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BIO 102 > Excretion (kidney and Liver Functions) > Flashcards

Excretion (kidney and Liver Functions) Flashcards

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1
Q
A
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2
Q

Which of the following is the structural and functional unit of the kidney?

A

A. Nephron

The nephron is responsible for filtering blood and forming urine. Each human kidney contains roughly 1–1.3 million nephrons.

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3
Q

What is the correct sequence for the path of urine in the human excretory system?

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B. Kidney → Ureter → Urinary bladder → Urethra

Urine is produced in the kidneys, flows through ureters to the urinary bladder for storage, and is expelled via the urethra.

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4
Q

Which of the following organs has no role in the elimination of excretory waste?

A

D. Esophagus

The esophagus is part of the digestive tract and not involved in waste excretion.

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5
Q

Which part of the nephron extends into the renal medulla and plays a key role in concentrating urine?

A

C. Loop of Henle

The loop of Henle creates a high osmotic gradient in the medulla, crucial for producing concentrated urine.

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6
Q

Which segment of the nephron has an extensive brush border (microvilli) to enhance reabsorption?

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B. Proximal convoluted tubule (PCT)

The PCT is the major site of reabsorption, with dense microvilli increasing surface area for nutrient absorption.

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7
Q

Which of the following is NOT part of a nephron?

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D. Ureter

A nephron consists of the renal corpuscle and renal tubule. The ureter transports urine from the kidney to the bladder.

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8
Q

Which substance is normally absent from the filtrate in Bowman’s capsule of a healthy kidney?

A

D. Large plasma proteins

The glomerular filtration membrane prevents large proteins from entering the filtrate.

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9
Q

The primary force that drives glomerular filtration in the kidneys is:

A

B. Blood pressure (hydrostatic pressure) in glomerular capillaries

Filtration is driven by blood pressure, which forces fluid and small solutes through the filtration membrane.

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10
Q

Approximately how much filtrate do the kidneys produce each day in a healthy adult, and how much urine is typically excreted?

A

C. 180 liters filtrate per day; ~1–2 liters urine

The kidneys filter about 180 L of fluid from the blood daily, with ~99% reabsorbed, resulting in about 1–2 L of urine output.

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11
Q

Which part of the nephron reabsorbs the majority of the water and solutes from the filtrate?

A

A. Proximal convoluted tubule

The PCT reabsorbs roughly 65% of filtered water and sodium, and nearly 100% of filtered glucose and amino acids.

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12
Q

Which segment of the nephron is impermeable to water under all conditions, even as it pumps out salts?

A

C. Ascending limb of loop of Henle

The thick ascending limb actively transports Na⁺, K⁺, and Cl⁻ out of the filtrate but is virtually impermeable to water.

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13
Q

In the renal corpuscle, specialized cells called podocytes are found:

A

B. In the inner (visceral) layer of Bowman’s capsule, wrapping around capillaries

Podocytes help filter blood by size and prevent large molecules from entering the filtrate.

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14
Q

The juxtaglomerular apparatus (JGA) is formed by the close contact of which structures in the nephron?

A

A. The afferent arteriole and the distal convoluted tubule

The JGA helps regulate kidney function and blood pressure.

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15
Q

Constriction of the afferent arteriole of a nephron will tend to:

A

B. Decrease GFR

Constriction of the afferent arteriole reduces blood flow into the glomerulus, decreasing glomerular filtration rate.

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16
Q

The presence of significant protein (albumin) in the urine, a condition called proteinuria, usually indicates:

A

C. Damage to the glomerular filtration membrane (kidney disease)

Proteinuria is often a sign of glomerular damage, allowing proteins to pass into urine.

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17
Q

Glucose is not normally found in urine because:

A

C. It is filtered but completely reabsorbed in the nephron (under normal conditions)

Glucose is almost entirely reabsorbed in the proximal convoluted tubule.

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18
Q

Approximately what proportion of the filtrate volume is reabsorbed by the nephron under typical conditions?

A

D. ~99%

About 99% of the water and many solutes filtered by the kidneys are reabsorbed.

