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cortex; medulla; renal pyramids; renal papillae; ducts of Bellini; minor calyx; major calyx; renal pelvis

The kidney has an outer ____ and an inner ____. The latter contains 6-12 striated regions called ____. The apex of these regions forms _____, and it is also perforated by about 20 openings of ____ (forms the area cribrosa). Each apex is surrounded by a ____, which combines with 2-3 others to form a ____, which also combines with others to form the ____ (proximal portion of the ureter).

Cortical arch

The portion of the cortex over each renal pyramid (contains renal corpuscles, cortical labyrinth, and medullary rays).

Lobe

____ is composed of renal pyramid, cortical arch, and half of the surrounding cortical columns.

Lobule

____ is composed of medullary ray and cortical labyrinth.

Renal corpuscles, cortical labyrinth, and medullary rays.

List the components of the cortex.

Capsule

The dense irregular collagenous connective tissue investing the kidney.

Cortex

The outer layer of kidney tissue.

Renal corpuscles

Appear as red, dot-like granules.

Cortical labyrinth

____ is comprised of vasculature in addition to glomeruli and proximal and distal convoluted tubules.

Medullary rays

Longitudinal striations that are cortical continuations of material located in the renal pyramids.

Medulla

Majority of loop of Henle located here.

Renal pyramids

____ contain collecting tubules, thin/thick limbs of loop of Henle, vasa recta, and renal interstitium.

Cortical (renal) columns

____ separate the renal pyramids.

Renal corpuscles (cortex)

Where are the majority of glomeruli located?

Renal pyramids (medulla)

Where are the majority of the loops of Henle found?

Ureter, renal artery & vein

What structures comprise the renal pelvis?

Lobated kidney

Kidney in which lobes are accentuated by deep clefts; this is normal in fetus but is supposed to go away in adult.

Uriniferous tubule

Functional unit of kidney, composed of a nephron and a collecting tubule.

Glomerulus, proximal and distal convoluted tubules, and loop of Henle

List the components of a nephron.

Glomerulus

A globular capillary network that intrudes into Bowman's capsule.

Bowman's capsule

Dilated, pouch-like proximal end of nephron.

podocytes

The visceral layer of Bowman's capsule is composed of modified epithelial cells (____) in immediate contact with cells of the glomerulus.

Urinary space (Bowman's space)

Space in the bowman's capsule between the infolded podocytes and the outer capsule wall that's continuous with the proximal convoluted tubule

Parietal layer of Bowman's capsule

Outer wall of Bowman's capsule composed of simple squamous epithelial cells (sitting on a thin basal lamina).

Vascular pole of corpuscle

Region where vessels supplying and draining glomerulus enter and exit Bowman's capsule.

Urinary pole of corpuscle

Region of continuation between renal corpuscle and the proximal tubule, which drains Bowman's space.

Afferent glomerular arteriole; efferent glomerular arteriole

The ____ supplies the glomerulus (with blood) and the ____ drains it.

Mesangial cells

____ replace the CT of afferent glomerular arterioles.

Intraglomerular mesangial cells

____ are located within the renal corpuscle and are likely phagocytic and function to resorb the basal lamina as well as contractile and provide physical support to capillaries of glomerulus (like podocytes).

capillaries; podocytes

Mesangial cells are located between ____ in ____.

Fenestrated capillaries

What type of capillaries are found in the glomerulus?

Large (70-90 nm) pores with no diaphragm covering, which act as barrier only to formed elements of blood and macromolecules with larger diameters.

What is characteristic of the pores found in capillaries of the glomerulus?

fenestrations (pores)

The endothelial cells of the glomerular filtration barrier contain ____.

pedicels

Podocytes have secondary processes off the primary processes called ____ which envelop most of the glomerular capillary by interdigitation.

Filtration slits

Gaps between interdigitation of pedicels. Covered by slit diaphragm which has a row of pores on each side of central bar.

Lamina rara externa

Layer of basal lamina that contacts visceral layer of Bowman's capsule.

Lamina rara interna

Layer of basal lamina that contacts endothelial cells of capillary.

Lamina densa is composed of type IV collagen; fibril network serves as physical barrier. Lamina rara layers contain polyanionic sites due to GAGs.

What properties of the basal lamina provide physical barrier functions?

endothelial cells

Blockage of the glomerular capillary lumina resulting in hypertension, uremia, and hematuria indicates abnormality/damage to the glomerular ____.

basement membrane

Proteinuria, hypoalbuminemia, and edema that accompany diabetes mellitus and membranous nephropathy indicate abnormality/damage to the glomerular ____.

Minimal change nephropathy

Collapse of foot processes of podocytes results in ____ (glomerular capillaries covered by a continuous sheet of podocyte cytoplasm; loss of polyanionic charge results in protein leak).

Fluid leaves glomerular capillaries via fenestrations and is filtered by the basal lamina. It then passes through pores of the slit diaphragm of filtration slits into the urinary space.

