excretory system Flashcards
What is excretion?
It is the elimination of waste from the body?
How is red blood cells eliminated from the body?
it leaves as bile pigments through the G.I. tract
What products are expelled through the urine excretion?
CO2 NH3 and toxic nitrogenous compounds creatinine H2O urea uric acid toxic drugs
Where is urine produced?
it is produced in the kidneys (because of the blood) transported down tubular ureters. into muscular sacs the bladder out through the urethra.
by peristalic wave transport.
What is affects the filtration of blood?
urine blood volume/blood pressure
what are the parts of the kidney?
Hilum - concave border (ureter vessels connect there)
Renal pelvis- divides into 2 or 3 major calyx
major calyx - divided into minor calyx
what is the grainy looking outside called?
cortex
What is the inner dark striated area called?
Medulla
What is the function of the kidney in a general sense?
filtration-reabsorption-secretion(excretion) organ
What is the nephron?
It is the functional unit of the kidney composed of renal corpsucle and the renal tubule.
What is the responsibility of the renal corpuscle?
filtration of blood
What is the renal corpuscle composed of?
Glomerulus - tangled ball of capillaries
Bowmans capsule- sac like structure which surround the glomerulus
What leads to and away from the glomerulus?
afferent and efferent arterioles
What is the renal tubule divided into?
proximal and distal convoluted tubules. The tube ends in the collecting duct.
a loop of henle is between.
The blood is filtered by which three layers of the glomerulus before entering the bowmans capsule?
first layer - formed by the endothelial cells
second layer - glomerular basement membrane third layer - podocytes(negatively charged cells
What is the rate of filtration equal to?
hydrostatic pressure vs osmotic pressure
What is filtrate?
Blood plasma without the proteins
After leaving the bowmans capsule where does the filtrate go?
Proximal convoluted tube
What is the function of the proximal convoluted tube?
Reabsorption of compounds that the body need. Amino acids glucose. over 75% of water and ions is reabsorbed by the PCT.
How is the surface area increased in the PCT?
Microvilli. H+, urea and penicillin is secrerted into the PCT
Afte the PCT where does the filtrate go?
into the ascending and decsneding limbs of the loop of henle which extends into the renal medulla.
What is the purpose of the loop of henle?
Concentrate the filtrate by the transport of ions (Na and Cl) into the medulla which produces an osmotic gradient
What is the consequence of the transport of ions into the medulla?
The medulla gets concentrated with ions and pulls water out of the tubule by osmosis
where does the filtrate go after leaving the medulla?
the distal convoluted tubule.
What is the purpose of the DCT?
It reabsorbs ions actively and water passively and secretes variuos ions
What hormone acts on the DCT?
aldetosterone acts on the DCT to absorb Na+ and secrete K+ and retain water
What is the final path of the filtrate?
It is now called urine. it passes into the collecting ducts leads to larger and larger ducts which lead to renal papillae, calyces, the renal pelvis then the ureter
What is the affect of ADH on the DCT?
it concentrates urine by by increasing the permeabilty of the DCTand the collecting ducts allowing the medulla to draw water out by osmosis.
How is water returned to circulation?
by a system of vessels called the vasa recta
What is juxtaglomerular cells?
cells near the DCT that secret renin
What is the mascula densa?
modified tubular cells that influence the secretion of renin
what is the juxtaglomerlar apparatus?
the mascula densa and the juxtaglomerular cells collectively.
