Excretory System Overview
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Questions and Answers

Which structure carries deoxygenated blood away from the kidney?

  • Urethra
  • Renal artery
  • Ureter
  • Renal vein (correct)

The nephron is responsible for reabsorbing essential solutes and water back into the blood.

True (A)

What is the primary function of nephrons in the kidney?

Blood filtration

The _____ carries urine from the kidney to the bladder.

<p>ureters</p> Signup and view all the answers

Match the following structures of the excretory system with their functions:

<p>Renal artery = Carries oxygenated blood to the kidney Urethra = Carries urine out of the body Bowman's Capsule = Site of fluid and solute filtration Ureters = Carries urine from the kidney to the bladder</p> Signup and view all the answers

Which substance is NOT transported across during filtration in the kidneys?

<p>Blood cells (A)</p> Signup and view all the answers

The proximal tubule is involved in the reabsorption of glucose and water.

<p>True (A)</p> Signup and view all the answers

What is the primary function of Bowman’s capsule in the kidney?

<p>To catch everything pushed out of the blood during filtration.</p> Signup and view all the answers

The process of __________ involves the movement of substances out of the tubules across interstitial fluid into the blood of capillaries.

<p>reabsorption</p> Signup and view all the answers

Match the following structures with their function:

<p>Efferent arteriole = Carries filtered blood away from the glomerulus Afferent arteriole = Brings unfiltered blood to the glomerulus Glomerulus = Site of filtration Proximal Tubule = Site of reabsorption</p> Signup and view all the answers

What is primarily reabsorbed in the proximal tubule of the nephron?

<p>Water and solutes (A)</p> Signup and view all the answers

Glucose, amino acids, vitamins, and hormones are reabsorbed in the distal convoluted tubule.

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

What happens to NaCl in the ascending Loop of Henle?

<p>NaCl is removed by active transport.</p> Signup and view all the answers

In the descending Loop of Henle, water travels into the blood by ______.

<p>osmosis</p> Signup and view all the answers

Match the following sections of the Loop of Henle with their characteristics:

<p>Descending Loop = Permeable to water, impermeable to solutes Ascending Loop = Impermeable to water, permeable to solutes Thin segment of the descending loop = Main site for water reabsorption Thin segment of the ascending loop = Main site for NaCl reabsorption</p> Signup and view all the answers

What is the primary role of the excretory system?

<p>To remove metabolic waste (A)</p> Signup and view all the answers

Urea is more toxic than ammonia.

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

What are the main components of the excretory system?

<p>Kidneys, ureter, urinary bladder, and urethra</p> Signup and view all the answers

The filtering units in the kidneys are called __________.

<p>nephrons</p> Signup and view all the answers

Match the following waste products with their sources:

<p>Ammonia = Breakdown of proteins Urea = Conversion of ammonia in the liver Uric acid = Breakdown of nucleic acids Water = Regulated by kidneys</p> Signup and view all the answers

What percentage of the body's blood supply can be found in the kidneys at any given moment?

<p>25% (A)</p> Signup and view all the answers

In unicellular organisms, all cells can easily get nutrients and excrete waste by diffusion.

<p>True (A)</p> Signup and view all the answers

What happens to ammonia in the liver?

<p>It is converted to urea.</p> Signup and view all the answers

Which substance is primarily reabsorbed in the distal convoluted tubule when the body is dehydrated?

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

The collecting duct is responsible for the excretion of excess water and creatinine.

<p>True (A)</p> Signup and view all the answers

What is the primary function of the glomerulus?

<p>Blood filtration</p> Signup and view all the answers

Drinking ocean water leads to ____ in the body due to high salt content.

<p>dehydration</p> Signup and view all the answers

Match the substances with their respective processes in the nephron:

<p>Urea = Excretion NaCl = Reabsorption Excess H+ ions = Secretion Water = Homeostasis</p> Signup and view all the answers

What hormone primarily regulates Na+ and water permeability in the nephron?

<p>Aldosterone (A)</p> Signup and view all the answers

Excessive sweating decreases urine concentration.

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

What happens to urine concentration during cold weather?

<p>It becomes dilute.</p> Signup and view all the answers

Flashcards

Nephron

The functional unit of the kidney where blood filtration and urine formation occur.

Bowman's Capsule

A cup-shaped structure at the beginning of a nephron where blood is filtered.

What is excretion?

The process of removing metabolic waste products from the body.

What is deamination?

Amino acids are the building blocks of proteins, and their breakdown creates ammonia, a toxic waste product.

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Filtration

The process where blood is filtered in the Bowman's Capsule, separating waste products from the blood.

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Reabsorption

The process where useful substances (water, glucose, etc.) are reabsorbed from the nephron back into the blood.

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What is the excretory system?

The excretory system is responsible for removing waste products from the body, such as urea and uric acid.

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Secretion

The process where waste products are actively transported from the blood into the nephron (specifically the distal tubule), further refining urine.

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What are the kidneys?

The kidneys are the main organs of the excretory system, responsible for filtering waste products from the blood.

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What are nephrons?

Nephrons are tiny filtering units inside the kidneys that remove waste products from the blood. There are millions of nephrons in each kidney.

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What is urea?

Urea is a less toxic form of ammonia that is produced in the liver and excreted by the kidneys.

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What is uric acid?

Uric acid is a waste product that is formed from the breakdown of nucleic acids like DNA and RNA.

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How does the excretory system regulate water balance?

The excretory system also helps to maintain the body's water balance, ensuring that the right amount of fluids is present.

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Filtration in the Nephron

The process where substances from the blood are pushed through the capillary walls of the glomerulus into the Bowman's capsule, forming filtrate.

