1_HST110 Intro to Kidney Structure and Function 2017

Question 1

Homeostasis: The maintenance of relatively stable internal (X) under fluctuating (Y)

Answer 1

X = physiological conditions
Y = environmental conditions

Question 2

List 4 primary functions of the kidney

Answer 2

1. Regulate water and electrolyte balance
2. Excrete metabolic waste products and foreign substances
   e. g. urea, creatinine, uric acid, drugs
3. Regulate acid-base balance
4. Produce and secrete hormones
   - Renin (regulation of blood pressure)
   - Calcitriol (active form of vitamin D)
   - Erythropoietin (red blood cell production)

Question 3

What is the first step in production of urine?

Answer 3

Glomerular filtration

Question 4

Glomerular filtrates include roughly everything present in blood except for what two things?

Answer 4

Blood cells and large molecules (e.g. proteins)

Question 5

Secretion of unwanted substances involves either simply leaving the substance in filtrate or to a lesser extent (X)

Answer 5

X = Active secretion into the urine

Question 6

Reabsorption of useful components of the filtrate (e.g. Na+, water, other electrolytes) back into the bloodstream is highly (X) to maintain what 3 types of balance?

Answer 6

X = Regulated

Fluid, electrolyte, and acid-base

Question 7

What structures sit on top of the kidneys?

Answer 7

Adrenal glands

Question 8

What is the port into/out of the kidney?

Answer 8

Hilum

Question 9

What arteries feed into the hilum?

Answer 9

Abdominal aorta to renal artery

Question 10

What veins leads away from the hilum?

Answer 10

Renal vain to inferior vena cava

Question 11

What is the approximate size of a kidney?

Answer 11

12x6x4 cm (computer mouse)
0.5% of body weight, 125-170 (M) or 115-155 (F) grams

Question 12

Which kidney is slightly larger?

Answer 12

Left is larger

Question 13

What is a calyx?

Answer 13

Cup or receptacle features to collect urine (minor and major)

Question 14

What is the tip of the renal pyramid called?

Answer 14

Papilla

Question 15

The renal pyramid forms what border in a segmented fashion?

Answer 15

Corticomedullary border

Question 16

What are the two major anatomical divisions of the kidney?

Answer 16

Cortex and medulla

Question 17

The kidneys receive what percentage of cardiac output?

Answer 17

20-25%

Question 18

Kidneys have the highest blood flow per weight for delivery of oxygen & nutrients as well as filtration and clearance. What is this blood flow?

Answer 18

400 mL/100g/min

Compared to heart and liver (70 mL/100g/min each)

Question 19

Trace the renal circulation from the abdominal aorta to the inferior vena cava

Answer 19

Abdominal aorta - renal artery - interlobar arteries - arcuate arteries - interlobular arteries - afferent arterioles - glomerular capillaries - efferent arterioles - peritubular capillaries - (vasa recta) - interlobular veins - arcuate veins - interlobar veins - renal vein - inferior vena cava

Question 20

How many nephrons are there in the kidney?

Answer 20

1.0 - 1.3 million, varying vastly

Question 21

Name the 5 structures composing the nephron

Answer 21

Renal corpuscle (glomerulus+Bowman’s capsule), Proximal Tubule, Loop of Henle, Distal Tubule, Collecting duct system

Question 22

Renal corpuscle is made up of a (X) layer of cells

Answer 22

X = single

Question 23

The Glomerulus is surrounded by a layer of epithelial cells called (X) capsule. Blood filtered by the glomerular capillaries enters into (X) space, which then empties the filtrate into the (Y) of the nephron

Answer 23

X = Bowman’s
Y = tubules

Question 24

What are the 3 layers to the glomerular filtration barrier?

Answer 24

Capillary endothelial cells (fenestrated, 50-100nm)
Glomerular basement membrane (GBM)
Pococytes

Question 25

Capillary endothelial cells are fenestrated with 50-100nm holes. They are freely permeable to (X)

Answer 25

X = water, solutes, and most proteins in the blood but not blood cells or platelets

Question 26

GBM: Gel-like meshwork of (X) and (Y). Limits the passage of intermediate to large sized molecules and is (Z) charged, which repels (Z) charged proteins such as albumin

Answer 26

``` X = Glycoproteins Y = Heparan Sulfate Proteoglycans Z= negatively ```

Question 27

What is another name for the podocyte?

Answer 27

Visceral epithelial cells (0f Bowman's capsule)

Question 28

Podocytes have long finger-like (X) that surround the outer surface of glomerular (Y)

Answer 28

``` X = foot processes Y = capillaries ```

Question 29

Foot processes interdigitate and are separated by gaps called (X) bridged by a (X) diaphragm with a pore size of (Y)

