Lecture 28: Kidneys

Question 1

Where are kidneys in body cavity?

Answer 1

Primarily retro-peritoneal

Question 2

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

Answer 2

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

Question 3

Kidney blood supply

Answer 3

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.

Question 4

Length of renal veins

Answer 4

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

Question 5

Where is the ureter

Answer 5

Drains inferiorly from that kidney

Question 6

Parts of the kidney

Answer 6

cortex, medulla, papilla, calyces

Question 7

Renal column

Answer 7

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

Question 8

Renal papilla

Answer 8

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.

Question 9

purpose of kidney

Answer 9

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

Question 10

Urine formation

Answer 10

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

Question 11

Separate functions of kidneys

Answer 11

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

Question 12

what is the nephron

Answer 12

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

Question 13

Parts of the renal tubule

Answer 13

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

Question 14

Parts of the corposcule

Answer 14

the bowman capsule, the glomerulus

Question 15

parts of the bowman capsule

Answer 15

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

Question 16

glomerulus

Answer 16

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

Question 17

Loop of Henle

Answer 17

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

Question 18

Does the nephron contain the collecting duct?

Answer 18

No. It has a different embryological primordial.

Question 19

podocytes structure

Answer 19

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.

Question 20

efferent arteriole vs. afferent arteriole

Answer 20

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

Question 21

What sits between the efferent and afferent arterioles

Answer 21

The distal tubule.

Question 22

Schema of renal circulation

Answer 22

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

Question 23

Glomerular basement membrane

Answer 23

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

Question 24

Podocytes contents/function

Answer 24

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

Question 25

Three components of the filtration barrier

Answer 25

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

Question 26

What can go through the filtration barrier

Answer 26

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?

Question 27

Mesangium

Answer 27

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

Question 28

functions of the mesangium

Answer 28

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)

Question 29

Distal convoluted tubule cells

Answer 29

simple cuboidal

Question 30

PCT cells

Answer 30

microvilli simple cuboidal, called the brush border

Question 31

loop of henle cells

Answer 31

Squamous

Question 32

collecting tubule cells

Answer 32

simple cuboidal

Question 33

PCT vs. DCT AZO dye

Answer 33

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

Question 34

PCT qualities

Answer 34

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

Question 35

lateral plasma membrane interdigitation

Answer 35

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.

Question 36

why does PCT have apical surface microvilli?

Answer 36

asorptin of 80% of ultrafiltrate

Question 37

microvilli membranes on PCT purpose?

Answer 37

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

Question 38

endocytic vesicles and lysosomes purpose?

Answer 38

breakdown absorbed proteins

Question 39

mitochondria PCT purpose

Answer 39

energy for active transport

Question 40

DCT qualites

Answer 40

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

Question 41

Aldosterone

Answer 41

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

Question 42

basal plasma membrane infoldings of DCT why?

Answer 42

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

Question 43

Collecting duct cells

Answer 43

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

Question 44

Function of collecting duct

Answer 44

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

Question 45

Justaglomerular (JG) apparatus;

Answer 45

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

Question 46

Parts of JG apparatus

Answer 46

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

Question 47

Where is the macula densa

Answer 47

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.

Question 48

Where are the JG cells

Answer 48

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

Question 49

Urinary passage

Answer 49

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

Question 50

Types of cells in excretory passages

Answer 50

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?

Question 51

Placques of transitional epithelium

Answer 51

Thickened plasma membranes, coverings of pillowing cells on top.

Question 52

Urinary bladder characteristics and functions

Answer 52

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