urinary system and homostasis - anitas notes

homeostasis

maintainence of a constant internal environment within the body

things homeostasis keeps constant

body temp

waterbalance

blood glucose conc

co2 conc

stimulus

change in the internal or external environemnt

response

action taken to return conditions to normal

receptors

detect changes

effectors

carry out responses

where do responses occur

nervous system (quickly) and hormonal system (slow)

negative feedback

response reverses original change

excretion

removal of waste products of metabolism from the body

roles of excretory system in homeostasis

• regulate body temperature

• maintain fluid balance

what does the kidney excrete

urine (urea, salt and water)

what do lungs excrete

water and carbon dioxide

what does the skin excrete

salt and water (sweat)

differentiate between excretion and egestion

excretion is the removal of waste products of metabolism from the body

egestion is the removal of undigested waste

structures / labels of the urinary system

• two kidneys

• two ureters

• bladder

• urethra

• adrenal gland

• aorta

• vena cava

• sphincter

where is the kidney located

abdominal cavity below the diaphragm

blood supply to kidneys

renal artery

blood supply away from kidney

renal vein

is blood in renal artery oxygenated or deoxygenated, does it have metabolic waste?

oxygenated with metabolic waste

is blood in renal vein oxygenated or deoxygenated, does it have metabolic waste?

deoxygenated and contains less metabolic waste

labels on kidney

pelvis, medulla, cortex, ureter

function of kidney

filters the blood to remove waste products and regulate water and salt balance

functions of urters

tubes carrying urine from kidneys to bladder

bladder function

stores urine

urethra function

carries urine from bladder to outside of body

osmoregulation

control of water and salt conc in the body

organs that participate in maintaning constant ph of blood

kidneys and lungs

how o kidneys work

• filter the blood and reabsorbing materials it needs into the renal vein

• waste materials form urine, reabsorbed materials are useful substances that remain in blood

filtration def

water and small molecules move under high pressure from blood into the kidney

reabsorption

useful substances are reabsorbed into the blood

whats a nephron

structure in kidney that filters blood and produces urine

where does filtration occur in the kidney

cortex - outer darker region

where does reabsorption happen in the kidney

mainly in the cortex (outer darker) and partly in medulla (lighter middle)

labels in nephron diagram

• from renal artery

• afferent arteirole

• efferent arteriole

• glomerulus

• bowmans capsule

• proximal convoluted tubule

• loop of henle

• distal convoluted tubule

• collecting duct

• to renal vein

name of cup shaped structure in nephron

bowmans capsule

name of network of capillaries that are found in cup shaped structure

glomerulus

what happens in bowmans capsule

smaller molecules in blood are forced out of plasma under pressure and into the lumen of the bowmans capsule

whats glomerular filtrate

molecules passed from capsule into bloodw

where do i find glomerular filtrate

in the bowmans capsule

how does filtration occur in nephron

• renal artery divides into different arterioles and then a capillary network

• cup shaped funnel is surrounded by glomerulus

• molecules passed from capsule into blood are glomerular filtrate

what doesnt enter the bowmans capsule

white blood cells, clotting proteins

substances filtered into bowmans capsule

glucose, lactic acid, water, vitamins, oxygen, amino acids, co2, salts, urea

substances not filtered out of the blood

rbcs, wbcs, platelets, large proteins (antibodies, clotting porteins)

adaptation of the glomerulus for filtration

• high pressure in afferent ateriole is increased by efferent arteriole as its narrower

• capillaries in glomerulus have large surface area (more filtration)

• walls of capillaries in glomerulus are more porous - bowmans capsule is one cell thick

diffusion

movement of molecules from areas of higher to lower concentration

osmosis

movement of water from an area of high water concentration to low water concentration across a semi permeable membrane

active transport

movement of molecules across a concentration gradient

urea

substance formed in the liver from the breakdown of excess protein (deanimation)

what is reabsorbed in the proximal convoluted tube and how

water glucose, amino acids and vitamins through osmosis, diffusion and active transport

what is reabsorbed in the descending loop of henle and how

only water is reabsorbed through osmosis

what is reabsorbed in the ascending loop of henle and how

no water - only salts through active transport (and a lil diffusion)

what is reabsorbed in the distal convulted tube and how

maintains a careful control of water through osmosis

end product in collecting duct

urine

how does osmoregulation work

when the kidney regulates the amount of water in the body by varying the volume and concentration of urine

what does ADH do

controls wheter the distal tuble and collecting tube reabsorb water or not - causes walls of distal convoluted tubes to become more or less permeable to water

where is ADH produced and stored

produced in hypothalmus, stored in the pituitary gland

what does adh do when you are dehydrated

more adh is released as blood is more / too concentrated

kidney tubules more permeable to water

more water is reabsorbed, more concentrated urine is produced

what does adh do when you are hydrated

blood is dilute, so less adh is released and less water is reabsorbed, so more dilute/lighter urine is produced