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

The learning objectives for this chapter include: Describe the structure, location, and functions of the kidney; explain how nephrons filter blood and form urine; compare the locations, structures, and functions of the ureters, bladder, and urethra; describe the causes, signs and symptoms, and treatments of various diseases and disorders of the urinary system.

The Urinary System

Learning Outcomes (cont.)

31.1 Describe the structure, location, and

functions of the kidney

31.2 Explain how nephrons filter blood and

form urine

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

• System functions to remove waste products

from the blood

• Nephrons filter the blood and form the urine

Kidneys

Ureters

Bladder

Urethra

The Kidneys (cont.)

– Expansion of the ureter

– Divides into calyces

Kidney

• Renal cortex – outermost layer

• Renal medulla

– Middle portion

– Divides into renal pyramids

• Renal column – between pyramids

The Kidneys (cont.)

Kidney

Nephrons (cont.)

Afferent arterioles

Renal artery

Efferent arterioles

Efferent arterioles

Peritubular Capillaries

Peritubular Capillaries

Renal vein

Nephron

Glomerulus

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!

Urine Formation

• Glomerular Filtration

– Occurs in renal corpuscles

– Fluid part of the blood

• Into Bowman’s capsule

• Becomes glomerular filtrate

Glomerulus

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

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

Tubular Secretion

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

Apply Your Knowledge

Match the following:

_ Second process in urine formation

_ Substances move from blood

into renal tubules reabsorption

_ Depends on filtration pressure

_ Third process of urine formation

_ First process of urine formation

_ Filtrate flows into the proximal convoluted tubule

C Tubular Secretion

Urinary Bladder

• Trigone – triangle on internal floor of bladder

• Detrusor muscle – smooth muscle of bladder

Stretch receptors

Spinal cord

Parasympathetic nerves stimulate detrusor muscle

Brain stem and cerebral cortex

• 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

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

T

ANSWER:

trigone

Diseases and Disorders of the Urinary System

(renal) failure Kidneys slowly lose ability to function; not reversible

Cystitis Urinary bladder infection; more

common in females

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

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

Apply Your Knowledge

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

D J O B

!

In Summary

31.1 The retroperitoneal kidneys are

composed of the outer renal cortex and inner renal medulla

Their function is to remove metabolic wastes from the body

In Summary

31.2 A nephron is a single kidney cell

It is composed of a renal corpuscle composed

of the glomerulus and the Bowman’s capsule and the three sections of the renal tubule: the proximal convoluted tubule, the loop of Henle, and the distal convoluted tubule

The nephrons filter blood and form urine through three processes: glomerular

filtration, tubular reabsorption, and tubular secretion

In Summary (cont.)

31.3 The ureters are long tubes extending from

each renal pelvis that bring urine to the bladder for storage

The urethra is the muscular tube extending from the bladder that allows urine to be expelled from the body

In Summary (cont.)

31.4 There are many common diseases and

disorders of the urinary system with varied signs, symptoms, and treatments

Some of these include acute kidney (renal) failure, chronic kidney (renal)

failure, cystitis, glomerulonephritis,

incontinence, polycystic kidney disease,

pyelonephritis, and renal calculi.

End of Chapter 31

This too shall pass—just

like a kidney stone.

~H Madson