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A&P Winter 2023 > Exam 4 - Chapter 25 Deck > Flashcards

Exam 4 - Chapter 25 Deck Flashcards

1
Q

Functions of the urinary system

A

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

Maintains osmolarity of extra/interstitial fluid of blood

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2
Q

What are the major organs of the urinary system?

A

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

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3
Q

Discuss the general location and structure of the kidney

A

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

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4
Q

What is the renal hilum?

A

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

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5
Q

What does the external layer of the kidney consist of?

A

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

Renal fascia

Adipose capsule

Renal capsule

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6
Q

Renal fascia of the external layer of kidney?

A

Anchors to other structures

Outermost

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7
Q

Adipose capsule of the external layer of kidney?

A

Protects, anchors, and supports kidney

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8
Q

Renal capsule of the external layer of kidney?

A

Continuous with ureter

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9
Q

What does the internal layers of the kidney consist of?

A

Renal cortex

Renal medulla

Renal pyramids

Renal columns

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10
Q

Renal cortex of the internal layer of the kidney?

A

Outer layer

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11
Q

Renal medulla of the internal layer of the kidney?

A

Inner region

Forms pyramid

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12
Q

Renal pyramids of the internal layer of the kidney?

A

Secreting apparatus and tubules

Contain multiple collecting ducts

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13
Q

Renal columns of the internal layer of the kidney?

A

Anchor the cortex

Between renal medulla and pyramids

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14
Q

Functions of the kidney

A

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

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15
Q

Purpose of calcitriol in the kidney

A

Activated vitamin D

Increases absorption of calcium in GI tract

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16
Q

Purpose of erythropoietin in the kidney

A

Secreted in response to hypoxia

Stimulates development of RBCs

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17
Q

Explain blood supply to the kidneys

A

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

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18
Q

List the blood vessels located in the kidney

A

Cortical radiate artery

Arcuate artery

Interlobar artery

Segmental artery

Renal artery

Renal vein

Interlobar vein

Arcuate vein

Cortical radiate vein

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19
Q

Trace blood flow through the vessels of the kidney

A

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

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20
Q

Function of the nephron

A

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

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21
Q

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

A

Glomerulus

Glomerular (Bowman’s) capsule

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22
Q

Glomerulus

A

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

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23
Q

Glomerular (Bowman’s capsule)

A

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

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24
Q

List the filtration membranes of the renal corpuscle

A

Fenestration (pore) of glomerular endothelial cell (innermost)

Basement membrane of glomerulus

Slit membrane between pedicels (outermost)

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25
Q

Purpose of the fenestration (pore) of glomerular endothelial cell

A

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

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26
Q

Purpose of the basement membrane of glomerulus

A

Prevents filtration of larger proteins

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27
Q

Purpose of the slit membrane between pedicels

A

Prevents filtration of medium-sized proteisn

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28
Q

Cortical nephrons

A

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

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29
Q

Juxtamedullary nephrons

A

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

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30
Q

Juxtaglomerular apparatus

A

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

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31
Q

Role of nephron in filtration

A

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

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32
Q

Glomerular filtration

A

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

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33
Q

Tubular reabsorption

A

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

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34
Q

Tubular secretion

A

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

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35
Q

Discuss the mechanisms of filtration

A

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

36
Q

Structure of renal corpuscle

A

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

37
Q

Plasma with respect to normal composition

A

Pale yellow fluid portion of blood where WBC, RBC, and platelets are suspended

Located inside blood vessels

Contains suspended proteins and other large molecules

38
Q

Glomerular filtrate with respect to normal composition

A

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

39
Q

Define glomerular filtration rate (GFR)

A

The amount of filtrate formed by both kidneys each minute

40
Q

What factors regulate GFR?