Summarize filtration from the glomerulus into the urinary space.

Urinary space → proximal tubule → loop of Henle → distal tubule → collecting duct

Trace the course of the glomerular filtrate from the urinary space in Bowman's capsule to a collecting duct.

proximal convoluted tubule

The ____ is the first and major site of reabsorption.

Composed of cuboidal/columnar cells with well-developed microvilli, pinocytic vesicles, basal interdigitation, and extensive mitochondria. It functions in glomerular filtrate resorption.

Describe the structure and function of the proximal convoluted tubule.

decreases

The height of the cells and microvilli ____ along the length of the tubule.

Na+ is actively pumped out of filtrate, Cl- follows, then water. Glucose, amino acids, and proteins via endocytosis.

What happens to Na+, Cl-, water, glucose, amino acids, and proteins as they pass through the proximal convoluted tubule?

Composed of squamous epithelium, nuclei bulge into lumen, have short microvilli and few mitochondria in cytoplasm surrounding nucleus.

Describe the basic histology of the descending and ascending thin limbs of the loop of Henle.

Have slightly thicker lining and the lumina will not contain blood cells. Also, nuclei stain less densely.

How can one differentiate between the thin limbs of the loop of Henle and vasa recta/capillaries?

descending; ascending

The ____ thin limb of the loop of Henle is highly permeable to water and slightly permeable to urea, Na, Cl, and other ions, whereas the ____ thin limb is only moderately permeable to water.

Cuboidal epithelial cells with extensive basal and lateral interdigitation, but less well formed microvilli.

Describe the structure of the distal tubule.

Active resorption of almost all Na+ (and passively Cl-)

What effect does aldosterone have on the distal convoluted tubule?

Fluid/ion exchange, acid-base balance, and urine concentration.

What is the function of the distal tubule?

Excretion of K+ and H+ ions to regulate extracellular K+ and acidity of urine.

What role does the distal tubule play in acid-base balance?

Pars recta

Region of the distal tubule that is not permeable to water or urea. It has Cl- (and possibly Na+) pumps that actively transport Cl- (and Na+) from lumen of tubule. It also contains zonulae occludentes.

Macula densa

Region of the distal tubule between afferent and efferent arterioles. It contains tall and narrow cells with much denser nuclei.

Pars convoluta

Region of the distal tubule with fewer mitochondria and less extensive basal interdigitation. Impermeable to water and urea, but has high Na-K ATPase activity in basolateral plasmalemma of cells.

Juxtaglomerular apparatus

Consists of macula densa of distal tubule, juxtaglomerular cells of adjacent afferent (and some efferent) glomerular arteriole, and extraglomerular mesangial cells.

Macula densa

Part of the juxtaglomerular apparatus characterized by tall, narrow pale cells with central nuclei. Have numerous microvilli, small mitochondria, and infranuclearly located Golgi apparatus.

Na; decrease; renin

The macula densa of the juxtaglomerular apparatus monitors filtrate volume and ____ concentration, if below level, will cause dilation of afferent glomerular arterioles to ____ blood flow to glomerulus and cause juxtaglomerular cells to release the enzyme ____ into circulation.

Tunica media of afferent (and some efferent) glomerular arterioles

Where are juxtaglomerular (renin-secreting) cells located within the juxtaglomerular apparatus?

Juxtaglomerular cells

Modified smooth muscle cells of the juxtaglomerular apparatus innervated by sympathetic nerves that contain a round nucleus and granules of renin, ACE, angiotensin I and II.

Renin

A proteolytic enzyme that converts angiotensinogen (present in bloodstream) into angiotensin I (a mild vasoconstrictor).

Extraglomerular mesangial cells

Cells located in space bounded by afferent arteriole, macula densa, efferent arteriole, and vascular pole of renal corpuscle. May have granules and are continuous with intraglomerular mesangial cells.

Collecting tubules

Composed of simple cuboidal epithelium, convey and modify the ultrafiltrate from the nephron to the minor calyces of kidney.

principal; intercalated; type A; type B

The cortical collecting tubule is located in medullary rays and composed of ____ and ____ cells. The former have aquaporin-2 channels that are sensitive to ADH. The latter are either 1) ____ - luminal membrane has H+-ATPase for acidifying urine and 2) ____ - basolateral membrane has H+-ATPase for resorption of H+ and secreting HCO3-.

outer; inner

The medullary collecting tubule has a larger caliber, ____ zone has principal and intercalated cells, ____ zone has only principal cells.

area cribrosa

The papillary collecting tubule has larger ducts, open at ____ of renal papilla to deliver urine to minor calyx of kidney. Lined by tall columnar principal cells only.

ADH (antidiuretic hormone)

Causes collecting tubules to become permeable to water (and urea), which causes urine to be lower in volume and more concentrated.

