Human Anatomy: Kidneys and Nephrons
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Questions and Answers

Where are the kidneys located in relation to the vertebral column?

  • Between the last thoracic and 3rd lumbar vertebrae (correct)
  • Between the 5th and 8th lumbar vertebrae
  • At the level of the 1st and 2nd thoracic vertebrae
  • Between the 8th and 10th thoracic vertebrae

Which statement correctly describes the position of the right kidney?

  • It is displaced somewhat by the stomach.
  • It is located higher than the left kidney.
  • It is aligned exactly with the left kidney.
  • It sits slightly lower than the left kidney. (correct)

What are the main parts of a nephron?

  • Renal corpuscle and renal tubule (correct)
  • Afferent arteriole and collecting duct
  • Vasa recta and glomerulus
  • Distal convoluted tubule and nephron loop

What is the term for the position of the kidneys relative to the peritoneum?

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

What is the role of the afferent arteriole in the nephron?

<p>Supplies blood to the glomerulus (B)</p> Signup and view all the answers

What structure is located on the superior surface of each kidney?

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

What material primarily holds the kidneys in place?

<p>Connective tissue, overlying peritoneum, and adjacent organs (A)</p> Signup and view all the answers

Which of the following structures is involved in urine concentration?

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

What distinguishes a juxtamedullary nephron from a cortical nephron?

<p>Length of the nephron loop (C)</p> Signup and view all the answers

What can result from damage to the suspensory fibers of the outer fibrous layer of the kidney?

<p>Dislocated or floating kidney (A)</p> Signup and view all the answers

Which part of the kidney is covered by a fibrous capsule and surrounded by adipose tissue?

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

Which part of the nephron is primarily responsible for filtration?

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

What is the role of the fibrous capsule that covers the kidneys?

<p>To anchor the kidneys to surrounding structures (A)</p> Signup and view all the answers

Which component is primarily responsible for the filtration process in the nephron?

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

What structure does the term 'pedicels' refer to in the context of the filtration membrane?

<p>Finger-like projections of podocytes (B)</p> Signup and view all the answers

Which part of the nephron's filtration membrane is located adjacent to the capsular space?

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

Which is NOT a component of the filtration membrane as depicted in the description?

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

What function does the basement membrane serve in the context of the filtration membrane?

<p>Prevents large molecules from entering urine (B)</p> Signup and view all the answers

What is the first vessel that blood passes through when entering the kidneys?

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

What percentage of the total cardiac output do the kidneys receive?

<p>20-25 percent (B)</p> Signup and view all the answers

Which of the following structures runs between the renal pyramids?

<p>Renal columns (C)</p> Signup and view all the answers

From which structure does blood exit the kidneys?

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

Which arteries are located along the cortex-medulla boundary?

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

What type of capillaries surround the nephron?

<p>Peritubular capillaries (C)</p> Signup and view all the answers

Which veins collect blood from the peritubular capillaries?

<p>Cortical radiate veins (B)</p> Signup and view all the answers

What is the final structure blood passes through before exiting the kidneys?

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

The renal cortex is primarily located:

<p>On the outer layer of the kidney (D)</p> Signup and view all the answers

Which structure is formed by the convergence of minor calyces?

<p>Major calyx (C)</p> Signup and view all the answers

What is the primary function of the cells lining the proximal convoluted tubule?

<p>Reabsorption of organic nutrients and plasma proteins (C)</p> Signup and view all the answers

Which statement about the nephron loop is correct?

<p>Fluid in the descending limb flows toward the renal pelvis. (D)</p> Signup and view all the answers

What occurs in the distal convoluted tubule?

<p>Active secretion of ions, acids, drugs, and toxins takes place. (B)</p> Signup and view all the answers

Which of the following describes the composition of the nephron loop?

<p>It is composed of a descending limb and an ascending limb. (A)</p> Signup and view all the answers

How does water move from the descending limb of the nephron loop?

<p>By osmosis into the peritubular fluid. (A)</p> Signup and view all the answers

What role do juxtaglomerular cells play in the renal corpuscle?

