Excretory System Flashcards
kidney function
- regulates BP
- regulates pH
- synthesis RBC
kidney structure
- cortex on outside
- medulla in the middle
- pelvis on inner (filtrate exits kidney)
how is urine created and its path
- created in nephron
- enters renal pelvis > ureter > bladder > urethra
main functions of nephron
filtration, reabsorption, secretion, and excretion
where does filtration occur
in renal corpuscle
what does filtration consist of
glomerulus and Bowmann’s capsule
filtration
- blood enters afferent arteriole and is filtered through glomerulus as a seive
- hydrostatic pressure forces plasma through the sieve
- Bowman’s capsule podocytes surround glomerulus to form fenestrations
- small substances (water and solutes) filter into Bowman’s capsule
- larger substance (proteins and RBC) remain in blood
- blood leaves via efferent arteriole –> peritubuluar capillaries
filtration membrane
- endothelial fenestration pore: prevents filtration of blood cells but allows all components of blood plasma to pass through
- basal lamina: prevents filtration of collagen, glycoproteins
- silt membrane: prevents filtration of medium-sized proteins
reabsorption
useful materials (water and solutes) are reabsorbed
where does reabsorption occur
occurs in proximal convoluted tubule via active transport
distal convoluted tubule
reabsorption absorbs Na+ and Cl-
what is almost completely reabsorbed?
glucose and aa because they are important in the body
secretion
urea, waste, drugs, are secreted into nephron by active and passive transport
Loop of Henle
concentrates urine only by allowing water to exit on the way down and salts to exit on the way up
what surrounds the loop of henle
vasa recta (capillaries)
where is water reabsorbed
down the descending limb (filtrate becomes more concentrated)
ascending limb
- impermeable to water
- solutes reabsorbed as it travels up ascending limb
- filtrate becomes less concentrated
longer loop =
MORE concentrated urine
what secretion occurs at distal tubule
K+/H+/HCO3-
excretion
- loop of henle –> DCT
- DCT: Na+ and Cl- rebabsorbed and water follows
- DCT –> collecting ducts; water moves passively out and concentrates urine
excretion pathway
collecting ducts –> renal pelvis –> ureter –> bladder (stores urine)
* singal sent to excrete urine –> urine leaves via urethra
juxtaglomerular apparatus
detects changes in blood pressue and blood volume
* LOW BP = secretes renin
* sympathetics = increase renin
renin
draw out diagram and insert pic!!
angiotensin II effects
- increase aldosterone release
- increase Na+ reabsorption from PCT
- vasoconstriction = increase TPR
- increase thirst so increase in blood volume
ADH/vasopressin
- release from posterior pitutary upon stimulation from hypothalamus
- causes aquaporins to insert into the collecting duct of nephron (increase water reabsorption)
- alcohol inibits ADH = urinate more
aldosterone
- produced from adrenal cortex
- increase salt and water reabsorption
- K+ secretion in distal tubules and collecting ducts
atrial natriuretic peptide (ANP)
- produced by atrial cells in rsponse to atrial distension by increase BP and pressure
- increase GFR –> decrease Na+ reabosrption and increase Na+ excretion
- inhibits renin and RAAS