Answer 29

``` X = filtration slits Y = 4 to 14 nm ```

Question 30

Filtration slits function primarily as (X)-selective barriers and prevent proteins and macromolecules from entering Bowman's space

Answer 30

X = size

Question 31

What is the mesangium composed of?

Answer 31

Mesangial cells and mesangial matrix

Question 32

What are the 6 functions of the mesangial cells?

Answer 32

1. Share properties with smooth muscle cells 2. Provide structural support for glomerular capillaries 3. Secrete extracellular matrix 4. Phagocytize cells 5. Secrete prostaglandins and proinflammatory cytokines 6. May influence glomerular filtration

Question 33

What 3 structures comprise the juxtaglomerular apparatus?

Answer 33

Macula densa (– (“dense spot”) specialized cells of the thick ascending limb that pass between the afferent and efferent arterioles) Extraglomerular mesangial cells Granular cells of the afferent arteriole – produce, store, and release the hormone renin

Question 34

The JGA is on component of the (X) involved in regulating renal blood flow and glomerular filtration rate

Answer 34

X = tubuloglomerular feedback mechanisms

Question 35

Each tubule is made up of (X) of epithelial cells, separated by (Y), resting on a tubular basement membrane

Answer 35

``` X = a single layer Y = tight junctions ```

Question 36

Nearly all tubular epithelial cells possess a primary cilium at their apical surface, which may play a role in sensing (X)

Answer 36

X = urine fluid flow

Question 37

What is the first tubule segment, continuous with the Bowman's capsule consisting of a coiled segment (X) followed by a straight segment (Y), which extends towards the medulla?

Answer 37

Proximal Tubule ``` X = proximal convoluted tubule Y = proximal straight tubule ```

Question 38

The proximal tubule reabsorbs what percentage of the glomerular filtrate?

Answer 38

55-60% (65-70% by other estimates)

Question 39

What is the primary site of NaCl and water reabsorption in the nephron?

Answer 39

Proximal tubule

Question 40

At their apical membrane, proximal tubule cells have a (X) with numerous microvilli that increase surface area to optimize the reabsorption of solutes and water. This is the only tubule segment with this feature

Answer 40

X = brush border

Question 41

Cytoplasm of proximal tubule cells contain numerous (X) needed for active transport processes

Answer 41

X = mitochondria

Question 42

Name the 3 segments of the Loop of Henle

Answer 42

Thin descending limb Thin ascending limb Thick ascending limb

Question 43

What percentage of filtered NaCl is reabsorbed by the LOH?

Answer 43

25-35% (15-25% by other estimates)

Question 44

The LOH plays a critical role in what function of the kidney?

Answer 44

Concentration of the urine

Question 45

What percentage of filtered NaCl is reabsorbed by the Distal Convoluted Tubule?

Answer 45

~5%

Question 46

What is the primary site for regulation of calcium in the kidney?

Answer 46

Distal Convoluted Tubule

Question 47

The collecting duct is divided into what 2 structures?

Answer 47

Cortical and medullary collecting ducts

Question 48

The cortical collecting duct consists of what cells with which functions?

Answer 48

Principal cells - reabsorption of NaCl and secretion of K+ Intercalated cells - regulate acid-base balance

Question 49

The medullary collecting duct is responsible for regulation of transport of water and urea under the influence of what hormone?

Answer 49

ADH

Question 50

The Proximal Tubule Reabsorbs what percentage of filtered substances from the glomerular filtrate? NaCl and water HCO3- Glucose & Amino Acids

Answer 50

65-70% 90% Almost all

Question 51

What other electrolytes and molecules does the PT reabsorb?

Answer 51

K+, PO43-, Ca2+, Mg2+, urea, uric acid

Question 52

What is the major site of ammonia production in the nephron?

Answer 52

Proximal Tubule

Question 53

The LOH participates in (X) to produce a concentrated urine

Answer 53

X = countercurrent exchange

Question 54

What is the major site of active regulation of Mg2+ excretion?

Answer 54

LOH

Question 55

Name the 3 key features of the cortical collecting duct

Answer 55

Principal cells: reabsorb Na+ and Cl-, secrete K+ Intercalated cells: secrete H+, reabsorb K+, secrete HCO3- Reabsorbs water in presence of ADH

Question 56

What is the final site of modification of the urine?

Answer 56

Medullary collecting duct

Question 57

What is reabsorbed and secreted in the medullary collecting duct?

Answer 57

Reabsorbs NaCl Reabsorbs water and urea, depending on presence of ADH Secretes H+ and NH3

Question 58

The efferent arteriole forms what type of capillaries in the juxtamedullary nephrons that are not formed in the cortical nephrons?

Answer 58

Vasa recta | Peritubular capillaries are formed in both

Question 59

Where do efferent fiber (TO the kidney) originate?

Answer 59

Sympathetic nerve fibers originating in the celiac plexus (T10-L2)

Question 60

Does the kidney have parasympathethic innervation?

Answer 60

No, just sympathetic

Question 61

What are the effects of sympathetic nervous stimulation of the kidneys?

Answer 61

Cause vasoconstriction Increase tubular Na+ reabsorption Stimulate renin secretion by granular cells of the JGA

Question 62

What 2 types of receptors are found in the afferent (sensory) fibers (FROM the kidney)?

Answer 62

Baroreceptors in interlobular arteries and afferent arterioles respond to changes in perfusion pressure Chemoreceptors in the renal pelvis respond to high extracellular levels of K+ and H+

Question 63

What are the 3 renal processes and what is the formula for urinary excretion derived from these processes?

Answer 63

Filtration, Reabsorption, & Secretion Urinary Excretion = Filtration - Reabsorption + Secretion