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male genitourinary > Structural and Functional Organization of the Urinary System > Flashcards

Structural and Functional Organization of the Urinary System Flashcards

1
Q

What does the urinary system consist of?

A

2 kidneys
2 ureters
1 bladder
1 urethra

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2
Q

What is the scientific study of the kidneys, and of the male and female urinary system?

A

Nephrology

Urology

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3
Q

What are the five basic functions of the kidneys?

A

1) Regulation of ion levels in the blood.

2) Regulation of blood volume and blood pressure.

3) Regulation of blood pH.

4) Production of hormones.

5) Excretion of wastes.

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4
Q

What are the most important ions that the kidneys help to regulate in the blood?

(One of the five basic functions)

A

Sodium (Na+), potassium (K+), calcium (Ca2+), chloride (Cl-), and phosphate (HPO4^2-).

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5
Q

How do kidneys regulate blood volume?

What enzyme is secreted by the kidneys to regulate blood pressure, and what does it activate?

(One of the five basic functions)

A

1) By returning water to the blood or eliminating it in urine.

2) The enzyme renin is secreted and it activates the renin-angiotensin-aldosterone pathway.

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6
Q

The concentration of what ion is regulated by the kidneys in order to control the pH of blood?

(One of the five basic functions)

A

H+ (hydrogen)

*Blood bicarbonate ions (HCO3-) are important buffers of H+ and are conserved by the kidneys.

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7
Q

What two hormones are produced by the kidneys?

(One of the five basic functions)

A

Calcitriol, the active form of vitamin D, which helps regulate calcium homeostasis.

Erythropoietin, which stimulates the production of RBCs.

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8
Q

What are the wastes that are excreted by the kidneys?

(One of the five basic functions)

A

1) Ammonia and urea from the breakdown of amino acids.

2) Bilirubin from the breakdown of hemoglobin.

3) Creatinine from the breakdown of creatine phosphate in muscle fibers.

4) Uric acid from the breakdown of nucleic acid.

5) Other wastes that are foreign to the body like drugs or environmental toxins.

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9
Q

Describe where the kidneys are located.

A

On either side of the vertebral canal, between the peritoneum and the back wall of the abdominal cavity (retroperitoneal space) at the level of T12-L3. The 11th and 12th ribs provide some protection for the superior portions of the kidneys.

The right kidney is slightly lower than the left due to the liver.

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10
Q

Describe the pathway of urine drainage.

A

Collecting duct

Minor calyx

Major calyx

Renal pelvis

Ureter

Urinary bladder

Urethra

The world

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11
Q

This indentation in the kidney is located near the center of the medial border and is the location where the ureter leaves the kidney, and blood vessels, lymphatic vessels, and nerves enter and exit.

A

The renal hilum.

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12
Q

What is a smooth, transparent collection of connective tissue sheath that surrounds each kidney? What is it for?

A

The renal capsule.

It helps maintain shape and serves as a barrier against trauma.

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13
Q

What is the purpose of adipose tissue in regards to the kidneys?

A

It anchors the kidney to the posterior abdominal wall.

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14
Q

What are the two main regions of the kidneys?

A

Renal cortex
-Outer light red region

Renal medulla
-Inner dark red-brown region
-Several cone-shaped renal pyramids are contained within the medulla.
-Renal columns are between each pyramid - these are extensions of the renal cortex.

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15
Q

What are cup-like structures that urine passes through, and how many does each kidney have?

A

8-12 minor calyces

2-3 major calyces

*Urine also passes through a single large cavity called the renal pelvis.

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16
Q

About 20-25% of resting cardiac output flows into the kidneys. How many mLs of blood per minute is that?

A

1,200 mL per minute.

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17
Q

The renal artery in the kidney branches into what four smaller arteries that eventually deliver blood to the afferent arterioles.

A

Segmental

Interlobar

Arcuate

Interlobular

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18
Q

Afferent and Efferent arterioles divide or reunite into what structures?

A

Afferent arterioles divide into a tangled capillary network called a glomerulus.

Capillaries of the glomerulus reunite to form an efferent arteriole.

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19
Q

What do efferent arterioles form upon leaving the glomerulus?

A

Each efferent arteriole divides to form a network of capillaries around the kidney tubules, called peritubular capillaries.

These form peritubular veins, which merge into other veins of the kidneys, and eventually drain into the renal vein.

