Chapter 48: Osmoregulation, Excretion, & Thermoregulation (Urinary)

1.

Question: Summarize the mechanisms cells use to exchange water and solutes with the surrounding fluid. Answer: Osmosis and transport mechanisms.

2.

Question: Describe the structure and function of excretory tubules. Answer: Tubular structures involved in filtering body fluids and excreting waste products.

3.

Question: Compare and contrast the solubility and toxicity of the nitrogen compounds in metabolic wastes. Answer: Ammonia is highly toxic and soluble. Urea is less toxic and soluble. Uric acid is least toxic and insoluble.

4.

Question: Summarize osmoregulation and excretion processes in invertebrates. Answer: Invertebrates use various structures like protonephridia and metanephridia for osmoregulation and excretion.

5.

Question: Describe the components of the mammalian urinary system. Answer: Kidneys, ureters, urinary bladder, and urethra.

6.

Question: Discuss the processes of filtration, reabsorption, and secretion in the mammalian kidney. Answer: Filtration occurs in the glomerulus, reabsorption returns essential substances to the blood, and secretion moves additional wastes into the filtrate.

7.

Question: Describe the systems that regulate mammalian kidney function. Answer: Hormonal systems (e.g., RAAS, ADH) and local controls.

8.

Question: Compare and contrast kidney function in nonmammalian vertebrates. Answer: Kidney function varies among nonmammalian vertebrates depending on their environment and physiology.

9.

Question: Compare and contrast ectothermy and endothermy. Answer: Ectotherms obtain heat primarily from the external environment; endotherms generate most of their heat internally.

10.

Question: What is a hyperosmotic solution? Answer: A solution with higher osmolarity.

11.

Question: What is a hypoosmotic solution? Answer: A solution with lower osmolarity.

12.

Question: What is an isosmotic solution? Answer: Solutions on either side of a membrane have the same osmolarity.

13.

Question: Ammonia Answer: NH3, result of biochemical steps.

14.

Question: Renal cortex Answer: Pale outer region of the kidney.

15.

Question: Renal medulla Answer: Darker central region of the kidney.

16.

Question: Renal artery Answer: Carries blood into the kidneys.

17.

Question: Renal vein Answer: Filtered blood leaves the kidney by the renal vein.

18.

Question: Urine pathway Answer: Collecting ducts → renal pelvis → ureter → urinary bladder → urethra.

19.

Question: Daily filtration in humans Answer: Bowman’s capsule filters 180L of fluid each day from 1,400L of blood.

20.

Question: Major calyces Answer: Funnel-like structures formed from minor calyces, forming the ureter within a kidney.

21.

Question: Minor calyces Answer: Form major calyces and act as collecting cups for urine, fitting over renal pyramids.

22.

Question: Renal pyramids Answer: Cone-shaped renal tissue in the medulla containing tubules that transport urine to the calyces.

23.

Question: Efferent arteriole Answer: Formed from capillaries after the glomerulus.

24.

Question: Peritubular capillaries Answer: Formed by the efferent arteriole, surrounding the renal tubules before returning to the venous system.

25.

Question: Glomerulus Answer: A group of anastomosing capillaries (glomerular tuft) in the nephron, invested by Bowman’s capsule.

26.

Question: Bowman’s capsule Answer: Double layer of epithelial cells investing the glomerulus.

27.

Question: Filtration unit of the nephron Answer: The whole glomerulus.

28.

Question: Bowman’s capsule components Answer: Visceral epithelial cells (podocytes and filtration slits) and parietal epithelial cells.

29.

Question: Afferent arteriole (A) Answer: Carries blood to the glomerulus.

30.

Question: Efferent arteriole (B) Answer: Carries blood away from the glomerulus.

31.

Question: Glomerular capillaries (C) Answer: Capillaries within Bowman's capsule where filtration occurs.

32.

Question: Bowman’s capsule (D) Answer: Cups around the glomerulus to collect filtrate.

33.

Question: Endothelium (E) Answer: The lining of the glomerular capillaries.

34.

Question: Distal convoluted tubule (F) Answer: Part of the nephron tubule after the loop of Henle.

35.

Question: Urine formation processes Answer: Glomerular filtration, selective reabsorption, tubular secretion.

36.

