3. Structure & Function of the Kidney - Part II
Ureter Underlying muscularis consists of 3 layers of smooth muscle; what are the 3?
1)inner longitudinal, 2)middle circular, and 3)outer longitudinal (vs. Outer circular in bladder)
Three Components of Glomerular Filtration Barrier: 1. Fenestrated endothelial cells have _______ nm pores & ______ ly charged. 2. GBM is ______ nm thick. both sides are _______ly charged. 3 Podocytes have _____ & _____ processes. Slits are _____ nm. Bridged by __________.
1. 50-100 nm, negatively. 2. 200-300 nm thick, negatively. Negative charge repel anionic protein & molecules retaining them in the blood vessel. (NOT 100% retained, if leak out, will be reabsorbed by endocytosis). 3. primary & secondary. slits are 25 nm. bridged by diaphragm.
GBM acts as a Physical Barrier & Ion-Selective Filter. 1. Restricts the movement of particles, usually proteins, larger than ~________ daltons or ____ nm radius (e.g., albumin or hemoglobin). 2. The ___________ of the GBM have negative charges and restrict the movement of anionic particles and molecules across the GBM, even those smaller than ______ daltons.
1. 70,000 daltons or 3.6 nm. 2. polyanionic glycosaminoglycans 70,000.
Nephron Segments: Collecting duct (CD) What are the 3 parts of collecting duct?
1. Cortical collecting duct (CCD) 2. Outer medullary collecting duct (OMCD) 3. Inner medullary collecting duct (IMCD)
What are 4 specialized cells in proximal tubules for reabsorption? 1. __________ to increase surface area of apical membrane up to 36 fold, permitting reabsorption of vast quantities of solute and water; 2. an extensive __________ and numerous __________ (high energy consumption), 3. ______tight junctions in early part for _________ transport of water & solute. 4. Lot of infolds in _________ side as well to increase SA. & ____________.
1. Dense microvilli 2 Endocytotic system, Mitochondria 3. Leaky, Paracellular 4. Basolateral, Na+K ATPase. Proximal tubule is characterized by a prominent brush border (increases the membrane surface area by a factor of ~ 40 fold). Basolateral infoldings, lined with mitochondria, are interdigitated w/ basolateral infodings of adjacent cells.
Renal corpuscle(RC) is in 3 layers of Glomerular Filtration Barrier. 1. Luminal Capillaries in Renal corpuscles have _________ endothelial cells because we want a large SA for the movement of fluid 2. Thick matrix called _____________. -filtration barrier. (side selectivity to it via charges). Prevent proteins from crowssing out of the blood vessels So very large molecuels & proteins will be retained. But water & electrolytes will move through. 3. Podocytes (outside the RC) - continuous w/ the cells of __________ - podocytes have foot processes (extend up off the basement membarne to provide even more SA for the fluid movement to occur)
1. Fenestrated 2. glomerulus basement membrane (GBM) 3. bowman's capsule
Describe the three layers of the glomerular filtration barriers and identify podocytes, foot processes, slits and basement membrane 3 Components of Glomerular Filtration Barrier are
1. Fenestrated endothelial cells 2. Glomerulus basement membrane 3. Podocytes On the outside.
2 parts of Renal Corpuscles?
1. Glomerulus - tuft of capillaries. - fed by afferent arteriole & blood leave by efferent arterioles. - Filtration occurs here. - is surrounded by Bowman's capsule. 2. Bowman's Capsule. Is continuous w/ the cells of proximal tubule. has 3 parts 1. Basement membrane 2. parietal epithelium 3. Visceral epithelium (podocytes). Parietal layer = Simple squamous epithelium. Space b/w the two = Bowman's space—filtrate will move into the Bowman's space. Then Filtrate is going to move down to the proximal tubule.
What are 2 cell types of IMCD? Inner Medullary Collecting Duct
1. IMCD cells - 90% of cells in IMCD Function in sodium, chloride and water homeostasis. 2. Intercalated cells - 10% of cells in IMCD - function in acid-base balance.
3 components of Glomerulus Basement Membrane?
1. Lamina Rara Externa (LRE) 2. Lamina Rara Interna (LRI) 3. Lamina densa (LD) this is thick! So, the GBM matrix is the predominant barrier holding back proteins within the vasculature. Thus, Hemoglobin & Albumins dont pass.
What forms the JGA?
