Chapter 38

Question 1

What are the primary functions of the Kidney’s?

Answer 1

1. Maintain a stable internal environment for optimal cell and tissue metabolism.
2. Balance solute and water transport.
3. Excrete metabolic waste products.
4. Conserve nutrients.
5. Regulate acids and bases

Question 2

What hormones do the kidneys secrete as their endocrine functions?

Answer 2

1. Renin: Regulation of blood pressure
2. Erythropoietin: Production of erythrocytes
3. 1,25-dihydroxyvitamin D3: Metabolism of calcium

Question 3

Synthesis of glucose from amino acids.

Answer 3

Gluconeogenesis

Question 4

What substance forms in the kidneys and drains into the bladder?

Answer 4

Urine

Question 5

Define the structure of the kidneys.

Answer 5

Paired organs located in the posterior region of the abdominal cavity behind the peritoneum (retroperitoneal).

Question 6

What is a tightly adhering capsule that surrounds each kidney; each kidney is then embedded in a mass of fat.

Answer 6

Renal Capsule

Question 7

What is the fibrous tissue that attaches each kidney to the posterior abdominal wall?

Answer 7

Renal Fascia

Question 8

This is where the renal blood vessels, nerves, lymphatic vessels, and ureter enter and exit the kidneys.

Answer 8

Hilum

Question 9

This is the outer layer of each kidney. It also contains all the glomeruli, most of the proximal tubules, and some segments of the distal tubule.

Answer 9

Renal Cortex

Question 10

This is the inner part of each kidney that contains tubules and the collecting duct. It also consists of the regions called the pyramids.

Answer 10

Renal Medulla

Question 11

Extends from the cortex down between the renal pyramids.

Answer 11

Renal Columns

Question 12

Apexes of the pyramids that projects into a cup-shaped cavity that joins together to form a major calyx?

Answer 12

Minor Calyx

Question 13

Joins to form the renal pelvis.

Answer 13

Major Calyx

Question 14

Joins the proximal end of the ureter.

Answer 14

Renal Pelvis

Question 15

What is the functional unit of the kidney? (Hint, each kidney contains 1.2 million)

Answer 15

Nephron

Question 16

This makes up 85% of all nephrons, which extend partially into the medulla.

Answer 16

Superficial Cortical Nephrons

Question 17

These have short or long loops.

Answer 17

Midcortical Nephrons

Question 18

Lie close to and extend deep into the medulla and are important for the process of concentrating urine.

Answer 18

Juxtamedullary Nephrons

Question 19

Three main components of the Renal Corpuscle.

Answer 19

1. Glomerulus
2. Bowman Glomerular Capsule
3. Mesangial Cells

Question 20

Tuff of capillaries

Answer 20

Glomerulus

Question 21

Bowman space; Circular space between visceral and parietal epithelium

Answer 21

Bowman Glomerular Capsule

Question 22

1. Secrete mesangial matrix; lie between and support the glomerular capillaries. Some of these contracts like smooth muscle cells to regulate glomerular capillary blood flow.
   - Have phagocytic properties and release inflammatory cytokines and growth factors.

Answer 22

Mesangial Cells

Question 23

Filters selected blood components through its three layers

Answer 23

Glomerulus

Question 24

What are the three layers of the glomerular filtration membrane?

Answer 24

1. Inner Capillary Endothelium
2. Middle Glomerular Basement Membrane (GBM)
3. Outer Layer: Visceral Epithelium that forms the inner layer of the Bowman’s capsule.

Question 25

1. Synthesize Nitric Oxide (a vasodilator) 2. Synthesize Endothelin-1 (a vasoconstrictor) 3. Regulate glomerular blood flow.

Answer 25

Glomerular endothelial cells

Question 26

1. What part of the Nephron: Is composed of cells bodies called podocytes, which are foot like projections? 2. Form an elaborate network of intercellular clefts called filtration slits, modular filtration. 3. Supplied by the afferent arteriole and drained by the efferent arteriole.

Answer 26

Visceral Epithelium of the Bowman's Capsule

Question 27

What are the two components of the Juxtaglomerular Apparatus?

Answer 27

1. Juxtaglomerular Cells 2. Macula Densa

Question 28

These specialized cells are located around the afferent arteriole where the afferent arteriole enters the glomerulus.

Answer 28

Juxtaglomerular Cells

Question 29

Between the afferent and efferent arterioles of the distal convoluted tubule; sodium-sensing cells.

