Urinary System

Question 1

Describe the basic function of the urinary system

Answer 1

• homeostasis
• excrete waste
• water balance
• filter blood
• activate vitamin D
• Regulates blood pressure
• erythropoiesis regulation

Question 2

List the major components of the urinary system

Answer 2

• Kidneys
• Ureters
• Urinary bladder
• urethra

Question 3

Define retroperitoneal as it relates to kidney

Answer 3

-external to parietal peritoneum to hold the kidneys in place

Question 4

List the 3 protective layers of the kidney

Answer 4

• Renal capsule (immediately surrounding kidney)
• adipose capsule
• renal fascia (anchors kidney to abdominal wall)

Question 5

Describe the Hilus

Answer 5

-External concave area where blood vessels, urters enter/exits kidney

Question 6

Describe the cortex

Answer 6

-the outer portion of the kidney

Question 7

Describe the renal medulla

Answer 7

-the inner part of the kidney

Question 8

Describe the pyramid

Answer 8

• the inner medulla has triangular shaped regions

Question 9

Describe the renal papillae

Answer 9

• is the apex of each pyramid is a papilla (makes urine)

Question 10

Describe the renal pelvis

Answer 10

-is the funnel like structure inside the kidney in the region of the hilus collecting urine from the pyramids

Question 11

Describe the renal calyces

Answer 11

• the extensions into the pyramids
• collecing urine and empty into ureter
  
  • major calyx (8-18)
  • minor calyx (2-3)

Question 12

Describe the blood flow to the kidney

Answer 12

• there is A LOT

- via the renal arteries, about 1/5 of the cardiac output

Question 13

Name the functional microscopic unit of the kidney and describe its specific parts

Answer 13

Nephron

• glomerulus and glomerular capsules
• renal tubules
  
  • proximal convoluted tubule
  • descending limb of the loop of nephron
  • loop of nephron
  • ascending limb of loop of nephron
  • distal convoluted tubule
• collecting ducts

Question 14

Describe the glomerulus and the renal corpuscles

Answer 14

• glumerulus is a netowrk of permeable blood capillaries
• surrounded by the (bowmans) capsule
• these two structures make the renal corpuscle
• renal= Kidneys

Question 15

Describe the overall nephron physiology. Define urine

Answer 15

• Nephrons filter blood to make liquid waste (urine)
• control blood pressure, volume, and pH
• remove waste from the bloodstream
  
  • Protein metabolic waste (urea)

Question 16

Describe glomerular filtration

Answer 16

• Filtration occurs from the glomerulus into the glomerular capsule
• passive process
  
  • influenced by size of the particles and if they can fit through the process of the glomerulus
  • not based off of need
• blood pressure in the glomerulus is the driving force

Question 17

Describe the factors that favor and oppose glomerular filtration.

Answer 17

• glomerular hydrostatic pressure (blood pressure) drives filtration
• the opposing factors are not strong enough to oppose filtration, but include the osmotic pressure in the glomerular as well hydrostatic pressure in the glomerular capsule

Question 18

Discuss the effects of increased blood pressure and decreased blood pressure (as in hemorrhaging) on glomerular filtration

Answer 18

• Increased pressure increases filtration

- decrease pressure decreases filtration

Question 19

Describe active and passive tubular reabsorption and give examples

Answer 19

• active reabsorption requires ATP, passive does not
• Glucose is reabsorbed from the proximal convoluted tubule to the bloodstream by active transport
• water flows passively

Question 20

discuss the significance of an increasingly concentrated intrstitial fluid as you descend from the cortex to the medulla. Describe how this concentration is maintained.

