Excretory Products and Human Excretory System
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Questions and Answers

What triggers the release of antidiuretic hormone (ADH)?

  • Excessive loss of fluid from the body (correct)
  • Increased blood pressure
  • Excessive fluid retention
  • Increased sodium concentration in blood

What effect does angiotensin II have on glomerular blood pressure?

  • Increases blood pressure (correct)
  • Causes blood pressure to fluctuate
  • Decreases blood pressure
  • No effect on blood pressure

How does aldosterone affect kidney function?

  • Promotes urination
  • Increases urine production
  • Inhibits water reabsorption
  • Facilitates reabsorption of Na+ and water (correct)

What role does Atrial Natriuretic Factor (ANF) play in kidney regulation?

<p>Causes vasodilation and decreases blood pressure (D)</p> Signup and view all the answers

Which mechanism primarily regulates glomerular filtration rate (GFR) during low blood pressure?

<p>Renin-Angiotensin mechanism (B)</p> Signup and view all the answers

What physiological change signals the central nervous system to initiate micturition?

<p>Stretching of the urinary bladder (B)</p> Signup and view all the answers

Which structure plays a key role in monitoring kidney function by releasing renin?

<p>Juxtaglomerular apparatus (JGA) (D)</p> Signup and view all the answers

What activates osmoreceptors in the body?

<p>Changes in blood volume and ionic concentration (C)</p> Signup and view all the answers

What role does the counter current mechanism play in the kidneys?

<p>It maintains a concentration gradient in the medullary interstitium. (A)</p> Signup and view all the answers

How does the flow of blood through the vasa recta correlate with the flow of filtrate in Henle's loop?

<p>Both flow in a counter current pattern. (C)</p> Signup and view all the answers

What substances contribute to the osmolarity gradient in the inner medulla?

<p>Both NaCl and urea. (B)</p> Signup and view all the answers

What is primarily transported by the ascending limb of Henle's loop?

<p>NaCl. (D)</p> Signup and view all the answers

What does the counter current mechanism ultimately assist in regarding urine production?

<p>Concentrating the filtrate (urine). (D)</p> Signup and view all the answers

What is the typical osmolarity of urine compared to the initial filtrate formed?

<p>Urine is concentrated four times more than the filtrate. (A)</p> Signup and view all the answers

How does the thin segment of the ascending limb of Henle's loop contribute to urine concentration?

<p>It transports urea back to the interstitium. (A)</p> Signup and view all the answers

Which structures are primarily involved in the counter current mechanisms for maintaining osmolarity?

<p>Henle's loop and vasa recta. (A)</p> Signup and view all the answers

What is the primary function of the ascending limb of Henle's Loop?

<p>Transport electrolytes while being impermeable to water (A)</p> Signup and view all the answers

Which segment of the nephron is primarily responsible for the reabsorption of nearly all essential nutrients?

<p>Proximal Convoluted Tubule (PCT) (C)</p> Signup and view all the answers

What role does the collecting duct play in urine concentration?

<p>Reabsorbs large amounts of water to produce concentrated urine (D)</p> Signup and view all the answers

How does the descending limb of Henle's Loop affect the filtrate?

<p>Is permeable to water but not electrolytes, concentrating the filtrate (B)</p> Signup and view all the answers

Which of the following substances is secreted by tubular cells during urine formation?

<p>Hydrogen ions (B)</p> Signup and view all the answers

What is the unique property of the ascending limb of Henle's Loop regarding water?

<p>Impermeable to water, facilitating active transport of electrolytes (C)</p> Signup and view all the answers

What percentage of water is reabsorbed in the proximal convoluted tubule (PCT)?

<p>70-80% (A)</p> Signup and view all the answers

Which of these statements is true regarding the function of the distal convoluted tubule (DCT)?

<p>It enables the reabsorption of HCO3– and regulates pH through selective ion transport (B)</p> Signup and view all the answers

Flashcards

Countercurrent Mechanism

The loop of Henle and vasa recta work together to create a concentration gradient in the medulla, which helps to concentrate urine.

Descending Limb of Loop of Henle

The descending limb of the loop of Henle is permeable to water, but not to salts. This allows water to move out of the tubule and into the interstitial fluid, concentrating the filtrate.

Ascending Limb of Loop of Henle

The ascending limb of the loop of Henle is impermeable to water, but actively pumps out salts. This increases the concentration of the interstitial fluid.

Vasa Recta

The vasa recta is a network of capillaries that runs alongside the loop of Henle. It plays a role in maintaining the concentration gradient by transporting water and salts.

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Collecting Duct

The collecting duct is the final segment of the nephron where water is reabsorbed under the influence of antidiuretic hormone (ADH).

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Urine Concentration

The ability of the kidneys to produce urine with a higher osmolarity than the initial filtrate.

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pH Regulation

The process by which the kidneys regulate the pH of blood by selectively secreting H+ and K+ ions.

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Ionic Balance

The process by which the kidneys maintain the ionic balance in the blood by selectively secreting H+ and K+ ions.

