Exam 4 - Chapter 25 Deck

Question 1

Functions of the urinary system

Answer 1

Maintains homeostasis by managing the volume and composition of fluid reservoirs (primarily blood)

Maintains osmolarity of extra/interstitial fluid of blood

Question 2

What are the major organs of the urinary system?

Answer 2

Kidneys, ureters, bladder, and urethra

Two kidneys (left/right) connect two ureters (right/left)

Kidneys produce urine

Ureters connect urine to bladder

Urethra removes urine from temporary storage out of the body

Question 3

Discuss the general location and structure of the kidney

Answer 3

Retroperitoneal (not in peritoneal cavity, behind peritoneum)

Partly protected by the lower ribs

Attached to the back muscles

Bean-shaped organ

Indented area is called the renal hilum

Question 4

What is the renal hilum?

Answer 4

It is an entrance/exit for the renal artery (brings oxygenated blood to the kidney), renal vein (deoxygenated blood drained), ureter, nerves, and lymphatics

Question 5

What does the external layer of the kidney consist of?

Answer 5

Made of connective tissue (superficial/outermost to deep/innermost)

Renal fascia

Adipose capsule

Renal capsule

Question 6

Renal fascia of the external layer of kidney?

Answer 6

Anchors to other structures

Outermost

Question 7

Adipose capsule of the external layer of kidney?

Answer 7

Protects, anchors, and supports kidney

Question 8

Renal capsule of the external layer of kidney?

Answer 8

Continuous with ureter

Question 9

What does the internal layers of the kidney consist of?

Answer 9

Renal cortex

Renal medulla

Renal pyramids

Renal columns

Question 10

Renal cortex of the internal layer of the kidney?

Answer 10

Outer layer

Question 11

Renal medulla of the internal layer of the kidney?

Answer 11

Inner region

Forms pyramid

Question 12

Renal pyramids of the internal layer of the kidney?

Answer 12

Secreting apparatus and tubules

Contain multiple collecting ducts

Question 13

Renal columns of the internal layer of the kidney?

Answer 13

Anchor the cortex

Between renal medulla and pyramids

Question 14

Functions of the kidney

Answer 14

Long term regulation of pH, acid base balance, and blood volume

Ability to retain, excrete, and adjust composition of ions in body fluids based on body’s needs

Regulation of blood ionic composition; Na+, K+, Cl-

Regulation of blood pH; H+, HCO3-

Regulation of blood volume; H2O (higher blood volume = higher BP)

Regulation of BP

Regulation of blood osmolarity

Regulation of blood glucose level (when hyperglycemia - high blood sugar/glucose - develops, glucose appears in urine; also a way to lower blood glucose concentration)

Production of hormones; calcitriol and erythropoietin

Excretion of metabolic wastes and foreign substances (drugs or toxins) - pushed from blood to urine

Question 15

Purpose of calcitriol in the kidney

Answer 15

Activated vitamin D

Increases absorption of calcium in GI tract

Question 16

Purpose of erythropoietin in the kidney

Answer 16

Secreted in response to hypoxia

Stimulates development of RBCs

Question 17

Explain blood supply to the kidneys

Answer 17

Kidneys constitute less than 0.5% of total body mass, BUT receive 20-25% of resting cardiac output (volume of blood the heart pumps per minute)

Renal nerves primarily carry sympathetic outflow and regulate blood flow through kidneys

Question 18

List the blood vessels located in the kidney

Answer 18

Cortical radiate artery

Arcuate artery

Interlobar artery

Segmental artery

Renal artery

Renal vein

Interlobar vein

Arcuate vein

Cortical radiate vein

Question 19

Trace blood flow through the vessels of the kidney

Answer 19

Renal artery → segmental arteries → interlobar arteries → arcuate arteries → cortical radiate arteries → afferent arterioles → glomerular capillaries → efferent arterioles → peritubular venules → cortical radiate veins → arcuate veins → interlobar veins → renal veins

Question 20

Function of the nephron

Answer 20

Functional unit of kidney

Filters 45 gallons of blood daily (blood flow is via nephron)

Tubular system surrounded by blood vessels that exchange between fluid

Question 21

What are the two parts of the renal corpuscle in the nephron?