1. MD cells, 2. afferent and efferent arterioles and 3. the adjacent extraglomerular mesangial cells (extra- b/c outside) forms the JGA.
Intercalated cells 1. ________ and many _______. 2. Abundant __________ - major function in ____________.
1. Microvilli and many mitochondria 2. Abundant carbonic anhydrase II 3. Acid-Base Balance.
Cortical collecting duct has 2 major cell types: what are those & %?
1. Principal cells- 40% of cells in CCD. 2. Intercalated cells - 60% in CCD.
Mictritition is composed of 2 processes:
1. Progressive filling of bladder until pressure reaches a critical value (approx. 300 ml) - Sense it's "filled" 2. Neuronal reflex (micturition reflex) that empties bladder
Distal Convoluted Tubule 1. ______ than proximal tubule. 2. Cells are ____________ in shape, 3. with short stubby ______ & 4. deep basolateral infoldings containing __________. 5. Primarily involved in ______________ transport.
1. Shorter 2. simple cuboidal, 3. short stubby microvili 4. mitochondria. 5. sodium, calcium and magnesium
Loop of Henle makes a hairpin loop into the medulla. What are 4 parts of loop of Henle?
1. Terminal portion of the proximal tubule 2. Thin descending limb 3. Thin ascending limb 4. Thick Ascending limb * NOTE THICK descending limb = Straight Proximal tubule
2 characteristics of Lamina Rara Interna: 1. adjacent to the_________________; 2. contains laminin & other proteins that are involved in the attachment of the _______________ to the GBM.
1. adjacent to the capillary endothelium; 2. contains laminin and other proteins that are involved in the attachment of the endothelial cells to the GBM.
3 characteristics of Lamina rara externa (LRE): 1. adjacent to the ________________. 2. rich is _________ that impedes the passage of negatively charged molecules 3. contains ____________ that are involved in the attachment of the "podocytes" to the GBM
1. adjacent to the podocyte processes; 2. rich in heparan sulfate that impedes the passage of negatively charged molecules 3. contains laminin and other proteins that are involved in the attachment of the podocytes to the GBM
Juxtaglomerular (JG) Apparatus (JGA) 1. In the cortex, the distal convoluted tubule approaches its "parent" glomerulus" and lies in close proximity to the ______________ arterioles. 2. Tubular epithelial cells are______ in this region and the nuclei are closely packed together- cells referred to as the ____________.
1. afferent & efferent 2. Taller, macula densa (MD)
MD cells detect what 2 things?
1. changes in tubular ionic composition & 2. changes in tubular flow rate. When MD cells detect changes, it promotes release of signals from adjacent mesangial cells, which in turn regulate GFR(glomeruli filtration rate) and renal blood flow.
How is fenestration in Endothelium of Glomerular Capillaries different from fenestrations in other capillaries?
1. larger (70 to 90 nm in diameter), 2. more numerous, and 3. more irregular in outline than fenestrations in other capillaries.
Loop of Henle Thin descending & ascending limbs are characterized by 1. flattened, _______ cells with 2. ____ apical projections, mitochondria, or basolateral invaginations.
1. squamous 2. few
Structures Nephron Segment 1. Proximal Tubule. - Early portion is tortous - referred to a _____________ and is situated in cortex. (directly behind the ___________) - Late portion is straight and is referred to as __________ and is situated in outer stripe of __________.
1.- proximal convoluted tubule - Renal corpuscles. - thick descending limb - outer medulla.
What is trigone?
3 openings in urinary bladder- 2 for ureters and 1 for urethra- form a triangle
Micturition reflex 1. Filling of bladder (______ ml) activates stretch receptors in bladder wall. Signals travel via pelvic nerve & hypogastric nerves to spinal cord. This initiates a reflex increase in PSNS efferent activity.
>300
What is the difference in components & functions of tDL (thin descending limb) & TAL (THICK ascending limb)?
A cross section through THIN DL in outer medulla. As name suggests, shallow epithelia w/o prominent mitochodnria of more proximal segments. THICK limb, in contrast, is taller epihtelium w/ basolateral infoldings & well-developed mitochondria. This segment is water IMPERMEABLE, and transport along this segment is important for generation of interstitial solute gradient & a low salt concentration and to dilute fluid in the tubular lumen.
Structure of the renal corpuscle. Important regulatory system for renin.
