Anatomy and Physiology - Urinary System - Lecture Slides |, Study notes of Physiology

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The Urinary System

Chapter 15 Lecture

The Urinary System

‡ The urinary system removes wastes from the body

‡ Consists of:

± Kidneys

± Ureters

± Urinary bladder

± Urethra

Kidneys

‡ Kidneys

± Reddish-­‐brown, bean-­‐shaped organs

± Positioned retroperitoneally on either side of the vertebral

column

‡ Between T12 and L ‡ Left kidney sits slightly higher than the right

± Surrounded by adipose and connective tissues

Kidneys

‡ Kidney Structure

± Lateral surface is convex, medial side is concave

‡ Medial depression leads to the hollow renal sinus ± Blood vessels, nerves, lymphatic vessels, and the ureter enter the kidney

‡ Superior end of the ureter forms the renal pelvis within the renal sinus ± Divided into major and minor calyces ( tubes ); small renal papillae project into each minor calyx

± Two distinct regions within the kidney:

‡ Renal medulla Ȃ renal pyramids; appears striated ‡ Renal cortex Ȃ contains the nephrons

Kidneys

‡ Renal Blood Vessels

± Renal arteries

‡ Carry O 2 -­‐rich blood from the abdominal aorta into the kidneys ± Branch into smaller diameter arteries and arterioles ± Afferent arterioles lead to the nephrons

± Renal veins

‡ Move O 2 -­‐poor blood from the kidneys into the inferior vena cava in the abdominal cavity

Urine Formation

‡ Glomerular Filtration

± Filtration of the blood plasma by the glomerular capillaries

‡ Substances move from the glomerular capillaries into the glomerular capsules ± Filtrate consists mostly of water

± Hydrostatic pressure of the blood moves substances via

filtration through the walls of the glomerular capillaries

‡ Osmotic pressure of the blood resists filtration

± Filtration rate is influenced by:

‡ Vasoconstriction of afferent and efferent arterioles ‡ Plasma colloid osmotic pressure