University:
Glendale Community College
Course:
BIO160 | Introduction to Human Anatomy and Physiology
Academic year:

2020
Views:

240

Pages:

22
Author:

Iris Powell

Urinary System Anatomy Kidneys Ureters Urinary Bladder Urethra Position of the Kidneys • The kidneys are retroperitoneal, located behind the peritoneal membrane of the abdomen. • Adipose Capsule – Adipose cushions and positions kidney. – This fat is not normally used to store energy, rather it is protection from mechanical injury and for maintaining position of kidney and vessels. – Loss of this fat can lead to renal ptosis (drooping of kidney. – Renal ptosis can lead to renal failure if vessels get pinched. Position of the Kidney Gross Anatomy of the Kidney Kidney Anomalies Occasionally people will have only one kidney on one side or one horseshoe-shaped kidney as in these images. Kidney Functions • Filters blood plasma and eliminates nitrogenous wastes and returns useful substances to blood. • Regulates water balance and osmolarity of body fluids which also affects blood volume and blood pressure. • Secretes renin which is part of the angiotensin system that regulates blood pressure. • Secretes erythropoietin (RBC production). • Regulates acid-base balance of the blood. • Contributes to calcium homeostasis through Vitamin D activation (the liver also activates Vitamin D). Excretion • Excretion is the separation and elimination of wastes from body fluids. • Excretion is accomplished by several organ systems: – respiratory system: CO2 exhaled into the air – integumentary system: water, salts, urea in sweat – digestive system: water, salts, excess lipids, undigested fibers in feces – urinary system: water, salts, toxins, drugs, hormones, excess H+, nitrogenous wastes and many other metabolic wastes into urine Nitrogenous Wastes • Urea – amino acid catabolism produces highly toxic ammonia (NH3) that the liver converts into less toxic urea • Uric Acid – uric acid is produced from nucleic acid catabolism • Creatinine – Creatinine is a breakdown product of creatine, which is a byproduct of the phosphagen enzyme system for ATP production in skeletal muscle. The normal daily production of creatine and subsequently creatinine, is usually very stable. Creatinine is excreted from the body entirely by the kidneys. With normal renal excretory function, the serum creatinine level should remain at a constant low level. Properties and Composition of Urine Composition and Properties of Urine • Appearance – ranges from almost colorless to deep amber; yellow color is partly due to urochrome, from breakdown of hemoglobin – other colors from digestion of food (carotenoids) or drugs – cloudiness can be due to bacteria • Odor - bacteria degrade urea into ammonia • Osmolarity - ranges from dilute in a well-hydrated person (50 mOsm/L) to highly concentrated (1,200 mOsm/L) in a dehydrated person. Normal blood = 300 mOsm/L. • pH – is usually around 6, but can vary 4.5 - 8.2 • Chemical composition: 95% water, 5% solutes – solutes are mostly urea, ammonia, Na+, K+, Cl+, creatinine Urine Output • • • • Normal volume: 1-2 liters/day Polyuria > 2 liters/day Oliguria < 500 ml/day Anuria: 0 to 100 ml/day Anatomy of the Kidney Hilum Hilum • • • • Renal Cortex: outer 1 cm Renal Medulla: composed of renal pyramids Renal Pelvis: connective tissue cavity that collects urine Hilum is the indented area of the kidney where the blood vessels and ureter attach Kidney Stones x-ray of “Staghorn” Kidney Stone and the kidney stone after surgery Blood Flow Through the Kidney Renal Artery  Glomerulus  Renal Vein Nephrons: the functional units of the kidney have vascular parts and tubular parts Efferent Arteriole Afferent Arteriole vascular parts of the nephron: afferent arteriole glomerulus efferent arteriole peritubular capillaries vasa recta tubular part of the Nephron Bowman’s Capsule Proximal ConvolutedTubule Loop of Henle (nephron loop) - descending thin limb - ascending thick limb Distal Convoluted Tubule Collecting duct Renal Filtrate Formation and Excretion plasma in glomerular capillary Bowman’s capsule proximal convoluted tubule (PCT) loop of Henle (nephron loop) distal convoluted tubule (DCT) collecting duct minor calyx major calyx renal pelvis ureter urinary bladder urethra Summary of Filtration by the Nephron Filtration, Reabsorption, Secretion and Excretion by the Nephron