B3 Urinary System Structure And Functions Flashcards
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
Kangaroo rats
• remains underground during day. Air in their burrows is cooler and more humid, less water is lost from body by evaporation
• kangaroo rats is able to conserve body water by producing highly concentrated urine. Also produce dry faeces
• nasal passages are adapted to cool the air before it’s breathed out. So respiratory moisture condenses in nasal passages
Distal convoluted tubule (DCT) role
• helps contra blood Ph by adding it removing hydrogen ions
• make final adjustments to the water and salts that are reabsorbed.
• the permeability of its wall become altered under the influence of various hormones such as aldosterone
• too acidic = H+
• make it less acidic = HCO3-
• enzymes are denatured = not doing it’s job
Role of collecting duct and ADH
- Collecting duct runs parallel to loop of henle
- Important role in osmoregulation
- Water content of blood is to low the pituitary gland releases the hormone ADH (anti diuretic hormone)
- Hormone makes cells of collecting duct develop membrane channels called aquaporins making collecting ducts permeable to water
- Filtrate passes down collecting duct due to high concentration of solutes in medulla most of water is reabsorbed back into blood by osmosis
- Leads a small concentration of urine being produced
Role of the renin angiotensin aldersterone mechanism in blood pressure regulations
• when blood pressure drops some cell in kidney produce renin
• renin converts angiotensinogen to angiotensin I.
• angiotensin I is converted into angiotensin II by enzymes angiotensin converting enzyme (ACE)
• hormones aldosterone is then released
• more sodium ions are reabsorbed into blood
• water enter blood
• blood pressure increases
Kidney failure is caused by what
Cancer, physical trauma, disease
What happens in kidney dialysis/ haemodialysis
• The patient blood is pumped into a device that contains a large surface area of the membrane
• one side of the membrane is the patients blood and on the other side is a solution the dialystates that is similar in chemical make up to the patients blood but does not have urea in it at the start of dialysis
• small enough to diffuse through membrane and slowly some of the urea leaves the blood and enters of the dialystate
• balance of water and some ions can also be regulated by adjusting which fluid on either side of the dialysis membrane has a greater concentration each substances kidney dialysis takes several hours a season
Kidney transplant
• all organs and tissue as it’s imperative that the patient and donors tissue match, in order to minimize rejection of the organs by patients immune system
• people can live with only a single kidney
• family members can donate the kidney if blood and tissue match appropriately
• family member cannot decreases donor
• waiting list is to long
• after receiving kidney patient will need immunosuppressants drugs for rest of their life
Glucose
• Is in a healthy individual there should be no glucose in the urine.
• glucose is filtered is normally completed reabsorbed in location such as PCT
Blood cells
• glomerular filtrates should have no blood cells in it’s because of the blood cells are too large to fit through the fenestration of the glomerulus
• finings blood cells in urine can be a sign of kidney malfunction or perhaps infection and bleeding elsewhere in renal tubes
Proteins
Are to large to make their way through the fenestration of the glomerulus and so they shouldn’t be found in the urine
Drugs
• Most drug make their was into blood stream and filtered by the kidney
• become common for employers to test individuals regularly for unprescribed chemicals
