Chapter 23 (Urinary) Study Guide

Question 1

What 6 principal organs make up the urinary system? Which organs of the urinary system are singular and which are paired?

Answer 1

1&2) Paired kidneys
3&4) Paired ureters
5) Urinary bladder
6) Urethra

Question 2

What is different between a male and female urinary tract system?

Answer 2

1) Males have a longer urethra (18cm) that has 3 regions; females have a shorter urethra (3-4cm) with 1 region.
2) Males also have a prostate gland surrounding a region of their urethra.

Question 3

Name the 8 functions of the kindeys

Answer 3

1) Filter blood and excrete toxic metabolic wastes
2) Regulate blood volume, pressure, and osmolarity
3) Regulate electrolytes and acid-base balance
4) Secrete erythropoietin, which stimulates RBC production
5) Help regulate calcium levels by participating in calcitriol synthesis
6) Clear hormones from blood
7) Detoxify free radicals
8) Gluconeogenesis in starvation

Question 4

What organic compound is broken down to produce urea?

Answer 4

Proteins are broken down into amino acids, an NH2 is then removed, which forms ammonia, which is converted into urea by the liver

Question 5

What organ converts ammonia to urea?

Answer 5

The liver

Question 6

1) The catabolism of nucleic acids gives rise to what nitrogenous waste? 2) Creatine phosphate catabolism gives rise to what nitrogenous waste?

Answer 6

1) Nucleic acid catabolism leads to uric acid
2) Creatine phosphate catabolism leads to creatinine

Question 7

1) What is blood urea nitrogen (BUN)?
2) What’s the normal level?

Answer 7

1) The level of nitrogenous waste in blood
2) Normal concentration of blood urea is 10 to 20 mg/dL

Question 8

What is the scientific name for an elevated BUN (blood urea nitrogen) level and what organ appears to be functioning improperly?

Answer 8

Azotemia; the kidneys may be deficient

Question 9

1) What gives rise to uremia?
2) What are symptoms and treatments for uremia?

Answer 9

1) A worsening elevated BUN level (azotemia)
2) Symptoms: A syndrome of diarrhea, vomiting, dyspnea, and cardiac arrhythmia stemming from the toxicity of nitrogenous waste
Treatments: hemodialysis or organ transplant

Question 10

Name the 4 major nitrogenous wastes

Answer 10

Ammonia, urea, uric acid, and creatinine.

Question 11

1) Define excretion.
2) What 4 body systems carry out excretion?

Answer 11

1) Defined as separating wastes from body fluids and eliminating them
2) Respiratory, integumentary, digestive, and urinary

Question 12

1) Describe the location of the kidneys, include explanation of retroperitoneal.
2) Which kidney is lower and why?

Answer 12

1) They’re retroperitoneal in the superior lumbar region. Retroperitoneal means they’re behind the peritoneum, which means that they’re right up against the posterior abdominal wall.
2) The right kidney because the right lobe of the liver is larger and pushes it down.

Question 13

What is the hilum of the kidney and what vessels would enter and exit at this location?

Answer 13

The hilum is an opening where the ureters, renal blood vessels, lymphatics, and nerves enter and exit the kidney

Question 14

What are the three protective coverings on the kidney? Which tissue binds it to the abdominal wall? Which cushions the kidney and holds it in place? Which protects if from trauma and infection?

Answer 14

1) Renal fascia: deep to parietal peritoneum that binds it to abdominal wall
2) Perirenal fat capsule (Adipose capsule): cushions kidney and holds it into place
3) Fibrous capsule: protects it from trauma and infection

Question 15

What is nephroptosis and who would exhibit nephroptosis?

Answer 15

1) Nephroptosis is when the kidneys drop down much further than the typical 3cm when you go from lying down to standing up
2) Those with anorexia and no longer have a perirenal fat capsule and those who frequently experience vibrations (ex: truck drivers)

Question 16

A frontal section of the kidneys results in three regions; name and describe them. Which region contains the blood vessels and loop of Henle? Which region contains the Bowman’s capsule and convoluted tubules? Which region contains the lymphatic system structures and urine collecting structures?

Answer 16

1) Cortex: Contains the Bowman’s capsule and convoluted tubules
2) Medulla:
a) Pyramids: contains the loops of Henle and collecting ducts
b) Columns: Contains the blood vessels
3) Renal sinus: Blood/lymphatic vessels, nerves, urine-collecting structures, and adipose

Question 17

1) Which two regions of the kidney are part of the renal parenchyma?
2) To form a major calyx of the kidney, what had to merge?