Question: Nephron Answer: Functional unit of the kidney (~1.2 million per human kidney).

37.

Question: Glomerular filtration location Answer: Occurs in Bowman’s capsule around the glomerulus.

38.

Question: Ultrafiltrate of plasma Answer: Produced by the glomerulus.

39.

Question: Podocytes Answer: Visceral epithelial cells of Bowman’s capsule, forming filtration slits with glomerular endothelial cells and basement membrane.

40.

Question: Filtration slits Answer: Formed by podocyte foot processes and glomerular endothelial cells, allowing filtration.

41.

Question: Diameter difference in arterioles Answer: Diameter of afferent arteriole > efferent arteriole.

42.

Question: Reabsorption in the PCT Answer: Reabsorption of water, ions, and nutrients into the interstitial fluid.

43.

Question: Na+/K+ pumps in PCT Answer: Move Na+ and K+ from the filtrate into the interstitial fluid.

44.

Question: Cl– ion reabsorption in PCT Answer: Reabsorbed from the tubule with positive ions due to a voltage gradient.

45.

Question: Reabsorption of glucose and amino acids in PCT Answer: Via specific active transport proteins.

46.

Question: Renin Answer: Enzyme that cleaves angiotensinogen to angiotensin I.

47.

Question: Angiotensinogen Answer: Precursor protein cleaved by renin.

48.

Question: Angiotensin I Answer: Decapeptide formed from angiotensinogen.

49.

Question: Angiotensin Converting Enzyme Answer: Converts angiotensin I to angiotensin II.

50.

Question: Osmoregulation in terrestrial amphibians Answer: Conserve water and salt. Salt reclaimed in the bladder by active transport.

51.

Question: Ectotherms Answer: "Cold-blooded" animals obtaining heat primarily from the external environment.

52.

Question: Endotherms Answer: "Warm-blooded" animals obtaining most of their heat from internal physiological sources.

53.

Question: Ectotherm thermoregulation Answer: Regulate body temperature by controlling heat exchange with the environment through behavior and physiology.

54.

Question: Endotherm thermoregulation Answer: Keep bodies at optimal temperature by regulating heat generated internally and heat loss.

55.

Question: Temperature-regulating mechanisms Answer: Metabolic heat production, heat loss by evaporation (vasoconstriction or vasodilation), shivering.

56.

Question: Response to cold (hypothalamus) Answer: Hypothalamus sends signals to trigger compensating mechanisms via the autonomic nervous system.

57.

Question: In animals with a circulatory system, the ECF includes both ______ ___ and _____ _____. Answer: Interstitial fluid and blood plasma

58.

Question: _____ is the diffusion of water across a membrane Answer: Osmosis

59.

Question: The total solute concentration of a solution is called its _____, and it is measured in _____ Answer: Osmolarity, Osmoles

60.

Question: A solution with a higher osmolarity is ____osmotic to the other solution Answer: Hyperosmotic

61.

Question: A solution with lower osmolarity is ____osmotic to the other solution Answer: Hypoosmotic

62.

Question: What is the difference between an osmoconformer and an osmoregulator? Answer: Osmoconformer - match the osmolarity of environment; Osmoregulator - Control osmolarity independent of the environment

63.

Question: Give the 4 key steps of Excretory System function? (in correct order) Answer: Filtration, Reabsorption, Secretion, Excretion

64.

Question: What are nitrogenous products broken down and excreted as? (give all 3 options) Answer: Ammonia, Urea, Uric Acid

65.

Question: - Give an example of an organism that excretes each waste product Answer: Ammonia - aquatic animals; Urea - mammals; Uric Acid - birds, reptiles

66.

Question: The ___ ____ is the body’s way of converting toxic ammonia into urea Answer: Urea Cycle

67.

Question: 1. Core temperature Answer: (Fill in the blank)

68.

Question: 2. Thermoreceptors Answer: (Fill in the blank)

69.

Question: 3. Ectotherms, external environment Answer: (Fill in the blank)

70.

Question: 4. Endotherms, internal physiological sources/biochemical reactions Answer: (Fill in the blank)

71.

Question: 5. Decreases, increases Answer: metabolism ___________

72.

Question: 6. Peripheral, central Answer: The two types of thermoreceptors are ____________ and _____________ thermoreceptors

73.

