Urinary System Flashcards
1
Q
what type of gland is the kidney?
A
compound tubular
2
Q
what are the major functions of the kidney?
A
- filtration
- secretion
- (re)absorption
3
Q
Describe the organization of the kidney
A
- outermost capsule (CT)
- Outer cortex
- Inner medulla
4
Q
what types of cells make up the kidney capsule?
A
fibroblasts and myofibroblasts
5
Q
What makes up the kidney cortex?
A
- Renal corpuscle
- Renal columns
- Medullary Rays
6
Q
What makes up the renal corpuscle?
A
- Capillary Glomerulus
2. Bowman’s capsule
7
Q
what is the capillary glomerulus?
A
branched fenestrated capillary tube that is derived from and afferent arteriole and drained by an efferent arteriole (arterial portal system!)
8
Q
What is a medullary ray?
A
straight portions of the 1. proximal and 2. distal tubules and the 3. collecting ducts as they extend into the medulla
9
Q
What does the medulla of the kidney contain?
A
tubules + collecting ducts grouped into pyramids
10
Q
what is a medullary pyramid?
A
cone shaped bundle of tubules that converge to form a papilla with a rounded apex that projects into a minor calyx
11
Q
What does the renal sinus contain?
A
Renal Pelvis with its:
major/minor calyx, branches of renal arteries, veins, nerves, and fatty connective tissue
12
Q
what is the renal pelvis
A
an expanded funnel shaped portion of the ureter
13
Q
what defines a kidney lobe?
A
medullary pyramid + associated cortex tissue (humans have 8-18 per kidney); bound by interlobar arteries
14
Q
What does premature birth cause with respect to kidney development?
A
can cause a decrease in the number of kidney lobes and thus develop into hypertension during the ADULT LIFE
15
Q
what defines a kidney lobule?
A
medullary ray + associated cortex tissue (the lobule is centered around the medullary ray and bound by interlobular arteries)
16
Q
What is a uriniferous tubule?
A
a nephron + the associated collecting tubule
17
Q
What is a nephron
A
the function unit of the kidney, around 2 million per kidney
18
Q
what is Bowman’s capsule?
A
blindly ending tubule indented by glomerular capillary
19
Q
What makes up a thick segment of the nephron?
A
the convoluted and straight tubules (proximal or distal)
20
Q
What makes up the Loop of Henle?
A
it is a loop that includes the entire U-shaped portion of the nephron with its hairpin turn; made of the THIN segment of a nephron
21
Q
what are the two types of nephrons?
A
- cortical/supcapsular
2. juxtamedullary
22
Q
Describe the cortical/supcapsular nephron? (the defining characteristic, location, function)
A
SHORT loops of Henle in the cortex and outer medulla ;
located in the outer cortex
function: do not concentrate urine significantly
23
Q
Describe the Juxtamedullary nephron? (the defining characteristic, location, function)
A
LONG loops of Henle deep into the pyramids ;
renal corpuscle is located near the corticomedullary junction
function: significantly contribute to the concentration of urine
24
Q
Regardless of nephron type, where are the straight portions of the neprhon/collecting tubules located?
A
in the medullary ray (WITHIN IN THE CORTEX, but extending into the medulla)
25
Describe afferent blood flow in the kidney
Renal artery to interlobar artery to arcuate artery to interlobular artery to afferent arterioles to glomerular capillary
26
Describe efferent blood flow in the subcapsular nephrons
from the glomerular capillary to the efferent arteriole to the PERITUBULAR CAP to the interlobular vein to the arcuate vein to the interlobar vein to the renal vein
27
Describe efferent blood flow in the juxtamedullary glomerulus
from the glomerular capillary to the efferent arteriole to the STRAIGHT ARTERY (VASA RECTA) to the VENOUS VASA RECTA to the arcuate vein to the interlobar vein to the renal vein
28
where are the interlobar arteries/veins located in the kidney?
between pyramids
29
where are the arcuate arteries in the kidneys located?
between the cortex and base of the pyramids
30
where are the interlobular vessels in the kidneys located?
run radially in the cortex between the medullary rays
31
How does the morphology of an efferent arteriole compare to that of an afferent arteriole? Why is this significant?
the diameter of the efferent arteriole is smaller than that of an afferent arteriole;
this allows for maintenance of the filtration pressure
32
what is the function of the renal corpuscle?