Answer 17

1) The cortex and medulla
2) 2 or more minor calyxes

Question 18

Trace blood flow starting with the renal artery and ending with the renal vein; includes both macroscopic and microscopic vessels. (13 steps)

Answer 18

1) Renal artery
2) Segmental artery
3) Interlobar artery
4) Arcuate artery
5) Cortical radiate artery
6) Afferent arteriole
7) Glomerulus
8) Efferent arteriole
9) Peritubular capillaries
10) Cortical radiate vein
11) Arcuate vein
12) Interlobar vein
13) Renal vein.

Question 19

What blood vessels branch to give rise to the peritubular capillaries? What nephrons are the located with the peritubular capillaries? Where is this located, cortex, medulla or sinus?

Answer 19

In the cortex, peritubular capillaries branch off of the efferent arterioles. Found on Cortical nephrons (on proximal and distal convoluted tubules).

Question 20

What blood vessels branch to give rise to vasa recta capillaries? What nephrons are the located with the vasa recta capillaries? Where is this located, cortex, medulla or sinus?

Answer 20

In the medulla, the efferent arterioles give rise to the vasa recta, supplying the nephron loop portion of the Juxtamedullary nephrons.

Question 21

1) What is the functional unit for the kidney? 2) How many of these structures are in each kidney?

Answer 21

1) The nephron
2) Each kidney has about 1.2 million nephrons

Question 22

What are the two principal parts of the nephron? Which filters the blood plasma? Which converts filtrate into urine?

Answer 22

1) Renal corpuscle: filters the blood plasma
2) Renal tubule: long, coiled tube that converts the filtrate into urine

Question 23

1) What two structures make up the renal corpuscle?
2) One of these structures has 2 parts; what are they?

Answer 23

1) A glomerulus and a two-layered glomerular (Bowman’s) capsule.
2) Bowman’s capsule has a parietal outer and visceral inner layer.

Question 24

What blood vessel enters the renal corpuscle? What blood vessel exits the renal corpuscle?

Answer 24

Afferent arteriole enters the renal corpuscle, efferent arteriole exits the renal corpuscle.

Question 25

1) If blood leaves the renal corpuscle, what structure is it entering, and is the fluid considered blood, filtrate or urine and why? 2) What capillary bed is in the renal corpuscle?

Answer 25

1) It’s entering the proximal convoluted tubule of the nephron, and it’s considered filtrate
2) The glomerular capillaries

Question 26

What are the four regions of the renal tubule? Where does most reabsorption occur? Which region is the longest? Which is a loop that can transport either water or salt? Which are convoluted? Which is the shortest convoluted tubule? Which receives fluid from several nephrons? Which converges toward the tip of the medullary pyramid forming the papillary duct?

Answer 26

1) Proximal convoluted tubule (PCT): Longest and most coiled region; most reabsorption occurs here (microvilli present)
2) Nephron loop (Loop of Henle)
a) Descending limb: thick and thin segments
-Thick segment: active transport of salts
-Thin segment: permeable to water
b) Ascending limb: mostly thick segment
3) Distal convoluted tubule (DCT): Shorter and less coiled than PCT, no microvilli
4) Collecting duct: Receives fluid from the DCTs of several nephrons as it passes back into the medulla
-Numerous collecting ducts converge toward the tip of the medullary pyramid forming papillary duct; 30 papillary ducts end in the tip of each papilla

Question 27

List the flow of fluid from the glomerular capsule to the urethra (12 steps)

Answer 27

1) Glomerular capsule
2) Proximal convoluted tubule
3) Nephron loop
4) Distal convoluted tubule
5) Collecting duct
6) Papillary duct
7) Minor calyx
8) Major calyx
9) Renal pelvis
10) Ureter
11) Urinary bladder
12) Urethra

Question 28

1) Which of the two types of nephron is most abundant?
2) Which capillary bed surrounds it?
3) Where is it mostly located?

Answer 28

1) Cortical nephrons make up 85% of all nephrons
2) They have short nephron loops and peritubular capillaries around PCT and DCT
3) Mostly located in the cortex

Question 29

1) Which of the two types of nephron is least abundant?
2) What do they do?
3) Which capillary bed surrounds it?
4) Where is it nephron loop located?

Answer 29

1) Juxtamedullary nephrons make up 15% of all nephrons.
2) They have very long nephron loops and maintain salinity gradient in the medulla and concentrates urine
4) Has a vasa recta capillary bed around a long nephron loop
5) The long nephron loop is located in both the cortex and medulla

Question 30

Name the two types of nephrons

Answer 30

Juxtamedullary and cortical

Question 31

1) What is the renal plexus and what does it carry; parasympathetic or sympathetic innervation?
2) What does this stimulation do? (2 things)

Answer 31

1) The renal plexus is made of nerves and ganglia wrapped around each renal artery that branch inside kidney. It carries sympathetic innervation.
2) a) Sympathetic stimulation reduces glomerular blood flow and rate of urine production
b) It responds to falling blood pressure by stimulating the kidneys to secrete renin

Question 32

What is the stimulus for the release of renin?

