Biology: Homeostasis and Excretion
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Questions and Answers

What is the primary role of the afferent arteriole in the kidney?

  • To filter large proteins from blood
  • To deliver blood to the glomerulus (correct)
  • To regulate urine output
  • To reabsorb glucose and amino acids

Which substances are typically able to pass through Bowman's capsule?

  • Large proteins and urea
  • Gases and hormones
  • Red blood cells and proteins
  • Glucose, amino acids, and salts (correct)

What creates the higher pressure in the glomerulus compared to Bowman's capsule?

  • The density of blood cells
  • The size of the afferent arteriole
  • The reabsorption of water
  • The pumping action of the heart (correct)

Which of the following substances cannot pass through Bowman's capsule due to their size?

<p>Red blood cells (D)</p> Signup and view all the answers

During the filtration process, what primarily gets excreted through Bowman's capsule?

<p>Waste products like urea (B)</p> Signup and view all the answers

What is one of the primary functions of the kidneys in regulating bodily fluids?

<p>Regulation of blood pressure (D)</p> Signup and view all the answers

Which of the following is an incorrect function of the kidneys?

<p>Storage of nutrients (D)</p> Signup and view all the answers

How many kidneys are part of the urinary system?

<p>2 (A)</p> Signup and view all the answers

What role do the kidneys play in the homeostatic regulation of volume?

<p>Maintain a constant volume of blood (B)</p> Signup and view all the answers

Where are the kidneys located in relation to the peritoneum?

<p>Posteriorly beneath the peritoneum (D)</p> Signup and view all the answers

What is the function of the renal pelvis?

<p>Collects urine produced by the nephrons (A)</p> Signup and view all the answers

What is the role of the efferent arteriole in the blood circulation of the kidney?

<p>Carries blood away from the glomerulus (C)</p> Signup and view all the answers

Which process occurs first in the renal processes?

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

What component is contained within the glomerulus?

<p>Network of capillaries (A)</p> Signup and view all the answers

Which structure stores urine temporarily in the urinary system?

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

What is the normal rate of forming glomerular filtrate in humans per minute?

<p>125 ml (C)</p> Signup and view all the answers

What percentage of the glomerular filtrate is typically reabsorbed into the blood capillaries?

<p>99% (A)</p> Signup and view all the answers

Which process is primarily involved in the reabsorption of useful nutrients?

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

Which of the following substances is NOT absorbed during reabsorption?

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

Where does the majority of reabsorption occur in the nephron?

<p>Proximal convoluted tubule (C)</p> Signup and view all the answers

What is the total daily production of glomerular filtrate in liters?

<p>15 liters (C)</p> Signup and view all the answers

Osmosis in the context of reabsorption primarily refers to the movement of which substance?

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

Which mechanism is NOT involved in the reabsorption process?

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

What is the primary function of surface area enhancement in the proximal convoluted tubule?

<p>To increase the surface area for reabsorption (A)</p> Signup and view all the answers

Why is it important for the wall of the proximal convoluted tubule to be a single layer of cells?

<p>To shorten the diffusion distance for reabsorption (B)</p> Signup and view all the answers

What role do mitochondria play in the proximal convoluted tubule cells?

<p>They provide energy for active transport (D)</p> Signup and view all the answers

What does the term 'highly convoluted' refer to in the structure of the proximal convoluted tubule?

<p>A series of loops and turns to increase time for filtration (B)</p> Signup and view all the answers

What percentage of urea is typically reabsorbed in the proximal convoluted tubule?

<p>50% (C)</p> Signup and view all the answers

Which of the following substances is absorbed in the highest percentage within the proximal convoluted tubule?

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

What adaptation helps to increase the time that filtrate remains in the proximal convoluted tubule?

<p>Highly convoluted design (B)</p> Signup and view all the answers

In the structural adaptations of the proximal convoluted tubule, what is the primary reason for increased reabsorption efficiency?

<p>Increased surface area and time for filtration (C)</p> Signup and view all the answers

What is the primary function of juxtamedullary nephrons?

