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“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.