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20
Q

What are the functional units of the kidneys, and how many does each kidney have?

A

Nephrons

1 million

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21
Q

What does a nephron consist of?

A

A renal corpuscule, where blood plasma is filtered

A renal tubule, where the filtered fluid, called glomerular filtrate, is passed

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22
Q

What are the two parts of a renal corpuscle?

A

Glomerulus and the glomerular capsule (Bowman’s capsule)

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23
Q

What are the three main parts of the renal tubule?

A

1) Proximal convoluted tubule
-Attached to the glomerular capsule
-Lies within the renal cortex

2) Loop of Henle
-Extends into the renal medulla via the descending and ascending limbs

3) Distal convoluted tubule
-Lies within the renal cortex
-Empties into the common collecting duct, eventually leading into the minor and major calyces, renal pelvis and ureter

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24
Q

What is the first step of urine production?

A

Glomerular filtration. Blood pressure forces water and most solutes in blood plasma across the wall of glomerular capillaries, forming glomerular filtrate.

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25
Q

What must filtered fluid undergo before it is considered urine?

A

Tubular reabsorption and tubular secretion.

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26
Q

What cells make up the inner walls of the glomerular capsule, and are adhered closely to the endothelial cells of the glomerulus?

A

Podocytes

Together with the glomerular endothelium, they form a filtration membrane that permits the passage of water and solutes from blood into the capsular space.

Blood cells and plasma proteins remain in blood because they are too large to pass through this membrane.

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27
Q

What is the pressure that causes filtration?

What are the two additional pressures that oppose glomerular filtration, and what happens if these pressures increase?

A

Causes: Blood pressure in the glomerular capillaries.

Opposes: Blood colloid osmotic pressure, and glomerular capsule pressure
-If either of these pressures increases, glomerular filtration decreases

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28
Q

What is the net filtration pressure of the kidneys? What is the average volume of filtrated fluid per day in the kidneys for males and females?

A

10 mmHg

150L for females

180L for males

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29
Q

What is the formula for net filtration pressure?

A

Blood colloidal osmotic pressure + glomerular capsule pressure - glomerular capillary blood pressure

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30
Q

What does constriction of the afferent arteriole cause?

A

It decreases blood flow into the glomerulus, which decreases net filtration pressure.

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31
Q

What does constriction of the efferent arteriole cause?

A

It slows the outflow of blood and increases net filtration pressure.

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32
Q

What is glomerular filtration rate? What are the averages for males and females? What happens with high and low GFRs?

A

The amount of filtrate that forms in the kidneys every minute. Occurs via net filtration pressure.

-105mL/min for females
-125mL/min for males

If GFR is too high, substances pass so quickly that they cannot be reabsorbed and pass out of the body as part of urine.

If GFR is too low, nearly all filtrate is reabsorbed and waste products are not adequately excreted.

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33
Q

What is a hormone that promotes the loss of sodium ions and water in the urine?

A

Atrial Natriuretic Peptide

34
Q

How much filtered water is reabsorbed in the body and how much leaves as waste?

A

99% absorbed, 1% leaves the body in urine.

35
Q

What portion of the kidney provides the largest contribution to tubular reabsorption?

A

Proximal convoluted tubule cells, which reabsorb 65% of filtered water, 100% of glucose and amino acids, and large quantities of other ions.

36
Q

What is described as the transfer of materials from the blood through tubule cells and into tubular fluid? What are examples of these secreted substances?

A

Tubular secretion

Hydrogen ions, potassium, ammonia, urea, creatinine, certain drugs like penicillin.

37
Q

What is the most important hormonal regulators of ion reabsorption and excretion?

A

Angiotensin II and Aldosterone

Angiotensin II enhances reabsorption of Na+ and Cl- in the proximal convoluted tubules, and it also stimulates the adrenal cortex to release aldosterone.

Aldosterone stimulates the tubule cells in the distal convoluted tubules and collecting ducts to reabsorb Na+ and Cl-, and to secrete K+. This is a 2-1 exchange.

38
Q

What is the major hormonal regulator of blood K+ levels?

A

Aldosterone stimulated secretion of K+

-Elevated levels of K+ in plasma can cause serious disturbances in cardiac rhythm or cardiac arrest.

39
Q

What is antidiuretic hormone? How is it released?

A

The major hormone that regulates water reabsorption, which operates via a negative feedback system.