to filter plasma from the glomerular capillary
33
what is the renal corpuscle composed of?
bowman's membrane + glomerulus
34
what type of capillary is the glomerulus?
branched fenestrated (w/open fenestrae)
35
what is the vascular pole of the nephron?
where the Afferent ateriole enters the renal corpuscle and the efferent arteriole leaves it
36
what is the urinary pole of the nephron
where the parietal layer of the bowman's membrane is continuous with the beginning of a proximal convoluted tubule
37
What does Bowman's space enclose?
the urinary space with contains provisional urine
38
what type of epithelium is found in the parietal layer of Bowman's capsule?
simple squamous epithelium
39
what type of epithelium is found in the visceral layer of Bowman's capsule?
podocytes
40
Describe podocyte morphology
have interdigitating pedicals (foot processes) separated by slit pores spanned by slit membranes
41
what makes up the filtration barrier of the nephron?
1. glomerular endothelium
2. glomerular basement membrane
3. slit membrane
4. glycocalyx of podocytes
42
How does the glomerular endothelium contribute to the filtration barrier of the nephron?
it has OPEN FENESTRAE that restrict the entry of molecules >70kD into the glomerular basement membrane; some fenestrae with diaphragms are also present
43
How does the glomerular basement membrane contribute to the filtration barrier of the nephron?
it contains type IV collagen, heparin sulfate, laminin and fibronectin;
the negative charge of the heparan sulfates limits the movement of negatively charged proteins less than 70 kD across the GBM although they may enter the GBM
44
What molecules does the glomerular basement membrane contain that contributes to the filtration barrier of the nephron
it contains type IV collagen, heparin sulfate, laminin and fibronectin
45
What is the slit membrane formed by?
nephrin (an adhesion protein) and its anchoring comoplex
46
where are the slit membranes located?
between the pedicels of a podocyte (in the visceral layer of the bowman's capsule)
47
How does the glycocalyx of the podocytes contribute to the filtration barrier of the nephron?
it is polyanionic (negatively charged) and limits the passage of negatively charged molecules into the filtrate
48
What is glomerular nephritis? what is the most severe form?
when anitgen-antibodies complexes accumulate in the GBM; auto-antibodies to GBM produce the most severe form
49
What is congenital nephrotic syndrome caused by? what are typical symptoms?
caused by lethal defects in gene producing NEPHRIN; thus defect in slit membrane thus things can filter through more easily to the urine in the nephron;
in Children (symptoms): low albumin in BLOOD high albumin in URINE
50
What are mesangial cells?
specialized contractile cells, pericyte like
51
where are mesangial cells located?
within the stalk of the capillary tuft (intraglomerular mesangium) and the vascular pole (extraglomerular mesangium)
52
what is the function of intraglomerular mesangium cells?
1. maintenance of the basement membrane through phagocytosis
2. structural support
3. regulation of blood flow through the glomerulus
4. secrete interleukin-1 and platelet derived growth factor (PDGF)
53
How does the basement membrane of the glomerular endothelial cell and the slit membrane (on podocyte) appear?
fused basal laminae of endothelial cell and podocyte appears trilaminar
54
what are mesangial cells derived from? why is this interesting?
FROM SMOOTH MUSCLE CELLS!!! rare occurrence where the phagocytic cell is NOT derived from a monocyte.
55
what is the function of the proximal tubule (convoluted and straight)
1. recovery of 2/3 of glmoerular filtrate including water, ions, glucose, amino acids and small proteins
56
what is transported actively in the proximal tubule? passively?
active transport of Na+ passive transport of Cl-
57
How does water enter the proximal tubule?
it follows the ions by paracellular and transcellular routes; absorption is aided by aquaporin-1 channels in the PM of the proximal tubule cells
58
what does the proximal tubule secrete?
creatine, some dyes, and drugs
59
Describe the morphology of the epithelial cells in the proximal tubule
Simple cuboidal with a well developed brush border (apical microvilli), basal striations and lateral interdigitating folds of the plasma membrane;
Has prominent endocytotic apparatus with pinocytic vesicles, vacuoles, and lysosomes for intracellular degradation
60
what is present in the proximal tubule for intracellular degradation?
prominent endocytotic apparatus with pinocytic vesicles, vacuoles, and lysosomes f
61
where are the peritubular capillaries located? what type of capillary?
close to the peritubular capillaries; usually fenestrated capillaries
62
what is the thin limb of the nephron located near?
vasa rectae
63
what type of epithelial cells are found in the thin limb of the nephron?
simple squamous epithelium
64
What are the functions of the ascending thin limb?
