Urinary System

Histology 13 NSU Spring 2009 Taken by: Gregory Rodocker

Merkel Cell Carcinoma 

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Merkel cell carcinoma is a rare type of skin cancer that usually appears as a flesh-colored or bluish-red nodule, often on your face, head or neck. Like other types of skin cancers, the incidence of Merkel cell carcinoma is increasing worldwide. Also called neuroendocrine carcinoma of the skin Older people Long-term sun exposure Weak immune system

The Urinary System 

Consists of the    

Kidneys Ureters Urinary bladder Urethra

Job of the Urinary System     

Filtration Active reabsorption Passive reabsorption Secretion Also, releases renin (BP control), produces erythropoietin (to stimulate RBC production), and monitors and regulates salt and water balance for the body

Kidneys 

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Paired organs located retroperitoneal in the abdominal cavity Right kidney lower than the left due to the large liver on the right side Kidney has unique visual appearance when sliced in a frontal plane

Retroperitoneal

Renal corpuscle: “little body” 

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The nephron begins in the glomerulus (a tuft of capillaries) surrounded by a glomerular capsule or Bowman’s capsule The two collectively represent the renal corpuscle

Function of the glomerulus 

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This is the site of the process of filtration 1.2 - 1.3L of blood feeds the kidneys every minute All of the blood in the body passes through the kidneys every 4-5 minutes

Filtration 

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The two kidneys produce about 125 ml of filtrate/minute 123-124 ml/minute is reabsorbed Leaving 1-2 ml/min of urine produced About 1500 ml urine/day is produced

Structural and functional unit – the nephron

Structure of the glomerulus

Nephron 

Consists of the      

glomerulus Bowman’s capsule Proximal convoluted tubule (PCT) Loop of Henle Distal convoluted tubule (DCT) Collecting duct

Overview of kidney - Cortex

Higher Magnification of Cortex

Macula densa  

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Special regulatory structure Part of the Juxtaglomerular apparatus (JGA) Name means dense spot Composed of tightly packed cells in the wall of the DCT

Macula densa

Juxtaglomerular apparatus   

Specialized cells in the wall of the afferent arteriole Cytoplasm full of granules []-Release renin, an enzyme that converts angiotensinogen into angiotensin I, which when converted to angiotensin II serves as a potent vasoconstrictor

Ureters 

Drain the urine from the kidneys to the urinary bladder

Urinary bladder 

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Bladder lined by transitional epithelium Multiple layers of smooth muscle in bladder wall running in many directions