filtration, absorption and secretion Flashcards
what are the three processes of urine formation?
glomerular filtration, tubular filtration, tubular secretion
true or false: the filtrate at the end of glomerular filtration contains plasma proteins?
false
what are the three filtration barriers of the glomerular membrane?
the fenestrated endothelium, the basal membrane and the epithelial layer with podocytes which contain slit pores.
what is the role of the slit diaphragm?
to control the size of the slit pores
where do the peritubular capillaries branch from?
the efferent arterioles but they line the tubules
what substances do peritubular capillaries absorb?
water, glucose, ions and amino acods
which tubule does most reabsorption occur?
the proximal convoluted tubule
what are the different ways substances can be transported from the renal tubule into peritubular capillaries?
active transporters of apical membrane to transport substances into tubule epithelial cell, then carrier proteins on basolateral membrane transport the substance via facilitated diffusion into the peritubular fluid
–> plasma
or active transporters are located on the basal membrane which transport the substance out of tubule epithelial cell and into peritubular fluid–> plasma
how does water diffuse into the plasma?
osmosis. solutes are reabsorbed into the plasma which increases plasma solute concentration and decreases osmorality of the tubular fluid, therefore water diffuses from a high concentration to a low concentration.
what is meant by the transport maximum?
all protein carriers are saturated by a substance
what is meant by the renal threshold?
the plasma concentration at which a specific substance/ion begins to appear in urine
where is glucose filtered?
in the glomerulus
what % of glucose is normally absorbed?
100%
what happens during tubular secretion?
substances move from the plasma of the peritubular capillaries to the renal tubules, involves same 3 barriers.
what are examples of substances secreted during tubular secretion?
K+ and H+, choline and creatinine, foreign substances
what happens to plasma’s solute concentration after tubular secretion?
the urine becomes more concentrated which decreases the plasma’s solute concentration.
what is urination?
the excretion of solute and water from the body in the form of water
where is urine stored?
in the bladder
where is urine excreted through?
urethra
what is the rate of substance secretion dependent on?
plasma volume and plasma composition
how do you calculate the amount excreted?
(amount filtered + amount absorbed) - amount reabsorbed
