ureters, bladder, urethra #urinary

ureter

fibromuscular, epithelial lined tubes that transport urine to bladder

ureter histology

1. Mucosa: impermeability of urine passage + lamina propia

2. Muscularis: circular layer of SM that contracts urine through ureters

3. Adventitia: external layer of wall - collagen and elastic fibers

Ureter NS innervation

ANS via sympathetic and parasympathetic nerves

Bladder

• expandable, muscular sac that holds urine

• retroperitoneal

bladder histology

1. mucosa: transitional epithelium and lamina propria

2. submucosa: dense CT that supports bladder wall.

3. muscularis: 3 layers of SM called detrusor

4. adventitia: outer layer

trigone

functions as a funnel to direct urine to the urethra

Urethra

epithelial-lined, fibromuscular tube that goes from bladder to urethral openingurethr

urethra histology

1. internal urethral sphincter: involuntary, controlled by ANS

2. external urethral sphincter: voluntary, controlled by somatic NS

3. external urethral orifice: opening of the urethra where urine exits body

Urethra: females

single function

transports urine

Urethra: males

dual function

urinary and reproductive

Three segments

1. prostatic urethra

2. membranous urethra

   1. spongy urethra

Clinical view: Renal Calculi

Kidney stones

formed by crystalline minerals building up in kidney

Micturition

another word for ‘urination’

• stretch receptors trigger reflex

• parasympathetic input contracts bladder

• micturition center in pons

Sympathetic NS: bladder effect

• causes contraction of the internal urethral sphincter

• prevents micturition

parasympathetic NS: bladder

• causes contraction of detrusor muscle

• relaxation of the internal urethral sphincter

• promotes micturition

Somatic NS: bladder

• causes contraction of the external urethral sphincter.

• allows conscious control of micturition

Storage reflex

• continuous sympathetic stimulation

• stimulates contraction of the internal urethral sphincter

• allows the bladder to fill w urine.

Micturition reflex

when bladder vol. reaches max (200-300 mL), baroreceptors send signal to pons > activates parasympathetic nerves > relaxes internal urethral sphincter

Conscious control

occurs within cerebral cortex

stores up to 500-600 mL

associated w contraction of abs and expiratory muscles

Clinical view: UTI

• when bacteria or fungi multiply in urinary tract

• women are more prone due to shorter urethra

• treated with antibiotics

incontinence

inability to voluntarily control urination

retention

failure to eliminate urine normally