It is impermeable to water but has Na/K ATPase that increase the osmotic gradient in the itnerstitium; this is essential for the counter current multiplier system in order to produce HYPERTONIC URINE IN COLLECTION DUCTS
65
what results from inhibition of the ion pumps in the thin limb of the nephron? what would cause this?
caused by a diuretic; inhibition of NaCl uptake causes an increase of urinary excretion of NaCl and therefore an increase in water excretion
66
Describe the morphology of the distal tubule epithelium
simple cuboidal and a few short microvilli NO BRUSH BORDER; little endocytotic activity
extensive system of lateral interdigitations and basal lamina striations with associated mitochondria (for active absorption of Na+, bicarbonate and secretion of K+/H+)
67
What allows for active absorption of the Na+, bicarbonate and secretion of K+/H+ in the distal tubule?
extensive system of lateral interdigitations and basal lamina striations with associated mitochondria
68
what controls the active absorption of Na+ in the distal tubule?
aldosterone
69
what does the secretion of H+ in the distal tubule contribute to?
the acidification of urine
70
what is the straight portion of the distal tubule located near? the convoluted portion?
```
straight = near vasa recta
convoluted = near peritubular capillaries
```
71
what is the macula densa a part of?
Juxtoglomerular apparatus
72
what is the macula densa of the nepron
a group of tall narrow cells in the wall of the DISTAL at the site of contact with the afferent and efferent arterioles (vascular pole)
73
what is the function of macula densa cells?
they respond to low Na+ concentrations in filtrate and lowered blood pressure and simulate justaglomerular cells to produce renin in response
74
what do macula densa cells respond to?
lowered Na+ concentrations in the filtrate and lowered blood pressure
75
what does stimulation of the macula densa cells result in?
simulation of the juxtaglomerular cells to produce renin (to increase blood pressure)
76
Describe the polarity of the macula densa cells
reversed; release secretion (ATP, adenosine, Nitric Oxide, prostaglandins) at the BASAL surface
77
What is the function of the juxtaglomerular apparatus?
to regulate Na+ absorption and BP
78
What is the juxtoglomerular apparatus made up of?
1. Macula Densa cells of the DISTAL TUBULE
| 2. Juxtaglomerular Cells (JG Cells)
79
what are Juxtoglomerular cells?
modified SMC (myoepitelioid) in arteriole wall hat produce Renin in response to signaling from macula densa
80
what cells produce Renin?
JG cells
81
what is renin?
a protease that catalyzes the hyrdolysis of angiotensinogen (circular protein in plasma) to aniotensin I
82
where is angiotensin I converted to angiotensin II? by what?
in the lungs by Angiontensin Converting Enzyme (ACE)
83
what is the role of angiotensin II?
potent VASOCONSTRICTOR
84
what does angiotensin stimulate?
the adrenals to produce aldosterone which acts on the distal convoluted tubule to increase Na+ absorption and thus increase blood pressure and blood volume levels
85
what is the function of aldosterone? where is it produced?
it acts on the distal convoluted tubule to increase Na+ absorption and thus increase blood pressure and blood volume levels; produced in the adrenals;
86
How do ACE inhibitor and ACE receptor blockers work? what is it used to treat?
they interfere with the renin/angiotensin system and inhibit/block ACE from converting angiotensin I to angiotensin II thus preventing vasoconstriction and stimulation of Na+ absorption via aldoserone;
Used to treat chronic ypertension
87
What do the arched collecting tubules drain into? (what do those drain into..)
empty into straight collecting ducts which fuse to form papillary ducts hat converge at the apex of papilla and open at the minor calyx
88
what do the light (principal) cells of the collecting ducts resorb? secrete?
resorb Na+
| secrete K+
89
what do the light (principal) cells of the collecting ducts respond to?
antidiuretic hormone (ADH)
90
what is the function of the antidiuretic hormone (ADH)
regulates he insertion of water channels (aquaporin 2) into the cell membranes and therefore increase water intake
91
where is aquaporin-1 present? aquaporin-2?