<p>Maintaining a salinity gradient in the medulla (C)</p> Signup and view all the answers

What percentage of nephrons in the human kidney are cortical nephrons?

<p>80-85% (D)</p> Signup and view all the answers

Which structure surrounds the glomerulus?

<p>Bowman's capsule (D)</p> Signup and view all the answers

In which part of the nephron does the majority of reabsorption occur?

<p>Proximal convoluted tubule (C)</p> Signup and view all the answers

What is the composition of the renal vein?

<p>Oxygen-poor blood returning from the kidneys (D)</p> Signup and view all the answers

Which of the following nephrons primarily contributes to the concentration of urine?

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

What is true about the incoming and outgoing flow in a nephron?

<p>Incoming flow is through the renal artery (B)</p> Signup and view all the answers

Where does the renal artery lead to in the kidney?

<p>The glomerulus for filtration (D)</p> Signup and view all the answers

Flashcards

Kidney's role in blood regulation

The kidneys regulate the volume and composition of blood, ensuring a stable internal environment.

Kidney's role in ion balance

Kidneys maintain the balance of electrolytes, like sodium, potassium, and calcium, essential for various bodily functions.

Kidney's role in waste elimination

The kidneys eliminate waste products from metabolism, including urea and creatinine, preventing their buildup in the body.

Kidney's role in hormone production

The kidneys are responsible for producing hormones like erythropoietin, which stimulates red blood cell production, and renin, which regulates blood pressure.

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Kidney's role in nutrient conservation

The kidneys conserve essential nutrients, reabsorbing them back into the bloodstream to prevent their loss.

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Nephron

Microscopic units in the kidney responsible for filtering blood and producing urine.

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Types of Nephrons

The two types of nephrons are cortical nephrons, which are shorter and more numerous, and juxtamedullary nephrons, which are longer and help regulate water balance.

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Bowman's Capsule

A double-walled, cup-shaped structure that surrounds the glomerulus, where filtration of blood begins.

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Proximal Convoluted Tubule

The coiled portion of the nephron tubule closest to Bowman's capsule, where most reabsorption of nutrients and water occurs.

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Loop of Henle

The descending loop of Henle is responsible for water reabsorption, while the ascending loop of Henle reabsorbs salts.

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Collecting Duct

The collecting duct receives urine from multiple nephrons and carries it to the renal pelvis.

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Renal Artery and Vein

The renal artery carries oxygenated blood to the kidney, while the renal vein carries deoxygenated blood away from the kidney.

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Hilus

The hilus is the indented region of the kidney where the renal artery, renal vein, and ureter enter and exit.

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Renal Pelvis

A funnel-shaped structure inside the kidney that collects urine from the nephrons.

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Ureter

The tube that carries urine from the kidney to the bladder.

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Urinary Bladder

A muscular sac that stores urine before it is expelled from the body.

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Urethra

The tube that carries urine from the bladder to the outside of the body.

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Glomerulus

A network of capillaries within the nephron where blood filtration occurs.

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Afferent arteriole

The afferent arteriole is a blood vessel that carries blood to the glomerulus in the kidney. It is responsible for delivering oxygenated blood and nutrients to the nephrons, the functional units of the kidney.

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Efferent arteriole

The efferent arteriole is a blood vessel that carries blood away from the glomerulus in the kidney. It takes the filtered blood and transports it to the peritubular capillaries, where further reabsorption and secretion of substances occur.

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High glomerular pressure

The high blood pressure in the glomerulus is due to the pumping action of the heart and the narrow diameter of the efferent arteriole compared to the afferent arteriole. This pressure gradient drives filtration, forcing water and small solutes into Bowman's capsule.

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Reabsorption in kidneys

The process by which the kidneys return useful substances from the glomerular filtrate back into the bloodstream.

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Glomerular filtration rate

The rate at which glomerular filtrate is formed in the kidneys, approximately 125 ml per minute.

