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Biology 322 Human Anatomy I Renal System Organs of Renal System Kidney Located high in abdominal cavity Posterior to peritoneum Liver pushes right kidney more inferiorly Mass ~ Size ~ Kidney : External covering of dense irregular connective tissue Outer solid region Inner solid region 8 to 12 cone-shaped masses (apex toward hilus) called renal , separated by renal . Hollow medial region, extensions = calyces Connects medially with ureter Kidney: Each renal artery (direct branch of aorta) divides into lobar (segmental) arteries, which divide into interlobar arteries, then arcuate arteries (between cortex & medulla), which give off interlobular arteries into both cortex & medulla. You learned these as part of the renal lab exercise. Be sure you also know them for lecture exams In cortex, interlobular arteries send blood through afferent arterioles into groups of capillaries called glomeruli. This is where filtration will occur to begin formation of urine From a glomerulus, blood flows out an efferent arteriole to another set of capillaries called peritubular capillaries which surround the tubules where urine is forming. Each renal artery divides into lobar arteries, interlobar arteries, arcuate arteries, interlobular arteries, afferent arterioles, glomeruli, efferent arterioles, peritubular capillaries Blood then flows into interlobular veins or arcuate veins, interlobar veins, and lobar veins to reach the renal vein which carries it to the inferior vena cava. Let’s go back to the glomerulus: Consists of a group of interconnected capillaries. As blood flows through these capillaries, plasma (the liquid part of blood) is filtered out and flows though a series of tubes to form urine. This series of tubes is called a nephron. Structure of Glomerulus Capillary wall (simple squamous epithelium, fenestrated) plus podocytes plus basement membrane between them form the filtration membrane across which liquid is filtered from the blood to the glomerular capsule. Each kidney contains ~ 1,000,000 nephrons Pattern of nephrons creates pattern of cortex and medulla: Cortex consists primarily of convoluted tubules which twist many directions. Medulla consists primarily of loops of Henle & collecting ducts all oriented in the same direction This fluid filtered out of the blood flows into the proximal convoluted tubule, through other parts of nephron, into collecting duct. Recall that nephron is surrounded by peritubular capillaries for resabsorption of water and solutes Urine passes from a collecting duct into a minor calyx, then a major calyx, then the pelvis of the kidney. Urine leaving the pelvis enters the ureter, which carries it to the urinary bladder. Ureters: Retroperitoneal. Anterior to common iliac arteries & veins. Deliver urine to posterolateral parts of urinary bladder. Ureter: Mucosa: Transitional epithelium Lamina Propria (loose C.T.) Muscularis: Thick wall of smooth muscle Adventitia: Dense irregular C.T. Urinary Bladder: In pelvis, posterior to pubic bone Superior surface covered by peritoneum Female: Anterior to uterus/vagina Male: Anterior to rectum Superior to prostate Urinary Bladder: Mucosa: Transitional epithelium Lamina propria Muscularis: Thick smooth muscle (“detrusor”) Adventitia (C.T.) covers most of bladder Serosa on its superior surface Urinary Bladder: Urinary Bladder: Urinary Bladder: Muscularis (detrusor muscle) and Internal Urethral Sphinter both smooth muscle; thus involuntary Urine leaving bladder enters urethra Urethra: Adventitia: Dense irregular C.T. Muscularis: Thick wall of smooth muscle Mucosa: Epithelium varies from transitional near bladder to stratified squamous at end Male urethra much longer, has middle region of stratified columnar. Female urethra does not. Lamina Propria (loose C.T.) External Urethral Sphincter External Urethral Meatus Tonight: On yourself or another person, locate kidneys ureters bladder urethra
"Biology 211 Anatomy _amp; Physiology I"