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biology assessmet. > excretion yeen talmbout dat shi bruh > Flashcards

excretion yeen talmbout dat shi bruh Flashcards

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1
Q

excretion def

A

The removal of waste products of metabolism from the body, ie urea or CO2.

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2
Q

what are 2 main products of metabolism that are excreted?

A

Nitrogenous waste

CO2.

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3
Q

why is excretion important?

A

excretion is important bc it removes waste products that could build up + harm metabolic functions.

  • it helps maintain a normal metabolism
  • it helps to maintain homeostasis by helping to keep levels of certain substances in blood roughly constant
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4
Q

what are the functions of the liver

A
  • produce bile -> used to emulsify fats
  • store glycogen -> liver converts XS glucose into glycogen + stores it in granules until cell needs to respire gluc for NRG
  • deamination
  • detox
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5
Q

deamination def

A

The removal of an amino group from an amino acid, or a compound containing amino group in mitochondria + hepatocytes.

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6
Q

detoxification def

A
  • the removal of toxic substances from the body by action of liver.
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7
Q

describe the stages of deamination

A

1) amino acids used up by cells + excess is broken down into NH3 + keto acid
2) Keto acid is respired to release ATP or converted to glucose in gluconeogenesis.
3) NH3 enter ornithine cycle to be converted to UREA which is excreted in kidney as urine

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8
Q

what is the purpose of ornithine cycle?

A
  • to convert NH3 made from XS amino acids into urea which is a less toxic compound than NH3 that can be excreted in urine as it is soluble.
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9
Q

what is removed in deamination ?

A
  • amine group from amino acid.
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10
Q

what are 3 substances that are broken down in detoxification

A
  • alcohol
  • paracetamol
  • insulin
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11
Q

why is alcohol broken down in the liver

A
  • its toxic + damages cells

- excess can lead to cirrohsis which is where scar tissue of dead liver cells block blood flow

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12
Q

why is paracetemol broken down in liver

A
  • excess paracetamol can damage liver + kidney function
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13
Q

why is insulin broken down in liver

A
  • excess insulin will reduce to blood glucose levels too a too low level
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14
Q

where does deamination take place?

A

in hepatocytes

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15
Q

where are toxins obtained from?

A
  • ingestion

- metabolic products

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16
Q

what are the 4 main veins, ducts + arteries that are connected to the liver

A
  • hepatic artery
  • hepatic portal vein
  • central vein + hepatic vein
  • bile duct
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17
Q

what are the 2 main sources of blood in liver

A
  • hepatic artery (oxygenated blood from the aorta)

- hepatic portal vein

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18
Q

what is Hepatic artery

A
  • artery that supplies liver w/ o2 blood from aorta of heart.
  • liver has good supply of O2 for respiration thus providing liver w/ lots of NRG in form of ATP.
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19
Q

what is the Hepatic portal vein?

A
  • provides liver with blood containing products of digestion from the duodenum + ileum. Any harmful ingested substances can be filtered out + broken down.
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20
Q

What is the central vein?

A
  • the vein that blood from HA + HPV , now deoxygenated , drain into.
  • it connects to the hepatic vein
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21
Q

what is the bile duct

A
  • it takes bile (used to emulsify fats )to the gallbladder to be stored
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22
Q

what is the hepatic vein

A

vein made up of lots of central veins joining together, to carry deoxygenated blood towards the heart.

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23
Q

what are sinusoids?

A

capillaries which the connects the HA + HPV to the CV/HV

24
Q

what happens when blood runs through sinosoids?

A
  • blood runs through the sinusoids , past hepatocytes that remove the harmful substances (ie urea) and O2 (for respiration) from the blood.
25
Q

where does the blood run in liver lobule?

A

towards the central vein

central veins from all LOBULES connect up to form the hepatic artery.

26
Q

what are kupffer cells?

A
  • removes bacteria

- breaks down old, worn out erythrocytes.

