urinary system

Question 1

Anatomy of Urinary System

Answer 1

• ureter - most proximal
• urinary bladder
• urethra - most distal
• transport and store
• kidneys - main organ for filtration, reabsorption and secretion
• kidneys are retroperitoneal
• renal cortex = all filtration
• renal medulla = urine concentration and volume
• golmerulus = filtration (no gas exchange)
• afferent arteriole = artery into glomerulus
• peritubular capillaries = reabsorption and secretion

Question 2

Renal Functions

Answer 2

H+ = acidic
HCO3 = basic

1) Filtration (out of blood)
- in the renal cortex
- moves from blood into renal tubules
- filters water, electrolytes, urea, glucose, amino acids
- does NOT filter protein, blood cells
- kidney damage = protein and cells in the urine
* increase filtration of H+ = alkalosis
* increate filtration of HCO3 = acidosis
- The renal filtrate passes from the glomerulus into Bowman’s capsule and contains no blood cells and few blood proteins.
- Filtration pressure is responsible for filtrate formation.

2) Reabsorption (into blood)
- in the proximal convoluted tubules, loop of henle
- water, sodium, glucose, amino acids
- from renal tubules back into the blood
* increase reabsorption of H+ = acidosis
* decrease reabsorption of HCO3 = acidosis
- About 99% of the filtrate volume is reabsorbed; 1% becomes urine.
- Proteins; amino acids; glucose; fructose; and sodium, potassium, calcium, bicarbonate, and chloride ions are among the substances reabsorbed.
- About 80% of the volume is reabsorbed in the proximal tubule and descending limb of the loop of Henle. About 19% is reabsorbed in the distal tubule and collecting duct.

3) secretion (out of blood)
- occurs in the loop of handle and distal convoluted tubules
- from blood back into the tubules
- anything that wasn’t filtered out gets secreted
- amonia, urea, creatinin, ions (hydrogen (acidic)), potassium (secreted when Na+ is reabsorbed)
* decrease secretion of H+ = acidosis
* increase secretion of HCO3 = acidosis
- Hydrogen ions, some by-products of metabolism, and some drugs are actively secreted into the nephron.

Question 3

hormonal regulation of urine volume

Answer 3

*** Renin Aldosterone Angiotensis System (RAAS), ADH, ANH
1) aldosterone
increase the amount of salt (sodium) reabsorbed into the bloodstream and the amount of potassium removed in the urine. Aldosterone also causes water to be reabsorbed along with salt; this increases blood volume and therefore blood pressure. Thus, aldosterone indirectly regulates blood levels of electrolytes (sodium, potassium and hydrogen) and helps to maintain the blood pH

2) ADH (anti-diueretic hormone)
Its most important function is to conserve the fluid volume of your body by reducing the amount of water passed out in the urine. It does this by increasing the permeability of a specific region of the kidney through which urine flows. Thus, more water returns to the bloodstream, urine concentration rises and water loss is reduced. Higher concentrations of anti-diuretic hormone cause blood vessels to constrict (become narrower), which causes an increase in blood pressure. The deficiency of body fluid can only be finally restored by increasing water intake.
- ADH is secreted from the posterior pituitary when the concentration of blood increases or when blood pressure decreases. ADH increases the permeability to water of the distal convoluted tubule and collecting duct. It increases water reabsorption by the kidney.

3) ANH (atrial naturetic hormone)
in response to increases in blood pressure, acts on the kidney to increase sodium and water loss in the urine.

4) renin
- Renin is secreted from the kidney when the blood pressure decreases or when the concentration of sodium ions decreases in the blood. Renin converts angiotensinogen to angiotensin I which is then converted to angiotensin II by angiotensin-converting enzyme. Angiotensin II stimulates aldosterone secretion, and aldosterone increases the rate of sodium chloride reabsorption from the nephron.

