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Essentials of Human Anatomy & Physiology
Mr. Hildebrandt
The Urinary SystemAnatomy & Physiology II
Urinary System FunctionsUrinary System Functions Regulates homeostasis:
Water & Electrolytes
Blood pressure & pH
Red blood cell production
Elimination of waste products: Nitrogenous wastes
Toxins
Drugs
Urinary system OrgansUrinary system Organs
Kidneys
Ureters
Urinary bladder
Urethra
The Kidneys The Kidneys Against dorsal body
wall Right kidney is slightly
lower than the left 3 Regions:
Renal cortex – outer region
Renal medulla – inside the cortex
Renal pelvis – inner collecting tube
Kidney CharacteristicsKidney Characteristics Attached to ureters, renal
blood vessels, and nerves at renal hilus
Atop each kidney is an adrenal gland
Renal capsule - Surrounds each kidney
Kidney stones – filtrate concentrates, crystallizes and forms stony masses
UretersUreters Slender tubes attaching the
kidney to the bladder
Continuous with the renal pelvis
Enters posterior portion of the bladder
Runs behind the peritoneum
Peristalsis aids gravity in urine transport
Urinary BladderUrinary Bladder Smooth, collapsible, muscular sac
Temporarily stores urine
UrethraUrethra Thin-walled tube that carries
urine from the bladder to the outside of the body by peristalsis
Release of urine is controlled by two sphincters
Both sphincter muscles must open to allow
micturition (voiding)
Urethra Gender DifferencesUrethra Gender Differences
Function: Females – only carries
urine Males – carries urine &
sperm cells
Length: Females – 3–4 cm (1 inch) Males – 20 cm (8 inches)
Nephrons:Nephrons: filter “junk” out of bloodfilter “junk” out of blood Structural & functional units of kidneys Responsible for forming urine Nephron structures:
Glomerulus Bowman’s capsule Proximal convoluted
tubule Loop of Henle Distal convoluted tubule Collecting duct
Urine Formation ProcessesUrine Formation Processes Filtration - Water and
small solutes (filtrate) are forced out of glomerulus & into Bowman’s capsule
Reabsorption - Blood capillaries reabsorb 99% of water, glucose, amino acids, & ions from renal tubule
Secretion - Hydrogen & potassium move back into renal tubules resulting in urine
Formation of UrineFormation of Urine
Characteristics of UrineCharacteristics of Urine Colored somewhat
yellow due to the pigment urochrome and other solutes
1.8 liters produced per day
Slightly aromatic
pH normally 6ish
Sterile
Maintaining the BalanceMaintaining the Balance Water intake must equal water output
Blood pH must remain between 7.35 and 7.45 to maintain homeostasis
Kidneys increase water volume & sodium in blood to control blood pressure
Kidneys recognize hypoxia (low oxygen levels) & responds:
Erythropoietin is released in blood Bone marrow produces more RBCs
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