Deck 12: Body Defenses

Question 1

The osmolarity of the medullary interstitial fluid always equilibrates with the descending limb of the loop of Henle.

Answer 1

True

Question 2

NaCl is actively transported from the descending limb of the loop of Henle to establish the medullary osmotic gradient.

Answer 2

False

Question 3

A pure loss or gain of H₂O that is not accompanied by comparable solute deficit or excess in the body leads to changes in ECF osmolarity.

Answer 3

True

Question 4

If a kidney stone blocked the renal pelvis and consequently caused a buildup of fluid pressure in the tubules and Bowman's capsule, the net filtration pressure across the glomerular capillary membrane would increase.

Question 5

Vasopressin is secreted from the anterior pituitary gland.

Question 6

The secretion of vasopressin increases if the extracellular fluid becomes hypertonic.

Question 7

Aldosterone promotes water reabsorption by controlling the reabsorption of salt.

Question 8

The average rate of urine formation is 1 mL/min.

Question 9

The secretion of aldosterone stimulates the tubular reabsorption of sodium and the tubular secretion of potassium.

Question 10

Only juxtamedullary nephrons contain a juxtaglomerular apparatus.

Question 11

The renal threshold represents the maximum amount of a particular substance that the tubular cells are capable of actively reabsorbing per unit of time.

Question 12

The T_m represents the maximum amount of a particular substance that can be excreted in the urine per unit of time.

Question 13

The osmolarity of the medullary interstitial fluid always equilibrates with the descending limb of the loop of Henle.

Question 14

Autoregulation of the GFR is accomplished by activation of the sympathetic nervous system.

Question 15

The vast majority of the filtered fluid is reabsorbed.

Question 16

Transepithelial transport occurs only for substances that are actively reabsorbed.

Question 17

Acute renal failure may be reversible, whereas chronic renal failure is not reversible.

Question 18

Contraction of mesangial cells closes off a portion of the filtering capillaries, which leads to a decrease in GFR if the filtration pressure remains unchanged.

Question 19

The glomerular filtrate is almost identical in composition to the plasma.

Question 20

If a substance is filtered and secreted but not reabsorbed, its plasma clearance rate is always less than the GFR.

Question 21

The afferent arteriole is the blood vessel that carries blood to the glomerular capillaries.

Question 22

Urea is passively reabsorbed down the osmotic gradient created by active Na⁺ reabsorption.

Question 23

Changes in the osmolarity of the extracellular fluid are detected by osmoreceptors in the hypothalamus.

Question 24

The receptor sites for vasopressin binding are located on the basolateral border, yet the end result is an increase in H₂O permeability of the luminal border of the tubular cells.

Question 25

In the tubular segments permeable to H₂O, solute reabsorption is always accompanied by comparable H₂O reabsorption.

Question 26

The glomerular capillary blood pressure is higher than capillary pressure elsewhere in the body primarily because the afferent arteriole has a larger diameter than the efferent arteriole.

Question 27

The Bowman's capsule hydrostatic pressure opposes filtration.

Question 28

Autoregulation is important to prevent unintentional shifts in the GFR that could lead to dangerous imbalances of fluid, electrolytes, and wastes.

Question 29

Glomerular filtration occurs by active transport of Na⁺, which then creates an osmotic gradient for the filtration of water.

Question 30

The smooth muscle of the bladder is innervated by parasympathetic fibres.

Question 31

By tubular secretion, substances leave the blood and enter the tubular portion of the nephron.

Question 32

For a substance to be actively reabsorbed, all of the steps of transepithelial transport require energy expenditure.

Question 33

The presence of vasopressin acts to prevent the reabsorption of water from the distal and collecting tubules.

Question 34

Because of autoregulation, changes in mean arterial blood pressure between the range of 80 to 180 mmHg do not directly produce changes in the GFR.

Question 35

The kidneys receive a disproportionately large share of the cardiac output for the purpose of adjusting and purifying the plasma.

Question 36

Vasopressin increases H₂O reabsorption in the proximal tubule.

Question 37

Blood pressure in the glomerular capillaries is the same as in capillaries elsewhere in the body.

Question 38

In active reabsorption, all of the steps involved in transepithelial transport are active.

Question 39

The glomerular capillary wall contains filtration slits formed by the clefts between the foot processes of adjacent podocytes.

Question 40

The group of cells located where the distal tubule comes into contact with the afferent and efferent arterioles of the same nephron is known as the juxtaglomerular apparatus.

