Urinary Function/Physiology Flashcards
Covers: Urinary tract functional anatomy, Glomerular filtration, Renal tubular function 1/2, Osmoregulation of urine, Renal acid-base balance, and Renal control of blood pressure lectures (84 cards)
1
Q
What structures make the final adjustments and remove fluid from the kidneys?
A
(Collecting ducts)
2
Q
What structure delivers blood to the tubules of the kidney and begins the filtration process?
A
(Glomerulus)
3
Q
What type of filtration is defined as the movement of water and solute across the glomerular membrane?
A
(Glomerular filtration)
4
Q
What is tubular secretion?
A
(Movement of substances from plasma into the tubules)
5
Q
What is tubular reabsorption?
A
(Movement of substances from the tubule back into the plasma)
6
Q
What two sections are the kidney cortex divided into?
A
(Cortical labyrinth and medullary ray)
7
Q
What are the two subdivisions of the outer medulla?
A
(Outer and inner stripe)
8
Q
What are the three types of nephrons, based on location?
A
(Superficial, mid-cortical, and juxtamedullary)
9
Q
Of the three types of nephron (based on location), which is more plentiful in animals who highly concentrate their urine?
A
(Juxtamedullary nephrons)
10
Q
What do the efferent arterioles of superficial or mid-cortical glomeruli help to form?
A
(The peritubular capillary network)
11
Q
What do the efferent arterioles of juxtamedullary glomeruli form?
A
(The vasa recta)
12
Q
(T/F) The kidneys are entirely innervated by the autonomic nervous system.
A
(T)
13
Q
(T/F) The kidneys receive sympathetic innervations only, via the minor and lumbar splanchnic nerves.
A
(T)
14
Q
Contractions of the detrusor muscle of the urinary bladder increase or decrease (choose one) the volume of the bladder.
A
(Decrease)
15
Q
The detrusor muscle of the urinary bladder is under autonomic or somatic (choose one) nervous control.
A
(Autonomic)
16
Q
(T/F) The external urethral sphincter is under voluntary control.
A
(T)
17
Q
What nerves provide sympathetic innervation to the bladder to facilitate storage?
A
(Hypogastric nerves)
18
Q
What nerve provides parasympathetic innervation to the bladder to facilitate emptying?
A
(Pelvic nerve)
19
Q
What nerves provide somatic innervation to the bladder to facilitate storage via providing motor innervation to the external urethral sphincter?
A
(Pudendal nerves)
20
Q
What is the filtering unit of the nephron?
A
(Glomerulus)
21
Q
What supplies the glomerulus with the blood that needs to be filtered?
A
(Afferent arteriole)
22
Q
What is considered the filtration unit of the kidney?
A
(Urinary/renal corpuscle)
23
Q
Does the glomerulus filter out negative, neutral, or positive particles (choose)?
A
(Filters out positive and neutral particles more than negative particles)
24
Q
What layer of the glomerular capillaries prevents red blood cells from passing into the filtrate?
A
(Endothelial layer of cells)
25
What layer of the glomerular capillaries prevents plasma proteins from passing into the filtrate and is considered the greatest barrier to filtration?
(Glomerular basement membrane)
26
What zipper-like protein composes the diaphragm of the visceral epithelial cell layer?
(Nephrin)
27
What is the first protein to elevate in the urine if capillaries in the glomerulus are abnormally leaky?
(Albumin → is 69 KD and 70 KD is the typical size limit for proteins)
28
What is the main force driving filtration in the glomerulus?
(Capillary hydrostatic pressure)
29
What is the term for the removal of a substance from the cortical peritubular capillary network and depositing it in the tubular fluid for subsequent excretion?
(Renal secretion)
30
What is the term for the removal of a substance from the renal tubular fluid back into the cortical peritubular capillary network?
(Renal absorption)
31
What is the term for the removal of a substance from the body through the glomerulus and/or cortical peritubular capillary network and the deposition of that substance into the renal tubular fluid to eventually be eliminated from the body via the urine?
(Renal excretion)
32
Damage to what region of the nephron results in Fanconi’s syndrome (which is characterized by glucosuria, aminoaciduria, hyperuricosuria, and phosphaturia)?
(Proximal convoluted tubule)
33
What occurs to all proximal straight tubules at the level of the junction of the outer and inner stripe of the outer medulla?
(They transition to the thin descending limb of the nephron loop)
34
At what point within the thin nephric loop does it transition from being highly permeable to water and lowly permeable to ions to impermeable to water and permeable to ions?
(At the bend in the loop i.e. going from descending nephric loop to ascending nephric loop)
35
What does the thick ascending limb resorb primarily?
