The renal system Flashcards
what is the function of the renal system?
excretion of waste
regulate H2O and electrolyte balance
hormones
what are the functions of the kidneys?
regulation of water, inorganic ion balance
removal of metabolic waste from blood
removal of foreign chemicals in blood via excretion in urine
gluconeogenesis - produce glucose during prolonged fasting
production of hormones/enzymes
describe the structure of the kidneys
renal medulla
renal cortex
nephron
renal pelvis
ureter- to urinary bladder
what are nephrons?
structural and functional units of kidneys, each nephron consists of a renal corpuscle and a renal tubercle
what do each renal corpuscle of nephrons contain?
a glomerulus and a bowman’s capsule surrounding the glomerulus
what is the structure of the kidney and urinary system?
glomerulus
bowmans capsule
tubule extends from BC and subdivides into proximal convoluted tubule,
loop of henle,
distal convoluted tubule
collecting- duct system
what occurs at the the level of the conducting-ducts?
multiple tubules join and empty into the renal pelvis from which urine flows through the ureters to the bladder
what supplies the glomerulus with blood?
an afferent arteriole and an efferent arteriole which leaves the glomerulus to branch into peritubular capillaries which supply the tubule
what are juxtaglomerular cells?
mechanoreceptors that sense BP in the afferent arteriole
what are mascula densa cells?
chemoreceptors that respond to changes in the NaCl content of the filtrate
what makes up the juxtaglomerular apparatus?
juxtaglomerular cells
mascula densa cells
what substances get filtered by the kidneys?
Na+
glucose
amino acids
small molecules
what substances don’t get filtered by the kidneys?
large molecules
RBC
large proteins
what substances don’t get filtered by the kidneys?
large molecules
RBC
large proteins
what are the 3 basic renal processes?
glomerular filtration GFR
tubular secretion
tubular reabsorption
what drives glomerular filtration and what opposes it?
hydrostatic pressure in the glomerular capillaries drives GFR
hydrostatic pressure in bowman’s capsule and the osmotic force due to the proteins in the glomerular capillary plasma oppose GFR.
the excretion of a substance is equal to what?
the amount of substance filtered (GRF) plus the amount secreted (by tubular secretion) - the amount reabsorbed (tubular reabsorption)
which substances get excreted immediately in urine and which are reabsorbed ?
foreign substances get completely excreted in urine
substances important to retain but require maintenance within a homeostatic range get reabsorbed and excreted
very importance substances for health get completely reabsorbed
amount excreted =
amount filtered + amount secreted - amount reabsorbed
what is glomerular filtration?
the amount of blood filtered by the glomeruli each minute
what factors influence GRF ?
capillary permeability
SA of capillary bed
hydrostatic pressure driving fluid out capillaries
osmotic forces which oppose exit of fluid
NET filtration pressure =
transcapillary pressure gradient - colloid pressure gradient
how are the kidney glomeruli a more efficient filter than other capillary beds?
filtration membrane is a large SA, very permeable to H2O and solutes
glomerular pressure is higher so they produce more L/day than other capillary beds
what is tubular secretion important for?
disposing of drugs and drug metabolites
eliminating undesired substances
removing excess K+
controlling blood pH
