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Lecture 24

Urinary System

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Urinary System Anatomy

Fig. 27.1

External Anatomy of Kidneys•Renal capsule

–surrounds each kidney•Hilum

–renal artery and nerves enter and renal vein and ureter exit kidneys

(a) Anterior view

Kidney

Ureter

Urethra

Urinary bladder

StomachPancreasLarge intestine

Abdominal aorta

Renal veinRenal artery

Renal hilum

Spleen

Left kidneyRib

Inferior venacava

Liver

Right kidney

Fibrous capsule

Fat

Anterior

Posterior Fig. 27.2

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Internal Anatomy of Kidneys• Renal cortex: Outer area

– Renal columns• Renal medulla: Inner

area– Renal pyramids

• Calyces– Major: Converge to

form renal pelvis– Minor: Collects urine

from individual renal pyramid

• Nephron: Functional unit of kidney

Fig. 27.3

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The Nephron

Fig. 27.5

• Renal corpuscle– Bowman’s capsule– Glomerulus

• network of capillaries

• Arterioles– Afferent

• blood to glomerulus

– Efferent• drains

• Tubules– Proximal (convoluted) tubule

– Loops of Henle• Descending limb

• Ascending limb

– Distal (convoluted) tubule

• Collecting ducts

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Ureters and Urinary Bladder• Ureters

– tubes through which urine flows from kidneys to urinary bladder

• Urinary bladder– stores urine

• Urethra– transports urine from

bladder to outside of body

– difference in length between males and females

– sphincters

• Internal urinary

• External urinary

Ureter

Peritoneum

Ureteral openings

Neck of urinary bladder

Internal urethral sphincter

External urethral sphincter

Fig. 27.9

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Review QuestionThink back for a moment to the lectures on histology.

What type of epithelium would line the inside of the ureters and urinary bladder?

(a) Stratified squamous(b) Pseudostratified columnar(c) Simple cuboidal(d) Transitional(e) Simple squamous

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Points to RememberPoints to Remember

• Kidney filters blood to eliminate metabolic wastes (e.g. urea formed from ammonia that is removed from blood by liver) and reabsorb substances such as sugars, amino acids, sodium and chloride

• Functional unit of kidney is nephron• Ureters, urinary bladder and urethra transport

urine (product of nephron) outside of body

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Questions?