A. Mesangial cells are associated with the capillary endothelium of the glomerulus and the glomerular basement membrane. The macula densa cells of the distal tubule are shown intimately associated with the juxtaglomerular cells of the afferent arteriole and the extraglomerular mesangial cells. B. Photomicrograph of an H&E-stained specimen showing a renal corpuscle. The macula densa is seen in close proximity to the vascular pole.
I clicker Q. Cancer Patient Damaged podocyte. What is MOST likely to develop? a. Renal failure b. Low serum albumin due to protein loss in the urine 3. Hypertension 4 Signs of inflammation in her urine.
A. not enough information for renal failure. B. damage podocyte (filtration barrier)—have selectivity on them (negatively charged) going to have albumin leaking acorss. Consequently will have the low serum albumin.
What happens as we go from CONVOULTED to STRAIGHT proximal tubules?
As we go to the straight portion, we lose basolateral infoldings & microvilli. These adaptations are most prominent in the FIRST part of proximal tubule & are less well developed later along the proximal tubule.
Loop of Henle What is the difference b/w thin descending limb & thin ascending limb?
Descending limb is permeable to water but ascending is not.
I clikcer Q. "Strept throat" patient has a glomerulonephritis. Dark brown urine due to RBC in urine. What will also be found in his urine? A. Na+ B. K+ C. Serum Albumin D. Creatine E. Urea.
C. Serum Albumin
Correctly Name the blue, yellow, pink, green Structures of Renal Corpuscle. a Central mesangial stalk b. widely patent peripherally located capillaries c. podocytes d. glomerular basement membrane
Central mesangial stalk (blue), widely patent peripherally located capillaries (yellow), podocytes (pink), glomerular basement membrane (green).
Collecting duct Figure.
Collecting duct changes its morphology as it travels from cortex (CCD) to Medulla (OMCD & IMCD). In the cortex there are 2 cell types: Principal cells (PC) & Intercalated cells (IC). **NOTE IC is darker in color.
Serosa is consists of?
Connective tissue covered externally by thin, simple squamous epithelium made of a continuous layer of mesothelial cells (not seen at this magnification).
Note the relationship of Mesangial cells, Capillary, & Bowmans space. Note Pedocyte, Basement membrane(BM), Pedicles (Pe), Slit membranes (SM)
Details of Filtration barrier is shown. Podocyte process and pedicles (Pe) contain a network of cytopalsmic filaments (Fi) Microtubules (Mt). The BM is b/w interlocking podocyte pedicles & fenestrated endothelium of a glomerular capillary. The gaps forming the filtration slits b/w pedicles are spanned by slit membranes (SM).
__________ sphincter is under voluntary control. It is innervated by the __________ which originate in the sacral spinal cord (S2-S4).
External pudendal nerve
True or false. Because of negative charges of GMB, no proteins can pass.
False, Despite the ability of the filtration barrier to restrict proteins, several grams of protein do pass through the barrier each day. Filtered protein is reabsorbed by endocytosis in the proximal convoluted tubule. Thus, In normal healthy individual, will not see a protein within urine.
What's the purpose of fenestrated endothelial cells & pedicles in renal corpuscle?
Fenestrations & Pedicels have little Diaphrams b/w them; confer further selectivity on this barrier.—whole point is to provide maximum surface area for movement of electrolyte & water. Yet, At the same time, protein & large molecules are retained in the vasculature. Note b/w parietal & visceral layers of Bowman's capsule is Bowman's space, which in life contains glomerular filtrate. Loops of glomerular capillaries(Cap) are close to podocytes of the visceral layer. Proximal and distal tubules surround the corpuscle. The macula densa of the JG complex is also seen.
Innervation of Urinary Bladder
Green - Parasympathetic. Innervating the detrusor mm. Also into internal sphincter. Blue - Hypogastric nerve (sympathetic) - relaxing the bladder wall detrusor muscle & controlling the constriciton of urethra & bladder neck. Yellow (somatic, pudendal) voluntary for relaxation for external sphicter. L1, first lumbar root; S1, first sacral root; SHP, superior hypogastric plexus; SN, sciatic nerve; T9, ninth thoracic root.
In the empty bladder, the urothelium has an ________ thickness (up to______ cell layers). The lamina propria is ______ fibrous w/ scatted connective cells & a _____ capillaries. Fibrous connective tissue surrounds irregular smooth muscle bundles. An arteriole & venule are in this connective tissue area.