<p>They produce hormones that affect blood pressure. (D)</p> Signup and view all the answers

What is the primary function of the macula densa?

<p>It detects sodium chloride concentrations. (A)</p> Signup and view all the answers

What happens to tubular fluid volume due to reabsorption in the proximal convoluted tubule?

<p>It decreases due to water following solutes. (A)</p> Signup and view all the answers

What is the primary function of the juxtaglomerular complex?

<p>Secreting hormones to regulate blood volume and pressure (C)</p> Signup and view all the answers

Which of the following describes the location of the macula densa?

<p>Region in the distal convoluted tubule near the glomerulus (A)</p> Signup and view all the answers

What structural feature is involved in the adjustment of final urine composition?

<p>Collecting ducts (C)</p> Signup and view all the answers

Which component of the renal corpuscle acts as a filter for blood?

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

What occurs after the distal convoluted tubules empty into collecting ducts?

<p>The fluid is adjusted before entering the minor calyx (C)</p> Signup and view all the answers

What is the effect of metabolic wastes being dissolved in urine?

<p>It necessitates water loss to maintain homeostasis (C)</p> Signup and view all the answers

What is the primary role of the parietal epithelium in the glomerular capsule?

<p>Protection and support of renal structures (A)</p> Signup and view all the answers

Which of the following statements accurately describes the flow of tubular fluid?

<p>It passes from the minor calyx to the collecting ducts (A)</p> Signup and view all the answers

Flashcards

Kidney Location

Kidneys are situated on either side of the vertebral column, behind the peritoneum (retroperitoneal).

Kidney Position (Vertebrae)

Located between the last thoracic and third lumbar vertebrae.

Kidney Position relative to other organs

The right kidney is slightly lower than the left, and the liver displaces it slightly.

Retroperitoneal

Behind the peritoneum; a position the kidneys hold.

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Renal support

Kidneys are held in place by peritoneum, adjacent organs, and connective tissues (fibrous capsule and adipose tissue).

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Adrenal gland location

Located on top of each kidney (superior surface).

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Fibrous Capsule

Protective outer layer of the kidney, anchors to surrounding structures.

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Floating kidney

A condition where the suspensory fibres of the outer layer are damaged; this can cause a kidney to move or float.

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Renal Cortex

The outer region of the kidney.

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Renal Medulla

The inner region of the kidney, containing renal pyramids.

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Renal Pyramids

Cone-shaped structures in the renal medulla.

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Renal Sinus

The cavity within the kidney, containing vessels and pelvis.

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Renal Pelvis

Funnel-shaped structure collecting urine from the kidney.

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Renal Artery

Artery delivering blood to the kidney.

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Afferent Arterioles

Small arteries delivering blood to nephrons.

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Efferent Arterioles

Small arteries carrying blood away from nephrons.

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Blood supply percentage to kidneys

Kidneys receive 20-25% of total cardiac output.

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Renal Vein

Vein carrying blood away from the kidney.

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What is a nephron?

The nephron is the basic functional unit of the kidney, responsible for filtering blood and producing urine.

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What are the two main parts of the nephron?

The nephron consists of the renal corpuscle and the renal tubule.

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What does the renal corpuscle do?

The renal corpuscle filters blood. It is made of the glomerulus, a network of capillaries, and the Bowman's capsule, a sac-like structure that surrounds the glomerulus.

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What structures are involved in blood supply to the nephron?

The afferent arteriole supplies blood to the glomerulus, and the efferent arteriole carries blood away from the glomerulus.

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Filtration Membrane

A specialized structure in the kidney that filters blood, consisting of the capillary endothelium, basement membrane, and podocyte foot processes.

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What does the renal tubule do?

The renal tubule processes the filtered fluid, reabsorbing useful substances and secreting waste products. It includes the proximal convoluted tubule, the loop of Henle, and the distal convoluted tubule.