Question: 1. List the methods of heat exchange and describe them. Answer: Radiation - emission of electromagnetic energy; Evaporation - heat loss through vaporization of liquid; Convection - transfer of heat by movement of air or liquid; Conduction - direct transfer of thermal energy between objects in contact

74.

Question: 2. What are the activity and food-intake changes in endotherms vs ectotherms at low temperatures? Answer: Endotherms - increase metabolic rate and food intake to generate heat; Ectotherms - decrease activity and food intake due to lowered metabolic rate

75.

Question: 3. Describe how endotherms vs ectotherms regulate their body temperature Answer: Endotherms - regulate internal heat production and heat loss through physiological mechanisms; Ectotherms - regulate body temperature through behavioral and physiological mechanisms of heat exchange with the environment

76.

Question: 1. The metabolic rate of endotherms is always higher than that of ectotherms of the same size Answer: True

77.

Question: 2. An ectotherm uses more energy in the cold than in the warm Answer: False

78.

Question: 3. There is a characteristic circadian fluctuation of about 1°C with temperature being highest during the night and lowest during the day Answer: True

79.

Question: Osmoregulation Answer: Regulation of water and ion balance.

80.

Question: Role of excretory tubule in osmoregulation Answer: Excretion of fluids and solutes maintains the body’s water and ion balance.

81.

Question: Importance of osmoregulation Answer: Maintaining metabolic and biochemical reactions and transport of nutrients.

82.

Question: Thermoregulation Answer: Homeostatic maintenance of body’s temperature.

83.

Question: Osmolarity units Answer: mosmoles/L.

84.

Question: Total solute concentration of body fluids Answer: 300mosmol/L.

85.

Question: Intravascular osmolarity Answer: Tends to be higher due to plasma proteins.

86.

Question: Osmosis definition Answer: Movement of water from a region of higher water concentration to a region of lower water concentration through a semipermeable membrane.

87.

Question: Hyperosmotic (AKA hypertonic) Answer: Higher solute concentration.

88.

Question: Hypoosmotic (AKA hypotonic) Answer: Lower solute concentration.

89.

Question: Isosmotic (AKA isotonic) Answer: Equal solute concentration.

90.

Question: Osmoconformers Answer: Osmolarity matches with the environment.

91.

Question: Osmoregulators Answer: Control osmolarity independent of the environment.

92.

Question: Nephron definition Answer: Structural and functional unit of the kidney.

93.

Question: Renal corpuscle Answer: Bowman's capsule and glomerular capillaries.

94.

Question: Renal tubule Answer: Extends from Bowman's capsule and includes the PCT, loop of Henle, DCT, and collecting duct.

95.

Question: Average number of nephrons per adult kidney Answer: ~1.2 million.

96.

Question: Components of the nephron Answer: Bowman’s capsule, glomerular capillaries, proximal convoluted tubule, descending thin limb of the loop of Henle, loop of Henle, ascending thin limb of the loop of Henle, ascending thick limb, distal convoluted tubule, connecting tubule, collecting duct.

97.

Question: Cortical nephrons Answer: Located in the outer part of the cortex.

98.

Question: Juxtamedullary nephrons Answer: Located along the base of the renal medullary pyramids.

99.

Question: Glomerular filtration Answer: Occurs in Bowman’s capsule; driving force is hydrostatic blood pressure.

100.

Question: Glomerulus structure Answer: Anastomosing network of blood capillaries.

101.

Question: Filtration in the glomerulus Answer: Blood gets filtered through tiny filtration slits formed by endothelial cells.

102.

Question: Kidney's role in cortical papillary osmotic gradient Answer: Produces a gradient of increasing osmolarity from the cortex to the medulla.

103.

Question: Kidney's role in urea recycling Answer: Urea is reabsorbed in the collecting duct and contributes to the medullary osmotic gradient.

104.

Question: Kidney's role in salt balance Answer: Regulates sodium and other ion excretion and reabsorption.

105.

Question: Kidney's role in blood pressure regulation Answer: Through the renin-angiotensin-aldosterone system (RAAS) and fluid volume control.

106.

Question: Local controls of GFR Answer: Vasoconstriction and vasodilation of afferent/efferent arterioles regulated by macula densa feedback.