ADH

Diabetes insipidus is characterized by the permanent absence of ____, resulting in failure of water resorption. It can also be characterized by a malformed receptor for this hormone.

Renal artery → anterior/posterior renal arteries → segmental arteries → lobar arteries → interlobar arteries → arcuate arteries → interlobular arteries → afferent glomerular arterioles

Briefly summarize the basic arterial supply of the kidney.

glomerulus

The ____ is the "capillary bed" of the afferent arteriole.

peritubular capillary network

The ____ is the capillary bed of the efferent arteriole.

Cells of the peritubular capillary network

Although it is not certain, where is it thought that erythropoietin is synthesized?

cortex; glomeruli

There is extensive distribution of blood in the ____ because the ____ are located here.

vasa recta

There is less blood distribution in the medullary and pelvic regions because space is occupied by medullary pyramids/renal pelvis/calyces; only ____ supply the medullary pyramids and they're too small to show up on the angiogram.

afferent

Capillary bed of ____ arteriole filters waste.

Efferent

____ arterioles and associated branches resorb substances from filtrate and gas exchange occurs at the capillary bed.

Source: arcuate arteries and efferent arterioles. Location: renal medulla

What is the source and location of vasa recta?

Ionic and fluid exchange with loops of Henle (urine concentration)

What is the function of vasa recta?

Cortex: (efferent glomerular arteriole) → stellate veins → interlobular v → arcuate v → interlobar v → renal v
Medulla: venae rectae → arcuate v → interlobar v → renal v

Briefly summarize the venous drainage of the medulla and cortex of the kidney.

Transitional epithelium

____ is exclusive to the urinary system. It is composed of many layers of cells (basally are either low columnar or cuboidal cells, middle are polyhedral cells, superficial are large and occasionally binucleate with round dome-shaped tops bulging into the lumen which are flattened during distension of bladder).

thicker

As one moves from the minor calyces toward the urinary bladder, the walls tend to become ____.

transitional epithelium; smooth muscle

Near the apex of the renal papilla, the minor calyx is covered by ____. Deep to lamina propria is a ____ layer propelling urine into the major calyx. The structure of the major calyces and renal pelvis is similar.

transitional; lamina propria; longitudinal; circular; outer longitudinal

The ureter has mucosa that lines the lumen and has a ____ epithelium. ____ is 3-5 layers thick of dense, irregular fibroelastic CT separated from epithelium by basal lamina. The superior 2/3 of the ureter is covered by an inner ____ layer and an outer ____ layer. The inferior 1/3 is covered by an additional ____ layer. The ureter also contains a fibrous outer coat that blends with the capsule of the kidney and CT of the bladder wall.

regurgitation of urine from bladder to ureter

At entrance to bladder, there is a valve-like flap of mucosa hanging over each orifice to prevent ____.

distension; gap junctions; water and salts; desmosomes; tight junctions;

In the bladder, mucosa is arranged in folds which disappear during ____. Plasmalemma is composed of a mosaic of plaques interspersed by normal cell membrane (interplaque regions). Plaques are folded during empty bladder, resemble ____ during stretching. Plaques are impermeable to ____ (maintain osmotic barrier). Epithelial cells are connected by ____ and ____.

Trigone; Lamina propria; urethral orifice;

____ of bladder is always smooth and has different origin than rest of bladder. ____ has a superficial dense, irregular CT and deeper layer has loose CT of collagen and elastic fibers. It has no glands except at ____ where it has mucous glands to lubricate it.

three; Adventitia; serosa; fat

Muscular coat of the bladder is ____ layers. Internal sphincter muscle formed around internal orifice of urethra by circular smooth muscle of muscular coat. ____ is dense, irregular collagenous CT with elastic fibers. Some areas of it are covered by ____, others by ____.

striated; lamina propria;

The urethra is surrounded by a ____ external sphincter and contains a ____ composed of loose fibroelastic CT with vascular supply.

glands of Littre

Lamina propria of the urethra has mucus-secreting glands (____) that lubricate the epithelium.

transitional epithelium

The prostatic urethra is lined by ____ and has ducts of prostate, prostatic utricle, and paired ejaculatory ducts.

stratified columnar epithelium; pseudostratified columnar epithelium

The membranous urethra, which passes through the perineal membrane, is lined by ____ with patches of ____.

stratified columnar epithelium; pseudostratified columnar; stratified squamous nonkeratinized epithelium

The spongy urethra contained within the corpus spongiosum is lined by ____ with patches of ____ and ____.

stratified squamous nonkeratinized epithelium

The navicular fossa (enlarged terminal portion in glans penis) is lined by ____

transitional epithelium; stratified squamous nonkeratinized epithelium; pseudostratified columnar epithelium

The female urethra is lined by ____ near the bladder and by ____ along rest of urethra with patches of ____.

Male urethra 4-5 times longer

How do male and female urethras differ?

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