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19
Q

About what percentage of resting cardiac output do the kidneys receive?

A

C. 20–25%

Roughly one-fifth of the resting cardiac output flows through the renal arteries to the kidneys.

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20
Q

How do the kidneys help maintain the pH balance of the blood?

A

C. By secreting hydrogen ions (H⁺) into the filtrate and reabsorbing bicarbonate

This process helps maintain blood pH around 7.4.

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21
Q

Which of the following is NOT a function of the kidneys?

A

D. Digestion of fats and proteins

The kidneys do not participate in digestion; they excrete metabolic wastes and regulate blood volume/pressure.

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22
Q

Which sequence correctly describes the basic steps of urine formation?

A

A. Glomerular filtration → Tubular reabsorption → Tubular secretion

Urine formation involves filtration, reabsorption, and secretion.

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23
Q

Tubular secretion in urine formation refers to:

A

B. Moving substances from the blood capillaries into the nephron tubule

Tubular secretion adds substances like H⁺ and K⁺ into the filtrate for excretion.

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24
Q

Under normal conditions, which of the following is completely reabsorbed from the filtrate so that it does not appear in urine?

A

C. Glucose

Glucose is entirely reabsorbed in the proximal convoluted tubule in healthy individuals.

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25
What is the primary substance that is completely reabsorbed from the filtrate under normal conditions?
Glucose ## Footnote Glucose is entirely reabsorbed in the proximal convoluted tubule, and none appears in urine under healthy conditions.
26
Glucosuria occurs when:
The transport carriers for glucose in the nephron are saturated ## Footnote This typically happens in uncontrolled diabetes mellitus when blood glucose levels exceed the renal threshold.
27
Which part of the nephron is primarily responsible for establishing the medullary osmotic gradient?
Loop of Henle (especially the long loops of juxtamedullary nephrons) ## Footnote The loop of Henle uses a countercurrent multiplier mechanism to create a concentration gradient in the medulla.
28
What is the main purpose of the countercurrent multiplier system in the nephron?
To create a hyperosmotic medullary interstitial gradient that allows production of concentrated urine ## Footnote This system enables the kidneys to conserve water and produce urine that is more concentrated than blood.
29
The vasa recta function to:
Maintain the osmotic gradient in the medulla by exchanging water and solutes ## Footnote This countercurrent exchange ensures the medulla remains concentrated while providing blood supply.
30
Osmoregulation refers to an organism’s ability to:
Control water balance and solute (salt) concentration in its body fluids ## Footnote In humans, the kidneys are the main osmoregulatory organs, adjusting urine volume and concentration.
31
The micturition reflex is initiated by:
Stretch receptors in the wall of the urinary bladder when it fills ## Footnote This reflex triggers contraction of the bladder’s detrusor muscle and relaxation of the internal urethral sphincter.
32
Which statement best describes the permeability characteristics of the descending limb of the loop of Henle?
It is highly permeable to water but not to solutes (NaCl) ## Footnote This allows water to diffuse out, concentrating the filtrate, while Na⁺/Cl⁻ are not significantly reabsorbed.
33
Which segment of the nephron reabsorbs the greatest fraction of filtered water?
Proximal convoluted tubule ## Footnote The proximal tubule reabsorbs about two-thirds of the filtered water along with solutes.
34
Urine is typically about 95% ______ by volume.
Water ## Footnote Normal urine composition includes approximately 95% water and 5% solutes.
35
Which of the following is a normal constituent of urine in a healthy person?
Urea ## Footnote Urea is the primary nitrogenous waste in urine, while glucose and large proteins are normally absent.
36
Urine is propelled from the kidneys to the urinary bladder by what mechanism?