1) When concentration of water in the blood decreases by as little as 1%, osmoreceptors in the hypothalamus stimulate the release of ADH from the posterior pituitary.

2) Another way it is released is a decrease in blood volume, like in hemorrhaging or severe dehydration.

40
Q

The kidneys can produce as little as ___-___mL of very concentrated urine per day when ADH concentration is maximal, like in severe dehydration.

A

400-500mL.

41
Q

What is the normal volume of urine eliminated per day?

A

1-2 liters, 95% of which is water.

42
Q

How is urine prevented from back flowing into the kidneys?

A

The ureters pass under the bladder which causes the bladder to compress the ureters when pressure builds inside the bladder.

Failure of this physiological valve can lead to a kidney infection.

43
Q

What are the 3 layers of the walls of the ureters?

A

1) Inner layer of mucosa
-Contains transitional epithelium with an underlying layer of areolar connective tissue.
-The transitional epithelium can stretch to accommodate fluid volume.

2) Middle layer of smooth muscle
-Urine is transported via peristaltic contractions of this smooth muscle.

3) Outer layer of areolar connective tissue
-Contains blood vessels, lymphatic vessels and nerves

44
Q

Where is the bladder located in males and females?

A

Males: directly in front of the rectum.

Females: in front of the vagina and below the uterus.

45
Q

What is the average capacity of the bladder?

A

700-800mL

46
Q

This sphincter is located around the opening to the urethra and is composed of smooth muscle.

A

Internal urethral sphincter

Involuntary

47
Q

This sphincter is comprised of skeletal muscle and is under voluntary control.

A

External urethral sphincter.

48
Q

What occurs when volume in the bladder exceeds 200-400mL?

A

Pressure in the bladder increases and stretch receptors in its wall transmit nerve impulses to the spinal cord.

This triggers the micturition reflex.

49
Q

Explain what occurs in the micturition reflex.

A

Parasympathetic impulses from the spinal cord cause contraction of the detrusor muscle and relaxation of the internal urethral sphincter muscle.

Simultaneously, the spinal cord inhibits somatic motor neurons causing relaxation of skeletal muscle in the external urethral sphincter.

This causes urination.

50
Q

In lean adults, body fluid makes up what amount of total body mass?

A

55%-60%

51
Q

How much of body fluid is intracellular and extracellular fluid?

A

2/3 is ICF or cytosol, the fluid within cells.

1/3 is ECF, the fluids outside cells including all other body fluids.
*About 80% of the ECF is interstitial fluid, and about 20% of ECF is blood plasma.

52
Q

What are the two barriers that separate intracellular fluid, interstitial fluid, and blood plasma?

A

Plasma membrane

Blood vessel walls

53
Q

Where and why can the exchange of water and solutes occur between blood plasma and interstitial fluid?

A

Capillaries, because the walls are thin and leaky enough to permit the exchange.

54
Q

What is the largest single component of the body, and its percentage?

A

Water, 45%-75%

55
Q

What are the main contributors of the osmotic movement of water?

A

Electrolytes

56
Q

Describe how the body gains water, and its amounts gained.

A

Ingested liquids - 1600mL (main source)
Moist foods - 700mL
Metabolic water from chemical reactions - 200mL

Total: 2500mL per day

57
Q

Describe how the body loses water, and its amounts lost.

A

Kidneys excrete 1500mL in urine
600mL evaporates from the skin surface
Lungs exhale 300mL as water vapor
GI tract eliminates 100mL in feces

*Women lose additional in menstrual flow

Total loss per day: 2500mL

58
Q

Where is the thirst center, and how does it get stimulated to be thirsty?

A

Located in the hypothalamus.

When water loss is greater than water gain, dehydration stimulates thirst.

*Mild dehydration exists when body mass decreases by 2% due to fluid loss.

59
Q

What are the receptors that stimulate the thirst center?

A

Osmoreceptors in the hypothalamus and increased angiotensin II in the blood stimulate the thirst center.

Neurons in the mouth detect dryness due to the decreased flow of saliva.

60
Q

What is the main factor that determines body fluid volume?

A

The extent of urinary salt loss.

Osmosis = water follows salt

61
Q

What are the three hormones that regulate the extent of renal sodium and calcium reabsorption?

A

Atrial natriuretic peptide, angiotensin II, aldosterone.

62
Q

What is natriuresis?

