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Chapter 12: Circulatory System Primary Tissue Layers • Endoderm – innermost layer – digestive and respiratory tracts and other organs • Mesoderm – middle layer – muscle, connective tissues, blood vessels • Ectoderm – outer layer, develops to skin Simpler Circulatory System • Open System – no closed vessels – Interstitial fluid surround cells – sinus: body cavity surrounding internal organs Simpler Circulatory Systems • Closed System – true blood vessels – pumping system • Purpose – – – – – Bring O2 and Nutrient to cells Take wastes away from cells Chemical messages Maintain balance Transport immune cells Blood Vessels and the Heart Fig 12.2 p 480 Heart – Superior view The Heart • • • • • • Right side = incoming blood Left side = outgoing blood Septum = separates these sides Atria = holds blood Ventricle = pumps blood Semilunar valves = prevents backflow Learning Check • Pg 481, Q 1-6 Arteries • carry blood away from heart • usually O2 rich (Except for __________) • connective tissue and muscle • walls elastic and thick • precapillary sphincters control blood flow Artery Problems • Aneurysm – bulge in artery • Arteriosclerosis – build up of plaque in artery Veins and Capillaries • Veins – carry blood to the heart – usually O2 poor (Except for __________) – valves push blood towards heart – smooth surface • Capillaries – smallest blood vessels for gas exchange Blood flow in veins • Valves prevent backflow • Less pressure than arteries • Skeletal muscles contract and pump blood back to the heart Arterioles and Venules • Arteries to arterioles to capillaries • Capillaries to venules to veins Circulation Types • Systemic Circulation – oxygenated blood to tissue and deoxygenated blood to heart • Pulmonary Circulation – between lungs and heart – deoxygenated blood goes to lungs and oxygenated blood goes to heart Components of Blood • 55% fluid = plasma – electrolytes, protein for immunity and clotting • 45% Red Cells – erythrocytes, leukocytes, platelets – produced in bone marrow • 1% White Blood Cells – Functional immune system cells Stem Cells Bone Marrow Erythrocytes • Red blood cells • no nucleus and biconcave = max oxygen • hemoglobin and iron carry oxygen • White blood cells in spleen remove old RBC’s –gives color to feces (bilirubin) • anemia = deficiency in hemoglobin or RBC Leukocytes • White blood cells • RBC outnumber WBC by 700:1 • immune system, phagocytosis • concentrated in lymph nodes • pus = dead WBC and microbe Leukocytes • Neutrophils – Most abundant • Eosinophils – Found in mucus lining of digestive and respiratory system • Basophils – Aids immunity by attracting phagocytes • Lymphocyte (B and T cells) – Secrete proteins called antibodies and aid in immune memory • Monocyte – Become specialized phagocytes called macrophages that engulf bacteria Leukocytes Antibodies and Antigen Platelets • Fragmented rbc • initiate blood clotting • no nucleus • fragile – rupture over torn blood vessel Blood Clotting • Blood vessel breaks, releases chemicals that attract platelets • Platelet ruptures and release chemicals to produce thomboplastin • When calcium present thromboplastin reacts with prothrombin to produce thrombin • Thrombrin reacts with fibrinogen to produce fibrin Learning Check • Pg 486, Q 7-12 Functions of Blood: Transport • Transport nutrients from intestine • Transport gasses • Transports and removes waste – minerals and cell waste to kidneys for excretion – CO2 from cells to lungs for expiration Functions of Blood: Temperature Regulation • Balancing loss of heat from the body with the production of metabolic processes • Mammals control heat by changing the volume of blood in the skin • Voluntary of involuntary? Controlled by autonomic branch of the nervous system Autonomic Nervous System • involuntary responses • Vasoconstriction: narrowing blood vessels • Vasodilation: widening blood vessels Factors effecting constriction • Blood pressure – An increase in BP is offset by vasodilation. If BP is too low, vasoconstriction will occur • Metabolic activity • Exercise – Vasodilation • Drugs – Alcohol and nicotine result in vasodilation Countercurrent Heat Exchange The Heart’s Tempo Setting the Heart’s Tempo • myogenic muscle = not attached to nerve. • Sinoatrial (SA) node = pacemaker • Atriventricular (AV) node = impulse passed to ventricels Conducting the Signal • Purkinjie Fibers – pass through the septum to carry rythym • Autonomic Nervous System – involuntary responses – Sympathetic = stress, increase heart rate – Parasympathetic = relaxation, decrease rate Electrocardiograph • P wave = atrial contractions • QRS wave = ventricular contractions • T wave = ventricle recovers Electrocardiograph “lub” “dub” Heart Sounds Heart Sounds • Diastole – relation of heart – atria fill with blood • Systole – contraction of ventricles – blood going out of heart • Systolic/Diastolic Pressure – pressure in arteries during these events Blood Pressure • Stated as Systolic pressure over Diastolic Pressure • Need stethoscope and a sphygmomanometer How to Check Pressure • Inflate the bladder to close off flow to brachial artery • Listening to pulse, slowly release air until pulse is heard and read the pressure – Systolic • Slowly release air until no pulse is heard and then read the pressure – Diastolic • Healthy = 120/80 (units = mmHg) Regulating Heart Rate • Sympathetic – release epinephrine – increase cardiac output – constrict arteries • Parasympathetic – opposite Cardiac output and stroke volume • Cardiac output is amount of blood pumped out by the heart in mL/min. Cardiac output = heart rate x stroke volume • Stroke volume is the volume of blood pumped out of the heart with each heartbeat • If the average person has a stroke volume of 70 mL and a resting heart rate of 70 beats per minute, what is the cardiac output? Cardiovascular Fitness • Capacity of the heart, lungs and blood vessels to deliver oxygen to working muscles • Look up table 12.3 on pg 492 • What do you notice? • Rank the fitness of the three individuals Cardiovascular Fitness • Cardiovascular fitness – Enlarges ventricles – Increses elasticity – Strengthening the ventricle walls • Cardiovascular changes increase the stroke volume • Good indication of fitness is how long it takes the heart to return to resting HR after strenuous exercise Learning Check • Pg 491, Q 13-18