E.Circulate

E.Circulate - Circulation Circulatory Systems • Cardio vascular System – Heart& Vessels –(Pumps& Pipes • Lymphatic System Circulatory

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Unformatted text preview: Circulation Circulatory Systems • Cardio vascular System – Heart & Vessels – (Pumps & Pipes) • Lymphatic System Circulatory Systems Functions: • Transportation – – – – – – – Water & electrolytes (salts) Dissolved gases— O2 & CO2 Nutrients Wastes Chemical messengers (hormones) Defense (immune) systems Repair (clotting) factors • Thermoregulation • Hydraulics Open Versus Closed Systems • “Open”: blood flow in openended vessels • “Closed”: blood stays within vessels Mammalian CV System • Closed, Two circuit system • Pulmonary : blood to and from lungs • Systemic : blood to and from body • Heart is a 2-sided pump Circulatory system in insect and earthworm Human Heart Anatomy CV system of a mammal Heart Anatomy (cont.) • Diagrams show heart from front – Viewer’s “right” is heart’s “left” • Enclosed in fluidfilled sac behind sternum • Like all organs, the heart is constructed of many tissues Human heart in chest cavity Heyer 1 Circulation Heart Anatomy (cont.) Cardiac Contractions • 4 chambers – 2 thin-walled Atria, 2 thick-walled Ventricles 1. Sinus node (pacemaker) fires 2. Signal spreads across atria 3. Cardiac muscle in atria contract 4. Signal reaches AV node; travels down Bundle of HIS to apex of heart 5. Signal spreads across venticles 6. Cardiac muscle in venticles contract • 4 valves – 2 AV valves, 2 SL valves – Valves keep blood moving in one direction The Beat of The Heart Heart Sounds • Diastole – Blood flows from the veins into the heart chambers 11 Heart is 2 relaxed. AV valves are open. Atria contract. • Systole 0.1 sec – The atria briefly contract and fill the ventricles with blood – Then the ventricles contract and propel blood out 0.4 sec 0.3 sec SYSTOLE 3 Ventricles DIASTOLE contract. Semilunar valves are open. • Sound: “lub-dupp, lub-dupp” • Sounds are vibrations from turbulent flow caused by the closing valves. • “Lub” : ventricles contract and AV valves slam shut — beginning of systole • “Dupp”: atria contract and SL valves slam shut — ending of systole • Heart murmur: hissing of blood squirting backward thru valve or a patent aperture. The cardiac cycle Vessel Adaptations • Arteries blood away from heart • Veins blood toward heart • Capillaries - thin-walled and highly branched – Thick-walled and elastic to withstand higher pressure – Internal valves prevent backflow – Only 1 cell thick to maximize diffusion rates Blood vessel structure Heyer Path of blood flow through the heart 1. Blood from systemic veins (vena cavae ) into right atrium . 2. From right atrium , through right AV valve (tricuspid), to right ventricle . 3. From right ventricle , through right semilunar valve (pulmonic), to pulmonary artery . 4. From pulmonary artery to lungs. 5. From lungs to pulmonary veins back to left atrium . 6. From left atrium , through left AV valve (mitral), to left ventricle . 7. From left ventricle , through left semilunar valve (aortic), to systemic arteries (aorta ). 2 Circulation Circulatory Changes During Exercise Cardiovascular Pathologies • Compromised local circulation: arterial blood flow cut off to tissuesÆØO2 deliveredÆcells die Æorgan fails – – – – – Atherosclerosis: plaques Thromboembolism : clot [thrombus] Gas embolism: bubble Edema: vessels compressed by surrounding swollen tissue Aneurysm: weakened vessel balloons & bursts • Heart failure: heart unable to pump adequate flow to support body’s needs. Cerebral blood flow remains constant via intrinsic mechanisms. Atherosclerosis Arteriosclerosis • Fat and calcium deposits (plaques) accumulate on artery walls • Arteriosclerosis: hardening of the arteries. Loss of compliance & elasticity. • Atherosclerosis: formation of hardened plaques. Obstruction of flow and promotion of clots. • Contribute to heart disease & stroke. ~50% of deaths in U.S., Europe & Japan. Stages of plaque formation Atherosclerosis Accumulation/hardening of plaque Æ slow block Plaque breaks through lining of vessel Æ clot formsÆ fast block Heyer 3 Circulation Healthy Heart Coronary Heart Disease (CHD) • Obstructing coronary blood flow starves the myocardium • Heart muscle does not derive any O2 nor nourishment from the blood flowing through its chambers • Cardiac muscle cells (myocardium) supplied by coronary arteries branching off the aorta. • Coronary atherosclerosis – most common cause • Coronary spasm – Drugs (cocaine) – Smoking/stress Æ↑risk Coronary Heart Disease (CHD) Coronary Heart Disease (CHD) Myocardial infarction (MI) — “heart attack” • Ischemia : lack of O 2 to myocardium • #1 cause of death in U.S. population! For both men and women. • Angina : chest pain / feeling of extreme pressure • Even if not fatal, damage to the heart is permanent. • Arrhythmia: erratic heart beat • Fibrillation : erratic & unproductive heart contractions • Myocardial infarction (MI) — “heart attack ”: death of myocardial tissue Coronary Heart Disease (CHD) • ~1.1 million emergency cases/year. 460,000 of them fatal ! Main cause of death in developed countries is mostly the