Urinary System Functions Chapter 25

Questions and Answers

Which of the following are functions of the urinary system? (Select all that apply)

Eliminating organic wastes (correct)

Synthesizing hormones (correct)

Regulating blood volume and pressure (correct)

Regulating plasma ion concentrations (correct)

What are the retroperitoneal organs?

Kidneys, Pancreas

What is the outer portion of the kidney called?

Cortex

What is the inner portion of the kidney?

Medulla Signup and view all the answers

What are renal pyramids?

Triangular shaped areas of tissue in the medulla of the kidney Signup and view all the answers

What separates the renal pyramids?

Renal Columns Signup and view all the answers

What structure is found at the end of each renal pyramid?

Renal Papilla Signup and view all the answers

What is a minor calyx?

A cup-shaped cavity that drains urine from the renal papillae Signup and view all the answers

What does a major calyx do?

Drains urine from minor calyxes into the renal pelvis Signup and view all the answers

Describe the renal pelvis.

The area where major calyces converge and narrows to become the ureter Signup and view all the answers

What is the function of the ureter?

A duct leading from the kidney to the urinary bladder Signup and view all the answers

Approximately how many nephrons does each kidney contain?

1 million Signup and view all the answers

What is the path of urine drainage?

Collecting duct → Papillary duct → Minor calyx → Major calyx → Renal pelvis → Ureter → Urinary bladder Signup and view all the answers

What type of epithelial tissue is present from the minor calyx down?

Transitional epithelium Signup and view all the answers

What is the path of blood supply to the kidneys?

Abdominal Aorta → Renal artery → Miscellaneous branches → Afferent arterioles → Glomerular capillaries → Efferent arterioles → Peritubular capillaries Signup and view all the answers

What is a glomerulus?

A capillary bed surrounded by Bowman's capsule in the nephron Signup and view all the answers

What is the function of vasa recta?

Capillary branches that supply loops of Henle in the medulla region of the kidney Signup and view all the answers

What is a nephron?

The functional unit of the kidneys Signup and view all the answers

What is the pathway through the nephron?

Bowman's capsule → Proximal convoluted tubule → Descending loop of Henle → Thin ascending loop of Henle → Thick ascending loop of Henle → Distal tubule → Collecting duct → Papillary duct Signup and view all the answers

What is a cortical nephron?

Nephrons located almost entirely in the renal cortex Signup and view all the answers

What is a juxtamedullary nephron?

Nephrons near the medulla that contain vasa recta and make up 15% of all nephrons Signup and view all the answers

What are the histological features of the renal tubule and collecting duct?

All regions have simple cuboidal epithelium except the nephron loop/descending limb and thin ascending limb which has simple squamous Signup and view all the answers

What are the three basic functions of the nephron?

Filtration, Reabsorption, Secretion Signup and view all the answers

What is glomerular filtration?

Blood plasma and dissolved substances get filtered into the glomerular capsule Signup and view all the answers

What is tubular reabsorption?

The process where water, ions, and other substances are reabsorbed from the renal tubule lumen into the peritubular capillaries Signup and view all the answers

What is tubular secretion?

The process where substances such as wastes, drugs, and excess ions are secreted from the peritubular capillaries into the renal tubule Signup and view all the answers

What is a renal corpuscle?

The site of filtration, consisting of Bowman's capsule and the glomerulus Signup and view all the answers

What are mesangial cells?

Cells located between glomerular capillaries that can contract and regulate glomerular filtration rate Signup and view all the answers

What are podocytes?

Cells that have foot processes (Pedicels) creating filtration slits for smaller molecules Signup and view all the answers

What is the function of macula densa?

Cells in the distal tubule that monitor electrolyte concentration and secrete a paracrine that constricts the afferent arteriole to regulate GFR Signup and view all the answers

What are juxtaglomerular cells?

Cells located in the wall of the afferent arteriole that secrete renin Signup and view all the answers

What are extraglomerular cells?

Contractile cells that help regulate glomerular filtration Signup and view all the answers

What are the four basic renal processes?

Filtration, Reabsorption, Secretion, Excretion Signup and view all the answers

What occurs during filtration?

Movement of fluid and substance out of the glomerular capillary into Bowman's capsule Signup and view all the answers

What is reabsorption?