(NaCl)
36
What does the thick ascending limb of the nephron produce that protects against UTIs, inhibits calcium crystallization, and down-regulates inflammation though may also be a nidus for urinary calculi?
(Uromodulin)
37
What is the primary purpose of the distal convoluted tubule?
(Regulation of pH by excreting/resorbing H ions and excreting/resorbing bicarbonate)
38
To facilitate renal secretion, the interstitium needs to have a lower concentration of solutes when compared to the capillary network, how is that gradient established? )
(Solutes that are to be secreted are removed from the interstitium into the renal tubules which gives the interstitium a lower concentration of secreted solutes so the solutes will want to move from the capillary network to the interstitium to be removed by the renal tubules and over and over
39
(T/F) The Na-K ATPase pump maintains higher concentrations of Na extracellularly and higher concentrations of K intracellularly.
(T)
40
Of the proximal and distal tubules, which respond to signals from elsewhere in the body whereas the other performs its functions pretty much no matter what?
(Distal tubules respond to signals from elsewhere in the body while the proximal tubules perform their functions pretty much no matter what)
41
The presence of what in the urine determines its weight and therefore its specific gravity?
(Solutes such as urea, creatinine, Na, K, etc.)
42
What is the term for urine with a specific gravity neither greater nor less than that of protein-free plasma?
(Isosthenuria)
43
What is the term for urine with a specific gravity less than the specific gravity of protein-free plasma?
(Hyposthenuria → dilute urine)
44
What is hypersthenuria?
(Urine with a specific gravity greater than protein-free plasma → concentrated urine)
45
(T/F) Both hypo and hypersthenuria implies the kidney is functioning while isosthenuria can be a sign the kidney is not functioning properly and the filtrate being produced is not modified.
(T)
46
What results from the stimulation of osmoreceptors by increased plasma osmolality? Two answers.
(Thirst and release of ADH from the posterior pituitary are both stimulated)
47
Where within the nephron of the kidney does ADH increase water permeability which results in increased water reabsorption? Two answers.
(Late distal tubules and collecting ducts)
48
(T/F) ADH increases the activity of the Na-K-2Cl cotransporter so during times of dehydration, the corticopapillary osmotic gradient is increased.
(T)
49
Where do loop diuretics (i.e. furosemide) inhibit the Na-K-2Cl transporter within the nephron?
(Ascending thick loop of Henle)
50
What does the inhibition of the Na-K-2Cl transporter by furosemide result in?
(Decreased Na, Cl, and K reabsorption in the ascending limb results in water being retained in the tubule and excreted)
51
Why do thiazide diuretics have a lesser effect when compared to loop diuretics?
(D/t site of action, thiazide diuretics inhibit sodium reabsorption in the distal renal tubules and a lot of water reabsorption has already occurred by the time tubule fluid reaches the distal tubules while furosemide works on the ascending loop limb)
52
What disease acts similarly to mannitol, which is a hyperosmotic diuretic that inhibits reabsorption of fluids from the renal tubules?
(Diabetes mellitus → the amount of glucose in the filtrate exceeds the tubular maximum for reabsorption so the excess stays in the tubules and draws water into the tubules which is then excreted)
53
What are the causes for medullary ‘washout’ which is the destruction of the osmotic gradient? Three answers.
(Severe PU/PD, iatrogenic over-administration of IV fluids, and not enough solutes being present such as urea deficiency d/t hepatic insufficiency or hyponatremia d/t typical Addison's dz)
54
What results from medullary ‘washout’?
(An inability to concentrate urine)
55
What does carbonic anhydrase use to form carbonic acid?
(CO2 and water)
56
What does carbonic acid dissociate into?
(Bicarbonate and hydrogen)
57
How do fixed acids (sulfuric acid from breakdown of sulfur containing amino acids, phosphoric acid from breakdown of phospholipid, etc.) differ from the volatile acid carbon dioxide?
(They differ in how they are dealt with → CO2 is blown off by the lungs which gives it the volatile acid title, the fixed acids cannot be blown off by the lungs so they need to be buffered in the blood by other substances)
58
(T/F) Kidneys reabsorb bicarbonate and excrete hydrogen.
(T)
59
How is bicarbonate transported from the lumen of the proximal tubule into the tubule cells to then be transported to the blood? (It’s a long process (5ish steps depending on how you break it down) but important to know)
(Hydrogen is pumped into the proximal tubule lumen by Na+-H+ exchangers, the hydrogen reacts with the bicarbonate to form carbonic acid, brush border carbonic anhydrase degrades carbonic acid into CO2 and H2O which are both readily absorbed into the tubule cells, intracellular carbonic anhydrase then reacts the CO2 and H2O back into carbonic acid to then dissociate into hydrogen and bicarbonate, hydrogen goes through the Na+-H+ exchanger and the bicarbonate is absorbed into the bloodstream)
60
What are the three mechanisms used by the kidneys to regulate extracellular fluid hydrogen concentration?