Answer 29

Macula Densa

Question 30

What three things are controlled by the Juxtaglomerular Apparatus (JGA) at this site?

Answer 30

1. Renal Blood Flow (RBF) 2. Glomerular Filtration 3. Renin Secretion

Question 31

This is where substances are reabsorbed from the filtrate or secreted into the filtrate.

Answer 31

Renal Tubules

Question 32

Is the only surface inside the nephron covered with microvilli?

Answer 32

Proximal Convoluted Tubule

Question 33

Is a hairpin-shaped loop composed of thick and thin portions of a descending segment that goes into the medulla.

Answer 33

Loop of Henle

Question 34

Extends from macula densa to collecting duct.

Answer 34

Distal Convoluted Tubule

Question 35

Descends down the cortex, through the renal pyramids of the inner and outer medullae, draining urine into the minor calyx.

Answer 35

Collecting Duct

Question 36

Reabsorbs sodium and water and secretes potassium.

Answer 36

Principle Cells

Question 37

Secretes hydrogen and reabsorb potassium.

Answer 37

Intercalated Cells

Question 38

Supplies blood to the kidneys.

Answer 38

Renal Arteries

Question 39

Travel down the renal columns and between the pyramids.

Answer 39

Interlobar Arteries

Question 40

1. Arch over the base of the pyramids and run parallel to the surface of the kidneys. 2. Interlobular arteries extend through the cortex toward the periphery of the kidneys and supply the afferent glomerular arterioles.

Answer 40

Arcuate Arteries

Question 41

1. Feed into the efferent Arteriole 2. Afferent arterioles subdivide into a fist like structure of four to eight glomerular capillaries. 3. Efferent arterioles convoy blood to a second capillary bed

Answer 41

Glomerular Capillaries

Question 42

Surround the proximal and distal convoluted tubules and loop of Henle.

Answer 42

Peritubular Capillaries

Question 43

Is a network of capillaries that forms loops and follow loops of Henlel

Answer 43

Vasa Recta

Question 44

Follow arterial path in reverse direction and have the same names as corresponding arteries, empty into inferior vena cava.

Answer 44

Renal Veins

Question 45

1. Are 30 cm long 2. Are long, intertwining smooth muscle Bundles. 3. Pass obliquely through the posterior aspect of the bladder 4. Peristaltic activity moves urine to the bladder 5. Micturition compresses the lower end of this ureter to prevent further urine reflux.

Answer 45

Ureters

Question 46

Bladder Detrusor muscle Transitional epithelium Trigon

Answer 46

Transitional epithelium

Question 47

1. Internal Urethral Sphincter \*Smooth muscle located at junction of bladder and urethra. 2. External Urethral Sphincters \*Striated skeletal muscle under voluntary control. 3. Between 3 and 4 cm long in females 4. Between 18 and 20 cm long in males

Answer 47

Urethra

Question 48

1. Parasympathetic Fibers Bladder and internal urethral sphincter 2. Skeletal motor Neurons in the pudenda nerve External Urethral Sphincter

Answer 48

Innervation

Question 49

Kidneys receive 1000-1200 mL of blood per minute.

Answer 49

Renal Blood Flow

Question 50

600-700 mL as plasma

Answer 50

Renal Plasma Flow (RPF)

Question 51

1. Filtration of Plasma into the Bowman space. 2. 20% of the RPF (120-140 mL/ minute) 3. Directly related to the perfusion pressure in the glomerular capillaries. 4. If mean arterial pressure decreases or vascular resistance increases then the RBF decreases.

Answer 51

Glomerular Filtration Rate (GFR)

Question 52

1. Strict maintenance of 80-180 mmHg provides constant GFR. 2. As the systemic blood pressure increases, afferent arterioles constrict, preventing an increase in filtration pressure. 3. Prevents wide fluctuations in the systemic arterial pressure from being transmitted to the Glomerular Capillaries. - Solute and water excretion is constantly maintained, despite arterial pressure changes. 4. Myogenic Mechanism (stretch) - As arterial pressure declines, glomerular perfusion increases. - Stretch on the afferent arteriolar smooth muscle decreases, and the arteriolar relaxes. - An increase in arteriolar pressure decreases glomerular perfusion. - Causes the arteriole smooth muscle to contract. 5. Tubuloglomerular feedback (sodium chloride NaCl content) - When sodium filtration increases, GFR decreases. - Macula densa cells stimulate afferent arteriolar vasoconstriction. - When sodium filtration decreases, the opposite occurs - GFR increases.

