B3 Urinary System Structure And Functions Flashcards
(35 cards)
The renal vein function
Carries blood from the kidney
Urethra function is
Carrie urine out of the bladder
Bladder function
Stores urine
Ureter function
Carries urine from the kidney to the bladder
Renal artery functions
Supplies blood to the kidney
Kidney function
Performs excretion and osmoregulation
Nephron function
Microscopic filtration unit
What does the kidney have
Have two distinct and outer cortex and an inner medulla
Where is blood brought to by the kidney
From the renal artery and then it’s taken away from the kidney by the renal vein. Inside it then divides into smaller blood vessels called arteriolar
Inside of the kidney function
Lie the functioning units called the nephrons which is part of each is in the cortex and part in the medulla
Nephrons structure step by step
- Begins with a group of convoluted blood capillaries called the glomerulus
- Glomerulus is surrounded by a cup shaped structure called bowman’s capsule
- Bowman’s capsule leads a longer part of the nephrons the proximal convoluted tubule
- PCT Leeds into the hairpin shaped structure called loop of henle
- Loop of henle leads the distal convoluted tubule
- DCT finally leads into the collecting duct
Function of the urinary system
Consists of kidney, ureters, bladders and urthera
1. Urinary bladder is hollow muscular organs that collects urine from kidney before disposal by urination. The urine enters bladder through the ureter and urine leaves bladder by urethra
2. Two types of blood vessels attached to kidney. Renal arteries which deliver an oxygen rich blood supply to the cells in each kidney once blood has processed here it leaves the kidney through renal veins
3. Transport Into inferior vena cava back to the heart
Main organs of excretory system functions
- Excretion - removal from the body of toxic waste made in cells during metabolism
- Osmoregulation - homeostatic control of water by adjusting concentration of the cells and body fluids. Ensures that cells don’t burst or shrink which would affect metabolism
Kidney producers urine in two stages
- Small molecules and ions are filtered out of the blood into glomerulus and into the bowman’s capsule = ultrafiltration
- Any ions and molecules that are required by the body are taken back from the nephrons and moved back into the blood and process called selective reabsorption example glucose
Formation of glomerulus filtrate
- Done by ultrafiltration similar process used to force tissue fluid out of capillaries
- Blood enters kidney through renal artery which branches into millions tiny arterioles each which enter the renal bowman capsule
- Afferent arteriole that enters the capsule is wider in diameter than efferent arteriole that exist. Causes high hydrostatic pressure in capillaries within capsule. These capillaries are known as glomerulus
- Tissues fluid is formed the higher than normal hydrostatic pressure the glomerulus leads to water, glucose, urea and mineral ions being forced out of fenestration (pores) in the capillaries to form glomerular filtrate
- Blood cells and large plasma proteins cannot pass through the small hole and remains in the capillaries
- Filtrates can pass out of the glomerulus due to the holes in the capillaries through the connective tissue and through the spaces between branches of podocytes. The filtrates than moves into PCT where nearly 85% of it is reabsorbed back into blood
- Ultrafiltration is not specific and only filters by size a lot of useful molecules are filtered out that we don’t want to waste such as glucose. Then they’re reabsorbed and waste such as urea , excess water and excess ions are removed
How is urea removed from blood
- Hydrostatic pressure and fenestartion of capillaries walls
- Causes ultrafiltration at bowman’s capsule
- Through the basement membrane
- Enabled by small size of urea molecules
Describe how ultrafiltration produces glomerular filtrate
- Higher than normal blood pressure
- Such as amino acid, glucose, ions, water and urea
- Pass through basement membrane
- Proteins are to large to go through
- Presences of pores
- Presences off podocytes
Proximal convoluted tubule (PCT) and selective reabsorption
- Osmoregulation is the control of water and solute levels within the blood
- Fluids enters the bowman’s capsule known as glomerular filtrate.
- Thai filtrate passes into the PCT
- All glucose, amino acids and most salt and water are reabsorbed into the PTC
- Glucose is an important energy source that body cannot afford to lose
Role of loop of henle
The role of loop of henle is to create a very high concentration of salts in the tissue fluids of the medulla, through which the collecting duct passes
What does loop of henle make possible
To excrete urine that is more concentrated than blood
Loop of henle has two regions
An ascending limb and descending limb both running parallel to each other and are surrounded by blood capillaries. Top part of both limb are thicker than the bottom parts.
• descending limb of loop of henle is permeable to water but not Na+ and Cl- ions
• ascending loop is permeable to Na+ and Cl- ions but not water
Function of loop of henle step by step
- Loop of henle creates a very high concentration of solutes in tissue fluid of medulla
- Top part of ascending limb, sodium and chloride ions are actively pumped out into surroundings tissue fluid of medulla
- Creates a high solute concentration in tissue fluid of medulla example very salty
- Descending and ascending limbs run parallel and very close to each other
- Filtrates moves down the descending limb, water is drawn out of the filtrate by osmosis
- Filtrates descend the loop of henle it becomes more and more concentrated because of the water that is leaving filtrate
- Water is relatively quickly removed by capillaries surrounding loop of henle
- Reaches into hairpin bend and concentration of solutes in the filtrates is very high
- Na+ and Cl- ions leave the filtrates by diffusion therefore further increasing the concentration of salt ions in the tissue fluid in medulla
Describe what happens to the concentration filtrates as it passed down the descending limb of loop of henle
Increases
Describe what happens to the concentration of filtrates as it passes up the ascending limb of loop of henle
Decreases