107.

Question: Kidney anatomy: Hilum Answer: Area where blood vessels, nerves, and ureter enter/exit the kidney.

108.

Question: Glomerular filtration driving force Answer: High hydrostatic pressure in the glomerular capillaries.

109.

Question: Selective reabsorption location Answer: Occurs along the renal tubules.

110.

Question: Tubular secretion location Answer: Occurs along the renal tubules.

111.

Question: Countercurrent multiplier system Answer: Mechanism in the loop of Henle that establishes the medullary osmotic gradient.

112.

Question: Water permeability of PCT Answer: Permeable to water due to aquaporins.

113.

Question: Water permeability of descending limb of loop of Henle Answer: Permeable to water due to aquaporins.

114.

Question: Water permeability of ascending limb of loop of Henle Answer: Impermeable to water (no aquaporins).

115.

Question: Water permeability of collecting duct Answer: Permeability regulated by ADH (aquaporins).

116.

Question: Macula densa function Answer: Cells in the DCT that sense sodium concentration in the filtrate.

117.

Question: Juxtaglomerular apparatus (JGA) function Answer: Secretes renin in response to low blood pressure or low sodium in the DCT.

118.

Question: Efferent arteriole diameter Answer: Smaller than the afferent arteriole.

119.

Question: Filtration barrier of glomerulus Answer: Glomerular endothelium (fenestrated), glomerular basement membrane, and podocytes with filtration slits.

120.

Question: Nitrogenous waste: Ammonia excretion Answer: Aquatic animals.

121.

Question: Nitrogenous waste: Urea excretion Answer: Mammals, most amphibians.

122.

Question: Nitrogenous waste: Uric acid excretion Answer: Birds, reptiles.

123.

Question: Methods of heat exchange Answer: Radiation, convection, conduction, evaporation.

124.

Question: How Renin Production is Stimulated? (Baroreceptors pathway) Answer: Decrease in blood pressure sensed by baroreceptors in afferent arteriole → Renin synthesized and secreted.

125.

Question: How Renin Production is Stimulated? (Intrarenal pathway - Decreased GFR) Answer: Decreased blood pressure → Decreased GFR → More Na+ reabsorbed in PCT → Low Na+ in DCT → Macula densa senses low Na+ in tubular fluid → Sends NO and prostaglandins → Activates baroreceptors → Stimulates renin release (into the afferent arteriole).

126.

Question: Juxtaglomerular Apparatus (JGA) Answer: Juxtaglomerular cells (sense blood pressure), macula densa (sense Na+ concentration in tubule).

127.

Question: Vascular component of JGA Answer: Baroreceptor cells (modified arteriolar smooth muscle cells).

128.

Question: Tubular component of JGA Answer: Macula densa (sense Na+ concentration, "likes tasting Na+").

129.

Question: Macule; densa Answer: Macule - patch; densa - looks dense under microscope.

130.

Question: Extra Glomerular Stimulation of Renin pathway Answer: Low blood pressure → Bleeding → Blood flow decreases → Sensed by baroreceptors in carotid sinus and aorta (via CN IX Glossopharyngeal N.) → Sends information to CNS → Stimulate sympathetic neurons via vasomotor center → Sympathetic postganglionic axons secrete norepinephrine into JGA (β₁ adrenergic receptors) → Stimulate renin synthesis (more renin).

131.

Question: Angiotensinogen to Angiotensin I reaction Answer: Angiotensinogen is cleaved by renin to form Angiotensin I.

132.

Question: Angiotensin I to Angiotensin II reaction Answer: Angiotensin I is converted to Angiotensin II by Angiotensin Converting Enzyme (ACE).

133.

Question: Angiotensin II effects Answer: Vasoconstriction, stimulates aldosterone release, increases ADH secretion.

134.

Question: Aldosterone function Answer: Increases Na+ reabsorption in the distal tubule and collecting duct.

135.

Question: ADH (Vasopressin) function Answer: Increases water reabsorption in the collecting duct.

136.

Question: Thermoreceptors types Answer: Peripheral and central thermoreceptors.

137.

Question: Peripheral thermoreceptors location Answer: In the skin (Krause end bulbs detect cold, Ruffini nerve endings detect warmth, free nerve endings detect a wide range of temperatures).