Answer 32

Sympathetic innervation

Question 33

Define and describe the four basic stages the kidneys use to convert blood plasma to urine.

Answer 33

1) Filtration: from blood to nephron; occurs in the glomerulus
2) Reabsorption: from nephron back into blood; 99% of filtrate is reabsorbed
3) Secretion: from blood to nephron
4) Water conservation: removal of water and concentrating wastes

Question 34

What structure is responsible for filtering substances from the blood to the nephron?

Answer 34

The glomerulus

Question 35

Define filtrate, urine, and blood

Answer 35

1) Filtrate: anything within the structures between the glomerular capsule and the collecting duct.
2) Urine: anything in the papillary duct and beyond
3) Blood: anything in a vein, capillary, or artery

Question 36

In glomerular filtration, list the three barriers the fluid passes through. Which involves podocyte cell extensions?

Answer 36

1) Fenestrated glomerular capillaries
2) Basement membrane
3) Filtration slits: Podocyte cell extensions (pedicels) wrap around the capillaries to form a barrier layer with filtration slits

Question 37

1) What does not normally pass through the filtration membrane?
2) What are substances that can pass freely?

Answer 37

1) RBCs, plasma proteins, large anions, all can’t fit through the membrane.
2) Water, electrolytes, urea, fatty acids, amino acids, glucose, vitamins, uric acid, creatinine, are all small enough to pass through into the filtrate.

Question 38

1) If you see blood or albumin what organ is malfunctioning?
2) Is it abnormal for a distance runner to have protein in the urine, why or why not?

Answer 38

1) The kidneys
2) Distance runners and swimmers often experience temporary proteinuria or hematuria due to strenuous exercise lowering perfusion of kidney (causes hypoxia)

Question 39

Define proteinuria, hematuria, and hypoxia.

Answer 39

1) Proteinuria: protein in urine
2) Hematuria: blood in urine
3) Hypoxia: low perfusion/ oxygen in the tissues

Question 40

Define the three filtration pressures: Blood hydrostatic, capsular hydrostatic and blood colloid osmotic pressure.
Which promotes pushing fluid out of blood capillaries? Which promotes pulling fluid back in to capillaries?

Answer 40

1) Blood hydrostatic pressure (BHP): 60 mm Hg, promotes filtration (pushing fluid out of blood capillaries)
2) Capsular hydrostatic pressure: 18 mm Hg, opposes filtration (pulling fluid back into capillaries)
3) Blood Colloid Osmotic Pressure (COP): 32 mm Hg, opposes filtration (pulling fluid back into capillaries)

Question 41

1) What is net filtration pressure?
2) Can you describe what is going on if the net filtration value is positive or is negative?

Answer 41

1) 60 out −18 in−32 in = 10 mm Hg out aka BHP - CHP - BCOP = net filtration pressure
2) If net filtration pressure is positive, then fluid is flowing out of the blood capillaries and into the glomerulus. If it’s negative, then fluid is flowing back into the blood capillaries.

Question 42

Why is high blood pressure in the glomerulus problematic?

Answer 42

High BP in glomerulus makes kidneys vulnerable to hypertension: can lead to rupture of glomerular capillaries, scarring of the kidneys (nephrosclerosis), atherosclerosis of renal blood vessels, and ultimately leading to renal failure

Question 43

How much filtrate is formed in a 24 hour period if you are male? If female?

Answer 43

180 L/day (male) and 150 L/day (female)

Question 44

What 3 things is GFR (glomerular filtration rate) directly proportional to?

Answer 44

1) Total surface area available for filtration
2) Filtration membrane permeability
3) NFP

Question 45

1) What is the issue if the glomerular filtration rate (GFR) is too high? What can this lead to?
2) What is the issue if the glomerular filtration rate (GFR) is too low? What can this lead to?

Answer 45

1) If GFR is too high, reabsorption is too low; fluid flows through renal tubules too rapidly for them to reabsorb the usual amount of water and solutes.
-Causes a chance of dehydration and electrolyte depletion
2) If GFR is too low, reabsorption is too high; everything including wastes are reabsorbed, so azotemia may occur.

Question 46

1) Which situation would increase blood pressure; glomerular filtration rate being too high or too low?
2) Which situation would increase urine output?