Answer 52

Autoregulation

Question 53

1. Sympathetic nervous system. - Vasoconstriction diminishes RBF and GFR - Increases renal tubular sodium and water reabsorption. - Increases blood pressure. 2. Decreased afferent renal sympathetic nerve activity produces opposite effects. 3. Renalase: Promotes Metabolism of catecholamines 4. Hormonal regulation of renal blood flow.

Answer 53

Neural Regulation

Question 54

1. Increases systemic arterial pressure and increases sodium reabsorption. 2. Renin: Enzyme is formed and stored in the afferent arterioles of the juxtaglomerular apparatus. 3. Renin helps form angiotensin I (physiologically inactive). 4. In the presence of angiotensin-converting enzyme (ACE), angiotensin I is converted to angiotensin II 5. Angiotensin II - Stimulates the secretion of aldosterone by the - adrenal cortex. - Is a potent vasoconstrictor. - Stimulates antidiuretic hormone (ADH) secretion and thirst.

Answer 54

1. Renin-Angiotensin-Aldosterone System (RAAS)

Question 55

1. Atrial natriuretic peptide (ANP) is secreted from myocardial cells in the atria. 2. Brain natriuretic peptide (BNP) is secreted from myocardial cells in the ventricles. 3. ANP and BNP - Inhibit sodium and water absorption by kidney tubules. - Inhibit secretion of renin and aldosterone. - Vasodilate the afferent arterioles, constrict the efferent arterioles. - Increase urine formation, leading to decreased blood volume and pressure.

Answer 55

Natriuretic Peptides

Question 56

1. Is secreted from vascular endothelium and in the nephron. 2. Causes vasodilation.

Answer 56

C-type Natriuretic Peptide

Question 57

1. Is secreted by the distal convoluted tubules and the collecting ducts. 2. Causes vasodilation, increases renal blood flow, and diuretic effects.

Answer 57

Urodilatin

Question 58

Influences RBF

Answer 58

Hormones and Mediators

Question 59

1. Filters the plasma at the glomerulus. 2. Reabsorbs and secretes different substances at various parts of its tubular structure. 3. Forms a filtrate of protein-free plasma, called ultrafiltration. 4. Regulates filtrate to maintain body fluid volume, electrolyte composition, and pH with narrow limits. - Requires tubular reabsorption and tubular secretion.

Answer 59

Nephron Functions

Question 60

Movement of protein-free plasma across the glomerular membrane (hydrostatic pressure)

Answer 60

Filtration

Question 61

Movement of fluid and solutes from tubular lumen to the peritubular capillaries.

Answer 61

Tubular Reabsorption

Question 62

Transfer of substances from the peritubular capillaries to the tubular lumen.

Answer 62

Tubular Secretion

Question 63

Elimination of substances in the final urine

Answer 63

Excretion

Question 64

1. Glomerulus is freely permeable to water and relatively impermeable to large colloids such as plasma proteins. - Size and electrical charge are important factors that affect permeability. - Positive-Charged particles permeate the membrane more readily that neutral- or negative-charged particles. - Capillary pressure - Hydrostatic pressure - Determined by systemic arterial pressure and resistance to blood flow in the afferent and efferent arterioles.

Answer 64

Glomerular Filtration

Question 65

1. Is the combined effect of forces favoring and forces opposing filtration. - Favoring forces: Capillary hydrostatic pressure - Opposing forces: Oncotic pressure in the capillary and hydrostatic pressure in Bowman's capsule 2. Includes glomerular hydrostatic pressure, capsular hydrostatic pressure, and blood oncotic pressure.

Answer 65

Net Filtration Pressure

Question 66

1. Total volume of fluid filtered by the glomeruli averages 180 L/day or approximately 120 mL/minute. 2. Filtration of plasma per unit of time is directly related to the perfusion pressure of the RBF. 3. 99% of the filtrate is reabsorbed into the peritubular capillaries and returned to the blood.

Answer 66

Filtration Rate

Question 67

In some molecules, active transport is limited as carrier molecules become saturated: Transport maximum

Answer 67

Active Transport

Question 68

1. Approximately 60% to 70% of filtered sodium and water and approximately 50% of urea have been reabsorbed, along with 90% or more of potassium, glucose, bicarbonate, calcium, phosphate, amino acids, and uric acid. 2. Chloride, water, and urea are passively reabsorbed.