(Secretion of hydrogen, reabsorption of filtered bicarbonate, and production of new bicarbonate)
61
In what non-dangerous form can hydrogen ions be moved around in the body?
(H2O is the non-dangerous form of hydrogen that can freely move through the body)
62
What occurs if the pH of urine drops lower than the 4.4 minimum?
(Net secretion of hydrogen ceases → so if you didn’t have any buffers in the urine (as it should normally), the hydrogen being secreted into the urine would quickly drop it below 4.4 and hydrogen secretion would stop even if there was severe acidemia, so that’s where buffers come in to play)
63
What is considered to be the almost ideal urinary buffer?
(Phosphate)
64
Why is 15% of phosphate excreted (which is pretty high when compared to other electrolytes of the body)?
(Because it is an important buffer, its high excretion is necessary to maintain its buffering effect as urine passes through the rest of the nephron)
65
What hormone regulates the reabsorption of phosphate in the proximal tubule by inhibiting the sodium-phosphate cotransporter?
(Parathyroid hormone)
66
In a metabolic alkalosis patient:
- The kidney initially tries to maintain blood pH by excreting alkaline urine.
-- What electrolytes are excreted with bicarbonate?
(Sodium and potassium)
67
In a metabolic alkalosis patient:
- The kidney initially tries to maintain blood pH by excreting alkaline urine.
- The patient will eventually have a volume deficit large enough that it triggers the kidneys to move from maintaining pH to instead expanding the extracellular volume by resorbing sodium.
-- What follows the potassium that is lost (via an aldosterone-mediated mechanism) that results in paradoxical aciduria of your alkalotic patient?
(Hydrogen ions)
68
What mineralocorticoid hormone produced by the zona glomerulosa is essential for sodium conservation in the kidney, thus playing a role in regulation of blood pressure?
(Aldosterone)
69
What effect does angiotensin II and III have on aldosterone secretion?
(Both stimulate aldosterone secretion)
70
What three structures comprise the juxtaglomerular complex?
(The macula densa, the juxtaglomerular cells (aka granular cells; they secrete renin), and the extraglomerular mesangial cells)
71
What do the juxtaglomerular cells secrete renin in response to?
(Decreased blood pressure)
72
Extraglomerular mesangial cells have a contractile property similar to vascular smooth muscles so they control what?
(Blood flow into and out of the glomerulus)
73
What does the macula densa decrease the GFR, by constriction of the adjacent afferent arteriole, in response to?
(Elevated sodium chloride in the distal tubule)
74
What do the macula densa cells produce if sodium concentrations are decreased? Two answers.
(Nitric oxide and prostaglandins → they vasodilate the afferent arterioles and increase renin release which eventually leads to aldosterone stimulation and subsequent conservation of sodium)
75
What four effects does angiotensin II have on the body?
(Increases aldosterone secretion, increases Na+-H+ exchanger rate, increases thirst, and causes vasoconstriction → all of these increase arterial BP which increases renal perfusion)
76
(T/F) Regulation of the GFR is mainly an autoregulatory process such that the kidney is receiving and responding to intrinsic signals without central input.
(T)
77
What is the primary mechanism of maintaining GFR?
(Altering diameter of afferent and efferent arterioles → increasing the diameter of the afferent while proportionally decreasing the diameter of the efferent arteriole will increase GFR and vice versa)
78
When does sympathetic/CNS override the local control of the diameter of the afferent/efferent arterioles occur?
(In times of severe stress such as pursuit, hemorrhagic hypovolemia, etc.)
79
What reflex results in afferent arteriolar constriction in response to increased afferent arteriolar pressure and vice versa?
(Myogenic reflex)
80
If there is increased pressure in the afferent arteriole, how does the efferent arteriole respond and why?
(It will relax which allows blood to more easily flow into it, this will prevent the hydrostatic pressure from being too high within the glomerulus i.e. to keep the GFR WNL)
81
If you have an increased flow rate or solute concentration within your distal tubule, what effect does this have on your arterioles and mesangial cells?
(Causes constriction of afferent and dilation of efferent arteriole; causes contraction of mesangial cells; tis the opposite if you have decreased flow rate or solute concentration → decreasing the GFR in the face of increased flow rate/solutes will fix those issue and vice versa)
82
What disease process stimulates a compensatory erythropoietin secretion to increase RBCs?
(Hypoxemia)
83
What is the active form of vitamin D that is made in the kidneys?
(Calcitriol)
84
Calcitriol acts on the kidney to stimulate the reabsorption of what two electrolytes?
(Calcium and phosphate)