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Kidney Function Regulation

The regulation of kidney function is a complex process involving hormonal feedback loops.

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Osmoreceptors

Specialized cells in the hypothalamus that detect changes in blood volume and ion concentration.

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Antidiuretic Hormone (ADH)

A hormone released from the posterior pituitary gland that increases water reabsorption in the kidney tubules.

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Juxtaglomerular Apparatus (JGA)

A specialized structure in the kidney that regulates blood flow and filters waste.

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Renin

An enzyme secreted by the JGA in response to low blood pressure; activates the renin-angiotensin system.

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Angiotensin II

A potent vasoconstrictor that increases blood pressure and promotes sodium reabsorption in the kidneys.

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Aldosterone

A hormone released from the adrenal cortex that increases sodium and water reabsorption in the kidney tubules.

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Atrial Natriuretic Factor (ANF)

A hormone released from the heart that promotes vasodilation and reduces blood pressure.

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Reabsorption

The process by which substances move from the filtrate in the nephron back into the bloodstream.

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Secretion

The movement of substances from the bloodstream into the filtrate in the nephron.

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Proximal Convoluted Tubule (PCT)

The first part of the nephron where most reabsorption occurs, including water, electrolytes, and essential nutrients like glucose and amino acids.

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Loop of Henle

The loop of Henle is divided into two parts: the descending limb, permeable to water, and the ascending limb, impermeable to water but permeable to electrolytes.

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Distal Convoluted Tubule (DCT)

The last part of the nephron before the collecting duct. Reabsorbs sodium and water and plays a role in regulating pH and potassium balance.

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Study Notes

Excretory Products and Their Elimination

  • Animals accumulate metabolic byproducts like ammonia, urea, uric acid, and various ions.
  • These substances need to be removed either completely or partially.
  • Ammonia is the most toxic form of nitrogenous waste, requiring significant water for elimination
  • Uric acid, being the least toxic, can be eliminated with minimal water loss.
  • Ammonotelism: Excretion of ammonia, common in bony fishes, aquatic amphibians, and aquatic insects. Ammonia is readily soluble and excreted by diffusion.
  • Ureotelism: Excretion of urea, found in mammals, many terrestrial amphibians and marine fishes. Urea is less toxic than ammonia and requires less water loss.
  • Uricotelism: Excretion of uric acid; characteristic of reptiles, birds, land snails, and insects. Uric acid forms a paste or pellet, minimizing water loss.

Human Excretory System

  • The human excretory system comprises a pair of kidneys, ureters, a urinary bladder, and urethra.
  • Kidneys are bean-shaped organs situated between the last thoracic and third lumbar vertebrae.
  • Each kidney contains approximately one million nephrons, the functional units of the kidney.
  • Nephrons: Composed of glomerulus and renal tubule.
  • Glomerulus: A tuft of capillaries.
  • Renal Tubule: Begins with Bowman's capsule enclosing the glomerulus. The tubule coils and forms convoluted sections (PCT, DCT). The loop of Henle is a hairpin loop, extending into the medulla in some nephrons.
  • The glomerulus filters blood, forming a filtrate.
  • Blood is filtered in the glomerular capillary network, forming a filtrate that is collected in Bowman's capsule.
  • PCT helps in reabsorption of essential nutrients, electrolytes, and water.
  • Loop of Henle plays a vital role in concentrating the filtrate.
  • DCT allows reabsorption of Na+, water, and HCO₃, secretion of H⁺ and K⁺.

Urine Formation

  • Urine formation is a three-step process: glomerular filtration, reabsorption, and secretion.
  • Glomerular filtration: Blood is filtered by the glomerulus in the Bowman's capsule. This forms a protein-free filtrate.
  • Reabsorption: The renal tubules selectively reabsorb essential substances and water from the filtrate.
  • Secretion: Tubular cells actively secrete substances like H+, K+, and ammonia into the filtrate.
  • Approximately, 1100-1200 ml of blood is filtered every minute.

Regulation of Kidney Function

  • Osmoreceptors in the hypothalamus respond to changes in blood volume and concentration.
  • ADH (antidiuretic hormone): Controls water reabsorption in the distal convoluted tubule.
  • JGA (juxta glomerular apparatus): Regulates glomerular filtration rate (GFR). It plays a crucial role in maintaining blood pressure.
  • Renin-angiotensin system: A complex mechanism involving renin, angiotensin, and aldosterone to regulate blood pressure and Na⁺ and water balance.
  • ANF (atrial natriuretic factor): Released by the heart in response to increased blood pressure, counteracts the renin-angiotensin system.

Micturition

  • Urine is stored in the urinary bladder.
  • The CNS initiates the expulsion of urine by triggering the contraction of bladder muscles and relaxation of the sphincter.

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Related Documents

Chapter 16: Excretory Products and Their Elimination PDF

Description

This quiz covers the different types of excretory products found in animals, including ammonia, urea, and uric acid, and their methods of elimination. It also explores the human excretory system, highlighting the anatomy and function of organs such as the kidneys and urinary bladder.

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