
- decreases WP inside cell, so water moves in via osmosis
-glucose and amino acids diffuse into blood

22
Q

Water reabsorption and loop of henle

A

-after selective reabsorption, 45cm3 fluid left in PCT
-function of loop is to create a salt bath in surrounding medullary fluid
-later this results in water reabsorption from collecting duct
-this decreases filtrate volume

23
Q

Descending limb

A

-permeable to water and salt
-water moves out via osmosis and enters capillary
-filtrate volume decreases so filtrate salt conc increases
-base of loop is impermeable

24
Q

Ascending limb

A

-filtrate moves up ascending limb and is impermeable to water
-permeable to salt
-at base Na+ and Cl- diffuse into tissue fluid
-decreases WP fluid, so water leaves descending via osmosis

25
Q

Loop of henle collecting duct

A

-conc of medullary fluid causes water to be removed from collecting duct via osmosis
-water then enters capillaries by osmosis

26
Q

Osmoregulation-

A

control of water potential in the body

27
Q

Dehydrated

A

-osmoreceptors in hypothalamus shrink and detect change
-sends impulse to pituitary gland
-this causes it to secrete ADH
-ADH travels in blood to target cells= cells in wall of collecting duct
-causes a chain of enzyme controlled reactions
-this causes aquaporins to fuse with the membrane, increasing its permeability to water
-therefore water moves into the capillary as it has a lower WP via osmosis
-therefore, more water is reabsorbed and less urine is produced

28
Q

Hydrated

A

-detected by osmoregulatory cells in hypothalamus
-sends impulse to pituitary gland
-secretes less ADH
-collecting duct walls less permeable
-less water reabsorbed

29
Q

Assessing kidney function

A

-assess glomerular filtration rate=volume of fluid that passes into the nephrons each minute
-analyse uribe for substances eg proteins

30
Q

Causes of kidney failure

A

-diabetes
-heart disease
-hypertension
-infection

31
Q

Treatment of kidney failure

A

-haemodialysis
-peritoneal dialysis (both types renal dialysis)
-kidney transplant

32
Q

Haemodialysis

A

-blood passes into machine containing an artificial membrane
-surrounded by dialysis fluid which flows opposite direction
-heparin added to avoid clotting
-dialysis fluid contents are monitored

33
Q

Peritoneal dialysis

A

-dialysis membrane in the body’s abdominal membrane
-surgeon implants permanent tube into abdomen
-dialysis solution poured through thins and fills space between abdominal wall and organs
-after few hours solution is drained

34
Q

What happens if kidneys fail

A

-urea, water, salts and toxins aren’t excreted
-less blood filtered by glomerulus, lower glomerular filtration rate
-build up of toxins in the blood

35
Q

Kidney transplant advantages and disadvantages

A

+free from dialysis
feeling fitter
improved QoL
-immunosuppressants
major surgery
regular checks for rejection

36
Q

Urine analysis

A

can be tested for:
-glucose in diagnosis of diabetes
-alcohol to determine blood alcohol in drivers
-recreational drugs
-hCG in pregnancy testing

37
Q

Pregnancy testing

A

-urine poured onto test stick
-hCG binds to mobile antibodies attached to blue bead
-mobile antibodies move down test stick
-if hCG present it binds to fixed antibodies holding the bead in place showing a blue line
-mobile antibodies with no hCG attached binge to another fixed site to show the test is working

38
Q

Testing for anabolic steroids

A

-increase protein synthesis so increase the build up of muscles
-banned in many sports
-tested by analysing urine sample using gas chromatography

Biology year 2 (14 decks)

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