138.

Question: Central thermoreceptors location Answer: Spinal cord, thermoreceptor neurons in hypothalamus, and abdominal organs.

139.

Question: Osmoconformers example Answer: Marine invertebrates.

140.

Question: Osmoregulators example Answer: Freshwater fish, terrestrial vertebrates.

141.

Question: Urea cycle location Answer: Liver.

142.

Question: Flame cells (solenocytes) Answer: Specialized cells in protonephridia for filtration.

143.

Question: Metanephridia Answer: Excretory organs in annelids with a nephrostome and nephridiopore.

144.

Question: Malpighian tubules Answer: Excretory organs in insects that empty into the gut.

145.

Question: Renal pelvis function Answer: Collects urine from the collecting ducts and drains it into the ureter.

146.

Question: Vasa recta Answer: Peritubular capillaries surrounding the loop of Henle in juxtamedullary nephrons, important for countercurrent exchange.

147.

Question: Glomerular mesangial cells function Answer: Support glomerular capillaries and help regulate filtration.

148.

Question: Juxtaglomerular cells location Answer: Modified smooth muscle cells in the wall of the afferent arteriole.

149.

Question: Renin release stimuli Answer: Low blood pressure, decreased sodium delivery to the macula densa, sympathetic stimulation.

150.

Question: Countercurrent exchange in vasa recta Answer: Maintains the medullary osmotic gradient by preventing washout of solutes.

151.

Question: Ureter function Answer: Carries urine from the kidney to the urinary bladder.

152.

Question: Urinary bladder function Answer: Stores urine.

153.

Question: Urethra function Answer: Carries urine from the urinary bladder out of the body.

154.

Question: Renal corpuscle function Answer: Filtration of blood.

155.

Question: Renal tubule function Answer: Reabsorption and secretion of substances.

156.

Question: Acid-base balance by kidneys Answer: Regulates pH by excreting or reabsorbing hydrogen and bicarbonate ions.

157.

Question: Erythropoietin production by kidneys Answer: Stimulates red blood cell production.

158.

Question: Activation of Vitamin D by kidneys Answer: Final hydroxylation step occurs in the kidney.

159.

Question: Gluconeogenesis by kidneys Answer: Synthesis of glucose from non-carbohydrate sources.

160.

Question: Myogenic mechanism in GFR regulation Answer: Afferent arterioles constrict in response to increased blood pressure, and dilate in response to decreased blood pressure.

161.

Question: Tubuloglomerular feedback Answer: Macula densa senses changes in filtrate flow/composition and signals the afferent arteriole to adjust GFR.

162.

Question: Atrial Natriuretic Peptide (ANP) effect on kidney Answer: Inhibits sodium reabsorption and renin release, increasing sodium and water excretion.

163.

Question: Parathyroid Hormone (PTH) effect on kidney Answer: Increases calcium reabsorption and phosphate excretion.

164.

Question: Aquaporins Answer: Water channel proteins in cell membranes that facilitate osmosis.

165.

Question: Urea transporters Answer: Proteins that facilitate the movement of urea across cell membranes, important in urea recycling.

166.

Question: Loop of Henle function Answer: Establishes the osmotic gradient in the renal medulla.

167.

Question: Collecting duct function Answer: Final site for water reabsorption and regulation of urine concentration.

168.

Question: Metabolic water Answer: Water produced during cellular metabolism.

169.

Question: Thermoeffector mechanisms for heat loss Answer: Vasodilation of skin blood vessels, sweating, panting.

170.

Question: Thermoeffector mechanisms for heat gain Answer: Vasoconstriction of skin blood vessels, shivering, non-shivering thermogenesis (brown fat).

171.

Question: Fever Answer: Elevated body temperature due to a resetting of the hypothalamic thermostat.

172.

Question: Heat stroke Answer: Dangerous condition with very high body temperature and failure of thermoregulatory mechanisms.

173.

Question: Hypothermia Answer: Dangerously low body temperature.

174.

Question: Brown adipose tissue (BAT) Answer: Specialized fat tissue that generates heat (non-shivering thermogenesis).

175.

Question: Osmotic diuresis Answer: Increased urination due to the presence of non-reabsorbable solutes in the renal tubules.