Answer 21

Glomerulus

Glomerular (Bowman’s) capsule

Question 22

Glomerulus

Answer 22

Mass of capillaries fed by afferent arterioles and drains into the efferent arteriole

Filters water and other substances from bloodstream

Blood flows through glomerulus, pushes water and solutes from capillaries through filtration membrane

Afferent (to): blood delivered to glomerulus capsule

Efferent (away): blood taken from glomerulus capsule

Question 23

Glomerular (Bowman’s capsule)

Answer 23

Visceral layer is in direct contact with glomerulus capillaries

Filtrate collected between visceral and parietal layers (space between layers called capsullar space)

Glomerular endothelial cells have large pores called fenestrations (opening that allow passage of small molecules) and are leaky

Basal lamina lies between endothelium and podocytes

Podocytes form pedicels, between which are filtration slits

Pedicels are the first step of urine formation (glomerular filtration); filtration of fluid from the blood in the glomerulus through the filtration slits, formed by podocytes into capsullar space

Question 24

List the filtration membranes of the renal corpuscle

Answer 24

Fenestration (pore) of glomerular endothelial cell (innermost)

Basement membrane of glomerulus

Slit membrane between pedicels (outermost)

Question 25

Purpose of the fenestration (pore) of glomerular endothelial cell

Answer 25

Prevents filtration of blood cells, but allows all components of blood plasma to pass through

Question 26

Purpose of the basement membrane of glomerulus

Answer 26

Prevents filtration of larger proteins

Question 27

Purpose of the slit membrane between pedicels

Answer 27

Prevents filtration of medium-sized proteisn

Question 28

Cortical nephrons

Answer 28

80-85% of nephrons (most abundant in renal cortex) Renal corpuscle in outer portion of cortex Short loops of Henle extend only into outer region of medulla Thick and thin segments but no vasa recta Create urine with osmolarity/concentration similar to blood

Question 29

Juxtamedullary nephrons

Answer 29

15% of nephrons "Close to medulla" Renal corpuscle deep (inside) in cortex with long nephron loops Receive blood from peritubular capillaries and vasa recta (blood vessels that create vertical osmotic gradient in medulla) Ascending limb has thick and thin regions Enable kidney to secrete very concentrated urine

Question 30

Juxtaglomerular apparatus

Answer 30

Ascending loop contacts the afferent arterioles at macula densa Wall of arteriole contains smooth muscle cells called juxtaglomerular cells ("close to glomerulus; apparatus regulates BP in the kidney in conjunction with the ANS) Release of renin activates angiotensin mechanism which increases BP body-wide

Question 31

Role of nephron in filtration

Answer 31

It increases the surface area allowing for maximum exchange and contact for urine processing, and allows time for the different stages of urine production

Question 32

Glomerular filtration

Answer 32

Passive transport (enters glomerular capsule) Occurs exclusively in the renal corpuscle, across the filtration membrane Driven by capillary hydrostatic pressure Water and small molecules move out of the glomerulus Pushes substances out of blood and into urine 150-180 liters of water pass out into the glomerular capsule daily In the glomerulus, blood plasma and dissolves substances get filtered into the glomerular capsule

Question 33

Tubular reabsorption

Answer 33

Second major step in urine formation (returned to blood) Driven by capsular hydrostatic pressure (pressure of fluid in capsular space) and blood colloid osmotic pressure Process that moves solutes and water out of the filtrate and back into your bloodstream (takes filtered substances and water back to blood) Much of filtrate is reabsorbed, especially water, glucose, amino acids and ions Along the renal tubule and collecting duct, water ions, and other substances get reabsorbed from the renal tubule lumen into the peritubular capillaries and into the blood

Question 34

Tubular secretion

Answer 34

Active transport (to become urine) Secretion helps to manage pH, and rid the body of toxic and foreign substances Anything secreted eventually becomes a part of urine because secretion pushes substances/waste products out of blood and into urine Along the renal tubule and collecting duct, substances such as wastes, drugs, and excess ions get secreted from the peritubular capillaries into the renal tubule. These substances ultimately make their way into the urine Excretion of a solute = glomerular filtration + secretion - reabsorption

Question 35

Discuss the mechanisms of filtration

Answer 35

Filtrate is produced by the glomerulus when the hydrostatic pressure produced by the heart pushes water and solutes through the filtration membrane Glomerular filtration is a passive process as cellular energy is not used at the filtration membrane to produce filtrate As blood flows through the glomerulus, BP pushes water and solutes from the capillaries into the capsule through a filtration membrane

Question 36

Structure of renal corpuscle

Answer 36

Consists of knot of capillaries (glomerulus) surrounded by a double-walled capsule (Bowman's capsule) that opens into a tubule Blood hydrostatic pressure drives filtration

Question 37

Plasma with respect to normal composition

Answer 37

Pale yellow fluid portion of blood where WBC, RBC, and platelets are suspended Located inside blood vessels Contains suspended proteins and other large molecules

Question 38

Glomerular filtrate with respect to normal composition

Answer 38

Filtrate that passes through the lumen of the glomerular capillary to the space of the glomerular (Bowman's) capsule Occurs inside the glomerulus Contains no blood cells, proteins or other large molecules

Question 39

Define glomerular filtration rate (GFR)

Answer 39

The amount of filtrate formed by both kidneys each minute

Question 40

What factors regulate GFR?