Answer 68

Tubular Transport

Question 69

1. Function: Active reabsorption of sodium. - Promotes the passive diffusion of water. - Reabsorption of water leaves an increased concentration of urea. - Hydrogen ions are actively exchanged for sodium ions. - Bicarbonate combines with hydrogen in the tubular cell and is eventually reabsorbed as carbon dioxide (CO2) and water. - Glomerulotubular balance (GTB) 2. Damaged renal tubules: Metabolic byproducts and drugs may accumulate, causing toxic levels.

Answer 69

Proximal Convoluted Tubules

Question 70

1. Provides the kidney with the ability to concentrate urine and conserve water for the body. 2. Fluid leaving the ascending limb of the loop is hypoosmotic and is more diluted than the fluid that entered. 3. Reabsorb more solute than water into the interstitium. 4. Primary function is to establish a hyperosmotic sate within the medullary interstitial fluid. 5. Thin, descending segment: Is highly permeable to water and moderately permeable to sodium, urea, and other solutes. 6. Thin, ascending segment: Is highly permeable to water and moderately permeable to sodium, urea, and other solutes. 7. Thick portion of the ascending segment: Is highly permeable to sodium, potassium, and chloride and significantly less permeable to water and urea.

Answer 70

Loop of Henle

Question 71

1. Performs the final adjustments in urine composition. 2. Convoluted portion of the distal tubule: Is limitedly permeable to water but readily absorbs ions and contributes to the dilution of the tubular fluid. 3. Straight segment of the distal tubule and the collecting duct: Is permeable to water as controlled by ADH. 4. Tamm-Horsfall Glycoprotein (uromodulin) - Is formed on the epithelial surface of the thick ascending segment and is the first segment of the distal tubules. - Is the most abundant urinary protein. - Protects against bacterial adhesion and urolithiasis. Is a renal ligand for lymphokines. 5. Sodium is readily absorbed by the latter segment of the distal tubule and collecting duct under the regulation of aldosterone. 6. Potassium is actively secreted by the principal cells and is reabsorbed in lesser amounts by intercalated cells in these segments; is controlled by aldosterone and other factors related to the concentration of potassium in body fluids. 7. Hydrogen is secreted by the distal tubule; it combines with non-bicarbonate buffers (ammonium and phosphate) for the elimination of excess acids in the urine. 8. Contribute to the regulation of acid-base balance by excreting hydrogen ions into the urine and by adding new bicarbonate to the plasma.

Answer 71

Distal Convoluted Tubules and Collecting Duct

Question 72

1. When GFR spontaneously decreases or increases. - Renal tubules and, primarily the proximal tubules, automatically adjust their rate of reabsorption of sodium and water to balance the change in GFR. - Constant fraction of filtered sodium and water is reabsorbed from the proximal tubule.

Answer 72

Glomerulotubular balance

Question 73

1. Are initiated in the thick ascending limb of the loop of Henle with active transport of chloride and sodium into the medullary interstitium. 2. Hyperosmotic interstitium causes water to move out of descending limb; the remaining fluid becomes increasingly concentrated. 3. As fluid enters the ascending limb, sodium and chloride are removed and water is retained. 4. Fluid becomes more and more dilute as it enters the distal tubule.

Answer 73

Water, Sodium, and Chloride

Question 74

1. Is the end product of protein metabolism and the major constituent of urine. 2. Approximately 50% of urea is excreted in the urine, and 50% is recycled in the kidneys.

Answer 74

Urea

Question 75

1. Promote afferent arteriolar vasoconstriction and decrease GFR and RBF. 2. Renalase: Is the hormone produced by the kidney that promotes the metabolism of catecholamines and regulates blood pressure.

Answer 75

Catecholamines

Question 76

1. Controls the concentration of final urine. 2. Increases water permeability in the last segment of the distal tubule and along the entire length of the collecting ducts. 3. In the presence of ADH, water reabsorption is high, causing less urine volume.

Answer 76

ADH

Question 77

Promotes diuresis

Answer 77

Natriuretic peptides

Question 78

Are the agents that enhance the flow and excretion of urine.

Answer 78

Diuretic Drugs

Question 79

1. Calcitriol (1,25-dihydroxyvitamin D3) - Is necessary for the absorption of calcium and phosphate by the small intestine. 2. Can be obtained in the diet or synthesized by action of ultraviolet radiation on cholesterol in the skin. 3. Decreased phosphate levels stimulate calcitriol.

Answer 79

Vitamin D

Question 80

1. Is produced in fetal liver and the adult kidney; is essential for erythropoiesis. 2. Chronic renal failure: Causes anemia from reduced erythropoietin secretion.

Answer 80

Erythropoietin