Answer 46

1) GFR being too low would cause blood pressure to be higher since it causes more reabsorption
2) GFR being too high would cause urine output to be higher since it causes less reabsorption.

Question 47

1) By adjusting ______________ _____________, GFR (glomerular filtration rate) can be controlled and adjusted.
2) What 3 things work together to regulate this?

Answer 47

1) Glomerular blood pressure
2) Autoregulation, sympathetic control and hormonal control work to regulate GFR

Question 48

1) Define renal autoregulation.
2) What does renal autoregulation enable the kidney to do?
3) What cells respond to drops in blood pressure and what do they do?
4) How stable does renal autoregulation make GFR?

Answer 48

1) Defined as the ability of the nephrons to adjust their own blood flow and GFR without external (nervous or hormonal) control through myogenic mechanism and tubuloglomerular feedback mechanism.
2) Enables the kidney to maintain a relatively stable GFR in spite of changes in systemic blood pressure.
3) Granular cells also contain renin, which they secrete in response to drop in blood pressure; they participate in the renin-angiotensin-aldosterone system that works to control blood volume and pressure.
4) Renal autoregulation regulates GFR but cannot keep it entirely constant; rises in blood pressure will cause a rise in GFR. If mean arterial pressure drops below 70 mm Hg, filtration and urine output cease.

Question 49

1) Define sympathetic regulation of GFR (glomerular filtration rate); what two things are involved?
2) What is sympathetic regulation stimulated by?
3) What does sympathetic regulation do to GFR and urine production?

Answer 49

1) Sympathetic nervous system and adrenal epinephrine constrict the afferent arterioles.
2) Stimulated by strenuous exercise or acute conditions like circulatory shock
3) Reduces GFR (GFR may by as low as a few ml/min. Redirects blood from the kidneys to the heart, brain, and skeletal muscles; amount of urine produced goes down.

Question 50

1) Define hormonal regulation of GFR; what is this mechanism called and what does it control?
2) What does this regulation do when BP drops?

Answer 50

1) The Renin–Angiotensin–Aldosterone; a system of hormones that helps control blood pressure and GFR.
2) Baroreceptors detect drop in BP and stimulate the sympathetic nervous system, then sympathetic fibers trigger release of renin by kidneys’ granular cells. Renin converts angiotensinogen, a blood protein, into angiotensin I. In lungs and kidneys, Angiotensin Converting Enzyme (ACE) converts angiotensin I into angiotensin II. Angiotensin stimulates the release of ADH and aldosterone; all increase blood pressure.

Question 51

What are the two mechanisms of renal autoregulation?

Answer 51

Myogenic mechanism and tubuloglomerular feedback mechanism

Question 52

1) Define the myogenic mechanisms of renal autoregulation; what is it based on?
2) What does the myogenic mechanism do when arterial blood pressure increases? Why?
3) What does the myogenic mechanism do when arterial blood pressure decreases? Why?

Answer 52

1) Myogenic mechanism: based on the tendency of smooth muscle to contract when stretched
2) If arterial blood pressure increases, the afferent arteriole is stretched, which causes constriction. This prevents blood flow into the glomerulus from changing
3) If arterial blood pressure falls, the afferent arteriole relaxes and dilates. This allows blood to flow more easily into glomerulus, so that flow rate remains similar and filtration remains stable

Question 53

1) Define the tubuloglomerular feedback mechanism of renal autoregulation; what is it, what does it respond to, and what does it change?
2) What happens with this mechanism when GFR is high? Why?

Answer 53

1) Tubuloglomerular feedback: The Macula densa of JGA (Juxtaglomerular apparatus) responds to changes in NaCl levels and adjusts filtration rate
2) When GFR is high, filtrate contains more NaCl. When macula densa absorbs more NaCl, it secretes ATP. Then ATP (metabolized into adenosine) stimulates granular cells to vasoconstrict afferent arterioles. Vasoconstriction reduces blood flow which reduces filtration rate

Question 54

1) What is the myogenic mechanism based on?
2) What happens if arterial blood pressure increases?
3) What happens if arterial blood pressure decreases?

Answer 54

1) Based on the tendency of smooth muscle to contract when stretched.
2) If arterial blood pressure increases, then the afferent arteriole is stretched and it causes constriction. This prevents blood flow into the glomerulus from changing
3) If arterial blood pressure falls, then the afferent arteriole relaxes and dilates. This allows blood to flow more easily into glomerulus, so that flow rate remains similar and filtration remains stable

Question 55

1) Explain the different roles of the macula densa and granular cells as they are involved in the tubuloglomerular feedback mechanism.
2) What happens if the GFR is too high in the tubuloglomerular feedback mechanism?
3) What substance is released and is it going to promote vasodilation or vasoconstriction of the afferent arteriole?
4) What cell is going to be responsible for changing the diameter of the afferent arteriole?

