Urinary/Excretory System

Produces urine for elimination

Essential for homeostasis

normal blood composition

acid base (pH) balance

*Uremia poisoning from wastes build up toxic

2 Kidneys: clear blood of waste products from cell metab.

2 ureters: extend from kidneys & drain urine into to bladder

1 bladder: stores urine

1 urethra: extends from bladder & drains urine to void

Urinary Meatus: opening at end of urethra

Kidney Location: Above waist, towards back, under muscles

Behind Parietal Peritoneum (lines abdomen)

Encased in fat cushion (protects, anchors)

Renal Ptosis: kidney drops tubes kink obstructs urine

drainage

Floating Kidneys: Obese w/ rapid wt loss lose xs fat @

kidneys drift

Internal Kidney Structure

Cortex: outer

Medulla: Inner

Pyramids: ∆ shape division of medulla

Papilla: ∆ Narrow innermost end of pyramid

Pelvis: Expansion of upper end of ureter

Calyx: Division of renal pelvis w/ papilla of pyramid

Narrow part of pyramid

Renal pelvis w/ pyramid

Inner layer

Outer layer

Triangle shape in medulla

Drains urine from calyx

Expansion of upper end of ureter

Clean deO2

Dirty & O2

Microscopic Structure

Each kidney > 1 million Nephrons Basic unit of S&F of kidney

Nephron: 2 main parts * Renal Corpuscle: Bowman’s Capsule: cap of glomerulus Glomerulus: Capillary network in BC Afferent arteriole (lg) in Efferent arteriole (sm) out creates ↑ pressure for filtration of wastes

* Renal Tubule: Proximal Convoluted Tubule (PCT) (cortex) 1st segment closest to Bowman’s Capsule

Loop of Henle: extension of PCT (medulla)

Distal Convoluted Tubule (DCT) (cortex) Extensions of ascending Loop of Henle Collecting Tubule: drains several DCT’s cortex medulla

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Urine from collecting tubules drain into collecting duct

papilla calyx renal pelvis

ureter bladder urethra

urinary meatus

3 Steps in Urine Formation in Nephrons

Filtration: continuous in renal corpusle

high glomerular pressure from A/E arteriole

pushes H2O & dissolved substances OUT of

glomerulus INTO BC

Ex. clean out desk remove most everything but most return thru “resorption”

If glomerular BP drops too low, (Ex. hemorrhage)

filtration stops kidney failure dialysis

Glomerular Filtration 125ml/min = 7500ml/hr = 180,000ml/day

180-190 qts!!!

But…most returns to blood thru peritubular capillary resorption!

Resorption: Mvmt of substances out of renal tubules

into peritubular capillaries

Substances resorbed: H2O, glucose, nutrients,

Na, Ions (based on intake)

Begins in PT, Loop of Henle, DT, CT

99% of H2O filtrate resorbed thru osmosis

& glucose absorbed into peritubular capillaries

thru AT in PT

K, H2O resorbed in DT

Diabetes Mellitus [blood glucose] ↑ so tubular filtrate contains more glucose than can be resorbed

Glucose in urine glycosuria

Secretion: Opposite of resorption

Substances move into urine in DT & CT from

capillaries @ tubules

Substances secreted: H+, K+, certain drugs (AT)

NH3 (diffusion)

Role in maintaining acid/base (pH) balance

& homeostasis

Control Of Urine Volume: Determined by amount of H2O & dissolved substances resorbed in PCT’s & DCT’s

ADH (Anti-Diuretic Hormone): “H2O retaining Hormone”

Made in hypothalamus

Stored in Posterior Pituitary Gland

↓’s amount of urine by making Distal/Collecting tubules

more permeable to H2O

↑ resorption, results in ↓ urine

More ADH = ↓ urine b/c tubules more permeable to H2O

Less ADH = ↑ urine b/c tubules less permeable to H2O

Caffeine & Alcohol: ↓ ADH ↑ urine ( dehydration) Nicotene: ↑ ADH ↓ urine

Aldosterone Hormone: “Salt & H2O retaining hormone”

Secreted by Adrenal Cortex

Stimulates tubules to resorb H2O & salt faster

Abnormal Urine Volume Excretion

* Anuria: no urine

* Oliguria: scant urine

* Polyuria: large amts of urine

Chilled vasoconstriction ↑ blood

flow to organs so

kidneys produce ↑ urine

Outer: adrenal cortexInner: adrenal medullaFx in tubule resorption

Ureters: Drain urine out of collecting tubules

into Renal Pelvis urinary bladder

Mucous Membranes line ureters & renal pelvis

Contraction of muscular coat peristaltic movement of

urine -> ureters bladder

Urinary Bladder: Empty, lies in pelvis

Full, projects up into lower abdominal cavity

Elastic fibers & Involuntary Muscle fx in expansion

Full: inner smooth

Empty: Rugae folds (like stomach)

Trigone:

Extends into urethra

*

males

Renal Colic: Pain from Kidney Stones (Renal Calculi)

Build up of Ca salts, uric acid, etc.

Avoid by ↑ H2O intake

Removal o kidney Stones:

Small, may pass

Large can obstruct urine flow or cause infection

Treat: Lithotripsy shock waves pulverize stones

in kidney, bladder, ureters, gall bladder too)

pass (Less invasive, faster recovery)

Surgery: Invasive, more complications, ? Infection & $$$$!

Urethra: Lower most part of urinary tract

Urine passes from bladder

↓urethra & out external

opening (Urinary Meatus)

***Same mucous membrane that lines renal pelvis, ureters, blaader, extends into urethra (so infections can spread up easily. 8” in males 1.5” in females

Urinary Catheteritization:

Insertion of catheter thru urethra into bladder

withdraw urine

(For sterile sample, surgery, urinary retention)

Requires asceptic technique to avoid infection,

cystitis (inflammation of bladder / infection)

UTI’s common nosocomial infection

Micturition: Urination / Voiding / Emptying Bladder

< 2 – 3yrs Reflex Action

>2 – 3yrs Voluntary Action

Internal Urethral Sphincter

@ bladder exit (Involuntary smooth muscle)

External Urethral Sphincter (compressor urethrae)

below bladder neck (Voluntary striated muscle)

Both contracted seal off bladder, urine accumulates & bladder stretches nerve impulses emptying reflex sphincters relax & contraction of bladder wall urine urethra void

Conditions

Urinary Retention: Kidneys produce urine but not voided

Urinary Suppression: Kidneys don’t produce urine but

bladder is able to empty

Incontinence: Void involuntarily

Elderly, stroke, spinal cord injury

lose muscle control affects emptying reflex

Cystitis: Bladder doesn’t empty completely

Residual urine chronic bladder infections

Polyuria: ↑ urine output

(hmm. ↓ levels of ADH, tubules less permeable don’t resorb as much H2O so it stays in urine))