Urinary System

Primary role of the urinary system

Elimination of waste products and maintenance of homeostasis

Four main parts of the urinary system

Kidneys (2), Ureters (2), Urinary Bladder (1), Urethra (1)

Filtration product created by the kidneys

Filtrate (includes metabolic wastes, ionic salts, toxins, drugs)

Hormone produced by the kidney to stimulate RBC production

Erythropoietin

Kidney product that causes vasoconstriction to regulate blood pressure

Renin

Hormone that targets the kidney to limit water loss (blood volume balance)

ADH (Antidiuretic Hormone)

Hormone that reclaims sodium (Na+) for electrolyte balance

Aldosterone

Location of the kidneys

Retroperitoneal (behind the peritoneum) against the posterior abdominal wall (T12-L3)

Gland located on top of each kidney

Adrenal gland

Kidney covering that provides protection and location; made of fat Adipose

Capsule

Term for a kidney dropping from its normal position

Ptosis

Outer region of the kidney (shell)

Renal Cortex

Middle region of the kidney, containing pyramids

Renal Medulla

Inner collecting tube that divides into calyces

Renal Pelvis

Structural and functional unit of the kidney

Nephron (over 1 million per kidney)

Two main components of the nephron

Renal Corpuscle and Renal Tubule

Knot of capillaries in the renal corpuscle

Glomerulus

Structure that encloses the glomerulus

Bowman's Capsule (Glomerular Capsule)

Arteriole carrying blood to the glomerulus

Afferent Arteriole

Arteriole carrying blood away from the glomerulus

Efferent Arteriole

Tubule section covered with dense microvilli for reabsorption

Proximal Convoluted Tubule (PCT)

The descending limb of the nephron

Loop of Henle

Tubules that merge to form the collecting duct

Distal Convoluted Tubules (DCT)

Tubule that collects urine but is technically NOT part of the nephron

Collecting Duct

Primary site of Filtration in the nephron

Glomerulus (Bowman's Capsule)

Primary site of Reabsorption (glucose, amino acids, needed ions)

Proximal Convoluted Tubule (PCT)

Four major processes of urine formation

Filtration: water and solutes, Reabsorption: water, glucose, amino acids , and ions in PCT, Secretion: Na, K, and electrolytes, ADH release

Where does ADH primarily act to promote water reabsorption

Collecting Duct

Percentage of nephrons that are Cortical (short loop)

85%

Efferent arterioles branch into blank around PCT and DCT

Particular capillaries

Percentage of nephrons that are Juxtamedullary (long loop)

15%

Capillaries surrounding the loop of Henle in juxtamedullary nephrons

Vasa Recta

Main component of urine

95% H2O, contains urea, uric acid, electrolytes, and amino acids

Normal urine output per hour

50−60 mL/hour

Vessel carrying blood into the kidney

Renal Artery

Vessel carrying blood away from the kidney

Renal Vein

Tubes carrying urine from the kidney to the bladder.

Ureters

How long are the ureters?

10-12 inches long. ¼ inches diameter

Mechanism that helps urine flow through the ureters

Peristalsis

Urine in male

60%

Urine in females

50%

Urine in babies

75%

Urine in elderly

45%

Feature that prevents backflow of urine into the ureter

Valve at the top of the bladder

Structure of the bladder's wall

(epithelium) Transitional Epithelium- allows for stretching

Has three openings (trigone)- 2 from ureters and 1 from urethra

Bladder

How much urine does the bladder hold ?

500mL of urine when moderately fill (urge to void). Full bladder twice that

Carries urine to the outside of the body by peristalsis

Urethra

Approximate volume of urine when the urge to void is felt

200 mL

Where bacterial diseases occur of the bladder

Trigone (area of three openings)

Sphincter that is involuntary smooth muscle

Internal Urethral Sphincter

Sphincter that is voluntary skeletal muscle

External Urethral Sphincter

Male urethral length

7-8 inches

Female urethral length

1-1.5 inches

Condition where one cannot control urination

Incontinence

Condition where one is unable to empty the bladder

Retention

Inflammation of the urethra

Urethritis

Inflammation of the kidneys (type of UTI)

Pyelonephritis