Anatomy and Physiology Overview
• Regulates fluid and electrolytes, removing wastes and providing hormones involved in
red blood cell production, bone metabolism, and control of blood pressure.
• Kidneys
o located behind the outside of the peritoneal cavity (retroperitoneally)
o contain nephrons: the structural and functional units of the kidneys responsible
for urine production.
• Ureters, bladder, and Ureters
o Urine flows from the kidneys, down the ureters, into the bladder, then to the
urethra.
o The usual capacity of the adult bladder is 300 to 500 mL, but it can distend.
o Micturition: voiding or urination.
o the only tie that the bladder is completely empty is the last seconds of
micturition, before effux of urine resumes
Function of the Kidney and Urinary system (view figure 53-3 pg1151) *
• Urine is formed in the neurons through glomerular filtration, tubular reabsorption, and
tubular secretion.
o Substances that are filtered, reabsorbed, and excreted include
▪ Sodium, potassium, chloride, bicarbonate, glucose, urea, creatinine, uric
acid
o Renal glycosuria: excretion of glucose in the urine
▪ Occurs in poorly controlled diabetes
o Proteinuria: protein in the urine
• Antidiuretic hormone
o Also known as vasopressin
o Hormone secreted by the posterior pituitary gland in response to the changes in
osmolality of the blood
o Decreased water intake increases blood osmolality, stimulating ADH release.
o Excess water intake causes the secretion of ADH is suppressed; less water is
absorbed which leads to diuresis (increased urine volume)
• Osmolality and Osmolarity
o Osmolarity: refers to the ratio of solute to water
o controlling either the amount of water or the amount of solute can change the
osmolarity
o Osmolality: the number of osmoles dissolved per kilogram of solution.
• Regulation of Electrolyte Excretion (View figure 53-4 pg 1552)
o The regulation of sodium volume excreted depends on aldosterone, hormone
released and synthesized by the renal cortex.
o Release of aldosterone from the adrenal cortex is under the control of angiotensin
II.