urinary system - westmont collegefunctions of the urinary system homeostasis of the internal...

Urinary SystemUrinary System

Makes urineMakes urine–– ((opposite of youopposite of you’’re outre out))

Functions of the Urinary SystemFunctions of the Urinary System

Homeostasis of the internal chemicalHomeostasis of the internal chemicalenvironmentenvironment

Regulation of blood pHRegulation of blood pH Regulation of blood pressure Regulation of blood pressure Stimulation of Stimulation of hemopoiesishemopoiesis Excretion of waste products through theExcretion of waste products through the

production of urine.production of urine.

StructuresStructures

KidneysKidneys

UretersUreters

BladderBladder

UrethraUrethra

Kidney Structures1. Location

a. Lateral to the vertebral column.

b. Inferior to the diaphragm.

c. Retroperitoneal.

Kidney StructuresRenal cortex

Renal medullaRenal artery

Renal vein

UreterRenal pyramid

Renal papilla

Renal column

Kidney Structures

Minor calyx

Major calyx

Renal pelvis

Pyelogram

The Nephron*Structural and functional unit of the kidney.

Structures of the NephronStructures of the nephron:

1. Renal corpuscle

2. Tubules

3. Collecting ducts

Renal CorpuscleStructures of the renal corpuscle:

1. Bowman’s capsule

2. Glomerulus

Urine Formation

The The nephronsnephrons form urine through three form urine through threeinterrelated processes:interrelated processes:–– FiltrationFiltration–– ReabsorptionReabsorption–– SecretionSecretion

Urine Formation

1. Glomerular filtration

a. Occurs in the renal corpuscle.

b. Occurs by bulk diffusion.

c. Forms an ultrafiltrate.

Urine Formation


2. Tubular reabsorption

Urine Formation



a. Occurs primarily in the PCT.

b. 99% of ultrafiltrate is reabsorbed.

c. Returns the ultrafiltrate to the blood.

Urine Formation



3. Tubular secretion

Urine Formation




a. Opposite of reabsorption.

b. Active transport returns unwanted materials to help form the urine.

c. Highly selective.

Urine Formation




4. Concentration

5. Acidification

Ureters1. Paired structures.

2. Two layers of smooth muscle.

3. Moves urine by peristalsis to the bladder.

Urinary Bladder1. Single structure.

2. Highly elastic smooth muscle called the detrusor -- 3 layers.

3. Lined with transitional epithelium.

4. Series of rugae.

Urethra1. Single tubular structure that carries urine to the outside of the body.

2. Thin smooth muscular layer surrounds the mucosa.

3. Sphincters.

4. Female urethra.

a. Located between theclitoris and vagina.

b. ~1.5” in length.

c. Urinary function.

Urethra1. Single tubular structure that carries urine

to the outside of the body.

2. Thin smooth muscular layer surroundsthe mucosa.

3. Sphincters

4. Female urethra.

5. Male urethra.

a. 3 portions.

b. ~8 inches in length.

c. Urinary and reproductive function.

MicturitionMicturition Reflex Reflex

The urge appears with approximately 200ml of urine

Baroreceptors relay information to sacral spinal cord and cerebral cortex

Activation in sacral spinal cord activates p-symp motor neurons to contract detrusor

Detrusor contracts the bladder against the internal urethral sphincter.

If internal urethral sphincter does not open, then the bladder gradually relaxes.

This repeats until…..

The external urethral sphincter relaxes, allowing the internal urethral sphincter torelax, and the detrusor contracts, expelling urine.

Urinary ProblemsUrinary ProblemsIncontenence: Decreased muscle tone of sphincter muscles. Results in slow

leakage of urine.

Calculi: aka Kidney stones. Accumulation of calcium or crystal within the urinarytract, leading to a condition called nephrolithiasis

Urinary Tract infection: Most common in females. Bacteria enters the urinary tract and infects some part (bladder, urethra, medulla). Asssociatedwith a frequent urge to urinate despite acute pain. Can be serious.

urinary system - westmont collegefunctions of the urinary system homeostasis of the internal...

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