Peristaltic contractions of the ureters ## Footnote This mechanism ensures urine flow toward the bladder regardless of body position.
37
After consuming a large volume of water, you would expect:
Production of a high volume of very dilute urine ## Footnote Excess water intake dilutes blood, leading to reduced ADH secretion and increased urine volume.
38
What is the primary effect of antidiuretic hormone (ADH) on the kidneys?
It increases water reabsorption in the collecting ducts, reducing urine volume ## Footnote ADH makes the distal tubules and collecting ducts more permeable to water.
39
On which part of the nephron does ADH primarily act?
Distal tubule and collecting duct ## Footnote ADH targets principal cells in these areas to enhance water reabsorption.
40
Increased secretion of ADH is stimulated by:
High blood osmolarity or dehydration ## Footnote Osmoreceptors sense increased plasma osmolarity, leading to ADH release.
41
Diabetes insipidus is caused by a deficiency of or insensitivity to:
Antidiuretic hormone (ADH) ## Footnote This results in excessive urination and thirst due to the inability to reabsorb water.
42
What effect does aldosterone have on kidney function?
It increases Na⁺ reabsorption (and K⁺ secretion) in the distal nephron, leading to water retention ## Footnote Aldosterone is often referred to as the 'salt-retaining hormone.'
43
Where in the nephron does aldosterone exert its action?
Distal convoluted tubule and collecting duct ## Footnote Aldosterone acts on principal cells to promote Na⁺ reabsorption and K⁺ secretion.
44
One of the actions of angiotensin II is to:
Stimulate the adrenal cortex to release aldosterone ## Footnote Angiotensin II plays a role in increasing blood pressure and volume through multiple mechanisms.
45
What system does Ang II stimulate to increase blood pressure?
Renin–angiotensin–aldosterone system (RAAS) ## Footnote RAAS is crucial for regulating blood pressure and fluid balance.
46
What is the effect of Ang II on aldosterone secretion?
Stimulates secretion ## Footnote Aldosterone promotes Na⁺ reabsorption, increasing blood volume.
47
What does Ang II cause in the kidneys to maintain GFR during low blood pressure?
Constricts efferent arterioles ## Footnote This helps to maintain glomerular filtration rate.
48
What triggers the juxtaglomerular cells of the kidney to release renin?
Low blood pressure (or low GFR) and low NaCl in the distal tubule ## Footnote This indicates a need to raise blood pressure.
49
Renin catalyzes the conversion of which substance?
Angiotensinogen (from liver) → Angiotensin I ## Footnote Renin cleaves angiotensinogen to form angiotensin I.
50
What are the effects of Angiotensin II?
Vasoconstriction and increased blood pressure ## Footnote It also stimulates aldosterone and ADH release.
51
What does atrial natriuretic peptide (ANP) do in response to high blood volume?
Increases excretion of sodium (and water) and reduces blood volume ## Footnote ANP opposes the effects of RAAS.
52
Which hormone is often referred to as the 'salt-retaining hormone'?
Aldosterone ## Footnote Aldosterone promotes sodium reabsorption, leading to water retention.
53
What is the effect of alcohol on urine output?
Inhibits ADH release, reducing water reabsorption ## Footnote This leads to increased urine production.
54
What reaction does angiotensin-converting enzyme (ACE) catalyze?
Conversion of angiotensin I to angiotensin II ## Footnote ACE is crucial for blood pressure regulation.
55
In which organ does the urea cycle occur?
Liver ## Footnote The urea cycle converts toxic ammonia into urea.
56
What is bilirubin?
A waste pigment formed from hemoglobin breakdown, excreted in bile ## Footnote Bilirubin buildup can cause jaundice.
57
Jaundice is caused by accumulation of ____ in blood and tissues.
Bilirubin ## Footnote It indicates liver dysfunction or bile duct blockage.
58
What does the liver do with excess amino acids?
Deaminates them, producing ammonia which is then converted to urea ## Footnote This process helps in nitrogen waste management.
59
What happens if the liver fails to convert ammonia to urea?
High blood ammonia levels (hyperammonemia), which can lead to neurological impairment ## Footnote Ammonia is toxic and can cause severe health issues.
60