Answer 40

Renal autoregulation, neural regulation, and hormonal regulation

Question 41

Renal autoregulation

Answer 41

Self-regulation by kidneys involving myogenic mechanisms and tubuloglomerular feedback

Question 42

Myogenic mechanism (renal autoregulation)

Answer 42

Increases stretching of smooth muscle fibers in afferent arterioles due to increased BP (narrowing lumen of afferent arterioles; decreases GFR)

Question 43

Tubuloglomerular feedback (renal autoregulation)

Answer 43

Decreased release of nitric oxide by juxtaglomerular apparatus (constriction of afferent arterioles; decreases GFR)

Question 44

Neural regulation

Answer 44

In the case of strong sympathetic stimulation (exercise or hemorrhage), afferent arterioles constrict and urine output is reduced, and more blood is aviable for other organs This causes a decrease in GFR (as well as BHP/GHP)

Question 45

Hormonal regulation

Answer 45

Angiotensin II constricts afferent and efferent arterioles; decreases GFR Atrial natriuretic peptide (ANP) relaxes mesangial cells, which increases capillary surface area and thus increases GFR

Question 46

The diameter of afferent arterioles is ____ than efferent arterioles because there is more blood ____ glomerulus than ____

Answer 46

greater; entering; leaving

Question 47

Primary active transport of tubular reabsorption

Answer 47

Uses ATP breakdown to transport molecules via Na+/K+ pumps At rest, accounts for 6% of total body ATP use

Question 48

Secondary active transport of tubular reabsorption

Answer 48

Driven by ions electrochemical gradient (energy stored in the form of ionic concentration differences between the two sides of a membrane) Symporters move substances in the same direction Antiporters move substances in the opposite direction

Question 49

Obligatory water reabsorption of tubular reabsorption

Answer 49

90% Water follows the solutes that are reabsorbed

Question 50

Facultative water reabsorption of tubular reabsorption

Answer 50

10% Depends on body's need and availability of specific hormone Regulated by ADH

Question 51

Where does water reabsorption occur?

Answer 51

Primarily along the PCT and the descending limb of the nephron loop, but also to a variable degree in the DCT and collecting system

Question 52

Where does variable water reabsorption occur?

Answer 52

Occurs in the DCT and collecting system

Question 53

Where does solute reabsorption occur?

Answer 53

Along the PCT, the ascending limb of the nephron loop, the DCT, and the collecting system

Question 54

Where does variable solute reabsorption or secretion occur?

Answer 54

Occurs at the PCT, the DCT, and the collecting system

Question 55

What is the fate of most of the water that leaves the glomerulus?

Answer 55

Only small amounts of the water makes it out of the glomerulus If it does, it get reabsorbed by tubules back into the blood

Question 56

Role of nephron loop and state changes in tubular fluid when it passes through descending and ascending limbs

Answer 56

Reabsorption in the loop of Henle Descending limb - continues water and solute reabsorption Ascending limb - solute reabsorption only (limb is too thick, little obligatory water reabsorption) Relatively impermeable to water, especially the ascending limb Na+ - K+ - 2Cl- symporters

Question 57

Role of DCT and collecting ducts in the final adjustment of urine composition

Answer 57

Reabsorption in DCT collecting duct Na+ - Cl- symporters reabsorb ions PTH stimulates reabsorption of Ca2+ (it also inhibits phosphate reabsorption in the PCT, enhancing its excretion) Na+ - K+ pumps reabsorb Na+ Water reabsorption is stimulated by ADH Reabsorb K+ and HCO3-, secrete H+

Question 58

Trace filtrate from its point of formation to the renal pelvis

Answer 58

Renal artery → glomerulus → Bowman’s capsule → proximal tubule → loop of Henle → distal tube → collecting duct → renal pelvis

Question 59

Trace filtrate from its point of formation to the renal pelvis

Answer 59

Renal artery → glomerulus → bowman's capsule → proximal tubule → loop of Henle → distal tube → collecting duct → renal pelvis

Question 60

List the parts of the nephron

Answer 60

Glomerulus, proximal convoluted tubule (PCT), PCT and descending limb, thick ascending limb, DCT and collecting duct, and urine production

Question 61

Glomerulus of the nephron loop

Answer 61

Filtrate produced at renal corpuscle and has the same plasma (minus plasma proteins and blood cells)

Question 62

Proximal convoluted tubule (PCT) of the nephron loop

Answer 62

60-70% of reabsorption Passive reabsorption - active removal of ions and organic substrates Produces osmotic water flow out of tubular fluid Reduces volume of filtrate

Question 63

PCT and descending limp of nephron loop

Answer 63

Primarily water reabsorption Water moves into peritubular fluids, leaving highly concentrated tubular fluid Reduction in volume occurs by obligatory water reabsorption

