the urinary system...© 2009 the mcgraw-hill companies, inc. all rights reserved the urinary system...

© 2009 The McGraw-Hill Companies, Inc. All rights reserved

The Urinary System PowerPoint® presentation to accompany:

Medical Assisting Third Edition

Booth, Whicker, Wyman, Pugh, Thompson


30-2

Learning Outcomes

30.1 Describe the structure, location, and functions of the kidney.

30.2 Define the term nephron and describe its structure.

30.3 Explain how nephrons filter blood and form urine.

30.4 List substances normally found in urine.


30-3

Learning Outcomes (cont.)

30.5 Describe the locations, structures, and functions of the ureters, bladder, and urethra.

30.6 Explain how urination is controlled.

30.7 Describe the causes, signs and symptoms, and treatments of various diseases and disorders of the urinary system.


30-4

Introduction

Kidneys

Ureters

Bladder

Urethra

System functions to remove waste products from the blood

Main functional units of the kidneys are the nephrons

Nephrons filter the blood and form the urine


30-5

The Kidneys

Functions

Remove metabolic waste products from the blood

Secrete the hormone erythropoietin, which stimulates

bone marrow to produce red blood cells

Secrete the hormone renin, which helps regulate blood

pressure

Description

The kidneys are bean-shaped organs that lie behind the

peritoneal cavity (retroperitoneal) on either side of the

vertebral column.


30-6

Renal sinus – concave depression of the

surface of the kidney

Hilum – point of entry for the renal artery,

renal vein, and ureter

Renal pelvis – expansion of the ureter that

further divides into calyces

The Kidneys (cont.)

Kidney


30-7

Renal cortex – outermost portion of the kidney that covers the pyramids and dips down between them

Renal medulla – middle portion that also divides into renal pyramids

Renal column – portion of the cortex between pyramids

The Kidneys (cont.)

Kidney


30-9

The Kidneys: Nephrons

Renal

Corpuscles

Composed of a group of capillaries

called a glomerulus

Glomerulus is surrounded by

Bowman’s capsule

Blood filtration occurs in corpuscle

Removes waste products from the blood

Each kidney contains about 1 million nephrons

Made of a renal corpuscle and a renal tubule

Extend from the Bowman’s

capsule of a nephron

Consist of three parts:

Proximal convoluted tubule

Loop of Henle

Distal convoluted tubule

Glomerulus


30-11

The Kidneys – Nephrons (cont.)

Veins of the Kidney

Afferent Arteriole

Glomerulus

Efferent Arteriole

Peritubular Capillaries

Afferent arterioles deliver

blood to the glomeruli

Efferent arterioles carry

blood from the glomeruli to

peritubular capillaries


30-12

Apply Your Knowledge

What are the functions of the kidney?

ANSWER: The kidney removes metabolic waste products

from the blood, secretes erythropoietin to help regulate RBC

production, and secretes renin to help regulate the BP.

Correct!


30-13

Urine Formation: Glomerular Filtration

First process occurs in renal

corpuscles

Fluid part of the blood is

forced from glomerulous into

Bowman’s capsule

Becomes glomerular filtrate

Glomerulus


30-14

Factors affecting glomerular filtration

Filtration pressure – amount of pressure

that forces filtrate from the glomerulus into

Bowman’s capsule.

Determined by blood pressure

Rate of filtration – sympathetic nervous

system control

Constriction of afferent arterioles decreases

filtration pressure

Urine Formation: Glomerular Filtration (cont.)


30-15

Second process in urine formation

Glomerular filtrate proximal convoluted tubule

Nutrients, water, and ions pass through the walls of the

renal tubule into the peritubular capillaries

Water reabsorption depends on hormones

Antidiuretic hormone (ADH)

Aldosterone

Both increase water reabsorption, which decreases urine

production

Urine Formation: Tubular Reabsorption

Tubular

Reabsorption


30-16

Urine Formation: Tubular Secretion

Third process of

urine formation

Substances move

from blood in the

peritubular

capillaries into the

renal tubules

Secreted substances

Drugs

Hydrogen ions

Waste products

Tubular

Secretion


30-18

Urine composition Mostly water

Urea and uric acid

Formed by the breakdown of proteins and nucleic acids

Trace amounts of amino acids and various ions

Secretion of waste products helps maintain the acid-base balance

Urine Formation (cont.)