Question 4

renal pelvis

Answer 4

• most occurrence of kidney stones get stuck here because of the curvature

Question 5

renal artery

Answer 5

• kidneys can end up killing other organs because it demands so much blood
• 20-25% of all cardiac output runs through the kidney
• kidney demands blood for volume, PH, electrolytes

Question 6

UTIs

Answer 6

• women at higher risk because: shorter urethra, proximity to anus, and the prostate secretes antibiotics that kill UTI bactera almost always in men
• occur in the trigone
• cysitis = bladder infection
• ecoli causes UTI

Question 7

urine pathway

Answer 7

renal pyramid –> renal papilla –> minor calyx –> major calyx –> renal pelvis

Question 8

Nephron

Answer 8

• functional unit of the kidney
• cortical nephrons: loop of hence is smaller, gloermulus further from cortex-medulla junction, efferent arteriole supplies peritubular capillaries. normal blood filtrate and urine production
• Juxtamedullary nephrons: increase concentration of urine, long loop of hence, glomerulus closer to cortex-medulla junction, efferent arteriole supplies vasa recta

Question 9

juxtaglomerular apparatus (JGA)

Answer 9

• glomerular filtration membrane has a negative charge that keeps out proteins (which are all mostly negative) so you don’t pee out any protein
• The juxtaglomerular apparatus is a microscopic structure in the kidney that regulates the function of each nephron. The juxtaglomerular apparatus is named for its proximity to the glomerulus: It is found between the vascular pole of the renal corpuscle and the returning distal convoluted tubule of the same nephron. This location is critical to its function in regulating renal blood flow and glomerular filtration rate. The three cellular components of the apparatus are the macula densa of the distal convoluted tubule, smooth muscle cells of the afferent arteriole known as juxtaglomerular cells, and extraglomerular mesangial cells.

1) macular densa:
- “detector”
- pressure and oxygen detection. measures sodium, o2 and BP
- when detects decreased pressure and decreased sodium then renin is released
- measure hypoxia
- kidney is the only place that can measure O2

2) juxtaglomerular cells:
- “secreter”
- secretes renin and EPO stimulated by hypoxia and low BP

Question 10

renal tubules

Answer 10

• structures of the nephron
  1) proximal tubule - major site of reabsorption
  2) loop of henle - into medullar, urine concentration and blood volume
  3) dista tubule - end secretions, 3 hormones (aldosterone, ANH, ADH)
  4) collecting duct - secretion and last time to reabsorb anything

Question 11

Filtration

Answer 11

• increase in BP/Hypertension = too much filtration

Effective Filtration Pressure & Glomerular Filtration Rate

1) Glomerular Hydrostatic Pressure - push out of glomerulus into bowman’s capsule.
- increase BP
- most important and strongest
- increase in BP = increase in GHP

2) Glomerular Osmotic Pressure - pull into glomerulus from bowman’s capsule
- protein and albumin
- 2nd most important
- liver disease when decreased albumin
- decrease in ablumin = increase in glomerular osmotic pressure

3) Capsular Hydrostatic Pressure - push from capsule into glomerulus
- obstruction in nephron increases capilary hydrostatic pressure
- pyelonephritis

4) capsular osmotic pressure - pull into capsule from glomerulus
- very weak force, negligible
- increase pressure from kidney stones = increase COP

Question 12

reabsorption

Answer 12

• tubule into blood
• proximal convoluted tubule
• movement of electrolytes out of various segments of the rubble back into the blood
• water, electrolytes (sodium, k+, chlorine, magnesium, calcium) glucose, amino acids enter the peritubular blood vessels
• needs ATP because it is active (Na+) and passive (H2O)
• countercurrent exchange affects urine concentration

Question 13

secretion

Answer 13

• from blood into tubule
• movement of substances from peritubular blood and renal tissues into renal tubule for removal in urine
• secretion of H+, K+, nitrogen, amonia, and urea

Question 14

concentration and dilution of urine

Answer 14

• urea - should beg in urine
• aldosterone - PCT
• ADH - opp of aldosterone, collecting duct
• ANH - opp aldosterone
• diuretics - opp ADH

Question 15

angiotensin 2 effects

Answer 15

• systemic vasoconstriction
• increased aldosterone secretion from renal cortex
• increaesd ADH secretion
• increased thirst
• increased BP
• increased blood volume
• hypothalamus increased thirst which increases blood volume
• posterior pituitary secretes ADH which increases H2O reabsorption which increases blood volume and icnreases BP

pathologies

• endothelial dysfunction
• decreased apoptosis = cancer
• atherosclerosis
• increase thrombosis
• increased platelet aggregation

acute rangiotensin 2 is good, chronic = death

Question 16

RAAAASTAA

Answer 16

• low na+ and low BP detected by macular densa –> kidneys (juxtaglomerular cells) secrete —> renin –> renin converts angiotensinogen (pro pro, from liver) into angiotensin 1 (pro) –> ace (lungs) converts angio 1 into –> angio 2