Answer 20

• as you descend into the medulla, the interstitial fluid is very concentrated which offers some great drawing power for pulling water out of the kidney tubules
• the concentration is maintained by having the vasa recta operate in the countercurrent mechanism so that all the solutes are not removed from the interstitial region
• urea adds to the interstitial concentration, as does differential permeability of the different proportions of the nephron

Question 21

Describe the reabsorption and secretion that occurs in all parts of nephron

Answer 21

• the proximal convoluted tubule
  
  • most reabsorption occurs (water and nutrients)
• descend the limb of the nephron
  
  • permeable to water, water reabsorbed
• the loop
  
  • urea enters the loop from the interstitial region and is recycled back into urine
• Ascending limb is permeable to salt but not h20
  
  • as you ascend into a weakly concentrated interstitial region, the sal will not reabsorb
• Distal convoluted tubule
  
  • ADH and Aldosterone dependent
  • If ADH is present, what is reabsorbed
  • Aldosterone is present, sodium is reabsorbed and water passively flows
• Collecting duct is also hormone dependent
  
  • ADH present, significant water reabsorption resulting in small amounts of highly concentrated urine
  • it gets so concentrated, that neat the bottom of the collecting duct, even urea is reabsorbed into the interstitial region
  • secretions of substances such as hydrogen ions, ammonia, and drugs occur primarily in the convoluted tubules
  • here substances can pass directly from blood stream into these tubules

Question 22

Describe juxtaglomerular apparatus. Name the enzyme made here and describe its function.

Answer 22

• juxta=near
• these are the cells of the wall of the distal convoluted tubule that make renin
• Renin is an enzyme that activates angiotensinogen (leads to increased blood pressure)

Question 23

Describe the function of ADH. Where is it made and stored

Answer 23

• ADH is made by the hypothalamus and stored in the posterior pituitary gland
• it causes water reabsorption in the nephron

Question 24

Describe the countercurrent multiplication mechanism of the kidneys

Answer 24

• 2 Parallel tubes running in opposite directions benefit each other
• for example if salt is pulled out of one tube, it facilitates pulling water out of the parallel tubes

Question 25

Describe the change in urine volume and concentration as urine passes through the nephron and collecting tubule.

Answer 25

- There is a vast decrease in volume and increase in concentration upon traveling through the proximal convoluted tubules - after descending limb the concentration increases and volume decreases - after ascending the limb, the concentration decreases and volume is unchanged - after DTC and collecting tubule, if ADH is present, the volume decreases and concentration increases.

Question 26

Describe the vasa recta and how it is part of the countercurrent mechanism

Answer 26

- Vasa recta serve the limbs of the nephron | - They are parallel tubes of blood flow running in opposite direction

Question 27

Describe the function of erythropoietin and where its precursor is made

Answer 27

- the precursor is made by the kidneys | - it stimulates RBC production

Question 28

what is the minimum daily urine volume and why?

Answer 28

-500ml urine per day is the minimum to wash your liquid waste out of your body

Question 29

Describe the location and function of the ureters and urinary bladder

Answer 29

- Ureters run retroperitoneal from kidney to urinary bladder. - Function: peristalsis - Urinary bladder is in the pelvic cavity and functions only to store urine - the urine is in its final form once it leaves the collecting ducts of the nephron in the kidneys

Question 30

Urine emptying from the bladder is controlled by what two muscles

Answer 30

- Two sphincters - internal smooth muscle - external skeletal muscle

Question 31

Define micturition. Describe the process. Explain why babies cannot control urination.

Answer 31

- micturition is voiding urine - as the bladder wall stretches, it reflexively sends message to the sacral region of the spinal cord, which synapses and sends a message back to the bladder wall to contract and the internal sphincter to relax - at this point you have the urge to urinate, and will do so unless you voluntarily contact the external sphincter - the pathway from the brain to external sphincter is not yet established in babies

Question 32

Describe the location and function of the urethra. is it longer in males or females

Answer 32

- Urethra passes from inferior bladder to external urethral orifice. - empties in the vulva of female and is about 1.5 inches long - male- passes through the penis in male and is about 8 inches long

Question 33

Describe the function of aldosterone, where is it made?

Answer 33

- Aldosterone is made by the adrenal cortex | - it causes sodium reabsorption from the nephron and water flows passively