Excretion Flashcards
Define excretion
Removal of metabolic waste from body cells
Importance of removing metabolic waste
Toxic products may interfere with pH = prevent metabolism
Act as inhibitors = prevent enzyme activity
3 main effects of CO2
O2 transport reduced - H+ formed from dissociation of carbonic acid = bind to Hb = less space for O2
O2 transport reduced = CO2 bind to Hb = Carbaminohaemoglobin = less affinity for O2
Blood pH reduced - H+ remain in blood, not buffered by proteins
Reduced pH detected by respiratory centre in medulla oblongata
= Inc breathing rate - remove CO2
Below 7.35 = respiratory acidosis
2 pathways of blood into liver
Pathway of blood out liver
Hepatic artery = oxygenated
Hepatic portal vein = nutrients rich blood
Hepatic vein = blood away - to vena cava back to heart
External structure of liver lobule
Outside each lobule =
Hepatic artery + hepatic portal vein (inter-lobular vessels)
Centre each lobule =
Hepatic vein (intra-lobular vessel)
Sinusoids + canaliculus
Bile collected by bile duct - next to inter lobular vessels
Internal structure of liver lobule
Sinusoid channel = mixture of blood - hepatic artery + hepatic portal vein
Blood from small intestine = oxygenated = aid aerobic = ATP for toxin metabolism
Bile canaliculus - bile released into
Travels away from centre
Collected in bile duct
Kupffer cells = specialised macrophages
Capture + destroy bacteria - which could have entered via small intestine
Recycle old RBC = makes bilirubin - excreted in bile
7 Functions of liver
FEACHESS
Fetus erythrocyte synthesis
Erythrocyte destruction
Alcohol + drug detox
Control levels : blood sugar, aa + lipids
Hormone breakdown
Synthesis: bile, plasma proteins, cholesterol
Storage: vitamin A, B12, D, iron + glycogen
Why have ornithine cycle
Ammonia = highly toxic + soluble
So shouldn’t be accumulated in cells
Is ornithine cycle an active process
What raw materials are required
Byproducts formed
Ammonia produced in one cycle
Site of process
Yes - ATP
ATP, CO2, H2O + 2X NH3
H2O
2
Cytosol + mitochondria
Define detoxification
Conversion of toxic molecules to less toxic/ non-toxic forms
What does detoxification of alcohol produce + why is this bad
Produces reduced NAD
So not enough NAD for fatty acids breakdown
Thus become lipids + stored in hepatocytes
= fatty liver
Kidney structure
Nephron structure
Kidney structure
Layers
Blood vessels
Protective layer = capsule
3 layers internal
Cortex
Medulla
Pelvis
Pelvis extends to mate ureter - connect to bladder
2 blood vessels
Renal artery = oxygenated blood from heart
Renal vein = return deoxygenated blood to heart
Nephron structure
Location
Bowman’s capsule (in cortex)
Glomerulus = knot of capillaries within capsule
Receives blood - renal artery via afferent arteries
Blood leaves via efferent arteries form renal vein
Bowman’s capsule = narrow into
Proximal convoluted tubule
Loop of Henle = PCT continued in cortex
Descending limb of loop of Henle = extension of loop of Henle down to medulla
Ascending limb of loop of Henle = turning of descending back into cortex
Distal convoluted tubule = ascending loop of Henle twisted in cortex
Collecting duct = collect contents of DCT
Runs back medulla into Pelvis region to ureter
Function of nephron
Filter unwanted substances in blood
Ensuring important substances not lost (ultrafiltration)
