URINARY

Major Excretory Organ

Kidneys

Kidneys Regulate Blood Volume and Pressure

By producing varying volumes of urine

Kidneys Regulate Ions

Glucose, Na+, Cl��, K+, Ca2+, and HPO4

Kidneys Regulate Extracellular Fluid pH

By secreting H+

Kidneys Secrete Erythropoietin

To regulate red blood cell synthesis

Kidneys Contribute to Vitamin D Synthesis

By regulating calcium levels

Kidney Shape

Bean-shaped

Kidney Location

Behind the peritoneum

Structure Surrounding Kidneys

Renal capsule

Fat Layer Function

To protect from mechanical shock

Hilum Function

The entry and exit point for blood vessels and nerves

Renal Sinus Contents

Blood vessels, urine collection system, fat

Kidney Divisions

Cortex and medulla

Calyx Definition

Funnel-shaped structure surrounding renal pyramid tips

Renal Pelvis Function

The funnel-shaped structure that narrows to form the ureter

Functional Unit of Kidney

Nephron

Number of Nephrons in Each Kidney

1.3 million

Nephron Components

Renal corpuscle, proximal tubule, loop of Henle, distal tubule

Fluid Entry in Nephron

Renal corpuscle

Fluid Path in Nephron

Proximal tubule → loop of Henle → distal tubule → collecting duct

Juxtamedullary Nephrons Percentage

15%

Cortical Nephrons

The other 85% of nephrons

Renal Corpuscle Components

Bowman's capsule and glomerulus

Inner Layer of Bowman's Capsule

Podocytes

Ureters Function

Carry urine from kidneys to bladder

Urinary Bladder Location

In the pelvic cavity

Urinary Bladder Function

To store urine

Maximum Bladder Volume

1000 mL

Urethra Function

From the bladder to the outside of the body

Trigone Definition

The portion of the bladder located between the openings of the ureters and urethra

Male Urinary Flow Control

Internal urinary sphincter

Male vs

Male extends through the penis, female is shorter and opens into the vestibule

Urine Components

Water, organic waste products, and excess ions

Urine Formation Processes

Filtration, reabsorption, secretion

Filtration Definition

Movement of substances from the blood into the nephron

Reabsorption Definition

Movement of substances from the nephron into the blood

Secretion Definition

Transport of substances from the interstitial fluid into the nephron

Filtrate

Blood plasma that enters the nephron

Tubular Reabsorption

Substances are reabsorbed from the filtrate into the blood

Protein Metabolism By-Product

Ammonia

Ammonia Conversion

By the liver

Tubular Secretion Function

Producing urine

Micturition Reflex

Activation by stretch of the bladder wall

Bladder Filling

Stimulation of stretch receptors in the bladder wall

Bladder Action Potentials

Conducted to the spinal cord

Parasympathetic Action Potentials

Cause bladder contraction

External Urinary Sphincter

Relaxes during the micturition reflex