Medical assisting Administrative and clinical procedures (5e) Chapter 31 The urinary system

CHAPTER

31
The Urinary
System


31-2

Learning Outcomes (cont.)
31.1 Describe the structure, location, and
functions of the kidney.

31.2 Explain how nephrons filter blood and
form urine.


31-3

Learning Outcomes (cont.)
31.3 Compare the locations, structures, and
functions of the ureters, bladder, and
urethra.
31.4 Describe the causes, signs and
symptoms, and treatments of various
diseases and disorders of the urinary
system.


31-4

Introduction
Kidneys
Kidneys
Ureters
Ureters
Bladder
Bladder
Urethra
Urethra
• System functions to remove waste products
from the blood
• Nephrons filter the blood and form the urine


31-5

The Kidneys
• Maintain homeostasis
– Remove metabolic waste products
– Secrete hormones
• Erythropoietin
• Renin

– Retroperitoneal at level of lumbar
vertebrae

Kidneys


31-7

The Kidneys

(cont.)

• Renal sinus
– Concave depression
on the kidney's surface
– Hilum
• Renal pelvis
– Expansion of the ureter
– Divides into calyces
Kidney


31-8

The Kidneys

(cont.)

• Renal cortex – outermost layer
• Renal medulla
– Middle portion
– Divides into renal pyramids
• Renal column – between pyramids

Kidney

31-10

Nephrons
• Renal corpuscle
– Glomerulus ~ capillaries
– Bowman’s capsule

Nephron


31-11

Nephrons
• Renal tubules – extend from Bowman’s
capsule
– Proximal convoluted tubule
– Loop of Henle
– Distal convoluted tubule

Nephron


31-12

Nephrons (cont.)
Renal
artery

Renal vein

Afferent
arterioles

Peritubular
Capillaries

Glomerulus

Efferent
arterioles
Nephron


31-14

Apply Your Knowledge
What is the function of the kidney?
ANSWER: Maintain hemostasis by removing metabolic
waste products from the blood, secreting erythropoietin
to help regulate RBC production, and secreting renin to
help regulate the BP.

Correct!


31-15

Urine Formation
• Glomerular Filtration
– Occurs in renal corpuscles

– Fluid part of the blood
• Into Bowman’s capsule
• Becomes glomerular filtrate

Glomerulus


31-16

Urine Formation (cont.)
• Glomerular filtration
– Filtration pressure – that needed to force
filtrate from the glomerulus into Bowman’s
capsule
– Rate of filtration
• Sympathetic nervous system control
• Constriction of afferent arterioles

Glomerulus


31-18

Tubular Reabsorption
• Glomerular filtrate  proximal convoluted
tubule
• Reabsorption of needed substances
• Water reabsorption  hormonal regulation
– Antidiuretic hormone (ADH)
– Aldosterone

  water reabsorption,  urine production
Tubular
Reabsorption


31-19

Tubular Secretion
• Substances move • Secreted
substances
from blood in the
peritubular
– Drugs
capillaries into
– Hydrogen ions
the renal tubules

– Waste products

Tubular
Secretion


31-21

Urine Composition
• Mostly water
• Urea and uric acid
• Trace amounts of amino acids and various
ions

• Secretion of waste products helps to
maintain the acid-base balance


31-22

Apply Your Knowledge
Match the following:

ANSWER:

B Second process in urine formation
___
C Substances move from blood
___
into renal tubules reabsorption
A
___

Depends on filtration pressure

A. Glomerular
filtration
B. Tubular
Reabsorption
C. Tubular
Secretion

C Third process of urine formation
___

A
___
First process of urine formation
B
___
Filtrate flows into the proximal convoluted tubule


31-24

Urinary Bladder
• Trigone – triangle on internal floor of bladder
• Detrusor muscle – smooth muscle of bladder
wall
• Micturition
– Process of urination
– Triggered by stretching of the bladder

Bladder


31-26

Urinary Bladder (cont.)
• Micturition
Impulses to contract
urethra  inhibit
micturition impulse until
ready to urinate

Brain stem
and cerebral
cortex

Spinal cord
Parasympathetic
nerves stimulate
detrusor muscle
Stretch
receptors

Bladder
distends


31-27

Urethra
• 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
Urethra


31-28

Apply Your Knowledge
True or False: ANSWER:
T Ureters move urine by peristalsis.
___
F The detrusor is formed by the openings of the ureters
___
and urethra. trigone
T The process of micturition is triggered when the bladder
___
contains about 150 ml urine.
ureters

F The urethra move urine from the kidney to the bladder.
___
F The urethra is longer in females.
___

males

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


31-29

Diseases and Disorders of the Urinary System
Disease/Disorder Description
Acute kidney
(renal) failure

Sudden loss of kidney function;
may be reversible with
treatment

Chronic kidney
(renal) failure

Kidneys slowly lose ability to
function; not reversible

Cystitis

Urinary bladder infection; more
common in females


31-30

Diseases and Disorders of the Urinary System
Disease/Disorder Description
Glomerulonephritis Inflammation of the glomeruli of
the kidney; one cause of
chronic renal failure
Incontinence

Inability to control urination

Polycystic kidney
disease

Enlargement of kidneys
because of the presence of
many cysts within them; slow,
progressive disease


31-31

Diseases and Disorders of the Urinary System
Disease/Disorder Description
Pyelonephritis

Complicated urinary tract
infection; begins 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


31-32

Apply Your Knowledge
Matching:

ANSWER:

G
O
B. Glomerulonephritis
O
C. Incontinence
D
D. Chronic renal failure
J
E. Renal calculi
O
F. Cystitis
B
G. Acute renal failure
!
H. Polycystic kidney disease

A Complicated urinary tract infection A. Pyelonephritis
___
C Inability to control urination
___
E Kidney stones
___
D Slow loss of kidney function
___
F Bladder infection
___
B Inflammation of the glomeruli
___

H Kidney enlargement due to cysts
___
G Sudden loss of kidney function
___