INCREASED, 8-10. Highly Few
1 collecting duct is associated w/
Important thing to know: When it gets at the level of collecting tubules (whehter they are in cortical region or medullary region or at the region of innner medulla, they are coalescing together—so we have glomerulus & proximal tubule & loop inserting into a COMMON collecting duct. So 1 collecting duct have MULTIPLE golmeruli associated with them.
Urinary Bladder Innervation Urinary Bladder is Innervated by what divisions of ANS?
Innervated by sympathetic (SNS) and parasympathetic (PSNS) divisions of ANS
LM of Wall of Urinary bladdder in transverse section; The mucosa, according to the degree of distention, may look corrugated, with _______ longitudinal folds created by shape changes. Smooth muscle in the muscularis externa of urinary bladder is ________ than that of the ureter.
Irregular Thicker
Vascular pole of a renal corpuscle showing features of the JG Complex
JG cells in the walls of afferent arteriole (AA) are closely apposed to the maculo densa (MD) of a distal convoluted tubule (DCT). A proximal convoluted tubule (PCT), peritubular capillaries (PC), Efferent arteriole (EA) and collecting duct (CD) are seen, as are glomerular capillaries (GC), and Bowman's space (BS). Nuclei of simple squamous cells of the parietal layer of Bowman capsule are indicated (*).
What is an important feature of IMCD cells?
Lack cilia and no invaginations of basolateral membrane.
Loop of Henle is composed of?
Loop of Henle is the portion of a nephron that leads from the proximal convoluted tubule to the distal convoluted tubule.
Micturition reflex 2. The detrusor muscle contracts (via ________ receptors), cause intrabladder pressure to rise sharply & create a sense of urgency, with contraction frequency & discomfort level increasing with _________.
M3 muscarinic bladder volume
Process of emptying bladder is called
Micturition
Compared to the smooth mm in ureter, how are they organized in urinary bladder?
Muscle bundles are LESS regularly arranged than in ureters, with muscle and collagen bundles being RANDOMLY mixed.
Voiding ______ then activates PSNS outputs to detrusor muscle & suppresses SNS outflow, resulting in a sustained detrusor contraction. Detrusor contraction continues until bladder is empty, although ______ of urine typically remain after voiding.
PMC 6-12 ml
Micturition reflex initiated by bladder filling (SNS = sympathetic nervous system) Q. Urethral burning following urination. Asked to provide a urine sample. What is Responsible for ininitating micturaition when providing a urine sample? 1. PMC 2. Uroeptheilaim mechanoreceptor. 3. Spontaneous detrusor contractions 4. Rising intrabladder pressure Internal urethral sphincter relaxation.
PMC He is under conscious control. So PMC. Voluntary action.
Note podocyte cell body & pedicles. What is the purpose of pedicles? Podocyte processes interdigitate on the __________ surface of glomerular capillary walls. Bowmans space is ________ to the podocytes and in life contains glomerular filtrate.
Pedicels - Finger like projections - increase Area for filtration surfaces - rest on the basement membrane (GBM). outer surface external
Ureter What makes urine to move from ureter to urinary bladder?
Peristaltic contraction of smooth muscle moves urine through ureter to bladder- "internal pacemaker activity" generates action potentials
Bladder Urothelium Plasma membrane of surface epithelial cells of bladder consists of ___________-thickened membranes attached to _____ filaments. As bladder distends, the cells _________ with the fusiform vesicles unfolding to increase surface area. In undistended bladders, plaques appear as a series of ___________. Lumena of vesicles are continuous with cell surface.
Plaques--thickened membranes attached to actin filaments. stretch and flatten fusiform vesicles.
How did Endothelium of glomerular capillaries adapt to filter 180L of water/day via glomerulus?
Possess a large number of aquaporin-1 (AQP-1) water channels that allow movement of water through the epithelium. Allows water to diffuse across the cells, transcellularly.
Parasympathetic (PSNS) ____________ fibers originate from _______ segments of spinal cord and travel in pelvic nerves to pelvic plexus & bladder wall.
Pre ganglionic S2-S4
Compare & Contrast principal & intercalated cells in cortical collecting duct. Principal cells 1. Have single _____, 2. short ________, and 3. small __________. Function in 1.______ absorption, 2. ________ secretion, and 3. _______ absorption. 4. Respond to aldosterone and ADH.
Principal cells 1. Have single cillium 2. short microvilli, and 3. small mitochondria. Function in 1. sodium absorption, 2. potassium secretion, and 3. water absorption. 4. Respond to aldosterone and ADH.