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Glomerulus

The curled-up mass of capillaries in the nephron that plays a key role in filtration by pushing blood at high pressure.

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Reabsorption in the Nephron

The process where substances from the filtrate in the nephron are reabsorbed back into the blood.

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Proximal Tubule

The part of the nephron where most of the reabsorption of important substances like glucose, water, and salts takes place.

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What is reabsorbed in the proximal tubule?

In the proximal tubule, the majority of water, glucose, amino acids, potassium ions (K+), sodium chloride (NaCl), and bicarbonate ions (HCO3-) are transported back into the bloodstream.

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What happens in the descending loop of Henle?

The descending loop of Henle becomes concentrated with NaCl as water moves out by osmosis.

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What happens in the ascending loop of Henle?

The ascending loop of Henle is impermeable to water but permeable to solutes, allowing NaCl to be actively transported out, forming a concentration gradient for water to follow by osmosis.

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What is the permeability of the thin segment of the descending loop of Henle?

The thin segment of the descending loop of Henle is impermeable to solutes but permeable to water.

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What is the permeability of the thin segment of the ascending loop of Henle?

The thin segment of the ascending loop of Henle is impermeable to water but permeable to solutes.

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What is Bowman's capsule?

This is the first part of the nephron where blood filtration occurs. Waste products are separated from the blood and go into Bowman's capsule.

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What is reabsorption in the nephron?

This part of the nephron is where the body reabsorbs important substances back into the blood from filtered waste.

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What happens in the distal convoluted tubule?

The distal convoluted tubule is vital for fine-tuning homeostasis.

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What happens in the collecting duct?

The collecting duct is where the final adjustments to urine composition occur.

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Why is the nephron important?

The nephron is responsible for filtering waste products from the blood, but it also helps maintain the balance of water in the body.

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When is urine more concentrated?

When you are dehydrated, your body will reabsorb more water to maintain its fluid balance. This results in more concentrated urine to conserve water.

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Why won't drinking ocean water save you from dehydration?

Drinking ocean water does not save you from dehydration because it increases the salt concentration in your body, leading to further water loss through urine.

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What is osmoregulation in the nephron?

The nephron is responsible for regulating the concentration of water in the urine, depending on the body's needs. For example, if you drink a lot of water, your urine will be diluted. If you are dehydrated, your urine will be concentrated.

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Study Notes

Excretion Overview

  • Excretion is the process of removing metabolic waste.
  • Single-celled organisms like amoeba use simple diffusion to remove waste.
  • Multicellular organisms need organ systems for excretion.

Excretory System Anatomy

  • The excretory system includes the kidneys, ureters, urinary bladder, and urethra.
  • Kidneys are the main filtering organs.
  • Other structures are involved in transporting and storing waste.
    • Kidneys are fist-sized, bean-shaped organs located on either side of the spine within the abdominal wall.
    • About 25% of the body's blood supply passes through the kidneys.

Excretory System Function

  • The excretory system filters blood.
  • Wastes are removed (excretion).
  • Fluids like water are kept constant (osmoregulation).

Waste Removal

  • Deamination breaks down proteins, producing nitrogen waste (toxic ammonia).
  • Ammonia is converted to urea (less toxic) in the liver.
  • The body removes urea, excess water, and other wastes.
  • These wastes are removed in urine.
  • Uric acid is a waste product from nucleic acid breakdown.

Nephron Structure

  • Nephrons are tiny filtering structures inside the kidneys.
  • The nephrons each have a set role
  • Each kidney contains approximately 1 million nephrons.
  • Nephrons consist of tubes (tubules) and a blood supply.
  • Glomerulus is the curled up mass of capillaries for filtering blood
  • Bowman's capsule catches the substances pushed out of the blood (filtrate).
  • filtrate is the filtered blood, containing mostly water, salt, sugars, urea, and other wastes.
  • The filtrate is processed further in the renal tubules.

Stages of Urine Formation

  • Filtration: Fluids and solutes (minus blood cells and large proteins) move into Bowman's capsule.
  • Reabsorption: Essential nutrients and water move from nephron back into blood.
  • Secretion: Larger wastes move from blood into nephron.
  • Excretion: Filtered wastes, water, and salts from urine. - Reabsorption happens in the tubules, collecting ducts.

Proximal Tubule Reabsorption

  • Proximal tubule reabsorbs glucose, amino acids, most of the water, sodium, chloride, bicarbonate, potassium, and other substances.
  • Substances are reabsorbed by active transport (energy required).

Loop of Henle Reabsorption

  • Descending loop reabsorbs water.
  • Ascending loop reabsorbs sodium and chloride.
  • Loop of Henle establishes a concentration gradient necessary for water reabsorption, resulting in more concentrated urine.

Distal Convoluted Tubule

  • Reabsorption and secretion of substances like sodium, potassium, and water occur in the distal tubule, further adjusting fluid and electrolyte balance.
  • Regulation via hormones like aldosterone and antidiuretic hormone.

Collecting Duct

  • Further water reabsorption in the collecting duct occurs depending on the body's needs.
  • Excess water, salts, and wastes form urine, which is expelled from the body through the urethra.

Importance of the Process

  • This process removes waste products like urea from the blood daily and maintains water and electrolyte homeostasis.

Osmoregulation

  • The urine concentration depends on blood concentration.
  • Eating salty food or sweating excessively leads to more concentrated urine.
  • Drinking and cold weather cause dilute urine.

Important note: Drinking ocean water will NOT hydrate you -- the high salt concentration will increase dehydration. The body will lose more water due to the salt in order to dilute the blood to normal levels.

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Description

Explore the functions and anatomy of the excretory system in this quiz. Learn about how different organisms excrete waste, the structure of the human excretory system, and the processes involved in waste removal and osmoregulation.

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