27
Q

how can u identify the bile duct on a liver lobule

A

the flow of substance (bile) goes AWAY from central vein

28
Q

describe the process of ultrafiltration

A

Blood from the arteries in the heart enters the afferent arterioles into the glomerulus.
Different sized lumen i.e larger afferent arteriole and narrower efferent arteriole → creates a filtration HYDROSTATICpressure in the glomerulus.
The filtered blood is taken away from the glomerulus by the efferent arteriole which carries blood at a higher pressure( due to smaller lumen) forcing molecules to be filtered out of the capillary into BC.
The wall of the endothelium in capillaries has fenestrations which allows smaller molecules and substances to leave. Furthermore the basement membrane which along with the fenestrations of the endothelium act as the 1st filter → molecules that are larger than the renal threshold of 69,000 molecular mass i.e. plasma proteins, RBC’s and WBC’s are too big thus cant diffuse out into the bowman’s capsule. Smaller molecules and ions ie Na+ and K+ can diffuse across fenestration s and basement into the bowman’s capsule
The wall of the bowman’s capsule has podocytes which are specialised cells that act a s 2nd filter. The podocytes have pedicels that will filter what enters the bowman’s capsule.
The substances in the liquid present in the bowman’s capsule is now known as FILTRATE and it contains gluc, urea, salt ions(Na+/K+), vitamins and hormones and water ⇒ most of these will be reabsorbed by blood in SR to maintain the body;s useful substances in the body.
NOTE : ONLY SUBSTANCES with a molecular mass of 9,000RMM are allowed to pass through to the bowman’s capsule.

29
Q

describe the process of selective reabsorbtion

A

Filtrate enters the pct from the bowman’s capsule after ultrafiltration. It is more dilute than the blood in the surrounding capillaries.
Na+ ions are actively transported OUT of the PCT CELLs into the interstitial space by a Na+ ion PUMP, where they will diffuse into the capillaries.
This reduces the conc of solutes in the pct cell and thus Na+ from the FILTRATE will diffuse via a COTRANSPORTER protein along with GLUCOSE into the PCT cell down their conc gradient. This occurs by facilitated diffusion.
They then diffuse into the blood in the capillaries.
As a result of the movement by ions out of the PCT, thus reducing the water potential of the capillaries, the WATER from the pct will move by OSMOSIS into the capillary down the water potential gradient
By the end of the pct, ~65% of water should be reabsorbed and all glucose, and aa’s should be reabsorbed → and thus will note leave the body as urine with urea.

30
Q

what is the def of ultrafiltration?

A

the process by which substances in the blood are filtered out of blood in capillaries + enter tubules of kidney (in nephron)

31
Q

would glucose be lower in the PCT or in the LOH + why?

A
  • in the LOH

glucose is reabsorbed into the capillaries at the PCT and thus by time filtrate enters the LOH, glucose conce will be 0.

32
Q

would glucose be lower in the PCT or in the LOH + why?

A
  • in the LOH

glucose is reabsorbed into the capillaries at the PCT and thus by time filtrate enters the LOH, glucose conce will be 0.

33
Q

describe conditions of the ascending limb in the LOH

A
  • impermeable to water
  • no ions IN
  • ions only move OUT
34
Q

describe the conditions of the descending limb in the LOH

A
  • permeable to water but water only moves OUT !
  • ions can NOT move IN
  • present ions CAN move OUT ( active transport).
35
Q

The level of ADH in the blood rises during strenuos excercies, explain the cause of the increased level of ADH?

A
  • increased excercise results in increased sweat production and thus a decline in water potential
  • as a result this is detected by osmorecptors in hyp which signal post pit to release ADH
36
Q

explain the effect of increased adh level on kidney function.

A
  • ADH binds to collecting duct membrane
  • stim cAMP + reactions, cAMP causes visicles with aquaporins to fuse to the membrane of CD + DCT making them more permeable to water
    water move by osmosis into medulla and is then reabsorbed by capillaries
  • urine is conc and small volume
37
Q

If an animal produces LESS urine compared to another one, suggest + how nephrons differ.

A
  • the Loop of Henle is longer
  • more ions can be actively transported out of acending loop into medulla increasing solute conc and thus more water moves by osmosis from CD + thus more water is reabsorbed by blood and thus less urine that is concetrated.
38
Q

If an animal produces LESS urine compared to another one, suggest + how nephrons differ.

A
  • the Loop of Henle is longer
  • more ions can be actively transported out of ascending loop into medulla increasing solute conc and thus more water moves by osmosis from CD + thus more water is reabsorbed by blood and thus less urine that is concentrated.
39
Q

what is GFR?

A

the glomerular filtration rate.
it estimates how much blood passes through the glomerulus each minute.
In a healthy person it will decrease with age.
It is measured by looking at the level of creatinine in the blood -> creatinine is a product of muscle breakdown and so if its high in conc -> indicates high GFR + kidney failure as BC cant filter it out.

