Urinary+System - Chapter 26 Theurinary Urinary System...

Chapter 26
The Urinary System
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Kidneys, ureters, urinary
bladder & urethra
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Urine flows from each
kidney, down its ureter to
the bladder and to the
outside via the urethra
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Filter the blood and return
most of water and solutes
to the bloodstream

Overview of Kidney Functions
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Regulation of blood ionic composition
–
Na+, K+, Ca+2, Cl- and phosphate ions
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Regulation of blood pH, osmolarity & glucose
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Regulation of blood volume
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conserving or eliminating water
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Regulation of blood pressure
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secreting the enzyme renin
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adjusting renal resistance
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Release of erythropoietin & calcitriol
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Excretion of wastes & foreign substances

External Anatomy of Kidney
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Blood vessels & ureter enter hilus of kidney
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Renal capsule = transparent membrane maintains organ shape
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Adipose capsule that helps protect from trauma
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Renal fascia = dense, irregular connective tissue that holds against
back body wall

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Urinary Bladder
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The urinary bladder is a hollow muscular organ
situated in the pelvic cavity posterior to the pubic
symphysis.
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Anatomy and Histology of the Urinary Bladder
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In the floor of the urinary bladder is a small,
smooth triangular area, the trigone . The ureters
enter the urinary bladder near two posterior points
in the triangle; the urethra drains the urinary
bladder from the anterior point of the triangle
(Figure 26.21).

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Histology of Urinary Bladder
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3 layers in wall
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mucosa is transitional epithelium & lamina
propria
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since organ must inflate & deflate
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mucus prevents the cells from being contacted by
urine
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muscularis (known as detrusor muscle)
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3 layers of smooth muscle
–
inner longitudinal, middle circular & outer longitudinal
•
circular smooth muscle fibers form internal urethral
sphincter
•
circular skeletal muscle forms external urethral
sphincter
–
adventitia layer of loose connective tissue

Blood Vessels around the Nephron
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