Book Questions Ch. 25 & 26

Question 1

The lowest concentration of nitrogenous waste occurs in the

Answer 1

renal vein

Question 2

The glomerular capillaries differ from other capillary networks in the body because they

Answer 2

are derived from and drain into arterioles

Question 3

Damage to the renal medulla would interfere first with the functioning of the

Answer 3

collecting ducts

Question 4

Which is reabsorbed by the proximal convoluted tubule cells?

Answer 4

Na+, K+, and amino acids

Question 5

Glucose is not normally found in the urine because

Answer 5

glucose is reabsorbed by the tubule cells

Question 6

Filtration at the glomerulus is inversely related to

Answer 6

capsular hydrostatic pressure

Question 7

Tubular reabsorption

Answer 7

of glucose and many other substances is a Tm-limited active transport process

Question 8

If freshly voided urine sample contains excessive amounts of urochrome, it has

Answer 8

a dark yellow color

Question 9

Conditions such as diabetes mellitus and starvation are closely linked to

Answer 9

ketonuria

Question 10

Which of the following is/are true about ADH?

Answer 10

it is secreted in response to an increase in extracellular fluid osmolality

Question 11

Body water content is greatest in

Answer 11

infants

Question 12

Potassium, magnesium, and phosphate ion are the predominant electrolytes in

Answer 12

intracellular fluid

Question 13

Sodium balance is regulated primarily by control of amount(s)

Answer 13

excreted in urine

Question 14

Water balance is regulated by control of amount(s)

Answer 14

ingested and excreted in the urine

Question 15

Two main substances regulated by the influence of aldosterone on the kidney tubules

Answer 15

potassium and sodium

Question 16

Two substances regulated by the parathyroid hormone

Answer 16

calcium and phosphate

Question 17

Two substances secreted into the proximal convoluted tubules in exchange for sodium ions

Answer 17

ammonium ions and hydrogen ions

Question 18

Part of an important chemical buffer system in plasma

Answer 18

bicarbonate

Question 19

Two ions produced during catabolism of glutamine

Answer 19

ammonium ions and bicarbonate

Question 20

Substance regulated by ADH’s effect on renal tubules

Answer 20

water

Question 21

Which of the following factors will enhance ADH release?

Answer 21

decrease in ECF volume and increase in ECF osmolality

Question 22

The pH of blood varies directly with

Answer 22

HCO-3

Question 23

In an individual with metabolic acidosis, a clue that the respiratory system is compensating is provided by

Answer 23

rapid, deep breathing

Question 24

What is the importance of perineal fat capsule that surrounds the kidney?

Answer 24

it cushions the kidney against blows and helps the kidney hold it in place

Question 25

Trace the pathway a creatinine molecule takes from a glomerulus to the urethra. Name every microscopic or gross structure it passes through on its journey

Answer 25

A creatine molecule travels the following route from a glomerulus to the urethra. It first passes through the glomerular filtration membrane, which is a porous membrane made up of a fenestrated capillary endothelium, a thin basement membrane, and the visceral membrane of the glomerular capsule formed by the podocytes. The creatine molecule then passes through the proximal convoluted tubule, the loop of Henle, and the distal convoluted tubule, and into the collecting duct in which it travels into the medulla through the renal pyramids. From the medulla the molecule enters the renal pelvis, and leaves the kidney via the ureter. Then it travels to the urinary bladder and then to the urethra.

Question 26

Explain the important differences between blood plasma and glomerular filtrate, and relate the differences to the structure of the filtration membrane

Answer 26

Renal filtrate is a solute-rich fluid without blood cells or plasma proteins because the filtration membrane is permeable to water and all solutes smaller than plasma proteins. The capillary endothelium restricts passage of formed elements, whereas the anion-rich basement membrane holds back most protein and some smaller anionic molecules.

Question 27

Describe the mechanisms that contribute to renal autoregulation

Answer 27

The mechanisms that contribute to renal autoregulation are the myogenic mechanism and the tubuloglomerular feedback mechanism. The myogenic mechanism reflects the tendency of vascular smooth muscle to contract when it is stretched. An increase in systemic blood pressure causes afferent arterioles to constrict, which impedes blood flow into the glomerulus and prevents glomerular blood pressure from rising to damaging levels. Conversely, a decline in systemic blood pressure causes dilation of afferent arterioles and an increase in glomerular hydrostatic pressure. Both responses help maintain a normal GFR.
The tubuloglomerular mechanism reflects the activity of the macula densa cells in response to a slow filtration rate or low filtrate osmolarity. When so activated they release chemicals that cause vasodilation in the afferent arterioles.
Renal autoregulation maintains a relatively constant kidney perfusion over an arterial pressure range from about 80 to 180 mm Hg, preventing large changes in water and solute excretion.

