URINARY+SYSTEM+-++ANATOMY+and++PHYSIOLOGY

**__FUNCTIONS OF THE URINARY SYSTEM__** **__ LOCATION OF THE KIDNEYS and the rest of this system __** Identify and label all the parts of the system. __** A closer look at the bladder **__ **__ Longitudinal Section through a kidney - Internal structure __** You should be able to draw and label the internal structure of the kidney **__ Locating the Nephrons within the kidney __** __** A closer look at a nephron **__ You should be able to draw and label a nephron. Structure can be simplified to show details more clearly. Hand-out will be provided. __** Types of nephrons **__ Cortical Nephrons: Located in cortex -- loops of renal tubules may extend into medulla Juxtamedullary Nephrons : Malpighian body (Renal corpuscle) lies on border between cortex and medulla. Henle's tubules in medulla. Collecting Tubulules converge to form the ducts of Bellini that runs down the centre of the renal papilla and is also referred to as the papillary duct or papillary duct of Bellini These papillary ducts converge into a calyx and these ducts form the renal pyramid as they narrow down into the calyx. **__ Focusing on the GLOMERULUS __** __ The Juxta-Glomerular complex/ apparatus __ **__ URINARY PHYSIOLOGY __** 3 MAJOR PROCESSES : Pressure Filtration, Tubular Reabsorption , Tubular Secretion __ Filtration __ Nonselective passive process : Water and solutes smaller than proteins are forced through capillary walls
 * __ ANATOMY OF THE URINARY SYSTEM __**

Blood cells cannot pass out to the capillaries ; Filtrate is collected in the glomerular capsule and leaves via the renal tubule ** Describe the structure of the Malpighian body (Renal corpuscle), hiliting the special features of this structure that facilitate efficient pressure filtration **

__ Reabsorption __ ** The peritubular capillaries reabsorb several materials : **
 * A.Some water
 * B.Glucose
 * C.Amino acids
 * D.Ions

Some reabsorption is passive, **most is active** Most reabsorption occurs in the **proximal convoluted tubule**

Nitrogenous waste products Excess water __ Tubular Secretion __ Some materials move from the peritubular capillaries into the renal tubules Materials left in the renal tubule move toward the ureter ** Describe the structure of the nephron, hiliting the special features of this structure to efficiently reabsorb and secrete (excrete) substances to maintain a healthy environment inside the body. ** __ CHARACTERISTICS OF URINE USED FOR MEDICAL DIAGNOSIS __ Colored somewhat yellow due to the pigment urochrome (from the destruction of hemoglobin) and solutes
 * MATERIALS NOT REABSORBED INCLUDE**
 * A.Urea
 * B.Uric acid
 * C.Creatinine
 * A.Hydrogen and potassium ions
 * B.Creatinine

Sterile (somewhat antiseptic), Slightly aromatic , Normal pH of around 6 , Specific gravity of 1.001 to 1.035

Both sphincter muscles must open to allow voiding
 * __ MICTURITION __**


 * A.The internal urethral sphincter is relaxed after stretching of the bladder
 * B.Activation is from an impulse sent to the spinal cord and then back via the pelvic splanchnic nerves
 * C.The external urethral sphincter must be voluntarily relaxed

__ Role of Kidneys in Osmoregulation __ AND THUS IN MAINTAINING HEALTHY BLOOD PRESSURE cf. The work done in the chapter on the Cardiovascular system needs to be reviewed here by yourselves.
 * Regulation is primarily by hormones**

A.Antidiuretic hormone (ADH) prevents excessive water loss in urine

B.Aldosterone regulates sodium ion content of extracellular fluid
 * Triggered by the rennin-angiotensin mechanism
 * Cells in the kidneys and hypothalamus are active monitors