Answer 55

1) Macula densa of JGA (Juxtaglomerular apparatus) responds to changes in NaCl levels and adjusts filtration rate. This causes ATP secretion, which metabolizes into adenosine, which causes granular cells to constrict afferent arterioles.
2) When GFR is high, filtrate contains more NaCl, and when macula densa absorbs more NaCl, it secretes ATP.
3) ATP (metabolized into adenosine) stimulates granular cells to vasoconstrict afferent arterioles.
4) Vasoconstriction reduces blood flow which reduces filtration rate.

Question 56

1) Which cell type also releases renin and what is the stimulus for renin to be released?
2) In sympathetic control, what hormone is released?
3) What happens to the amount of urine produce and why is this necessary?

Answer 56

1) Granular cells also contain renin, which they secrete in response to drop in blood pressure.
2) Sympathetic nervous system and adrenal epinephrine constrict the afferent arterioles.
3) Amount of urine produced is decreased to redirect blood from the kidneys to the heart, brain, and skeletal muscles

Question 57

1) What is the renin-angiotensin-aldosterone system designed to control?
2) What detects the drop in blood pressure?
3) What does a drop in BP trigger the kidneys to release and by what cells?
4) What converts angiotensinogen into angiotensin 1?
5) What organs are responsible for converting angiotensin 1 into angiotensin 2?

Answer 57

1) It’s a system of hormones that helps control blood pressure and GFR
2) Baroreceptors detect drop in BP and stimulate the sympathetic nervous system.
3) Sympathetic fibers trigger release of renin by kidneys’ granular cells
4) Renin converts angiotensinogen, a blood protein, into angiotensin I
5) In the lungs and kidneys, Angiotensin Converting Enzyme (ACE) converts angiotensin I into angiotensin I

Question 58

1) What is angiotensin 2? How does angiotensin 2 impact blood pressure?
2) What other organs does it stimulate to release their hormones? What are those hormones?

Answer 58

1) It’s an active hormone that increases BP and a potent vasoconstrictor. Constricts efferent arteriole, which lowers BP in peritubular capillaries, enhancing reabsorption.
2) Stimulates adrenal cortex to secrete aldosterone. Stimulates hypothalamus to secrete ADH and stimulates thirst center

Question 59

1) Define tubular reabsorption.
2) In what structure does most of the tubular reabsorption occur? Describe this structure.
3) What capillary is required to get the fluid back into the blood supply?

Answer 59

1) Defined as the process of reclaiming water and solutes from tubular fluid and returning them to blood
2) Most reabsorption is by proximal convoluted tubules (65% of glomerular filtrate) which has prominent microvilli and great length, and abundant mitochondria to provide ATP for active transport
3) The peritubular capillaries.

Question 60

What are the two routes of reabsorption? Describe them

Answer 60

1) Transcellular route: pulling the substance through the cells that make up the nephron and into the blood
2) Paracellular route: pulling the substance around the cells, often using solvent drag.

Question 61

1) What is solvent drag?
2) What ion is key for reabsorption; why?

Answer 61

1) Solvent drag: water carries a variety of dissolved solutes with it
2) Na^+ cation is key for reabsorption because it creates a steep concentration, osmotic, and electrical gradient that drives the reabsorption of water and other solutes into epithelial cells

Question 62

1) What pulls Na^+ into the cell during reabsorption?
2) What follows the sodium ions?
3) What diffuses through the paracellular route?
4) What is cotransported with Na^+?

Answer 62

1) Uses symports and antiports to pull Na+ into the cell, then uses Na-K pump to pump out Na+ to extracellular fluid (then picked up by peritubular capillaries)
2) Negative chloride ions follow the positive sodium ions by electrical attraction
3) Potassium, magnesium, and phosphate ions diffuse through the paracellular route with water
4) Glucose is cotransported with Na^+ by sodium–glucose transport (SGLT) proteins; normally all glucose is reabsorbed

Question 63

1) Of the nitrogenous wastes, which is not reabsorbed?
2) Which is about half reabsorbed?

Answer 63

1) Creatinine is not reabsorbed; it is passed in urine
2) About half of urea is reabsorbed (amount in blood at safe level)

Question 64

1) What ultimately happens to uric acid?
2) What helps water get reabsorbed at a constant rate in the structure that does most of the tubular reabsorption?
3) What is this constant rate called?