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Capillary Endothelium

The inner layer of the filtration membrane, made of simple squamous epithelium, allowing fluid and small solutes to pass through.

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Basement Membrane

The middle layer of the filtration membrane, composed of collagen and other proteins, preventing larger molecules from passing.

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Podocytes

Specialized cells with foot processes that wrap around capillaries, forming filtration slits.

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Filtration Slits

Narrow gaps between podocyte foot processes, allowing only very small molecules to pass through into the Bowman's capsule.

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Glomerular capillary

A network of tiny blood vessels within the glomerulus, where filtration occurs in the kidney.

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Glomerular Capsule

A double-walled structure surrounding the glomerulus, also known as Bowman's capsule, that collects the filtered fluid.

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Proximal Convoluted Tubule (PCT)

The first segment of the renal tubule, where most reabsorption of nutrients, water, and ions occurs.

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What is the purpose of the juxtaglomerular complex?

A specialized structure where the distal tubule comes into contact with the afferent and efferent arterioles, regulating blood pressure and filtration rate.

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What happens in the descending limb of the nephron loop?

Fluid flows towards the renal pelvis, and water moves out due to its high permeability to water.

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What happens in the ascending limb of the nephron loop?

Fluid flows towards the renal cortex, and sodium and chloride are actively transported out, concentrating the peritubular fluid.

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Distal Convoluted Tubule (DCT)

The last segment of the renal tubule, responsible for selective reabsorption of sodium and secretion of ions, acids, drugs, and toxins.

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What is the primary role of the DCT?

The DCT plays a critical role in maintaining electrolyte balance, regulating blood pressure, and removing waste products from the body.

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Macula Densa

A group of specialized cells in the distal convoluted tubule (DCT) that sense the concentration of sodium in the tubular fluid.

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Juxtaglomerular Cells

Specialized smooth muscle cells in the wall of the afferent arteriole that release renin, a hormone involved in blood pressure regulation.

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Juxtaglomerular Complex

Structure formed by the interaction of the macula densa, juxtaglomerular cells, and the afferent arteriole. It plays a crucial role in regulating blood volume and blood pressure.

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What does the collecting system do?

The collecting system transports tubular fluid from nephrons to the renal pelvis, adjusts the final fluid composition, determines the final osmotic concentration of urine, and determines the final volume of urine.

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What is the function of the macula densa?

The macula densa senses the sodium concentration in the tubular fluid and regulates the release of renin from juxtaglomerular cells, ultimately affecting blood pressure and volume.

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What is the function of juxtaglomerular cells?

Juxtaglomerular cells release renin, a hormone that helps regulate blood volume and pressure.

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What is the function of the juxtaglomerular complex?

The juxtaglomerular complex is involved in the regulation of blood volume and blood pressure through the secretion of erythropoietin and renin.

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What is the function of the collecting duct?

The collecting duct is a part of the nephron that carries urine from the distal convoluted tubule to the renal pelvis, playing a role in the regulation of water and electrolyte balance in the urine.

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Study Notes

Urinary System Overview

  • The urinary system's primary functions are: excretion of metabolic wastes (e.g., urea) from body fluids, elimination of these wastes into the external environment, and maintaining homeostasis of blood volume and solute concentration.
  • The urinary system is comprised of two kidneys, two ureters, a urinary bladder, and a urethra.

Kidney Structure and Location

  • Kidneys are bean-shaped organs, approximately 10 cm long, 5.5 cm wide, and 3 cm thick.
  • They are located on either side of the vertebral column, between the last thoracic and third lumbar vertebrae.
  • The right kidney is typically slightly lower than the left, in part due to the liver's position.
  • Kidneys sit behind the peritoneum (retroperitoneal) and are held in place by overlying peritoneum, contact with adjacent organs, and supportive connective tissue. The fibrous capsule surrounds the kidney, and adipose tissue encases the capsule further.
  • The hilum (indentation) is where the renal artery and nerves enter, and renal veins and ureter exit.