Question 64

Thick ascending limb in nephron loop

Answer 64

Tubular cells actively transport Na+ and C- out of tubule

Question 65

DCT and collecting ducts of nephron loop

Answer 65

Final adjustments in composition of tubular fluid Exposure to ADH Determines final urine concentration

Question 66

Urine production

Answer 66

Ends when fluid enter the renal pelvis

Question 67

Urine production

Answer 67

Fluid intake is highly variable Homeostasis requires maintenance of fluid volumes within specific limits Urine concentration varies with ADH (triggers additional water reabsorption) High intake of fluid results in dilute urine of high volume Low intake of fluid results in concentrated urine of low volume

Question 68

Formation of dilute urine

Answer 68

Glomerular filtrate and blood have the same osmolarity at 300mOsm/liter BUTTTT Tubular osmolarity changes due to a concentration gradient in the medulla

Question 69

What are the osmolarity changes in the tubule when dilute urine is formed?

Answer 69

Increases in the descending limb (because water was reabsorbed) Decreases in the ascending limb (because salt is reabsorbed and water is retained) Decreases more in the collecting duct

Question 70

Thick ascending limb in the formation of dilute urine

Answer 70

Symporters actively reabsorb Na+, K+, and Cl- Low water permeability Solutes leave, water stays in tubule

Question 71

Collecting duct in the formation of dilute urine

Answer 71

Low water permeability in absence of ADH

Question 72

Formation of concentrated urine

Answer 72

Juxtamedullary nephrons with long hoops Osmotic gradient is created by the countercurrent multiplier Solutes pumped out of the ascending limb, but water stays in tubule Medulla osmolarity is increased In presence of ADH (triggers additional reabsorption of water), collecting ducts become very permeable to water Tubular fluid there becomes very concentrated

Question 73

Location and structure of the juxtaglomerular apparatus

Answer 73

The ascending loop contacts the afferent arteriole at the macula densa The walls of the arteriole contains smooth muscle cells called juxtaglomerular cells

Question 74

Role of the juxtaglomerular apparatus

Answer 74

Regulates BP in the kidney in conjunction with the ANS

Question 75

Path of urine drainage

Answer 75

Collecting duct → papillary duct → minor calyx → major calyx → renal pelvis → ureter → urinary bladder

Question 76

Discuss the structure of the ureter

Answer 76

Ureters transport urine from the renal pelvis by the peristaltic waves, hydrostatic pressure, and gravity No anatomical valve at the opening of the ureter (transports urine to the urinary bladder) into bladder (assists in micturition) - when bladder fills, it compresses the opening and prevents backflow Bladder is a hollow, distensible, muscular organ with a capacity averaging 700-800 mL

Question 77

Purpose of rugae of mucosa

Answer 77

Allow expansion of urinary bladder as it fills

Question 78

Purpose of peritoneum in bladder

Answer 78

Holds urinary bladder in place

Question 79

Purpose of internal urethral sphincter

Answer 79

Involuntarily controls opening and closing of urethra

Question 80

Purpose of external urethral sphincter

Answer 80

In deep muscles of perineum Voluntarily controls opening and closing of urethra

Question 81

Purpose of detrusor muscle

Answer 81

Contracts to push urine into urethra

Question 82

Purpose of urethra

Answer 82

Passageway for discharging urine from body

Question 83

Role of antidiuretic hormone (ADH) in the regulation of homeostasis

Answer 83

Reduces loss of water in urine by inserting water-channel proteins (aquaporin-2) into cells in collecting ducts of kidneys Result in increased water permeability in these cells so more water is reabsorbed

Question 84

Role of parathyroid hormone (PTH) in the regulation of homeostasis

Answer 84

Blocks reabsorption of phosphate in the proximal tubule (PCT) while promoting calcium reabsorption in the ascending limb, distal tubule, and collecting tubule High blood calcium levels can lead to kidney failure

Question 85

Role of aldosterone in the regulation of homeostasis

Answer 85

Reduces loss of water in urine by promoting urinary reabsorption of Na+ therefore increasing water reabsorption via osmosis, which mainly occurs in descending limb of nephron Osmolarity increases here

Question 86

Normal urine composition

Answer 86

95% water Nitrogen wastes (urea, uric acid, creatinine) - nitrogen wastes are result of catabolism of proteins and amino acids Electrolytes (H+, sodium, potassium, calcium) Toxins (bacteria and drug traces) Pigments (urochromes from RBC breakdown) Excess hormones

Question 87

Urine abnormalities

Answer 87

Albumin (breaches in filtration membrane) Red blood cells (damage of glomeli) Microbes Ketone bodies (diabetes and hyperglycemia) Glucose (diabetes and hyperglycemia)