“If you’re interested in the kidneys, then urine luck.”- Mr. Ouimette

Excretion and Reproduction

Functions of the Urinary System Excretion: the removal of organic waste from the

body fluids. Elimination: the discharge of these products into

the environment. Homeostatic regulation: Maintaining volume

and solute concentration of blood plasma. Regulates blood volume by adjusting content of urine. Regulates blood pressure by controlling red blood cell

production. Regulates plasma concentrations of electrolytes:

sodium, potassium, and chloride. Regulates and stabilizes blood pH.

Adrenal Gland

Kidney

Rectum

Bladder

Posterior Vena Cava

Abdominal Aorta

Ureter

Urethra

Kidney

Placed against the dorsal body wall, in front of the last false rib.

The right kidney is slightly lower than the left to accommodate the liver.

Renal Cortex

Renal Capsule

Renal Pelvis

Renal Pyramid

Ureter

Renal Artery

Renal Vein

Renal Medulla

Calyx

Adrenal Gland

Located on the top of the kidney. Responsible for

releasing adrenaline into the blood stream

Causes fight or flight response

Kidney Filtration

Blood to be filtered enters through the renal artery and exits through the renal vein.

The functional unit of the kidney is the nephron. Each kidney has over

1.25 million with a total length of about 85 miles of tubing.

Kidney Reabsorption

As blood enters the nephron, water and any dissolved substances smaller than proteins enter the glomerulus, a network of capillaries. Large proteins and red blood cells

exit through the afferent arteriole.

This filtration is passive.

Substances needed by the body are reabsorbed in the renal tubule. Water Glucose Amino acids Electrolytes

Kidney Reabsorption

Other waste products are not reabsorbed and will be eliminated. Urea – Waste product of protein digestion. Uric acid – Waste product of nucleic acid

digestion Creatine – Waste product of creatine

phosphate digestion in muscles. Any remaining fluid will collect in the

renal pelvis and exit the kidneys through the ureter.

Urine

The kidneys have 64 sq. ft. of filtration surface, producing about 48 gallons of filtrate per day.

99% is reabsorbed back into the body.

Urine

About 1-2 liters of urine are produced every day.

Urine is… Sterile, or free from microorganisms Slightly acidic (pH = 6) Contains unneeded electrolytes, waste

products, and ammonia. Yellow due to a pigment produced when

old red blood cells are broken down.

Urine

The presence of other substances in urine could indicate a disease or disorder. Glucose – Excess intake of sugary foods;

Diabetes Proteins – Intense physical exertion,

pregnancy. Pus – Urinary tract infection. Erythrocytes – Damage to the urinary

tract. Bile – Liver disease.

The Urinary Tract Ureter

Drains urine into the urinary bladder

Urinary Bladder Stores urine.

Urethra Tube that exits the body from

bladder. Urinary Reflex

The process of urination is a the result of two actions occurring simultaneously:▪ The muscles surrounding the

urinary bladder contract, squeezing its contents out.

▪ The external urinary sphincter relaxes, allowing urine to leave the body.

Kidney Stones

Kidney stones are crystalized minerals in the urine.

Dietary factors that increase the risk of stone formation: Low fluid intake High intake of

animal protein, sodium, sugars.

Gender Differences

Males have a much longer and narrower urethra. Higher risk of kidney stones, lower risk

of urinary tract infection. Females have a shorter and wider

urethra. Higher risk of urinary tract infection,

lower risk of kidney stones.