product of lifestyle choices! Major risk factors : • Age / male hormones • Smoking • Diet high in cholesterol & saturated/trans fats • Hypertension (high blood pressure) • Sedentary life style • Obesity Blood: Cells Suspended in Plasma Even if CHD does not cause MI, chronic ischemia & hypertension may cause congestive heart failure. • Myocardium become weak and/or stiff; heart enlarges. • Cardiac output insufficient to sustain body activity. • Weakness, shortness of breath • Body fluids not well circulated; accumulate in pools (congestion). • ~2 million new cases/yr in U.S. The composition of blood Heyer 4 Circulation Blood Structure and Function • Red blood cells Stem Cells From Bone Marrow • Totipotent – Carry oxygen – Potential to become any cell • Stem cells are rare • Used for treatment of blood disease • White blood cells – Defense/clean up • Platelets – Blood clotting • Plasma – Carries proteins and nutrients Human blood smear The development of blood cells “Conditioning” the body fluids • Excretory System – Fluid balance — water and electrolytes – Remove waste products – Retain nutrients Excretory System Components • Capillaries – especially high permeability — very high diffusion rate – not permeable to blood cells or proteins — retained in blood – 20% of other plasma solutes and water are filtered out • Tubules • Respiratory System – reabsorb all nutrients and most salts back into blood – reabsorb most water – secrete additional wastes from blood – External gas exchange — sustain aerobic state • Bladder – compliant (expandable): store wastes – muscular: expel wastes Human Renal System Excretory System Components • Filtered fluids enter tubule • Tubule reabsorbs water & nutrients back into circulatory fluids • Concentrated wastes exit to bladder Concentrated wastes Nutrients and most water return to circulation Heyer tubule capillary Nephron of the kidney 5 Circulation Nephron Function • Blood enters Glomerulus. • Pressure forces fluids into Bowman's Capsule. • Loop of Henle reabsorbs water & salt. • Tubules reabsorb sugars & amino acids. Nephron Function Normal human kidney action: • 100% of circulating energy substrates (glucose, amino acids, etc.) are reabsorbed. • 98–100% of salt reabsorbed.* • 99–99.8% of water is reabsorbed. * – ~180 L body fluid filtered by nephrons per day – But only 0.5 –2 L /day urine excreted • \Wastes not reabsorbed are concentrated >100x in urine. * Precise amount regulated by need. Homeostasis & Osmoregulation H20/Salt Balance Regulation of plasma osmolarity Dehydration and/or Decreased water intake • Drink water & concentrate urine Increased water intake Thirst center Hypothalamus Plasma osmolality Osmo receptors Plasma osmolality Posterior pituitary Anti-Diuretic Hormone Retain water urine output ADH Kidney Increased reabsorbtion of water [A D H] H] AD H Kidney H AD Good water reabs. Normal production of normal urine Kidney Hypothalamus Posterior Pituitary ADH Insufficiency Poor water reabs. Increased production of dilute urine Diabetes insipidus Heyer 6 Circulation Glucosuria: glucose in urine • Glucose completely reabsorbed under normal conditions • Diabetes mellitis: insulin deficiency causes blood glucose levels to exceed renal threshold (more than can be reabsorbed) • Excess glucose excreted in urine • Glucose in urine osmotically holds more water in urine “Diabetes” = increased urine output Type Etiology Primary effect Diabetes insufficient renal tubule insipidus ADH water action permeability impaired Diabetes insufficient elevated mellitus insulin osmotic action pressure of renal filtrate Symptom Urine Osm increased dilute; urine output “bland urine” increased high [glucose]; urine output “sweet urine” “Organismal Respiration” WHY RESPIRE? • Mitochondria need O2 to make ATP. • Take away CO2 vs . “Cellular Respiration” • Internal gas exchange • External gas exchange • Cell membranes are permeable to simple diffusion of dissolved O2 and CO2 - What are the four parameters of diffusion rate? 300 Million Alveoli in Lungs — Greatly increase surface area for gas exchange Negative Pressure Breathing Fig. 18.9 Heyer 7 Circulation Respiratory Pigments Carry O2 • Proteins with a metal core, giving it color. • Hemoglobin is Hb. • Blood cells (RBCs) reduce viscosity. O2 Dissociation Curve for Hb Hb affinity for O2 shifts w/ blood oxygen content • Hemoglobin has – high O2 affinity when PO2 is high – low O2 affinity when PO2 is low • Blood O2 content is measured as its partial pressure. Regulation of Breathing Fig. 18.10 •Hemoglobin holds large quantities of O 2: thus O 2 levels slow to change. •Breathing rate stimulated more by build up of CO 2 or metabolic acids. Smoking • Lung disease — cancer; emphysema – Very rare in non-smokers • Other cancers — bladder, stomach, pancreas, esophagus, larynx, mouth, cervix • Heart disease & strokes – Accelerates formation of plaques & clots – ↑ risk 3x (males) to 6x (females) – Coronary & carotid spasms • Ulcers Heyer 8 ...
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This note was uploaded on 09/02/2011 for the course BIOL 11 taught by Professor Heyer during the Fall '08 term at UCSD.

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