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Maintain Homeostasis by:
- Regulating water balance and concentration of solutes
- Ensuring acid-base solute
- Excreting metabolic waste
- Production of erythropoietin (hormone that changes stem cells to red blood cells )and renin
- Converting Vitamin D to active form
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Urinary System
- Kidneys
- Ureters
- Bladder
- Urethra
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Structure of Kidneys
- 3 layers of supportive tissue
- Renal fascia = connective tissue "anchors" kidney
- Perirenal fat capsule = cushion kidney
- Fibrous capsule = prevents infections from surrounding area
Peritoneum - upper abdominal cavity
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Homeostasis Imbalance
- Renal ptosis = lack of fatty tissue supporting kidney causes it to drop
- Kink in ureter causes urine to back up and increase pressure on kidney tissues
- Hydronephrosis = "water in the kidney" can lead to necrosis (tissue death) and renal failure
- Pyelitis = infection of renal pelvis and calyces
- Pyelonephritis = infection or inflammation of entire kidney
- Usually caused by fecal bacteria spread from anal region (improper wiping techniques, sexual intercourse)
- Kidney swells, abcesses form, pelvis fills with puss
- Untreated infections may cause severe damage
- Treat with antibiotics
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Gross Anatomy of Kidney
- Fibrous capsule - outside surface
- Cortex - outer inside
- Medulla - pyramid
- Minor calyx - opening of pyramids
- Major calyx - central opening
- Pelvis - leads into ureter
- Ureter - going out of kidney
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Blood flow through the kidney
- aorta - renal artery - (segmental artery) - arcuate artery - cortical radiate artery
- afferent arteriole - glomerulus (capillaries) - efferent arteriole
- Peritubular capillaries or vasa recta
- Cortical radiate vein - arcuate vein - interlobar vein - renal vein - inferior vena cava
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Nephrons: Functional Unit of Kidney
- Renal corpuscle/glomerulus: fed and drained by afferent and efferent arterioles - filtration unit
- Renal tubule (~3 cm) long): begins in cortex, passes into medulla - 3 parts - reabsorb water and solutes needed by the body
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Urine Formation Step 1: Glomerular Filtration
- Passive process caused by hydrostatic pressure
- Porous membrane between blood and interior of glomerular capsule
- Allows water and small solutes to cross, plasma proteins are too big and do not cross
- Homeostatic Imbalace: Protein in urine indicates a problem with the membrane - anuria = low urinary output (indicates glomerular blood pressure too low to allow for filtration)
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Urinary Formation Step 2: Tubular Reabsorption
- Begins as soon as filtrate enter the proximal tubules
- Proximal Convoluted Tubule -
- Nephron Loop -
- Distal Convoluted Tubule -
- Collecting Duct - urine
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Urine Formation Step 3: Tubular Secretion
- Excreted urine contains both filtered and secreted substances
- Tubular secretion is important for: disposing of substances bound to proteins that cannot be filtered (drugs and metabolites) - (controlling blood pH)
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Non-lecture, but know for test
- Physical characteristics of urine p 978-979
- Urine transport, storage and elimination p 979-982: structures/functions - homeostatic imbalances
Specific Gravity - only water is pure (H2O 1.000)
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