Excretory System How to make pee …

Renal Artery Renal Vein Renal Cortex Adrenal Gland Renal Pelvis Kidney Renal Medulla Ureter Urinary Bladder Urethra

Every Cell in your body produces wastes Metabolic waste, not feces (undigested material)

Skin excretes water and salts in perspiration Lungs excrete CO2 as a gas Liver excretes bile pigments Kidneys excrete nitrogeneous wastes in urine

Role of Kidneys Important in protein breakdown (proteins are amino acid based which is nitrogen based) Nucleotides (metabolic products) are metabolized to form uric acid Uric acid is not very soluble - if it precipitates out of solution, you have gout

Urea H2N ---C---NH2 // O

What do kidneys do? 2 kidneys located high up in the abdomal cavity Purposes - filter blood maintain blood volume remove waste products recover vital substances Maintains homeostasis in the body

Little bit of protection by rib cage Covered by tough fibrous cap of connective tissue - surrounded by adipose tissue (inside fibrous tissue)

Ureters Ureters connect bladder to kidney - smooth muscle Ureters and bladder made of transitional epithelium

Urinary bladder can stretch to accommodate up to 600 ml or more (sometimes in excess of 1000ml) (600 ml is conservative) has folds - rugae (like folds of stomach) - running throughout is smooth muscle fibers Urethra extends from bladder to outside the body

Females urethra is about 1-2” - this leads to more frequent urinary tract infections Male urethra is about 6” - prostate in later years can enlarge (very often does) which causes an obstruction in urine flow Histology of Kidney Bean shaped

3 regions Cortex Medulla which contains renal pyramids (appear striated) Renal Pelvis (or inner space) - continuous with ureter

Nephron Plasma minus the proteins pass through filtration cells, then you need to recover vital molecules - glucose, water, etc. over 1 million nephrons Nephron is the filtration unit of the kidney - made of cells that are specialized for active transport, diffusion, moving substances across membranes

Nephron Structure of nephron cup shaped structure - Bowman’s capsule Parts of nephron beyond Bowman’s capsule specialized tube

Bowman’s Capsule Renal Arteriole Glomerulus Capillaries Collecting Tubule Loop of Henle

Nephron part closest to glomerulus is the proximal convoluted tubule (closest to renal corpuscle Loop of Henley or Henley’s Loop - descending and ascending limb with a hairpin turn Distal convoluted tubule - farthest away from renal corpuscle each has a role in recovery of nutrients and leads away from nephron to collecting duct and away

Formation of Urine Pressure Filtration Blood from arteriole is flowing into glomerulus, due to bp, filtration Everything from plasma that is filterable leaves through glomerulus - water, glucose, amino acids, salts, urea, uric acid and creatinine (nitrogen wastes) blood cells, platelets and proteins are not filtered

Concentration of water is same as plasma Body needs to recover water and nutrients Selective Reabsorption

Almost 180 L of filtrate pass into collecting tubules per day Almost 180 L of filtrate pass into collecting tubules per day. 90 - 2L bottles! Diffusion and active transport (passive and active processes) water glucose amino acids and salts are reabsorbed. About 99% of the water is reabsorbed.

Region most highly specialized for selective reabsorption is the proximal convoluted tubule Many mitochondria needed - produce atp for active transport

Reabsorption of water happens in loop of Henle Lower part of ascending limb - dealing with passive diffusion of NaCl Regulate pH of blood by regulating particular ions Beside filtration, keeping good stuff and getting rid of waste

Maintaining blood volume ADH - Produced in Hypothalamus by neurosecratory cells, stored and secreted from posterior pituitary gland ADH increases the permeability of the collecting duct to water so more water can be reabsorbed.

Increase Blood Pressure and Blood Volume Diuresis - increases amount of water in urine Alcohol is a diuretic - decreases production of ADH Believed after effects of alcohol (hangover) is due to dehydration Kidney stones - calcium salts or uric acid precipitate and form kidney stone