What is the major role of proximal tubule?
Proximal tubule reabsorbs 60% of filtered water, sodium, & chloride (Major role), as well as nearly all glucose, bicarbonate, and amino acids.
Start from Renal Corpuscle, what are the steps to Collecting duct? Describe in sequence the tubular segments through which ultrafiltrate flows after it is formed at Bowman's capsule to when it enters the urinary bladder.
Renal corpuslces -> Bowmans space proximal convulsed tubule --> proximal straight tubule loop of henle (thin descending limb & thin/thick ascending limb) -> distal convoluted tubule (direct proximity of the glomeruli) --> Collecting/connecting duct --> collecting duct --> outer medulla --> inner medulla exit via renal papilla.
Proximal tubules are in 3 segments: S1, S2, S3. "Proximal Straight tubule" corresponds to what?
S1 begins at glomerulus, Extends several millimeters, before the transition to the S2 segments. S3 (aka Proximal Straight tubule) descends into the renal medulla to the inner medulla.
Parasympathetic preganglionic fibres (shown in green) arise from the ______________ and travel in sacral roots and __________ (PEL) to ganglia in the _________ (PP) and in the bladder wall. This is where the __________nerves that supply parasympathetic innervation to the bladder arise.
S2-S4 spinal segments pelvic nerves pelvic plexus postganglionic
______________ to low columnar epithelium characterizes collecting tubules(*). The Smaller Loops of Henle are made of _______________. Vasa recta filled with __________ are in the stroma. These vessels are intimately associated w/ loops of Henle & collecting ducts & function as _________________.
Simple cuboidal simple squamous epithelium. erythrocyotes are in the stroma. countercurrent exchangers.
Loops of Henle in Transverse Section Interlocking cell processes from its ____________ epithelium. Sparse organelles, such as vesicles (Ve) and a few lysosomes (Ly), chracterize the _________. Adjacent cells have intercellular junctions (ovals). Except for a somewhat thicker wall and lack of blood cells, Henle loops resemble systemic capillaries.
Simple squamous Cytoplasm
Loops of Henle in the renal medulla. One—in the shape of a hairpin loop (curved arrow)—is sectioned longitudinally. It is lined by a thin layer of ________________, which have nuclei (three small arrows) protruding into the lumen. Another loop (*) is sectioned transversely. Other areas contain blood capillaries and ascending (straight) portions of distal tubules.
Simple squamous epithelial cells,
Describe layers & fxn of detrusor muscle in bladder. Which one is voluntary?
Smooth muscle, composed of Inner longitudinal (Internal Urethral Sphincter--INvoluntary) and Outer circular layers (External Urethral Sphincter--Voluntary) of the bladder wall forms the detrusor muscle. Contraction of detrusor muscle compresses the entire bladder, forcing urine into the urethra.
Based on the glomerulus location and length of the loop of Henle, distinguish between cortical and juxtamedullary nephrons. Glomeruli of short loop nephron are located in the ____________ or _____________. 80-90% (majority) are ______ looped nephrons.
Superficial or mid-cortical region. Short
Sympathetic activity of urinary bladder does what
Sympathetic - does not want to urinate. so. 1. relaxes detrusor muscle and 2. constricts bladder neck & urethra.
Sympathetic fibres (shown in blue) originate in the ___________ segments in the spinal cord and run through the ____________________(inferior mesenteric plexus, IMP) and the ______________(HGN) or through the paravertebral chain to enter the pelvic nerves at the base of the bladder and the urethra.
T11-L2 inferior mesenteric ganglia hypogastric nerve
What part is the 1. Site of action of loop diuretics. 2. Target for drugs used in hypertension.
THICK ASCNEDING LIMB.
What are 2 parts of distal convoluted tubule?
The distal convoluted tubule is customarily divided into 2 parts: 1. true distal convoulted tubule & 2. the connecting tubule, where cell morphology is somewhat more similar to the collecting duct. A. True distal convoluted tubule (DCT) & Connecting tubule (CT). B. Cross section of DCT. **SO far, they look similar to the proximal tubule, but here at distal convoluted tubule, we have cells that look different than those in the proximal regions.
How is superior bladder surface different from the usual outer layer of the bladder?
The superior bladder surface is covered externally by a Serosa of Peritoneum rather than by adventitia, the usual outer layer in the rest of the bladder.
_________ of the afferent arteriole in the region of the JG apparatus is modified. The JG cells contain ______.
Tunica media Renin.