Answer 64

1) The PCT reabsorbs uric acid, but it’s later secreted
2) 2/3rds of water in filtrate is reabsorbed in the PCT; the PCT uses osmosis, aided by aquaporins
3) In PCT, water is reabsorbed at constant rate called obligatory water reabsorption

Question 65

1) What is a transport maximum?
2) What happens if all transporters are occupied and more solute is around? In what substance would that appear?

Answer 65

1) Defined as the amount of solute that renal tubules can reabsorb is limited by the number of transport proteins in tubule cells’ membranes; it is reached when all transporters are saturated.
2) If all transporters are occupied, any excess solute passes by and appears in urine

Question 66

1) Define Tubular secretion.
2) If kidneys secrete free hydrogen and retain bicarbonate what happens to blood pH? Is it more acidic or more alkaline/basic?

Answer 66

1) Defined as when the renal tubule extracts chemicals from capillary blood and secretes them into tubular fluid.
2) Then blood pH rises and becomes more alkaline/basic.

Question 67

Why is tubular secretion important? (3 reasons)

Answer 67

1) Acid–base balance
a) If kidneys secrete H+ and retain bicarbonate, ph goes up
2) Waste removal
a) Urea, uric acid, bile acids, ammonia, etc.
3) Clearance of drugs and contaminants
a) Examples include: morphine, penicillin, and aspirin
b) Some drugs must be taken multiple times per day to keep up with renal clearance

Question 68

1) What is the purpose of the loop of Henle/nephron loop?
2) What do the DCT and collecting duct do and what are they regulated by?

Answer 68

1) The primary function of nephron loop is to generate salinity gradient that enables collecting duct to concentrate the urine and conserve water; it reabsorbs about 25% of filtrate
2) DCT and collecting duct reabsorb variable amounts of water and salt and are regulated by several hormones; aldosterone, atrial natriuretic peptide, ADH, and parathyroid hormone

Question 69

Can you explain the outcomes of aldosterone, atrial natriuretic peptide, and ADH regarding blood pressure and amount of urine produced?

Answer 69

1) Aldosterone: Blood pressure and blood volume increase, urine production decreases
2) Atrial natriuretic peptide: Blood volume and blood pressure decrease, urine production increases.
3) ADH: Blood volume and blood pressure increase, urine production decreases.

Question 70

1) What is aldosterone also called?
2) What triggers the release of aldosterone? (3)
3) What does aldosterone stimulate?
4) What is the result of aldosterone?

Answer 70

1) The “salt-retaining hormone”
2) Triggers for aldosterone secretion are:
a) When blood Na^+ concentration falls or
b) When K^+ concentration rises or
c) There is a drop in blood pressure renin release angiotensin II formation stimulates adrenal cortex to secrete aldosterone
3) Stimulates: reabsorption of Na^+ and secretion of K^+. Water and Cl^− follow the Na^+
4) Result: Blood pressure and blood volume increase and stabilize, urine production decreases

Question 71

1) What is ADH secreted by?
2) What triggers the release of ADH? (3)
3) What are the actions of ADH?
4) What does ADH result in?

Answer 71

1) Secreted by posterior pituitary
2) Triggers: dehydration, loss of blood volume, and rising blood osmolarity
3) Actions: ADH makes collecting duct more permeable to water (adds aquaporins) so water in the tubular fluid reenters the tissue fluid and bloodstream rather than being lost in urine
4) Result: Blood volume and blood pressure increase, urine production decreases.

Question 72

1) What are atrial natriuretic peptides secreted by and why?
2) What are the actions of ANP?
4) What does ANP result in?

Answer 72

1) Secreted by atrial myocardium in response to high blood pressure
2) ANP actions:
a) Dilates afferent arteriole, constricts efferent arteriole, increases GFR
b) Inhibits renin and aldosterone secretion
c) Inhibits secretion of ADH
d) Inhibits NaCl reabsorption by collecting duct
3) Result: Blood volume and blood pressure decrease, urine production increases.

Question 73

1) What is the stimulus for parathyroid hormone release? What is hypocalcemia?
2) Why under hypocalcemia is phosphate excreted from the body?
3) What does PTH also stimulate?

Answer 73

1) Secreted in response to calcium deficiency (hypocalcemia)
2) It increases phosphate excretion and calcium reabsorption. Because phosphate is not retained, calcium ions stay in circulation rather than precipitating into bone tissue as calcium phosphate.
3) PTH also stimulates calcitriol synthesis

Question 74

1) What is water diuresis? Does this lead to hypotonic or hypertonic urine?
2) Why?

