Urinary System Structure And Function

Question 1

Function of the urinary system

Answer 1

• urinary system consists of the kidneys ureters, bladder and urethra
• urinary bladder a hollow muscular organ that collects urine from the kidneys
• the urine enters the bladder through the ureter and urine leaves the bladder by urethra.
• 2 blood vessels attached to kidneys. The renal arteries and renal veins.

Question 2

Renal arteries

Answer 2

Deliver an oxygen rich blood supply to the cells in each kidney.

Question 3

Renal veins

Answer 3

Once the blood is processed in renal arteries it leaves the kidney via renal vein and is transported in the inferior vena cava back to the heart.

Question 4

Excretion

Answer 4

Removal of waste (urea) and removal of Toxic waste made in the cells during metabolism.

Question 5

Osmoregulation

Answer 5

Regulation of body water by adjusting solute conc of the cells and body fluids. This ensures that cells do not burst or shrink.

Question 6

The kidneys

Answer 6

• received blood supply from renal artery
• kidney consists of tiny filtering units called nephrons
• blood comes into the kidneys under high pressure to make filtration efficient.
• the filtered blood leaves the kidneys along the renal veins
• the filtered waste products are excreted by the kidney as urine.
• urine passes muscular tube called the ureter (connecting each kidney to the bladder).
• bladder (muscular sac which stores urine.

Question 7

Renal vein

Answer 7

Carries blood from the kidney

Question 8

Urethra

Answer 8

Carries urine out the bladder

Question 9

Ureter

Answer 9

Carries urine from the kidneys to the bladder

Question 10

Renal artery

Answer 10

Supplies blood to the kidney

Question 11

Kidney

Answer 11

Performs excretion and osmoregulation

Question 12

Nephron

Answer 12

Microscopic filtration unit

Question 13

Kidney structure

Answer 13

• has 2 distinctive regions an outer cortex and an inner medulla
• inside kidneys the arteries divide into smaller blood vessels called arterioles
• inside kidneys functioning units called nephrons, part of each is in the cortex and part in the medulla.

Question 14

Nephron

Answer 14

• begins with a group of convulsed blood capillaries called the glomerulus
• the glomerulus is surrounded by cup shaped structure called bowman’s capsule (renal capsule)
• it then leads to the longest part of the nephron proximal consulates tubule (PCT)
• it then leads to loop of henle
• which leads to distal convoluted tubule (DCT)
• leads into collecting duct.

Question 15

Ultrafiltration

Answer 15

Small molecules and ions are filtered out of the blood in the glomerulus and into the bowman’s capsule.

Question 16

Selective re absorption

Answer 16

Any of the ions and molecules required by the body are taken back from the nephron and moved back into the blood by selective reabsorption. Eg glucose

Question 17

Formation of glomerular filtrate

Answer 17

• done by ultrafiltration
• blood enters kidney through renal artery, branches into tiny arterioles which enter the bowman’s capsule.
• the afferent arterioles enters the capsule is wider in diameter than the efferent arterioles. This causes high hydrostatic pressure in the capillaries (glomerulus) within the capsule.
• the higher than normal hydrostatic pressure in the glomerulus leads to water, glucose, urea and mineral ions being forced out of the fenestrations (pores) in the capillaries to form the glomerular filtrate.

Question 18

Loop of henle

Answer 18

• create a very high conc of salts in the tissue fluids of the medulla, through which the collecting ducts passes
• it has 2 regions the ascending limb and a descending limb both running parallel to each other and surrounded by blood capillaries.
• the descending limb of the loop is permeable to water but not na+ and Cl- ions
• the ascending loop is permeable to na+ and Cl- ions but not to water

Question 19

What happens at the ascending and descending limb of loop of henle?

Answer 19

• top of ascending limb sodium and chloride ions are actively pumped out into the surrounding tissue fluids of the medulla
• this creates a high solute conc in the tissue fluids of the medulla
• the descending and ascending limbs run parallel
• as the filtrate moves down the descending limb water is drawn out of the filtrate by osmosis
• as the filtrate descends the loop of henle becomes more concentrated because of all the water that is leaving the filtrate.
• the water is quickly removed by the capillaries surrounding the loop of henle
• when it reaches and turns the hairpin bend the conc of solutes in the filtrate is very high
• na+ and Cl- ions leave the filtrate by diffusion therefore further increasing the conc of salt ions in the tissue fluid of the medulla.

Question 20

The role of the collecting duct and ADH

Answer 20

• collecting duct important role of osmoregulation
• if water content of the blood is too low the pituitary gland releases the hormone (ADH) anti-diuretic hormone. This hormone makes the cells of the collecting duct develop membrane channels (aquaporins) making the collecting duct permeable to water
• as the filtrate passes down the collecting duct due to high conc of solutes in the medulla most of the water is reabsorbed back into the blood by osmosis.

Question 21

Distal convoluted tubule role

Answer 21

• help to control blood ph by adding or removing hydrogen ions
• make final adjustments to water and salts that are reabsorbed

Question 22

The role of renin angiotensin aldersterone mechanism in blood pressure regulation

Answer 22

• when blood pressure drops some cells in the kidney produce renin
• renin converts angiotensin to angiotensin l
• angiotensin l is converted to angiotensin ll by the enzyme angiotensin converting enzyme (ACE)
• the hormone aldosterone is then released
• more sodium ions are reabsorbed into the blood
• water enters the blood (increase water potential)
• blood pressure increases