aquaporin-1 for water resorption in the proximal tubule; aquaporin-2 for water channels in collecting ducts (mediated by ADH)
92
what is the general function of the light (prinicipal) cells of the collecting duct?
involved in Na+ (and therefore water) resorption
93
what do the dark (intercalated) cells of the collecting duct resorb? secrete? general function?
general function = regulate acid-base balance
resorb = K+
secrete H+ or HCO3-
94
Describe the epithelium of the collecting ducts
```
smaller = simple cuboidal
larger = simple columnar
```
95
what are the most important things in setting up a gradient of Na+ concentration in the kidney?
juxtamedullary nephrons
96
what part of the nephron is impermeable to water?
distal thin ligament + parts of the straight ligament
97
where is the Na+ concentration the highest? why?
in the medulla because the distal thin ligament + parts of the straight ligament are impermeable to water
98
what is the result of the high Na+ concentration in the medulla of the kidney?
it passively draws water out of the collecting ducts (ADH concentration regulates the number of aquaporin -2 channels in the collecting duct PM)
99
what is the result of more ADH present?
= more highly concentrated the urine becomes and lower its volume
100
Describe the sodium concentration regulation of the kidney
when the macula densa senses low Na+ concentration in the provisional urine, it causes aldosterone binding to the DCT cells of the nephrons; DCT increase their Na+ uptake which is transferred into the blood via peritubular fenestrated capillary network causing an increase in blood Na+ concentration
101
what is diabetes insipidus caused by? symptoms?
due to defect in ADH effectiveness (ie: hypophyseal tumor or defective receptors) ; causes an increase in water consumption (polydipsia) and increase in urination (polyuria) but NO GLUCOSE IN URINE
102
what are the symptoms of diabetes mellitus (with respect to the kidney)
high glucose concentration in the blood acts as an osmotic diuretic in the nephron; GLUCOSE PRESENT IN THE URINE
103
what is the function of the interstitial cells of the kidney? what do they include?
endocrine function; includes 1. erythropoietin (stimulates RBC production in bone marrow) 2. thrombopoietin (stimulates platelet production in the bone marrow) 3.causes hyrdoxylation of vitamin D precursor to the hormonally active form
104
Where is translational epithelium found?
lining the minor/major calyces, renal pelvis, ureter, bladder (excretory passages); the walls gradually thicken as the passages near the bladder
105
Describe the mucosa in the renal pelvis and ureter
translational epithelium (urothelium) and fairly dense LP + muscularis mucosae
106
describe the muscle layers in the renal pelvis and ureter
inner longitudinal + outer circular SMC + anoter outer longitudinal layer added in the lower portion of the ureter (+muscularis mucosae in mucosa)
107
how do you ID the ureter?
small, translational epithelium, thin musculais layer, surrounded by adipose
108
Describe the mucosa of the bladder
translational epithelium that is thicker than the ureter (varies from 3-10 layers) with contraction and distension
109
what facilitates distension in the bladder epithelium? how?
intedigitated cell borders; the surface cells have plaques of thick asymmetrical PM and fusiform vesicles in the apical cytoplasm which are reserve packets of membrane material; thus the membrane can fold inward or reinsert for distension
110
what are the fusiform vesicles in the apical cytoplasm of the bladder epithelium?
reserve packets of membrane material
111
Describe the muscularis layer of the bladder
3 layers: longitudinal, circular, longitudinal; the circular layers are thickened near the opening of urethra to form internal sphincter; the muscles are pierced obliquely by he ureters
112
Describe the mucosa of the female urethra
translaional epithelium near the bladder hat turns into stratified squamous with patches of stratified or psuedostratified columnar;
the LP has LOTS OF ELASTIC FIBERS;
Has mucus glands of Littes (more present in the male)
113
where are the mucous glands of Littes located?
In the mucosa layer of the urethra (more in male)
114
Describe the muscularis layer of the urethra?
inner longitudinal, outer circular SMC; MUCH THICKER THAN IN THE URETER;
115
what type of muscle is the inner urethral sphincter? what does it arise from?
the inner sphincter of SMC = around the origin of the urethra from the bladder
116
what type of muscle is the external urethral sphincter? what does it arise from?
the external sphincter = SKELETAL muscle arises from the urogenital diaphragm
