Urinary System

Vocabulary Calyc-: small Cort-: covering Detrus-: to force away Glom-: little ball Mict-: to pass urine Nephr-: kidney Papill-: nipple Trigon: triangle De-: separation from Extra-: outside Im-: not Intra-: within Neutr-: neither

Kidneys Kidneys: reddish-brown, bean-shaped organ located posterior to the top of the abdominal cavity Renal Sinus: a hollow chamber on the surface of the kidney Renal Pelvis: a funnel-shaped structure that leads to the ureters

Kidney Functions Maintain homeostasis by regulating the composition and pH of extracellular fluid Removing waste from blood and forming urine Secrete erythropoietin hormone Activation of vitamin D Maintain blood volume and blood pressure

Urine Formation Urine: the product of the 3 processes below Glomerular filtration: glomerular capillaries filter plasma Happens through osmosis Produces 180 liters every 24 hours Tubular reabsorption: moves substances back into the blood stream Tubular secretions: moves substances from the blood to the kidneys

Filtration Rate Glomerular Filtration Rate GFR: affected by Blood flow Diameter of capillaries Hydrostatic pressure Kidney stone obstruction Increases when body fluids are abundant and decreases when the body needs to conserve fluids

Urine Composition 95% water 5% 0.6-2.5 liters/day Amino acids Urea Uric acid Electrolytes 0.6-2.5 liters/day Factors that affect urine production: Physical condition Emotional condition Temperature Fluid intake humidity

Ureters 25 cm long tube that starts at the renal pelvis and joins the urinary bladder Propel the urine to the bladder

Bladder A hollow, muscular organ that stores urine Internal urethral sphincter: prevents the bladder from emptying Detrusor muscle: the muscular wall of the bladder that functions during urination Holds 600 mL (2.5 cups) before stimulating pain receptors

Micturition (urination) The process of expelling urine from the bladder Micturition reflex center: in the spinal cord Responsible for the urge to urinate

Urethra The tube that transfers urine from the bladder to the outside Longer in men than in females

Maintaining Homeostasis Water and electrolytes are the 2 most important substances in the body 1) lost water and electrolytes must be replaced 2) excess water and electrolytes must be excreted Electrolytes: molecules which release ions (charged particles) in water

Fluid Compartments Females: 52% water Males: 63% water Intracellular compartment: includes all the water and electrolytes in all cells Extracellular compartment: all the fluid outside of cells Tissue spaces (interstitial fluid) Blood vessels (plasma) Lymphatic vessels (lymph) Transcellular Fluid Cerebro spinal fluid in the nervous system Aqueous and vitreous humor in the eyes Synovial fluid in the joints Serous fluid in the body cavities Secretions of the glands

Water Balance Intake equals output Intake: Output: 60% from beverages 30% from food 10% byproduct of cellular metabolism Regulated by the thirst center in the hypothalamus Output: 60% urine 6% feces 6% sweat 28% evaporation Regulated by urine production

Electrolyte Balance Intake: food, water, byproducts of metabolism Regulated by hunger and thirst (hypothalamus) Output: sweating, feces, urine Regulated by kidneys and aldosterone secreted by the adrenal gland

Acid-Base Balance Acids: release hydrogen ions H⁺ Bases: release ions that combine with hydrogen OH⁻ Hydrogen Ion (ACID) Sources 1) aerobic cellular respiration Produces CO₂ (carbonic acid) 2) anaerobic respiration produces lactic acid 3) incomplete oxidation of fatty acids Produces ketone bodies 4) oxidation of amino acids containing sulfur Produces sulfuric acid 5) Breakdown of proteins and nucleic acids Produces phosphoric acid

Regulation of Acid/Base Balance Respiratory system: rate and depth of breathing will increase to get rid of excess carbon dioxide (carbonic acid) Kidneys: nephrons excrete hydrogen ions into urine when there is excess acid

Elevated acid levels Respiratory Acidosis: increased CO₂ levels (carbonic acid) Causes: Injury to respiratory center of the brain Obstruction of airways Disease that decreases gas exchange Ex: pneumonia, emphysema Shallow breathing Symptoms: drowsiness, disorientation, stupor, labored breathing, cyanosis

Elevated acid levels Metabolic acidosis: Either accumulation of acids or loss of bases Causes: Kidney disease Prolonged vomiting Prolonged diarrhea Diabetes- fatty acids produce ketone bodies Symptoms: drowsiness, disorientation, stupor, labored breathing, cyanosis

Elevated base levels Respiratory Alkalosis: Excessive loss of CO₂ and carbonic acid Causes: Hyperventilation Anxiety Fever Poisoning High altitudes Symptoms- Light-headedness Agitation Dizziness Tingling

Elevated base levels Metabolic Alkalosis: Rise in the pH of blood Causes- Prolonged vomiting Diuretic drugs Too much antacids Symptoms- Decreased breathing