Renin
Angiotensinogen
Angiotensin 1
ACE
Angiotensin 2
Systemic Vasoconstriction
Thirst
ADH
Aldosterone

Question 17

acidification of urine

Answer 17

• urine PH is 4.6-8.0
• hydrogen excretion: H+ is acidic so when it is excreted the body becomes more alkaline
• ammonia excretion: NH4 is basic so when it is excreted the body becomes more basic.
• liver converts amonia to urea which is neutral
• amonia = breakdown of proteins

Question 18

renal hormones

Answer 18

• urodilatin (naturetic peptide) = synthetic, inhibits sodium and water reabsorption. decreases BP
• Vitamin D = acts on intestine and increase calcium absorption. necessary for absorption of calcium and phosphate
• erythropoietin EPO = released when decreased o2 dated by macula dense. made by JG cells

Question 19

tests of renal function

Answer 19

• creatinine = increased creatin in urine, kidney failure. can estimate GFR with creatine clearance test
• Plasma creatinine concentration = increased in blood means low kidney function
• blood urea nitrogen (BUN) = increased in blood during kidney failure

Question 20

Urinary Tract Obstructions

Answer 20

• Hydroureter = too much water/fluid in the ureters, usually due to a blockage at the entrance to the bladder
• Hydronephrosis = too much water/fluid in the kidneys. This can lead to increased pressure in the kidney and tubules, resulting in increased capsular hydrostatic pressure * This is more pathologic due to the negative effects on the kidney
• Obstructions in 1 kidney can lead to compensatory hypertrophy of the other healthy kidney to compensate for the lack of filtration and urine production (also from kidney removal)
• Once the obstruction is removed/alleviated, increased output from that kidney can be observed, called post-obstructive diuresis
• Kidney stones are called renal calculi, which are most often precipitated and crystallized minerals
  
  • Precipitation and supersaturation risk factors most likely come from changes in pH, but can also be due to temperature and changes in mineral concentration levels (dehydration)
  • symptoms = intense but intermittent flank pain (renal colic), hematuria, vomiting
  • most often made from calcium derived stones
  • lithotripsy = ultrasound waves used to break up kidney stones into smaller pieces

Question 21

Prostatitis

Answer 21

Prostatitis = inflammation of prostate in males.

can block flow of urine and lead to weak urine flow and painful urinations (dysuria)

Question 22

Neurogenic bladder

Answer 22

is the loss of nervous control of the bladder (detrusor dyssynergia)

Question 23

Renal adenomas

Answer 23

• Renal adenomas are typically benign growths, whereas renal cell carcinomas are highly malignant tumor growths.
• Bladder tumors are more common in older males, and present with painless hematuria

Question 24

Urinary Tract Infections (UTIs)

Answer 24

• Usually caused by bacteria, but can also be yeast (Candida albicans) or viral
• Cystitis = bladder inflammation/infection
  - Noninfectious = not bacteria (yeast, virus, autoimmune, hypersensitivity)
  - Bladder infections often present with cloudy urine, abdominal pain, dysuria, and increased frequency, sometimes have hematuria
• Pyelonephritis = kidney inflammation/infection (pyelo = pelvis; nephr = kidney tissues)
  - usually only affect 1 kidney, not both
  - leads to obstruction (lack of urine formation) because of lack of filtration
  - Acute = short term/localized infection (no tissue change)
  - Chronic = recurring acute infections or stone formation that lead to permanent scarring

Question 25

Glomerular Disorders

Answer 25

- Affect filtering at the glomerulus and disrupt the membrane functioning -decreased GFR -loss of negative charge! = proteinuria - Glomerulonephritis = inflammation of glomerulus -commonly due to hypersensitivity reactions (usually Type II and Type III) - also from post-streptococcal infection, viral infection, diabetes - systemic disorder that affects BOTH kidneys - can lead to Nephrotic syndrome = loss of more than 3.5g/day of protein in urine from increased glomerular permeability rapid onset, but it’s not kidney failure edema hypoalbuminemia

Question 26

Renal Failure

Answer 26

- Acute Kidney Injury (acute renal failure) = sudden lack of renal function lack of blood flow decreases filtration and lowers GFR generally from trauma or hemorrhage lack of edema due to rapid onset (~48hrs) - Chronic Renal Failure = irreversible loss of renal function = end stage failure loss of kidney function affects homeostatic control mechanisms and negative impacts multiple systems