Lamina densa (LD): 1. overlapping portion of the two basal laminae; 2. contains type ______ collagen, which is organized into a network that acts as a physical filter. 3. Proteins in this layer are responsible for the bulk of _________ charges found in GBM.
Type 4 (IV) Anionic charges
In order, how does filtrate move? lumen of blood vessel, fenestrated endothelium, GBM, diaphragm b/w food processes of podocytes, urinary space
Ultrastructure of the glomerulus and Bowman's capsule Filtrate is moving from the lumen of blood vessel --> fenestrated endothelium --> across the GBM --> across the slit diaphragm b/w the Foot processes --> ultimately out into urinary space.
Ureter & Urinary Bladder 1. Urine leaves kidney via _____ to __________ where it is stored; voided through __________. 2. Structurally, composed of a - mucosa (transitional epithelium), - muscularis, and - adventitia
Ureter Urianry bladder Urethra Each of nephron - single cell layer thick. When we get to ureter, no longer cell layer thick. Now multiple layer thick epithelium has specific name - transitional epithelium. (Urothelium). Urteter & urinary bladder have well developed masculature (smooth muscle). Outer - perotenium layer is going to be adventitia layer.
What is a Distensible reservoir for urine?
Urinary Bladder
2 Functions of uroplaque?
Uroplauque proteins provide rigidity to the surface of bladder. Also provide Impermeability.
Ureter 1. Lumenal surface lined by ________.
Urothelium
Ureter in transverse section ___________ (Ur) lines the star-shaped lumen. The lamina propria is highly vascular and cellular connective tissue, interlacing smooth muscle bundles occupy the mscularis externa, which is invested by an outer adventitia.
Urothelium
Somatic axons in the pudendal nerve also release _____ which produces a _________ of the __________ sphincter striated muscle by activating __________ receptors.
acetylcholine (Ach) Contraction of the External Sphincter nicotinic cholinergic
Loop of Henle Thick ascending limb _______ transports sodium into the interstitium. Cells exhibit 1. apical __________ - not a true microvilia), extensive 2. basolateral infoldings & 3. mitochondria.
actively micro-projections
Micturition reflex is an _____________ reflex. However, it can be inhibited or facilitated by ___________________ —for voluntary control.
automatic spinal cord centers in brain stem (Pontine micturation center (PMC)) & cerebral cortex
Glomeruli of long loop nephrons are located ____________. They have a short thick descending limb in __________ and long thin descending and ascending limb in ___________. Their glomeruli are slightly ______ - for maximal urinary concentration.
close to cortico-medullary border. Outer medulla. Larger
As bladder distends, openings of ureters are ___________, reducing reflux of urine Contraction of smooth muscle of bladder also __________ openings of ureters into the _______ - prevents spread of infection from urethra and bladder to kidneys.
compressed compress, bladder
Efferent pathways and neurotransmitter mechanisms that regulate the lower urinary tract. Parasympathetic postganglionic axons in the pelvic nerve release acetylcholine (ACh), which produces a bladder __________ by stimulating __________ receptors in the bladder smooth muscle. Parasympathetic postganglionic nerves also release ____ which excites bladder smooth muscle, and _______ which relaxes urethral smooth muscle.
contraction M3 muscarinic ATP nitric oxide
Cortical Collecting Duct Principal & Intercalated Cells one continuous layer of _______________(arrows) lines the lumen. Convex apical borders of the cells contact the duct lumen. Each cell has a rounded nucleus (*) and cytoplasm packed with various organelles.
cuboidal epithelial cells
The PSNS stimulates voiding by ______________ & relation of the urethra & internal (NOT external) sphincter.
detrusor contraction
Voiding Voiding begins by relaxation of ____________. Inhibition of activity of the sympathetic pudendal neurons causes _______________ of external sphincter (composed of skeletal muscle). __________ relaxes the internal sphincter, allowing urine to enter the urethra.
external sphincter. relaxation Pontine micturation center (PMC)
Somatic motor nerves (shown in yellow) that supply the striated muscles of the _____________ arise from _______________ and pass through the _________ nerves.
external urethral sphincter S2-S4 motor neurons pudendal
Loops of Henle in Transverse Section. Loops consist of _________ epithelial cells with nuclei (*) that bulge slightly into the lumen. Short, stubby ________(arrows) are on apical cell surfaces. Capillaries that form the_________ are close to the loops and have very thin walls.
flattened microvili vesa recta
Sympathetic fibers (_______________) form a plexus in the __________ (outer surface of urinary bladder) & innervates _____________ in bladder walls.
hypogastric nerve adventitia blood vessels
This micrograph shows intercalated cells (asterisks), with numerous short _____________ on their surface, and principal cells, each with a primary _______ on its free surface along with small microvilli. The terms light and dark refer to the staining character of sectioned cells and not to the density differences reflecting charge characteristics of the coated surface of the specimen.
lamellipodia or microridges cilium IC is darker in color than PC.
