Lecture 28: Kidneys Flashcards Preview

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Flashcards in Lecture 28: Kidneys Deck (52):

Where are kidneys in body cavity?

Primarily retro-peritoneal


What sits on top of the kidney? Are they connected?

The adrenal glands, which are not connected physically. But have a functional connection, i terms of the hormones they release that mediate sodium uptake.


Kidney blood supply

The branch of the aorta, the renal arteries. They lie posterior to the renal vein, which drains the venous blood of the kidneys. The renal veins drains into the IVC.


Length of renal veins

L. renal vein 2x longer than R. renal vein. THis means the l. testicular vein drains directly into the l. renal vein


Where is the ureter

Drains inferiorly from that kidney


Parts of the kidney

cortex, medulla, papilla, calyces


Renal column

Extension of renal cortex, which separates two renal pyramids (sections of renal medulla).


Renal papilla

The tip of the renal medulla, opening into one of the nine minor calyxes, which opens into one of two major calyxes. The major calyx opens into the renal pelvis which drains into the ureter.


purpose of kidney

filter blood and produce urine. 180 liters of fluid is filtered daily, 1-2 liters of urine is produced.


Urine formation

involve filtration, secretion and reabsorption of fluid by the renal corpuscles and tubules.


Separate functions of kidneys

Remove metabolic waste, foreign substance and drugs.
Regulate volume and composition of water and electrolytes in the extracellular fluid
control acid base balance
renin and erythropoietin creation: endocrine function
convert vitamin d into active form
gluconeogenisis --> make glucose from amino acids during starvation


what is the nephron

the functional unit of the kidney, 1 million in each kidney.
Components are the corposcule and the renal tubule


Parts of the renal tubule

The proximal convoluted tubule (PCT), the loop of henle, the distal convoluted tubule.


Parts of the corposcule

the bowman capsule, the glomerulus


parts of the bowman capsule

parietal layer, visceral layer (podocytes), the bowmans (urinary) space.



Many capillaries in a ball, supported by mesangium (mesangial cells, ECM)


Loop of Henle

Thick descending limb (PCT), thin limb (the bottom loop), thick ascending limb (distal convoluted tubule)


Does the nephron contain the collecting duct?

No. It has a different embryological primordial.


podocytes structure

Modified epithelial cells of the visceral layer of bowman's capsule. Sit on top of the capillaries of the glomerulus on their surface . Have primary foot process that branch into secondary foot processes that extend over entire glomerular basement membrane, creating covering network. These feet are divided by narrow slits called filtration slits.


efferent arteriole vs. afferent arteriole

The afferent arteriole enters the glomerulus, the efferent arteriole exits the glomerulus.


What sits between the efferent and afferent arterioles

The distal tubule.


Schema of renal circulation

Renal artery --> afferent arterioles-->capillaries --> efferent arterioles--> capillaries surrounding tubule OR vasa recta wrapping around the loop of Henle in the medulla --> Renal vein.


Glomerular basement membrane

Sits directly on top of the capillaries of the glomerulus. The secondary foot processes sits directly on the glomerular basement membrane.


Podocytes contents/function

cytoplasm contains actin filaments, lysosomes, microtubules, and have contractile and phagocytic properties.
They are partially responsible for creating the glomerular basement membrane.


Three components of the filtration barrier

The filtration barrier sits between the bowmans capsule and the glomerulus. Made up of:
fenestra between capillaries --> basement lamina --> filtration slits between podocyte feet


What can go through the filtration barrier

Hemoglobin, 65000 mw and smaller molecules- pass thru; Albumin, 68000 mw and larger molecules are retained.
Some proteins can go through. Ions can go through. Vitamins can go through. What else?



CT that sits between the capillaries of the glomerulus. Mesangial cells and mesangial matrix. Provides mechanical support.


functions of the mesangium

matrix production, which supports the glomerular cap.
Contractile, which can impact the rate of filtration
phagocytic of immune complexes that do not go through filtration and escape near mesangium.
Are proliferative in cases of glomerular disease
Can produce vasoactive substances that can induce constriction of afferent and efferent arterioles (endothelins)


Distal convoluted tubule cells

simple cuboidal


PCT cells

microvilli simple cuboidal, called the brush border


loop of henle cells



collecting tubule cells

simple cuboidal


PCT vs. DCT AZO dye

will label the brush border blue in the PCT.
lysosomes --> red


PCT qualities

Microvilli, endocytic vesicles, lysosomes, mitochondria, lateral plasma membrane interdigitation (infoldings of basal lateral PM containing mitochondria --> typical of of ion transporting epithelia), basal PM infoldings


lateral plasma membrane interdigitation

infoldings of basal PM containing mitochondria --> typical of of ion transporting epithelia
This leads to indistinc cell borders. These infoldings contain mitochondria with sodium pump localized in the membranes. It is active transport, need mitochondria. Amino acids and glucose are also transported out of the cell.


why does PCT have apical surface microvilli?

asorptin of 80% of ultrafiltrate


microvilli membranes on PCT purpose?

transport proteins for transporting sodium, amino acids and glucose into the cell


endocytic vesicles and lysosomes purpose?

breakdown absorbed proteins


mitochondria PCT purpose

energy for active transport


DCT qualites

sparse microvilli, nuclei featured on the top of the cell, basal PM infoldings but no lateral interdigitation, mitochondria



mediates the active transport of sodium from the tubular fluid of DCT into renal interstitium


basal plasma membrane infoldings of DCT why?

Na+-K+ ATPase pump for active transport of Na+ from the tubular fluid into the renal interstitium


Collecting duct cells

pale staining cells, cuboidal to columnar, lack brush border, distinct cell borders (no interdigitation)


Function of collecting duct

reabsorption of water from the ducts, is controlled bi antidiuretic hormone (ADH; vasopressin) from the posterior pituitary glands


Justaglomerular (JG) apparatus;

Involved in the regulation of systemic blood pressure via the renin-angiotensin aldosterone system)


Parts of JG apparatus

Macula densa of the DCT, JG cells ( renin-producing, protease), extraglomerular mesangial cells (lacis cells)


Where is the macula densa

The point of the DCT that passes between the afferent and efferent arterioles. Only the half side that is in contact with the JG cells of the afferent/efferent arterioles. Called so because they are larger/denser than the other cells of the DCT. The cells are very crowded together.


Where are the JG cells

The cells of the afferent (mostly)/efferent(few) arterioles that are in contact with the macula densa. Modified smooth muscle cells of the arterioles.


Urinary passage

Minor calyces --> major calycess --> renal pelvis --> ureter --> urinary bladder --> proximal urethra


Types of cells in excretory passages

Transitional epithelium/uroepithelium; lamina propria --> collagenous tissue --> smooth muscle (2 or 3 layers) --> adventitia or serosa (blood vessels, lymphatics or nerves) what is serosa/adventita? is this list from inside to outside?


Placques of transitional epithelium

Thickened plasma membranes, coverings of pillowing cells on top.


Urinary bladder characteristics and functions

Conduit of urine
Impervious to water
Resistant to bacteria
Stretch to cover varying size of bladder
Significance of plaques unknown possibly contribute to membrane strength and impermeability