A

Elevated urinary loss of sodium, chloride and water, which decreases blood volume.

63
Q

What is the major hormone that regulates water loss? What stimulates its release?

A

Antidiuretic hormone

The increase in osmotic pressure of body fluids stimulates the release of ADH.

ADH promotes the insertion of water channels into the plasma membranes in the collecting ducts of the kidneys, which allows water to move from the tubular fluid, to the cells, and then the bloodstream.

64
Q

What does an increase and decrease in osmotic pressure in interstitial fluid do to cells?

A

Increase in osmotic pressure of interstitial fluid draws water out of cells causing them to shrink.

Decrease in osmotic pressure of interstitial fluid causes cells to swell.

65
Q

What are the most abundant extracellular ions? What do they do?

A

Sodium ions, which represent 90% of extracellular cations.

Sodium accounts for almost half of the osmotic pressure of extracellular fluid.

Sodium is necessary for the generation and conducting of action potentials in neurons and muscle fibers.

66
Q

What are the most prevalent anions in extracellular fluid? What is the reason that it moves so easily between extracellular and intracellular compartments?

A

Chloride ions.

Because most plasma membranes contain many chloride leakage channels, chloride moves easily between the extracellular and intracellular compartments.

67
Q

What are the most abundant cations in intracellular fluid? What are they important for?

A

Potassium ions.

They play a key role in establishing a resting membrane potential and in the depolarization phase of action potentials in muscle fibers and neurons.

68
Q

What are the two main regulators of calcium?

A

Parathyroid hormone and calcitriol (vitamin D).

69
Q

What are the four functions of electrolytes?

A

Control the osmosis of water between fluid compartments.

Help maintain the acid-base balance required for normal cellular activities.

Carry electrical current which allows for action potentials.

Serve as cofactors needed for optimal activity of enzymes.

70
Q

What are the three major mechanisms that maintain the body’s pH?

A

1) Buffer systems

2) Exhalation of carbon dioxide

3) Excretion of hydrogen into the urine

71
Q

What do buffer systems do in regards to the acid-base balance? What are the primary buffer systems?

A

Buffers prevent rapid, drastic changes in pH by converting strong acids and bases into weak ones.

Protein buffer system (main and most abundant buffer)
Carbonic acid-bicarbonate buffer system
Phosphate buffer system

72
Q

What effect does an increase of carbon dioxide concentration in body fluids have?

A

An increase in carbon dioxide concentration increases hydrogen concentration and thus lowers pH (makes fluids more acidic).

*A decrease would raise pH (alkaline).

73
Q

What occurs to pH with increased ventilation?

A

More CO2 is exhales, hydrogen concentration falls, and blood pH rises (alkalinic).

74
Q

What happens to pH with decreased ventilation?

A

Less CO2 is exhaled, and blood pH falls (acidic).

75
Q

What receptors stimulate the inspiratory area of the medulla oblongata when blood acidity increases and blood pH decreases? What does it cause?

A

Chemoreceptors in the medulla oblongata, aortic body and carotid bodies.

This causes the diaphragm and respiratory muscles to contract more forcefully and frequently so more CO2 is exhaled, which raises blood pH back to normal homeostasis.

76
Q

What is the slowest mechanism for the removal of acids and excretion of hydrogen?

A

Kidney excretion of hydrogen

77
Q

What is acidosis, what does it cause, and what occurs at dangerous levels?

A

Acidosis: blood pH below 7.35

Acidosis causes depression of the CNS through depression of synaptic transmission

If pH falls below 7, CNS depression is so severe that patients become disoriented, comatose, and can die.

78
Q

What is alkalosis, and what are its effects?

A

Blood pH higher than 7.45

It causes over excitability of the CNS and peripheral nerves, causing neurons to repeatedly conduct impulses. Causes nervousness, muscle spasms, convulsions and death.

79
Q

What is respiratory compensation, and how long does it take to occur?

A

Hyperventilation or hypoventilation in order to return blood pH back toward the normal range.

It occurs within minutes and reaches its maximum within hours.

80
Q

If a person has altered blood pH due to respiratory causes, what form of compensation kicks in? How long does it take to occur?

A

Renal compensation - changes in the secretion of hydrogen and reabsorption of bicarbonate by the kidney tubules.

It begins in minutes and takes days to reach its maximum.

male genitourinary (4 decks)

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