physiology Flashcards
describe the structure of a capillary
single layer of endothelial cells
role of terminal arterioles
regulate regional blood flow to the capillary bed
role of precapillary sphincters
regulate flow in few tissues e.g. mesentary
what is ultra-filtration
exchange across the capillary wall of protein free plasma
how do lipid soluble substances diffuse into capillaries
through endothelial cells
how do water soluble substances diffuse into capillaries
through water filled pores
how do we calculate net filtration pressure
forces favouring filtration - forces opposing filtration
what is the name of forces involved in transcapillary fluid flow
starling forces
where is filtration favoured in a capillary
at the arteriolar end
where is reabsorption favoured in a capillary
at the venular end
what are the 2 forces that favour filtration
capillary hydrostatic pressure
interstitial fluid osmotic pressure
what is capillary hydrostatic pressure
pressure due to the blood flow across the capillaries
role of capillary hydrostatic pressure
forces water out of the capillary
what is interstitial fluid osmotic pressure
pressure of the proteins in the interstitium
role of interstitial fluid osmotic pressure
pulls fluid out of the capillary (negligible)
name the 2 forces that oppose filtration
capillary osmotic pressure
interstitial fluid hydrostatic pressure
what is capillary osmotic pressure
the pressure due to the presence of plasma proteins
role of capillary osmotic pressure
draws water from the interstitium back into the capillary
what is interstitial fluid hydrostatic pressure
pressure of the fluid in the interstitium
role of interstitial fluid hydrostatic pressure
forces fluid back into the capillary (negligible)
what do starling forces favour in pulmonary capillaries
reabsorption
benefit of starling forces in pulmonary capillaries
prevents the accumulation of interstitial fluid in the lungs (would affect gas exchange)
what is oedema
accumulation of fluid in the interstitial space
where in the body is ammonia synthesised
in the liver
what mediates bile excretion
ATP
what happens during phase 1 of drug metabolism
oxidation, reduction and hydrolysis
what is phase 1 of drug metabolism done by
CYP450 in the endoplasmic reticulum of hepatocytes
what happens in phase 2 of drug metabolsim
conjugation in the cytoplasm of hepatocytes
what happens in phase 3 of drug metabolism
secretion into the bile
what is stored in the liver
fat soluble vitamins
iron, copper
glycogen
role of kupffer cells in the liver
digest/destroy particulate matter
where is bile produced
hepatocytes
roles of bile
assist micelle formation, neutralise chyme, protection of mucosa
role of the gallbladder in bile production
where it is stored and concentrated
secretion of bile during a meal (3)
chyme in duodenum stimulates gall bladder smooth muscle contraction
sphincter of oddi opens
bile spurts into the duodenum
how does bile enter the duodenum
via cystic and common bile ducts
what is liver cirrhosis
bands of fibrosis separating regenerative nodules of hepatocytes
what commonly causes liver cirrhosis
alcohol consumption and Hep C
is liver cirrhosis reversible ?
NO
pathophysiology of liver cirrhosis
chronic inflammation damages liver leading to activation of hepatic stellate cells in the space of dis
increase fibrosis leading to cirrhosis
name some clinical signs of compensated cirrhosis
spider naevi
palmar erythema
clubbing
gynaecomastia
clinical features of decompensated liver cirrhosis
jaundice
ascites
encephalopathy
easy bruising
investigations for liver cirrhosis
serum markers
imaging
biopsy
what is used to determine the level of liver damage in cirrhosis
liver elastography
serum markers in liver cirrhosis
decreased albumin
increased prothrombin time
increased bilirubin