Question 41

The driving force for H₂O reabsorption across all permeable segments of the kidney tubule is an osmotic gradient.

Question 42

The kidneys are the organs that are primarily responsible for maintaining constancy of the volume and electrolyte composition of the internal fluid environment.

Question 43

Glomerular filtration occurs primarily by active transport.

Question 44

In the kidney, blood is filtered in the cortex, drains through the renal pelvis into the renal medulla, and from there travels in the ureter to the urinary bladder.

Question 45

Tubular secretion involves the movement of substances from the peritubular capillary blood into the tubular fluid.

Question 46

Water reabsorption cannot occur from any portion of the nephron in the absence of vasopressin.

Question 47

The renal threshold for glucose is well above the normal plasma glucose concentration, but the renal threshold for PO₄ is equal to the normal plasma PO₄ concentration.

Question 48

The glomerular filtrate contains only substances that are not needed by the body.

Question 49

ADH release is the main stimulus for the secretion of aldosterone.

Question 50

Angiotensinogen is produced by the kidney.

Question 51

The liver converts many foreign organic compounds into an anionic form that can be secreted by the organic anion secretory system.

Question 52

Plasma proteins are normally filtered in the nephron.

Question 53

ACE inhibitor drugs promote diuresis by blocking the conversion of angiotensin I into angiotensin II.

Question 54

When urine is eliminated from the body, the sphincter muscles in the urethra relax.

Question 55

During acidosis, H⁺ secretion increases.

Question 56

One can deliberately prevent urination in spite of the micturition reflex by voluntarily inhibiting the parasympathetic supply to the bladder to halt bladder contraction.

Question 57

If a substance is filtered and secreted but not reabsorbed, its plasma clearance rate is always less than the GFR.

Question 58

Tubular reabsorption and tubular secretion are highly selective processes, whereas glomerular filtration is not.

Question 59

The pores in the glomerular membrane are too small for albumin to pass through.

Question 60

The three major processes involved in urine formation are filtration, reabsorption, and excretion.

Question 61

A plasma clearance of 135 mL/min for a substance when the GFR is 125 mL/min indicates that net secretion of the substance occurs.

Question 62

The Na⁺ cotransport system in the proximal tubule facilitates elimination of foreign organic compounds from the body.

Question 63

The amount of glucose filtered is directly proportional to the plasma glucose concentration at all plasma glucose concentrations.

Question 64

The kidneys keep the urine volume and composition essentially constant.

Question 65

A rise in ECF K⁺ concentration leads to increased excitability of heart muscle, possibly producing fatal cardiac arrhythmias.

Question 66

In general, the substances in the filtrate that need to be conserved are selectively reabsorbed whereas the unwanted substances that need to be eliminated fail to be reabsorbed.

Question 67

Because of countercurrent multiplication, the loop of Henle is able to establish a vertical osmotic gradient in the renal medulla ranging from 300 to 1,200 mosm/litre, despite the fact that the active salt pump of the ascending limb is able to produce only a 200 mosm/litre osmotic gradient at each horizontal level.

Question 68

Twenty-five percent of the cardiac output goes to the kidneys because of their tremendous nutrient requirement for the active transport of Na⁺.

Question 69

The clearance rate for inulin is greater than the GFR.

Question 70

During the micturition reflex, the motor neuron supplying the external urethral sphincter is stimulated.

Question 71

Urine moves from the kidneys to the urinary bladder through the ureters passively by the force of gravity.

Question 72

The tubular cells display a T_m for urea.

Question 73

ACE inhibitor drugs promote diuresis by blocking the conversion of angiotensin I into angiotensin II.

Question 74

All of the plasma that enters the glomerulus is normally filtered into Bowman's capsule except for the plasma proteins.

Question 75

A plasma clearance of 135 mL/min for a substance when the GFR is 125 mL/min indicates that net secretion of the substance occurs.

Question 76

Sympathetic vasoconstriction of the afferent arterioles and a resultant fall in the GFR occur as part of the baroreceptor reflex response when the blood pressure is too low.

Question 77

The micturition reflex controls bladder emptying in adults.

Question 78

a substance is reabsorbed, it moves from the tubular fluid into the peritubular capillaries.

Question 79

The amount of glucose reabsorbed is directly proportional to the plasma glucose concentration at all plasma glucose concentrations.

Question 80

When tubular fluid enters the distal tubule, it is hypotonic.