40
Q

what is kidney failure caused by?

A
  • kidney infection (cause inflammation which damages cells , interferig w/ filtering of the BC and the reabsorbtion of parts of nephron.
  • high blood pa –> damages glomeruli as caps burst + larger molecule (ie proteins) get through capillary walls into filttrate + urine
  • diabetes.
41
Q

what problems in the body does kidney failure cause?

A
  • waste products that the kidney normally removes (ie urea) build up in blood —> too much urea –< vomit + weight loss.
  • fluid starts to accumulate in tissues of kidney bc they cant remove XS water from blood –> causes parts of body to swell (ie face, legs, abdomen).
  • balance of electrolytes bc unbalanced –> if blood to acidic + Ca2+ + PO42- inbalance –> brittle bones.
  • long term kidney failure –> anaemia.
42
Q

what are the 2 types of dialysis?

A
  • peritoneal

- hemodialysis

43
Q

what are advantages of a kidney transplant

A

+ cheaper than dialysis in long term

+ more convenient for patient + doent have to come in regularly to hospital for dialysis.

44
Q

what are disadvantages of kidney transplant

A
  • shortage of kidneys donor
  • risky operation
  • risk of rejection + thus need ot take immunospressants forever.
45
Q

what are the advantages of renal dialysis

A
  • more available + accessible + keeps patient alive whilst waiting for transplant.
  • less risky than operation for transplant
46
Q

what are disadvantages of renal dialysis

A
  • inconvenient for patient.
  • patient need to monitor diet v v carefully.
  • time consuming
  • long term cost v v high
47
Q

why are urine used as a diagnostic tool?

A

has a distinct colour + smell thus can be analysed

48
Q

what is urine used to test for?

A
  • glucose –> diabetes or kidney failure
  • proteins -> idicate kidney failure
  • hCG -> pregnancy.
49
Q

how are MCAB made?

A

mouse injected w /correct hcg hormone + will make correct Abs by B cells
- B cells that make the antibodies for HCG removed from spleen + fused with myeloma to produce hybrid cells that divide rapidly to reproduce + produce MCAB
mCAB are collected + purified to be used in a variety of diff ways.

50
Q

how do pregnancy tests work?

A

they detect hCG a hormone only found in urine of pregnant women.

  • application area of stick has MCAB for HCG attached to coloured blue bead. all MCAB are identical to each other.
  • when urine is applied to application area , any hCG present will bind to the antibody on beads forming hCG - mcab complex.
  • urine moves up stick to test window, where hCG -mcab complex bind IMMOBILISED mcab, test strip turn blue due to high conc of blue beads.
  • if NO hcg present. will not bind to immobilized mcab + will continue to move to control window where mcab bind to mcab bound to hcgo + w/o hcg to form a blue strip showing strip is working
51
Q

how can steroids be tested for in urine?

A
  • Gas chrom, Mass spec.
  • urine vaporised + passed throug colum cotaining a polymer.
    diff substances are separated by diff speeds taken to pass through the column.
    once the substances are separated, Mass spec convert them to ions which are separated depending on MASS + CHARGE
    the results are analysed on a computer + compared w/ results of known substances that were in a urine sample.
52
Q

how can recreational drugs be tested for in urine?

A
  • test for drug w/ a test strip
  • if high conc of drug detected, test strip will change colour indicating a positive result.
  • if this test is +ve, urine sent for further testing by GC/MS
53
Q

why are anabolic steroids banned in sports?

A
  • not fair to other competitors as it can enhance performance.
  • misuse can lead to kidney + liver damage +dangerous side effects.
54
Q

what are the signs of kidney failure

A
  • proteins in the urine bc if basememt membrane not working , larger proteins will enter the filtrate + be present in urine.
  • build up of urea
  • weakend bones
    high blood pa
  • anaemia
  • pain + shiftiness of joints
55
Q

+ and - of haemodialysis

A
  • each sesh is 3-5hrs, done 2-3x /week.
  • patients feel increasingly unwell b/w dialysis sessions as waste products build up in blood.
    + can enjoy relatively normal lifestyle
56
Q

+ and - of peritoneal dialysis

A

+ comfort of own home several times a day or during the night.

  • risk of infection around site of tube
  • patient doesnt have dialysis free days

biology assessmet. (16 decks)

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