Kidney Anatomy—Detailed

  • The kidney is made up of an outer renal cortex and inner medulla.
  • The medulla contains renal pyramids, with renal papillae projecting into the renal sinus.
  • Nephrons are the functional units of the kidney, producing urine. About 1.25 million nephrons are present in each kidney.
  • Urine flows through the minor and major calyces, then into the renal pelvis.
  • The renal pelvis empties into a ureter, transporting urine to the bladder.

Kidney Blood Supply

  • Kidneys receive approximately 20-25% of total cardiac output (blood flow).
  • Blood enters via the renal artery, then through interlobar arteries, arcuate arteries, cortical radiate arteries, and afferent arterioles, to the glomerulus.
  • Blood leaves via efferent arterioles that supply peritubular capillaries.
  • The blood then flows through cortical radiate veins, arcuate veins, interlobar veins, and the renal vein before exiting the kidney.

Nephron Structure and Function

  • The nephron is the basic functional unit of the kidney.
  • It consists of a renal corpuscle and a renal tubule.
  • The renal corpuscle's glomerulus filters blood plasma, producing filtrate.
  • The renal tubule (a series of tubules) processes the filtrate, reabsorbing desired substances and secreting waste into the filtrate.
  • The filtrate undergoes further processing by the nephron loop and distal convoluted tubule, transforming into tubular fluid.
  • The collecting duct empties the tubular fluid into the renal pelvis.

Renal Corpuscle

  • The renal corpuscle is a spherical structure composed of a glomerulus and a Bowman's capsule.
  • The glomerulus is a network of capillaries that filters blood plasma.
  • Fluid and dissolved substances in the filtrate are pushed from the glomerulus into the Bowman's capsule.

Renal Tubule

  • The renal tubule contains several segments where filtrate is modified by the selective reabsorption of vital substances and the secretion of wastes into the filtrate.
    • Proximal convoluted tubule: Majority of reabsorption occurs here.
    • Nephron loop (Loop of Henle): Modifies the filtrate's composition.
    • Distal convoluted tubule regulates water and electrolytes.

Juxtaglomerular Complex

  • The juxtaglomerular complex is a combination of cells located adjacent to the afferent and efferent arterioles in the distal convoluted tubule.
  • It is involved in regulating blood volume and blood pressure as well as secreting erythropoietin and renin.

Collecting System

  • Several collecting ducts merge to form a papillary duct which drains urine into minor calyces, then major calyces and ultimately the renal pelvis to be delivered into the ureter.
  • The collecting system is responsible for adjusting the osmotic concentration and volume of urine.

Metabolic Wastes

  • Metabolic wastes like urea, creatinine, and uric acid are eliminated in urine.
  • These substances are generated during various metabolic processes and require water for elimination.

Ureters

  • The ureters are paired muscular tubes that transport urine from the kidneys to the urinary bladder.
  • The ureter wall is formed by three layers: transitional epithelium, smooth muscle (responsible for peristalsis), and outer connective tissue.
  • Slit-like ureteral openings at the bladder help prevent backflow of urine.

Kidney Stones

  • Kidney stones (calculi) are solid deposits within the kidney, ureter, or urinary bladder.
  • They are formed from various substances like calcium deposits, magnesium salts, or uric acid crystals.
  • Formation of kidney stones can lead to painful conditions called nephrolithiasis. They can also block urine flow from the kidney and obstruct further processing.

Urinary Bladder

  • A hollow, muscular organ that stores urine until it's excreted from the body.
  • Size varies based on urine volume.
  • It's located within the pelvic cavity, held in place by peritoneal folds and connective tissue.

Urethra

  • The urethra is a tube that carries urine from the urinary bladder to the exterior of the body.
  • Males have a longer urethra also conducting semen.
  • The urethra passes through the pelvic floor, with an external urethral sphincter under voluntary control.

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Lecture 13 Urinary System PDF

Description

This quiz focuses on the anatomy and physiology of the kidneys and nephrons. Test your knowledge on their locations, structures, functions, and relationships with other body systems. Perfect for students studying human biology or anatomy.

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