Question 28

Describe the mechanism of extrinsic regulation of GFR, and their physiological role

Answer 28

Sympathetic nervous system controls protect the body during extreme stress by redirecting blood to more vital organs. Strong sympathetic stimulation causes release of norepinephrine to alpha-adrenergic receptors, causing strong vasoconstriction of kidney arterioles. This results in a drop in glomerular filtration, and indirectly stimulates another extrinsic mechanism, the renin-angiotensin mechanism. The renin-angiotensin mechanism involves the release of renin from the granular juxtaglomerular cells, which enzymatically converts the plasma globulin angiotensinogen to angiotensin I. Angiotensin I is further converted to angiotensin II by angiotensin converting enzyme (ACE) produced by capillary endothelium. Angiotensin II causes vasoconstriction of systemic arterioles, increased sodium reabsorption by promoting the release of aldosterone, decreases peritubular hydrostatic pressure, which encourages increased fluid and solute reabsorption, and acts on the glomerular mesangial cells, causing a decrease in glomerular filtration rate. In addition, angiotensin II results in stimulation of the hypothalamus, which activates the thirst mechanism and promotes the release of antidiuretic hormone, which causes increased water reabsorption in the distal nephron. Other factors that may trigger the renin-angiotensin mechanism are a drop in mean systemic blood pressure below 80 mm Hg, and activated macula densa cells responding to low plasma sodium.

Question 29

Describe what is involved in active and passive tubular reabsorption

Answer 29

Active tubular reabsorption requires ATP

Passive tubular encompasses diffusion, facilitated diffusion, and osmosis

Question 30

Explain how the peritubular capillaries are adapted for receiving reabsorbed substances

Answer 30

Peritubular capillaries are low pressure, porous capillaries that readily absorb solutes and water from the tubule cells as these substances are reclaimed from the filtrate.

Question 31

Explain the purpose of tubular secretion

Answer 31

The purpose of tubular secretion is to eliminate drugs, certain wastes, and excess ions and in maintaining acid-base balance of the blood.

Question 32

How does aldosterone modify the chemical composition of urine

Answer 32

Aldosterone targets the principal cells of the collecting ducts and cells of the distal portion of the DCT.
As a result, little or no Na+ leaves the body in urine.

Question 33

Explain why the filtrate become hypotonic (lower osmotic pressure) as it flows through the ascending limb of the nephron loop.

Answer 33

As it flows through the ascending limb of the loop
of Henle, the filtrate becomes hypotonic because it is impermeable to water, and because sodium and chloride are being actively pumped into the interstitial fluid, thereby decreasing solute concentration in the tubule. The interstitial fluid at the tip of the loop of Henle and the deep portions of the medulla are hypertonic because:
(1) the loop of Henle serves as a countercurrent multiplier to establish the osmotic gradient, a process that works due to the characteristics of tubule permeability to water in different areas of the tubule and ion transport to the interstitial areas

(2) the vasa recta acts as a countercurrent exchanger to maintain the osmotic gradient by serving as a passive exchange mechanism that removes water from the medullary areas but leaves salts behind. The filtrate at the tip of the loop of Henle is hypertonic due to the passive diffusion of water from the descending limb to the interstitial areas.

Question 34

How does the urinary bladder anatomy supports its storage function?

Answer 34

When empty, the bladder collapses into its basic pyramidal shape & its wall are thick and thrown into folds(rugae).
As urine accumulates, the bladder expands, becomes pear shaped, and rises superiorly in the abdominal cavity.
The muscular wall stretches and thins, the rugae disappear.
These changes allow the bladder to store more urine w/o a significant rise in internal pressure.

Question 35

Define micturition and describe the micturition reflex

Answer 35

Micturition (a.k.a urination) is emptying of the bladder.

Micturition reflex is stretching of the bladder wall.

Question 36

Describe the changes that occur in kidney and bladder anatomy and physiology in old age.

Answer 36

Three sets of kidneys develop from intermediate mesoderm.
With age, nephrons are lost, the filtration rate decreases, and tubule cells become less efficient at concentrating urine.
Bladder capacity and tone decrease with age