Anatomy 169 - Urinary System

Urinary system

Filters blood, removes wastes, regulates fluid, electrolytes, and pH

Kidneys

Main organs that filter blood and form urine

Ureters

Transport urine from kidneys to bladder

Urinary bladder

Stores urine until excretion

Urethra

Transports urine out of the body

Kidney location

Retroperitoneal in posterior abdomen, right lower than left due to liver

Perirenal fat

Structural fat that protects and anchors kidneys

Functional Fat

Fat stored for fuel

Structural Fat

Fat surrounding vital organs for protection

A WETBED kidney functions

Acid/base, Water balance, Electrolytes, Toxin removal, Blood pressure, Endocrine, Vitamin D activation

Normal blood pH

7.35 to 7.45

Renin

Enzyme that helps regulate blood pressure

Erythropoietin

Hormone that stimulates red blood cell production

Calcitriol

Active vitamin D for calcium/phosphate balance

Renal capsule

Outer covering that maintains kidney shape

Renal hilum

Entry/exit point for vessels and ureter

Renal cortex

Outer region of kidney

Renal medulla

Inner region with renal pyramids

Renal pyramids

Cone shaped structures in medulla

Renal papilla

Tip of pyramid that drains urine

Renal columns

Cortex tissue between pyramids

Nephron

Functional unit of kidney (~1 million per kidney)

Renal corpuscle

Site of filtration

Glomerulus

Capillary network that filters blood

Renal tubule

Processes filtrate

Proximal convoluted tubule

65% reabsorption (glucose, ions, water)

Loop of Henle

Concentrates urine, reabsorbs water

Distal convoluted tubule

15% reabsorption (ions, water)

Collecting duct

Final urine concentration

Filtration

Forces plasma out of blood into capsule

Reabsorption

Returns useful substances to blood

Secretion

Adds waste into filtrate

Fenestrated capillaries

Holes that prevent blood cells from filtering

Collagen basement membrane

Negative charge repels proteins

Podocytes

Slit structures that block plasma proteins

Minor calyx

Receives urine from papilla

Major calyx

Drains multiple minor calyces

Renal pelvis

Collects urine before ureter

Cardiac output to kidneys

1L of blood per minute

Filtration rate

120 mL per minute

Reabsorption rate

99% reabsorbed

Urine output

1.8L of urine per day

Ureters

Use peristalsis, pressure, and gravity to move urine

Goblet cells

Produce mucus to protect ureters

Urinary bladder

Hollow muscular organ that stores urine

Detrusor muscle

Muscle that contracts to expel urine

Trigone

Smooth triangular region that funnels urine

Internal urethral sphincter

Involuntary control

External urethral sphincter

Voluntary control

Micturition reflex

Urination reflex

Urine composition

95% water plus urea, uric acid, creatinine

UTI

Bacterial infection of urinary tract

UTI symptoms

Burning urination, urgency, frequent urination

Kidney stones

Hard mineral deposits in kidney

Kidney stone symptoms

Severe pain, burning urination

Urinary incontinence

Loss of bladder control

Chronic kidney disease

Gradual loss of kidney function

Interstitial cystitis

Chronic bladder pain and urgency

Urinalysis

Examines urine appearance, concentration, and contents

Dark urine

More concentrated

Cloudy urine

Indicates infection

Foamy urine

Indicates kidney problem

Protein in urine

Kidney damage

Glucose in urine

Diabetes

Ketones in urine

Type 1 diabetes or fat metabolism

Bilirubin in urine

Liver disease

WBCs in urine

Infection

Nitrites in urine

Bacterial infection

Blood in urine

Stones, cancer, or kidney disorder

Abnormal pH

UTI