Answer 74

1) The idea that drinking large volumes of water will produce a large volume of hypotonic urine
2) Cortical portion of the collecting duct reabsorbs NaCl, but it is impermeable to water, so salt is removed from the urine but water stays in

Question 75

1) What is dehydration? Does this lead to hypotonic or hypertonic urine?
2) Why?

Answer 75

1) The idea that not drinking enough water leads to production of hypertonic urine
2) High blood osmolarity stimulates posterior pituitary to release ADH which stimulates an increase in synthesis of aquaporin channels by renal tubule cells, so more water is reabsorbed by collecting duct, and urine is more concentrated

Question 76

1) What part of the nephron is critical for concentration of urine?
2) The ability of the kidney to concentrate urine depends on what?

Answer 76

1) The nephron loop is used to maintain and add salt to the renal medulla
2) The salinity gradient in renal medulla

Question 77

1) The fluid in the descending limb of the nephron is permeable to what chemical and impermeable to what chemical?
2) As fluid moves down the descending limb is it becoming more salty or less salty?

Answer 77

1) The descending limb permeable to water but not to salt
2) Passes through environment of increasing osmolarity (increasing saltiness) because the water passes from tubule into the ECF leaving salt behind. Tubular fluid is very concentrated at lower end of loop; becomes more salty

Question 78

1) The fluid in the ascending limb is permeable to what chemical and impermeable to what chemical?
2) As fluid moves up the ascending limb, is it becoming more salty or less salty?

Answer 78

1) The ascending limb is impermeable to water, but salt is actively transported into ECF.
2) It maintains the high osmolarity of renal medulla, but tubular fluid becomes dilute at top of loop (becomes less salty)

Question 79

1) What diffuses in and out of the descending capillaries of the vasa recta? What does this do to urine volume?
2) What diffuses in and out of the ascending capillaries of the vasa recta? What does this do to urine volume?

Answer 79

1) Descending capillaries of vasa recta: Water diffuses out of capillaries and salt diffuses in. (urine volume increases)
2) Ascending capillaries of vasa recta: Water diffuses into and NaCl diffuses out of blood; vasa recta gives the salt back and does not subtract from the osmolarity of the medulla (urine volume decreases)

Question 80

1) What is the color of urine?
2) What pigment is responsible for the color? What was broken down to produce the pigment responsible for urine color?

Answer 80

1) Varies from clear to deep amber
2) Yellow color due to urochrome pigment from breakdown of hemoglobin

Question 81

1) Define pyuria
2) Define hematuria and list possible situations that would cause this disorder
3) If urine is cloudy this is because of?

Answer 81

1) Pyuria: pus in the urine
2) Hematuria: blood in urine due to urinary tract infection, trauma, or kidney stones
3) Cloudiness or blood could suggest UTI, trauma, stones, or contamination

Question 82

1) What is the specific gravity range of urine?
2) What is the pH range of urine and the average?
3) What is the osmolarity range?

Answer 82

1) Specific gravity: compares urine sample’s density to that of distilled water. Ranges from 1.001 to 1.028 g/mL
2) pH range: 4.5 to 8.2, usually 6.0 (mildly acidic)
3) Osmolarity (blood = 300 mOsm/L): Ranges from 50 mOsm/L to 1,200 mOsm/L

Question 83

1) Urine is typically ____% water and ___% solutes
2) What are the normal chemicals in urine?
3) What are the abnormal chemicals in urine?

Answer 83

1) Urine is typically 95% water, 5% solutes
2) Normal: urea, NaCl, KCl, creatinine, uric acid, phosphates, sulfates, traces of calcium, magnesium, and sometimes bicarbonate, urochrome, and a trace of bilirubin
3) Abnormal to find: glucose, free hemoglobin, albumin, ketones, bile pigments

Question 84

If you smell ammonia in a urine sample, what can you conclude?

Answer 84

The typical odor of urine is due to bacteria degrading urea to ammonia; some foods and diseases impart particular aromas

Question 85

1) Define diabetes.
2) Describe diabetes mellitus and list its 3 types.
3) Describe diabetes insipidus.

Answer 85

1) Diabetes is defined as any metabolic disorder resulting in chronic polyuria; four forms of diabetes
2) Diabetes mellitus type 1, type 2, and gestational diabetes
-High concentration of glucose in renal tubule (exceeds transport maximum)
-Glucose opposes the osmotic reabsorption of water so more water passes in urine (osmotic diuresis)
3) Diabetes insipidus
-ADH hyposecretion causes not enough water to be reabsorbed in the collecting duct
-More water passes in urine

Question 86

1) What is a diuretic?
2) What are they commonly used to treat?
3) Give examples of diuretics.

