Urinary System

Question 1

principal organs of excretion in humans

Answer 1

lungs, liver, skin, kidneys

Question 2

What is the function of the kidney?

Answer 2

to maintain proper solute concentration in the blood through formation and excretion of urine

Question 3

3 regions of the kidney

Answer 3

outer cortex, inner medulla, renal pelvis

Question 4

what is a nephron?

Answer 4

a bulb called bowman’s capsule–> encapsulates a capillary bed known as the glomerulus–> lead to a long series of tubes known as: proximal conv tube; loop of henle; distal conv tubule; collecting duct

Question 5

how is the nephron position?

Answer 5

loop of henle and collecting duct run through medulla while the Bowman’s capsule and convoluted tubules are in the outer/renal cortex

Question 6

how does concentrated urine get excreted?

Answer 6

concentrated urine flows into the renal pelvis through a funnel like region that opens into the ureter–>ureters from the kidney empty into the urinary bladder, where urine collects and is expelled via the urethra

Question 7

what surrounds the nephron, and what is its purpose?

Answer 7

a complex peritubular capillary network that facilitates reabsorption of amino acids, water, salts, and glucose

Question 8

how is urine formed?

Answer 8

filtration, secretion, reabsorption

Question 9

describe filtration

Answer 9

• -blood pressures for 20% of the blood from the blood stream into the BC through the capillaries
• -fluids and small solutes entering the glomerulus are called filtrate (which is isotonic with the blood)
• -is a passive process–the hydrostatic pressure from the blood drives the process of filtration; if blood pressure increases, hydrostatic pressure increases, and this exerts extra pressure on kidney tissues leading to damage over time

Question 10

describe secretion

Answer 10

nephron secretes waste (e.g. ions, acids, metabolites) from intestinal fluids into the filtrate via passive and active processes–happens mostly in the dist. conv. tub

Question 11

describe reabsorption

Answer 11

essential substances such as glucose, salts, and water, are reabsorbed from the filtrate into the blood
–occur mainly in the proximal convoluted tubule; is mainly an active process; movement of these molecules causes the passive movement of water as well; creates concentrated urine, hypertonic to the blood–happens mostly in the prox conv tub

Question 12

primary function of nephron

Answer 12

to clean out unwanted substances from the blood

Question 13

how does the nephron achieve its primary function?

Answer 13

• -will selectively rabsorb substances back into plasma from the filtrate
• -nutrients reabsorbed at prox conv tub
• -loop of H and collecting duct have roles in water, Na, and K concentrations in the nephron
• -dist conv tub is the major site for secretion of substances into filtrate

Question 14

describe the loop of H permeabilities

Answer 14

descending loop v permeable to water but not Na or K; thin part of the ascending loop v permeable to Na and K but not to water; thick part of the ascending loop Na, K, and Cl are actively reabsorbed by from the urine

Question 15

describe the osmolarity gradient in tissues which forms concentrated urine

Answer 15

tissue osmolarity increases from the cortex to inner medulla; the gradient depends on the counter-current multiplier system–a system in which energy is used to establish an osmolarity gradient

Question 16

how does the counter-current multiplier system affect the tissues in the kidney?

Answer 16

causes the interstitual space in the medull to be hyperosmolar (containing more osmolytes) compared to the dilute filtrate; as water flows down the collecting duct to the the renal pelvis and ureter, water flows from the duct into the tissues via osmosis as the tissue is hyperosmolar (water returns to systemic circulation via capillaries in the medulla); the amount of reabsorption of water depends on the permeability of the collecting duct to water

Question 17

How is permeability of the CD controlled?

Answer 17

via antidiuretic hormone (aka vasopressin); ADH INCREASES the permeability of the CD to water, allowing water to flow out into the medulla and a more concentrated urine to form; some disease states cause people to released too much ADH and retain too much fluid

Question 18

how does aldosterone affect the kidney?

Answer 18

a steriod hormone that increases transport of Na and K in the dist. conv. tub and CD; results in a decreased excretion of Na and an increased excretion of K into the urine; water flows into urine?? more dilute?? has the same affect as ADH

Question 19

aldosterone does not affect renal blood flow

Answer 19

ya

Question 20

how do ADH and aldosterone differ?

Answer 20

o ADH has the same net effect of increased water reabsorption as aldosterone
♣ However, ADH directly affects water absorption b ythe DCT and CD, opening additional aquaporins—allows water to be reabsorbed more readily
♣ Both ADH and aldo. Cause a decrease in urine output and a corresponding increase in blood pressure
♣ This allows the human body to compensate for periods of dehydration or other causes of low blood pressure

Question 21

Diuretics

Answer 21

–caused more water to go into urine; loop diuretics inhibits the ascending loop’s uptake of Na; thiazide diuretics inhibit the Na-Cl transporter in the DCT; both have the same net affect of creating a more dilute urine

Question 22

How does the kidney maintain a consistent body fluid pH?

Answer 22

kidney removes CO2 (from lungs) and H ions

Question 23

How is pH assessed clinically?

Answer 23

arterial pH, arterial partial pressure of CO2, plasma bicarbonate ions (HCO3-)

Question 24

What are the two types of acid-bases disorders?

Answer 24

respiratory acidosis and alkalosis (affects blood pH by increases Pco2, metabolic acidosis and alkalosis(affects blood pH by causing changes in HCO3- concentration)

Question 25

describe respiratory acidosis

Answer 25

increased Pco2; blood pH decreases, body compensates by increasing HCO3-;

Question 26

describe metabolic alkalosis

Answer 26

increased HCO3-, increases pH, increase Pco2

Question 27

describe metabolic acidosis

Answer 27

decreased HCO3-, decreased pH, decreased Pco2

Question 28

describe respiratory alkalosis

Answer 28

decreases pco2, increased pH, decrease HCO3-

Question 29

♣ Compensation mechanisms that affect Pco2 are performed by the respiratory system and can effect change quickly
♣ However, compensation mechanisms that affect HCO3- are performed by the kidneys
• Therefore the compensatory effect can take longer to manifest
• Changes in acid-base chemistry within the body, as well as the cause of the change (respiratory or metabolic), dictate how a patient will be treated medically
• E,g, a change in pH due to a change in respiratory rate or function may be the result of airway obstruction or chronic obstructive pulmonary disease (COPD)
o Whereas metabolic acidosis may be due to a kidney dysfunction or volume loss;
• These diseases must be treated accordingly

Answer 29

ya