Movement of fluid and substances from the nephron tubule into the peritubular capillaries or vasa recta Signup and view all the answers

What is secretion?

Movement of fluid and substances from the peritubular capillaries into the nephron tubule Signup and view all the answers

What is excretion?

Formation of urine and transport out of kidneys to the bladder Signup and view all the answers

What substances are reabsorbed by the proximal tubule?

Glucose, Water Signup and view all the answers

What substances are secreted by the proximal tubule?

Penicillin, H+ Signup and view all the answers

What substances are secreted by the distal tubule?

K+, Ammonium ions Signup and view all the answers

What is aldosterone?

A hormone secreted by the adrenal cortex that increases reabsorption of Na+ and secretion of K+ Signup and view all the answers

What does Anti-Diuretic Hormone (Vasopressin) do?

Increases reabsorption of water by the distal tubule Signup and view all the answers

What is the function of the internal urethral sphincter?

Involuntarily controls opening and closing of urethra Signup and view all the answers

What is the function of the external urethral sphincter?

Voluntarily controls opening and closing of urethra Signup and view all the answers

Study Notes

Functions of the Urinary System

Regulates plasma ion concentrations, blood volume and pressure, and plasma pH.
Conserves nutrients by limiting excretion.
Eliminates organic wastes and synthesizes hormones.

Anatomy of the Urinary System

The kidneys and pancreas are classified as retroperitoneal organs.
The renal cortex is the outer portion of the kidney, typically lighter in color.
The renal medulla is the inner portion of the kidney, consisting of renal pyramids.

Renal Structures

Renal pyramids are triangular areas of tissue within the medulla.
Renal columns are extensions of the cortex that separate the renal pyramids.
Renal papillae are funnel-like structures at the ends of renal pyramids, leading to urine drainage.

Urine Drainage System

Minor calyx collects urine from renal papillae and directs it to major calyces.
Major calyx is formed by the convergence of several minor calyces and drains urine into the renal pelvis.
Renal pelvis is where major calyces converge and leads to the ureter.

Nephron Structure and Function

Each kidney contains approximately 1 million nephrons, the functional units of the kidneys.
Nephrons consist of several segments including Bowman's capsule, proximal tubule, loops of Henle, distal tubule, and collecting duct.
The flow of urine follows the pathway: collecting duct → papillary duct → minor calyx → major calyx → renal pelvis → ureter → urinary bladder.

Types of Nephrons

Cortical nephrons primarily located in the renal cortex, making up 85% of nephrons with shorter loops of Henle.
Juxtamedullary nephrons are situated near the medulla, contain vasa recta, and account for 15% of nephrons.

Epithelial Tissue in Nephrons

Most renal tubular regions are lined with simple cuboidal epithelium, except for the nephron loop and certain limbs which have simple squamous epithelium.

Nephron Processes

The three fundamental functions of nephrons include filtration, reabsorption, and secretion.
Filtration occurs at the glomerulus, allowing blood plasma and substances to enter Bowman's capsule.
Tubular reabsorption retrieves water, ions, and substances from the nephron back into the bloodstream.
Tubular secretion moves wastes, drugs, and excess ions from peritubular capillaries into the nephron.

Renal Corpuscle and Associated Cells

The renal corpuscle consists of Bowman's capsule and the glomerulus, where filtration occurs.
Mesangial cells regulate glomerular filtration rate by contracting and adjusting blood flow through capillaries.
Podocytes form filtration slits to filter smaller molecules during glomerular filtration.
Macula densa cells monitor electrolyte concentration and regulate glomerular filtration by influencing arteriole constriction.

Hormonal Regulation

Juxtaglomerular cells in the afferent arteriole secrete renin to help regulate blood pressure.
Aldosterone from the adrenal cortex increases sodium reabsorption and potassium secretion in the distal tubule.
Anti-diuretic hormone (ADH) increases water reabsorption in the distal tubule, helping maintain fluid balance.

Urinary Sphincters

Internal urethral sphincter controls involuntary opening and closing of the urethra.
External urethral sphincter consists of skeletal muscle allowing voluntary control over urination.

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Description

This quiz covers the essential functions of the urinary system, as outlined in Chapter 25. Participants will learn about the regulatory roles of the kidneys, as well as their anatomical significance. Get ready to test your knowledge on the key concepts associated with urinary function.