Answer 86

1) Diuretics: any chemical that increases urine volume.
2) Commonly used to treat hypertension and congestive heart failure
3) Ex: Caffeine dilates the afferent arteriole, increasing GFR, alcohol inhibits ADH secretion. Some act on nephron loop (loop diuretic): reduces the osmotic gradient in the medulla so less water is reabsorbed

Question 87

1) What is the purpose of the ureters?
2) What are the three layers of the ureter, outermost to innermost?

Answer 87

1) To transport urine from the kidney to the bottom of the urinary bladder; there’s a flap of mucosa at entrance of each ureter acts as a valve into bladder and keeps urine from backing up into ureter when bladder contracts
2)
a) Adventitia
b) Muscularis: two layers of smooth muscle with third layer in lower ureter. Urine enters, it stretches and contracts in peristaltic wave
c) Mucosa: transitional epithelium

Question 88

1) Why are kidney stones a problem in the ureters?
2) What tissue type is unique in the mucosa layer?

Answer 88

1) The lumen of the ureters is very narrow, so easily obstructed by kidney stones
2) Transitional epithelium in the mucosa layer

Question 89

1) What is the purpose of the urinary bladder?
2) What is the trigone and why is this clinically important?
3) How much volume the trigone hold?

Answer 89

1) It’s a collapsible, muscular sac that stores urine
2) The trigone is a smooth-surfaced triangular area on bladder floor that is marked with openings of ureters and urethra. Clinically important because infections tend to persist in this region.
3) Capacity: moderate fullness is 500 mL, maximum fullness is 700 to 800 mL

Question 90

What are the three layers of the bladder, outermost to innermost and vice versa? Which layer has rugae?

Answer 90

1) Adventitia: except for top which is covered by parietal peritoneum
2) Muscularis: detrusor muscle, consists of three layers of smooth muscle
3) Mucosa: transitional epithelium. Has Rugae

Question 91

Describe the female urethra

Answer 91

1) 3 to 4 cm long, bound to anterior wall of vagina; external urethral orifice is between vaginal orifice and clitoris
2) External urethral sphincter: where the urethra passes through the pelvic floor (Urogenital diaphragm). Made of skeletal muscle; somatic fibers through pudendal nerve offer voluntary control.
3) Lacks prostate

Question 92

Describe the male urethra

Answer 92

1) Male urethra: 18 cm long
2) Three regions
-Prostatic urethra (2.5 cm)
-Membranous urethra (0.5 cm)
-Spongy (penile) urethra (15 cm)
3) Internal urethral sphincter: detrusor muscle thickening
4) External urethral sphincter: skeletal muscle of pelvic floor (Urogenital diaphragm), somatic fibers through pudendal nerve offer voluntary control.

Question 93

1) Define micturition.
2) Voiding urine is a combination of reflex and _____________ control.
3) What is the sympathetic nerve doing to the detrusor muscle and internal urethral sphincter?
4) Who controls the external sphincter?

Answer 93

1) Micturition is the act of urinating
2) reflex and voluntary control
3) Detrusor muscle relaxes; internal urethral sphincter constricted
4) Somatic motor fibers (through pudendal nerve) allows voluntary control of external sphincter

Question 94

1) What would the parasympathetic nerves be doing to the detrusor muscle and internal urethral sphincter?
2) How is it possible to involuntarily void the bladder?

Answer 94

1) Contracts detrusor muscle; relaxes internal urethral sphincter
2) Urine is involuntary voided if not inhibited by the brain (Somatic nerves) that control the external urethral sphincter

Question 95

Differentiate between waste and metabolic waste

Answer 95

Waste is any substance that is useless to the body or present in excess of the body’s needs; metabolic waste is a waste substance produced by the body.

Question 96

Does each end of a blood capillary have the same pressure?

Answer 96

No

Question 97

1) How much urine is excreted a day?
2) Roughly what percent of filtrate is reabsorbed back into the body?

Answer 97

1) 1-2L
2) 99%

Question 98

1) Can you describe what happens if the GFR is too low regarding the tubuloglomerular feedback mechanism?
2) Is the tubuloglomerular feedback positive or negative feedback?

Answer 98

1) Then the macula densa relaxes the afferent arterioles which causes flow to increase; GFR increase back to normal.
2) Negative

Question 99

Are the ascending and descending limbs of the vasa recta permeable to the same substances?

Answer 99

No

Question 100

Why is an imbalance of the most abundant intracellular cation the most dangerous type of electrolyte imbalance?

Answer 100

Hyperkalemia can produce cardiac arrest, muscle weakness, loss of muscle tone. Hypokalemia can cause arrhythmia from irregular electrical cardiac activity.