Excretion Flashcards
Describe structure of the liver?
Lobule = basic functional unit
Hepatic vein = centre of lobule –> Acts as drain
Hepatic artery –> where oxygenated blood travels into lobule from (transport hormones)
Hepatic portal vein –> carries deoxygenated blood with nutrients (glucose) from intestines to liver
Bile duct –> where bile is drained -> gall bladder
Kupffer cells –> resident macrophages (attack pathogens)
What is the canaliculus?
Space where al bile drained into
Surrounded by hepatocytes
Hepatocytes - produce bile
–> emulsifies fats
What is the sinusoid?
Blood from HA + HPV mix
Increases O2 content for cells(hepatocytes/kupffer cells) to work
What are the functions of the hepatocytes?
Converts glucose to glycogen (BGL regulation)—> response to insulin
Deamination (removal of amine group)
Detoxification
What happens in deamination?
NH2 becomes NH3 (ammonia = very toxic)
(makes urea) –> through ornithine cycle –> removed through kidneys
Rest of amino acid = pyruvate
~> used in respiration for ATP production
What happens in detoxification?
(alcohol dehydrogenase) ethanol -> ethanal -> ethanoate -> fatty acids
Catalase breaks H2O2 into water and oxygen
Describe structure of the kidneys?
Cortex = dark outer layer
~> where blood filtered = dense capillary network carrying the blood from the renal artery to the nephrons.
Medulla = lighter
~>contains tubules of
nephrons that form collecting ducts.
Pelvis = central chamber ~>where the urine collects before passing out down the ureter.
Describe ultrafiltration process?
Afferent arteriole lumen larger than efferent arteriole –> creates filtration pressure in glomerulus
Forces substances to leave glomerulus into Bowman’s capsule
How are the substances filtered out of glomerulus?
Gaps in endothelium
Basement membrane
Podocytes
RBC, WBC, large plasma proteins too large to leave
Left with filtrate –> glucose, water, Na+, Cl-, amino acids, hormones
What happens in the PCT?
All of the glucose, amino acids, vitamins, and hormones are moved from the filtrate back into the blood by AT
Na+ absorbed by AT as well
Water reabsorbed via osmosis
Cl- reabsorbed by diffusion
How are the PCT walls adapted for selective reabsorption?
microvilli –> increase SA
Mitochondria = ATP needed in active transport systems.
What happens in the loop of Henle?
Water reabsorbed
Descending limb (impermeable to water)
= more concentrated because of less water
Hypertonic at bottom of loop –> high salt conc
Ascending limb = salts diffuse out
Conc of salt decreases –>solution isotonic
What happens in the DCT?
Balance of water needs + pH of blood
Permeability of the walls of the tubules varies with the levels of ADH.
Lacks salt = Na+ actively pumped out of DCT
Cl- = follow down electrochemical gradient
What happens in collecting duct?
main site where the concentration and volume of the urine produced is determined.
ADH determines permeability of collecting duct
Excess = urine
What does tissue fluid influence?
More water will move out from filtrate (high WP) to tissue fluid (low WP)
–>down WP gradient by osmosis
What is osmoregulation?
controlling WP of blood regardless of the activities of the body.
Too much water in blood:
Pituitary gland –>less ADH
Kidney reabsorbs less water
Water stays in urine –> less concentrated + higher volume
Too less water in the blood:
Posterior pituitary gland releases more ADH
Changes permeability of DCT
Kidney absorbs more water
Lower volume –> more concentrated urine
What is the role of osmoregulators?
Located in hypothalamus
ADH produced by hypothalamus and released by pituitary gland
ADH signals for more aquaporins to be deposited onto wall of collecting duct
Role of ADH:
binds to receptor
ATP –> cAMP
signals vesicles with aquaporins to fuse with plasma membrane
Insert aquaporins on inner wall —> increase permeability to H2O
More water reabsorption
Role of urine in pregnancy tests:
mouse + hCG = antibody
B-cells + myeloma = hybridoma
monoclonal antibodies purified
Main stages of pregnancy testing?
hCG bind to mobile antibodies –> form hCG/antibody complex
Bind to immobilised antibodies (pregnant)
Excess mobile antibodies bind to immobilised antibodies (control line)
What is urine also used for?
Anabolic steroids -> stimulate muscle growth.
Banned in sport
Drug testing -> illegal drugs detected
Why is the build of up ions in the body bad?
Loss of electrolyte balance
Build up of toxic urea in blood
High blood pressure
Weakened bones
Stiffness in joints
Anaemia
What can kidney failure cause?
Protein in urine –> no filtering system
Blood in urine
How to measure glomerular filtrate rate?
Indicates kidney disease
Measures levels of creatinine (breakdown product of muscles) in the blood.
lack of kidney function = creatinine build up
How to treat kidney failure with a dialysis machine?
Haemodialysis
Blood one way, dialysis fluid the other
~~> countercurrent system
Maintains concentration gradient –> exchange of substances can occur
Membrane in machine partially permeable (mimics membranes in ultrafiltration)
Dialysis fluid same glucose level but no urea (conc gradient)