A

Renal autoregulation, neural regulation, and hormonal regulation

41
Q

Renal autoregulation

A

Self-regulation by kidneys involving myogenic mechanisms and tubuloglomerular feedback

42
Q

Myogenic mechanism (renal autoregulation)

A

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

43
Q

Tubuloglomerular feedback (renal autoregulation)

A

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

44
Q

Neural regulation

A

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)

45
Q

Hormonal regulation

A

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

46
Q

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

A

greater; entering; leaving

47
Q

Primary active transport of tubular reabsorption

A

Uses ATP breakdown to transport molecules via Na+/K+ pumps

At rest, accounts for 6% of total body ATP use

48
Q

Secondary active transport of tubular reabsorption

A

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

49
Q

Obligatory water reabsorption of tubular reabsorption

A

90%

Water follows the solutes that are reabsorbed

50
Q

Facultative water reabsorption of tubular reabsorption

A

10%

Depends on body’s need and availability of specific hormone

Regulated by ADH

51
Q

Where does water reabsorption occur?

A

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

52
Q

Where does variable water reabsorption occur?

A

Occurs in the DCT and collecting system

53
Q

Where does solute reabsorption occur?

A

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

54
Q

Where does variable solute reabsorption or secretion occur?

A

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

55
Q

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

A

Only small amounts of the water makes it out of the glomerulus

If it does, it get reabsorbed by tubules back into the blood

56
Q

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

A

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

57
Q

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

A

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+

58
Q

Trace filtrate from its point of formation to the renal pelvis

A

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

59
Q

Trace filtrate from its point of formation to the renal pelvis

A

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

60
Q

List the parts of the nephron

A

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

61
Q

Glomerulus of the nephron loop

A

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

62
Q

Proximal convoluted tubule (PCT) of the nephron loop

A

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

63
Q

PCT and descending limp of nephron loop

A

Primarily water reabsorption

Water moves into peritubular fluids, leaving highly concentrated tubular fluid

Reduction in volume occurs by obligatory water reabsorption

64
Q

Thick ascending limb in nephron loop

A

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

65
Q

DCT and collecting ducts of nephron loop

A

Final adjustments in composition of tubular fluid

Exposure to ADH Determines final urine concentration

66
Q

Urine production

A

Ends when fluid enter the renal pelvis

67
Q

Urine production

A

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

68
Q

Formation of dilute urine

A

Glomerular filtrate and blood have the same osmolarity at 300mOsm/liter BUTTTT

Tubular osmolarity changes due to a concentration gradient in the medulla

69
Q

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

A

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

70
Q

Thick ascending limb in the formation of dilute urine

A

Symporters actively reabsorb Na+, K+, and Cl-

Low water permeability

Solutes leave, water stays in tubule

71
Q

Collecting duct in the formation of dilute urine

A

Low water permeability in absence of ADH

72
Q

Formation of concentrated urine

A

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

73
Q

Location and structure of the juxtaglomerular apparatus

A

The ascending loop contacts the afferent arteriole at the macula densa

The walls of the arteriole contains smooth muscle cells called juxtaglomerular cells

74
Q

Role of the juxtaglomerular apparatus

A

Regulates BP in the kidney in conjunction with the ANS

75
Q

Path of urine drainage

A

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

76
Q

Discuss the structure of the ureter

A

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

77
Q

Purpose of rugae of mucosa

A

Allow expansion of urinary bladder as it fills

78
Q

Purpose of peritoneum in bladder

A

Holds urinary bladder in place

79
Q

Purpose of internal urethral sphincter

A

Involuntarily controls opening and closing of urethra

80
Q

Purpose of external urethral sphincter

A

In deep muscles of perineum

Voluntarily controls opening and closing of urethra

81
Q

Purpose of detrusor muscle

A

Contracts to push urine into urethra

82
Q

Purpose of urethra

A

Passageway for discharging urine from body

83
Q

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

A

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

84
Q

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

A

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

85
Q

Role of aldosterone in the regulation of homeostasis

A

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

86
Q

Normal urine composition

A

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

87
Q

Urine abnormalities

A

Albumin (breaches in filtration membrane)

Red blood cells (damage of glomeli)

Microbes

Ketone bodies (diabetes and hyperglycemia)

Glucose (diabetes and hyperglycemia)

A&P Winter 2023 (9 decks)

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