How does the liver help eliminate excess cholesterol?
By converting cholesterol into bile acids and secreting them in bile ## Footnote This is the primary route for cholesterol excretion.
61
Which statement about bile is true?
Bile is produced by the liver, stored in the gallbladder, and contains wastes like bilirubin ## Footnote Bile aids in fat emulsification and waste excretion.
62
Bilirubin is derived from the breakdown of:
Hemoglobin from old red blood cells ## Footnote Bilirubin is a waste product of erythrocyte turnover.
63
Which organ is the primary site for detoxification of alcohol and many drugs?
Liver ## Footnote The liver modifies substances to prepare them for excretion.
64
What does an elevated blood urea nitrogen (BUN) indicate?
Impaired renal (kidney) function, causing urea to accumulate in blood ## Footnote High BUN often signifies kidney dysfunction.
65
Animals that excrete nitrogenous waste primarily as ammonia are termed:
Ammonotelic ## Footnote This is typical for aquatic animals.
66
Animals that excrete nitrogenous waste primarily as ammonia are termed:
Ammonotelic ## Footnote Ammonotelic animals excrete most of their nitrogenous waste as ammonia (NH₃), which is highly toxic but very water-soluble
67
Humans primarily excrete nitrogen in the form of:
Urea ## Footnote Humans (and most mammals) are classified as ureotelic, converting ammonia to urea for excretion
68
Birds, reptiles, and most terrestrial insects excrete nitrogen primarily as:
Uric acid ## Footnote Uric acid is very insoluble and non-toxic, precipitating as a paste or solid
69
Tadpoles are to ammonotelic as adult frogs are to:
Ureotelic ## Footnote Tadpoles excrete nitrogen as ammonia, while adult frogs excrete primarily urea
70
Which nitrogenous waste is most toxic and requires the greatest amount of water for excretion?
Ammonia ## Footnote Ammonia is highly toxic to tissues and must be diluted and quickly removed
71
Which nitrogenous waste form requires the least amount of water for excretion?
Uric acid ## Footnote Uric acid is excreted as a semi-solid paste, conserving water
72
Producing uric acid as a waste has the disadvantage of:
Costing more energy (ATP) to synthesize ## Footnote Uric acid production is metabolically expensive, involving a complex pathway
73
What is the primary nitrogenous waste product in human urine?
Urea ## Footnote Urea is the dominant nitrogenous solute, produced in the liver from ammonia
74
Why is uric acid suitable for egg-laying land animals?
It is non-toxic and can be stored as a solid inside the eggshell, with minimal water ## Footnote Uric acid's low toxicity allows safe accumulation in embryos
75
The white, paste-like substance in bird droppings is mostly:
Uric acid ## Footnote Bird droppings contain a mix of feces and uric acid-rich urine
76
Which pair (animal – primary nitrogenous waste) is incorrect?
Insects – ammonia ## Footnote Insects primarily excrete nitrogen as uric acid, not ammonia
77
Unlike most fish, sharks excrete nitrogen primarily as:
Urea ## Footnote Sharks synthesize and retain urea in their blood, which helps maintain osmotic balance
78
In humans, uric acid is a waste product formed from the metabolism of:
Nucleic acids (purines) ## Footnote Uric acid primarily comes from the breakdown of purines found in nucleic acids
79
Gout is caused by accumulation of _____ crystals in the joints.
Uric acid ## Footnote Gout involves needle-like urate crystals depositing in joints, causing inflammation
80
Compared to freshwater fish, marine bony fish tend to excrete:
A much smaller volume of more concentrated (saltier) urine ## Footnote Marine fish produce little urine to conserve water, and that urine is relatively concentrated
81
Marine birds can rid themselves of excess salt by:
Specialized salt glands (nasal glands) that secrete concentrated salt solutions ## Footnote Salt glands allow birds to eliminate salt from seawater they drink
82
Flame cells are excretory structures found in:
Flatworms (e.g. Planaria) ## Footnote Flame cells are the excretory units of flatworms, filtering waste from body fluid
83
Nephridia are the excretory organs of which organism?
Earthworms (annelids) ## Footnote Nephridia collect coelomic fluid, filter wastes, and reabsorb useful substances
84
Malpighian tubules are the excretory structures characteristic of:
Insects and other terrestrial arthropods ## Footnote Malpighian tubules extract waste products from hemolymph and conserve water
85
Crustaceans like crabs have specialized excretory organs called:
Green glands (antennal glands) ## Footnote Green glands filter hemolymph and excrete dilute urine
86
Which animal relies on diffusion for waste removal?
Hydra (cnidarian) ## Footnote Simple animals like Hydra do not have dedicated excretory organs and rely on diffusion
87
Single-celled freshwater organisms like Amoeba use ___ to expel excess water and wastes.
Contractile vacuoles ## Footnote Unicellular freshwater protists use contractile vacuoles for expelling excess water
88
What structure do single-celled freshwater organisms like Amoeba and Paramecium use to expel excess water and wastes?
Contractile vacuoles ## Footnote Contractile vacuoles collect excess water and periodically contract to pump it out of the cell, preventing it from bursting.
89
Which mammal is known for having extremely long loops of Henle, allowing it to produce highly concentrated urine?
Kangaroo rat (desert rodent) ## Footnote This adaptation allows kangaroo rats to reabsorb maximal water and survive with minimal water intake.
90
Reptiles primarily excrete nitrogenous waste as:
Uric acid ## Footnote This comes out as a semisolid paste, crucial for water conservation in arid environments.
91
Besides urea, what other nitrogenous waste is present in human urine?
Creatinine ## Footnote Creatinine comes from creatine phosphate breakdown in muscles and is present alongside urea.
92
Malpighian tubules in insects excrete wastes into which part of the body?
The digestive tract (hindgut) ## Footnote Wastes mix with feces in the hindgut, and insects do not have a separate liquid urine.
93
In freshwater fish, most ammonia waste is eliminated through the:
Gills ## Footnote Ammonia diffuses directly across gill membranes due to its high solubility.
94
Why do most birds lack a urinary bladder?
They excrete nitrogen as uric acid, which is a semi-solid paste ## Footnote This adaptation helps reduce body weight for flight.
95
Sharks and rays retain high levels of urea in their body fluids to maintain osmotic balance with seawater. True or False?
True ## Footnote This adaptation helps prevent dehydration in marine environments.
96
Which human organ, besides the kidneys, is involved in excretion of water and small amounts of urea and salts?
Skin ## Footnote The skin excretes water, salts, and a little urea through sweat glands.
97
The lungs are important excretory organs because they remove:
Carbon dioxide (CO₂) and water vapor ## Footnote This process is vital to prevent blood acidification.
98
Human sweat is composed of:
Water, Salts (e.g. NaCl), Urea (small amount) ## Footnote Sweat helps with thermoregulation and minor excretion.
99
Urea is produced by the _____ and excreted by the _____.
Liver; kidneys ## Footnote The liver converts ammonia to urea, which the kidneys filter out of the blood.
100
Which of the following is not a nitrogenous waste product?
Carbon dioxide ## Footnote Nitrogenous wastes include urea, uric acid, and ammonia, but CO₂ is not classified as such.
101
Which animals are able to produce urine more concentrated than their blood?
Mammals (and birds to a lesser extent) ## Footnote Only mammals and birds can produce hyperosmotic urine due to their kidney structures.
102
Uremia is characterized by:
High urea levels in the blood due to kidney failure ## Footnote Symptoms include fatigue and nausea, requiring dialysis or transplant for treatment.
103
Why don’t terrestrial animals excrete ammonia directly?
Ammonia is extremely toxic and requires a large amount of water to safely excrete ## Footnote Terrestrial animals convert ammonia to less toxic forms like urea or uric acid.
104
The excretion of excess salt in a hypertonic salt solution is a strategy employed by:
Marine birds and marine reptiles ## Footnote These organisms have specialized glands to eliminate excess salts from seawater.
105
Which organism uses a network of tubules with ciliated flame cells to eliminate waste?
Planarian (flatworm) ## Footnote Protonephridia in flatworms help regulate internal salt and water balance.

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