What is the Mesangial Cell & where is it located?
located within the glomerulus. it is a structural cell which together with their extracellular matrix constitute the "mesangium." Masangial cells secrete matrix that holds the capillary tufts together. They maintain the structure of the glomerular filtration barrier.
Sympathetic postganglionic neurons - release __________, which activates __________ receptors to relax bladder smooth muscle & - activates _________ receptors to contract urethral smooth muscle.
noradrenaline (NA) β3 adrenergic α1 adrenergic
EM showing parts of two epithelial cells of a collecting duct. —rounded euchromatic nucleus often has a _________ (nu). Randomly oriented mitochondria (Mi) are dispersed in the cytoplasm. Many small _________ (Ve) are in apical cytoplasm. Short basal infoldings of plasma membrnae (arrows) increase surface area and contain _________ . ___________(circle) link apicolateral cell borders and seal the lumen from the extracellular space. Cells rest on a thin basement membrane.
nucleolus. vesicles ion pumps tight junctions
Micturition reflex 3. Sensory signals also travel to brain. CNS control of micturation is complex and includes multiple sites including a _____________ which coordinates brain output to lower urinary system. If voiding is inconvenient, the PMC _____________ nerves that stimulate bladder contraction. Tonic contraction of ________ prevents urine flow until relaxed voluntarily.
pontine micturation center (PMC) suppresses presynaptic external sphincter
High magnification LM of mucosa of the ureter showing details of the multilayer urothelium. Surface cells of the epithelium appear_________ when the urter is contracted (empty) and __________ when it is distended with urine. The richly cellular lamina propria has many small blood vessels.
rounded, flattened
The wall of Proximal tubule The wall consists of _________. Each cell has a spherical euchromatic nucleus surrounded by cytoplasm filled w/ organelles. An apical brush border of many closely packed microvilli lines the lumen. __________are seen. A thin basement membrane underlies the basal aspect of the sell (arrows). Intercellular junctions (circles) link apical memranes of adjacent cells.
simple low columnar epithelium. Apical canalculi (Ca) nermous vesciels (*), and many pleomorphic mitochondria (Mit) are seen.
Based on length of the __________, nephrons are classified as short or long loop nephrons.
thin limb of Henle,
Structure of the Bladder Urothelium The mucous membrane of the urinary bladder consists of ___________ (Ep) with an underlying ___________ (LP). The epithelial cells contain unique __________ which are evident here at this relatively low magnification.
transitional epithelium (Ep) with an underlying lamina propria (LP). fusiform vesicles. What appears to be vesicles (contain proteins called Plaques within them)—they are NOT true vesciles. They are extensions of apical membrane deep in to the cell so the cell infolds.
Transitional Epithelium 1. Transitional epithelium or ___________ is a __________ epithelium that is ____________ to salt & water. 2. In ureter, ______ layers can be detected and _______ layers (in bladder) can be seen in empty bladder. 3. Upon distension of bladder as few as _____ layers can be detected - due to cells' ability to accommodate distension 4. Surface cells_________ to increase surface area
urothelium stratified epithelium impermeable 4-5 6 or more 3 ( Bladder expands as it gets filled. Bladder begins to unfold (microscopically)--# of cell layers actually decrease. (3 layers) & dramatic increase in SA in epithelial surface vs. Contracted bladder has 6-8 layer. 4. flatten & unfold
I clicker Q. A young woman develops an auto-immune disease and develops antigen-antibody complexes. Upon flowing into the glomerular capillary, these complexes deposit within the mesangium and within the capillary lumen. Because of their size, they do not pass through the basement membrane into the urinary space. Which of the following findings is LEAST likely to be present? 1. Renal failure 2. Low serum albumin due to protein loss in the urine 3. Hypertension 4 Signs of inflammation in her urine.
you would not predict low serum albumin b/c antigen antibody complexes are depositing.
