excretion Flashcards by ; ;

what are the main metabolic waste products in mammals

carbon dioxide - respiration

bile pigments - formed from breakdown of haemoglobin excreted in the bile to the s.intesine

nitrogenous waste products - breakdown of excess AA

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what are the adaptations of the liver

rich blood supply

blood is supplied by two blood vessels
(hepatic artery + hepatic portal vein)

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where does the hepatic portal vein carry blood from

contains products of digestion from intestines

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what is the structure of a hepatocyte

large nucleus

prominent golgi body

lots of mitochondria

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where is blood from the hepatic artery and hepatic portal vein mixed

what does this do

sinusoids

increases oxygen content

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what do sinusoids contain

what is their function

kupffer cells

act as resident macrophages, ingesting foreign particles

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where do hepatocytes secrete bile into

spaces called canaliculi

from there, biles drains into bile ductules carrying it to the gall bladder

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describe the function of carbohydrate metabolism in the liver

insulin stimulates glycogenesis

adrenaline stimulates gluconeogenesis or glycogenolysis

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describe the function of deamination of excess amino acids in the liver

deaminate AA and => ammonia (toxic) => urea

urea excreted by kidneys

remainder AA is used in respiration

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what is transamination

conversion of an AA into another

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describe the function of detoxification in the liver

> liver contains catalase (for hydrogen peroxide)

> and alcohol dehydrogenase
to ethanol => ethanal => ethanoate used to build fatty acids or used in respiration

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what are the kidneys involved in

excretion

osmoregulation

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what is the kidney’s function

filter nitrogenous waste products out the blood

maintain water balance

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what vein carries blood coming out the kidney

renal vein

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what is the kidney made up of

what do they act

nephrons

as filtering units

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where does urine leave the kidneys

ureter

how much urine can be stored in the bladder

400-600 cm^3

where does the urine leave the body from

urethra

give the structure of the kidney

cortex (dark outer layer)
filtering of blood takes place
dense capillary network

medulla (lighter inner layer)
contains tubules of nephrons that forms the pyramids and the collecting ducts

pelvis
where urine collects before leaving

how long is a nephron

how many nephrons in a kidney

3cm

1.5 million nephrons

give the structure and function of the bowman’s capsule

cup-shaped containing the glomerulus

blood goes into the glomerulus to go into ultrafiltration

give the structure and function of the proximal convoluted tubules

coiled region of the tubule
in the cortex

where substances needed are reabsorbed into the blood

what does the loop of henle do

tubule that creates a [high solute] in the medulla as tissue fluid

give the structure and function of the distal convoluted tubule

second twisted tubule where water balance maintenance takes place

ADH action is here

further ion + blood regulation is here too

what is the structure and function of the collecting duct

urine passes down the collecting duct in the medulla to the pelvis fine tuning of water balance takes place here (ADH action here)

what should the concentration of urea, glucose and amino acids be like when the blood leaves the kidney

urea = greatly reduced glucose + AA = the same

describe ultrafiltration

process that results in the formation of tissue fluid in the capillary beds of the body

which arteriole is wider in the kidney what does it cause

afferent pressure builds up forcing blood through capillary wall

describe the basement membrane

made up of network of collagen fibres + other fibres blood cells and proteins are retained in the capillary

describe podocytes

form pedicels that wrap around capillaries forming slits and make sure large substances go through epithelial cells

what is the ultrafiltrate

hypotonic (less conc. than) to blood plasma

what happens in the PCT

large substances are moved back into the blood by active transport 85% of NACl + water reabsorbed

what are the adaptations of the PCT

covered with microvilli many mitochondria

what is the filtrate reaching the loop of henle

isotonic (same conc) with tissue fluid and blood

what happens at the loop of henle

different areas of the loop have different permeabilities to water acts as a countercurrent multiplier

what happens in the descending limb

water moves out filtrate down gradient (lower part) conc of ions increases due to activity of ascending limb filtrate entering descending limb is isotonic with blood as it travels down, water passes out the loop by osmosis into the blood descending limb impermeable to ions, so no active transport fluid reaching the bend is hypertonic to blood

what happens in the ascending limb

the 1st section is permeable to ions and they move out by diffusion in the 2nd section, ions are actively pumped into medulla tissue fluid producing high [ion] in medulla ascending limb is impermeable to water so fluid in the limb is dilute while tissue fluid is very conc. by the time the fluid reaches the top of the ascending limb, it is hypotonic to blood, and enters the distal convoluted tubule

what happens at the distal convoluted tubule

water balance takes place contains many mitochondria if the body lacks salt, ions are pumped out the DCL

what do desert animals have more of in the kidneys

longer