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Urine production rate

The amount of glomerular filtrate lost as urine per minute, approximately 1 ml.

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Reabsorption mechanisms

The movement of substances from the glomerular filtrate back into the bloodstream through the process of diffusion, osmosis, and active transport.

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Distal convoluted tubule

A section of the nephron where the final adjustments to electrolyte and water balance take place before urine is formed.

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Why is the proximal convoluted tubule convoluted?

The proximal convoluted tubule (PCT) has a highly folded structure with many convolutions, increasing the surface area for reabsorption of useful substances from the filtrate.

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What is the effect of the PCT's convoluted structure on filtrate flow?

The PCT is highly convoluted to maximize the time the filtrate spends within the tubule, allowing for greater opportunity for reabsorption of valuable substances.

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Why does the PCT have a single layer of cells?

The single layer of cells in the PCT wall ensures a short diffusion distance for reabsorption of useful substances from the filtrate back into the bloodstream.

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What is the role of mitochondria in the PCT?

The numerous mitochondria present in the PCT cells power the active transport processes involved in reabsorption of valuable substances against their concentration gradients.

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What is the main function of the proximal convoluted tubule?

The PCT is responsible for reabsorbing most of the water and nutrients from the filtrate, returning them back into the bloodstream to prevent loss.

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How do the structural adaptations of the PCT contribute to its function?

The structural features of the PCT, such as its convolutions, single layer of cells, and abundant mitochondria, work together to facilitate efficient reabsorption of valuable substances from the filtrate.

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Study Notes

Homeostasis

  • Homeostasis is the maintenance of a stable internal environment in the body.
  • The internal environment, also known as tissue fluid or extracellular fluid (ECF), surrounds body cells.
  • The body's internal environment must be carefully controlled.

Excretion

  • Excretion is the process of removing metabolic wastes from the body.
  • Metabolic wastes include nitrogenous wastes (e.g., urea), carbon dioxide, and bile pigments.
  • Nitrogenous waste is produced by the liver when proteins are broken down.
  • Carbon dioxide is a product of cellular respiration.
  • Bile pigments are from the breakdown of old red blood cells (RBCs) in the liver.

Kidney Structure and Location

  • Kidneys are paired, bean-shaped organs.
  • They are located posteriorly, slightly above the waistline, behind the peritoneum.
  • The right kidney is situated slightly lower than the left kidney due to the liver's presence on the right side of the body.

Kidney Functions

  • Regulation of blood pressure
  • Osmolarity regulation
  • Electrolyte balance
  • Metabolic waste removal
  • Hormone production
  • Nutrient conservation

Nephrons

  • The nephron is the functional unit of the kidney.
  • About 1 million nephrons exist in each kidney.
  • There are two primary types: cortical and juxtamedullary nephrons.
  • Cortical nephrons are responsible for approximately 80–85% of the nephrons.
  • Juxtamedullary nephrons are responsible for the remaining 15–20%.

Filtration

  • Blood plasma is filtered into Bowman's capsule.
  • The filtrate contains water, glucose, amino acids, wastes, and salts, but not blood cells or proteins.
  • The process of filtration occurs due to high blood pressure in the glomerulus.

Reabsorption

  • Water, glucose, amino acids, and salts are reabsorbed from the nephron tubules into the capillaries.
  • This is achieved via diffusion, osmosis, and active transport throughout different regions of the nephron.

Secretion

  • Certain substances (e.g., drugs, toxic substances) are actively secreted from blood capillaries into the tubule to be excreted.

Antidiuretic Hormone (ADH)

  • ADH regulates the amount of water reabsorbed in the collecting duct.
  • This hormone's production changes the water excretion rate based on body conditions.
  • This is controlled by how much water the body needs to retain.

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Description

This quiz covers key concepts in biology related to homeostasis and excretion. You will learn about the maintenance of stable internal environments, the role of the kidneys, and the processes involved in removing metabolic wastes. Test your understanding of kidney structure and function in this engaging quiz.

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