30-19


Match the following:

___ Second process in urine formation A. Glomerular filtration

___ Substances move from blood into renal tubules B. Tubular reabsorption

___ Depends on filtration pressure C. Tubular secretion

___ Third process of urine formation

___ First process of urine formation

___ Filtrate flows into the proximal convoluted tubule

C

C

B

A

A

B

ANSWER:

Nice Job!


30-21

Ureters, Urinary Bladder, and Urethra (cont.)

Urinary bladder

Expandable muscular organ

Stores up to 600 ml urine on average

Detrusor muscle – smooth muscle in wall of bladder

Trigone – triangle on internal floor of bladder formed by

urethra and ureters

Micturation

Process of urination

Stretching of bladder triggers process

Approximately 150cc of urine

Bladder


30-22

Impulses to contract urethra; inhibit micturition impulse until ready to urinate

Urination

External urethral

sphincter relaxes

Micturation reflex –

impulses from pons

and hypothalamus

Detrusor muscle

contracts

Urine expelled

Bladder

distends

Stretch receptors

Spinal cord

Parasympathetic nerves stimulate detrusor muscle

Brain stem

and

cerebral

cortex



30-23

Urethra

Tube that moves urine from the bladder to the

outside world

Shorter in females – patient education

Urinate when urge occurs

Drink adequate clear fluids

Wipe front to back

Urinate after intercourse



30-24

True or False:

___ Ureters move urine by peristalsis.

___ The detrusor is formed by the openings of the ureters and urethra.

___ The process of micturition is triggered when the bladder contains about

150 ml urine.

___ The urethra move urine from the kidney to the bladder.

___ The urethra is longer in females.

___ Contraction of the detrusor muscle pushes urine from the bladder.


F

F

T

F

T

trigone

males

ureters

T

ANSWER:


30-25

Diseases and Disorders of the Urinary System

Disease/Disorder Description

Acute renal failure Sudden loss of kidney function; may be

reversible with treatment

Chronic renal

failure

Kidneys slowly use ability to function; not

reversible

Cystitis Urinary bladder infection; more common in

females

Glomerulonephritis Inflammation of the glomeruli of the kidney;

one cause of chronic renal failure

Incontinence Inability to control urination


30-26

Disease/Disorder Description

Polycystic kidney

disease

Enlargement of kidneys because of the

presence of many cysts within them; slow,

progressive disease

Pyelonephritis Complicated urinary tract infection; starts

with a bladder infection and spreads to both

kidneys; can be acute or chronic

Renal calculi Kidney stones; can become lodged in ducts

within kidneys or ureters

Diseases and Disorders of the Urinary System


30-27


Matching:

___ Complicated urinary tract infection A. Pyelonephritis

___ Inability to control urination B. Glomerulonephritis

___ Kidney stones C. Incontinence

___ Slow loss of kidney function D. Chronic renal failure

___ Bladder infection E. Renal calculi

___ Inflammation of the glomeruli F. Cystitis

___ Kidney enlargement due to cysts G. Acute renal failure

___ Sudden loss of kidney function H. Polycystic kidney disease

H

G

F

E

D

C

B

A

ANSWER:

GOOD JOB!


30-28

In Summary

The organs of the urinary system include the

kidneys, ureters, bladder, and urethra

The kidneys remove metabolic waste products from

the blood and secrete erythropoietin and renin

Urine travels through the ureters to the bladder

Stretching of the bladder triggers micturition reflex

Urine travels from the bladder through the urethra to

the outside world


30-29

This too shall pass—just like a kidney stone.

~H. Madson

the urinary system...© 2009 the mcgraw-hill companies, inc. all rights reserved the urinary system...

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