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Topic 6.2 + Option H5 Transport System

Topic 6.2 + Option H5 Transport System. IB Biology. Components of Transport System. Blood Heart Blood Vessels. Types of Circulation. 1) Pulmonary heart – lungs – heart 2) Systemic heart – body – heart. Types of Circulation. 3) Coronary

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Topic 6.2 + Option H5 Transport System

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  1. Topic 6.2 + Option H5 Transport System • IB Biology

  2. Components of Transport System • Blood • Heart • Blood Vessels

  3. Types of Circulation • 1) Pulmonary • heart – lungs – heart • 2) Systemic • heart – body – heart

  4. Types of Circulation • 3) Coronary • blood vessels that supply heart muscle with oxygen and nutrients / remove waste products

  5. Heart Structure • 2 sides with different functions: • right: to receive + pump blood to the lungs • left: to receive + pump blood to the body • 2 types of chambers: atrium + ventricle • 4 chambers: 2 atria/2 ventricles • Cardiac muscle: involuntary • Ultimate control: • Autonomic Nervous System (ANS)

  6. Heart Valves • Allow blood to flow in only one direction • Four valves • Atrioventricular valves – between atria and ventricles • Bicuspid valve (left) • Tricuspid valve (right) • Semilunar valves between ventricle and artery • Pulmonary semilunar valve • Aortic semilunar valve

  7. Vessels of the heart • Aorta • Leaves left ventricle • Pulmonary arteries • Leave right ventricle • Vena cava • Enters right atrium • Pulmonary veins (four) • Enter left atrium

  8. Blood in the heart chambers does not nourish the myocardium • The heart has its own nourishing circulatory system • Coronary arteries • Cardiac veins • Blood empties into the right atrium via the coronary sinus

  9. Heart contractions

  10. The Heart: Cardiac Cycle • Atria contract simultaneously • Atria relax, then ventricles contract • Systole = contraction • Diastole = relaxation • Cardiac cycle – events of one complete heart beat • Mid-to-late diastole – blood flows into ventricles • Ventricular systole – blood pressure builds before ventricle contracts, pushing out blood • Early diastole – atria finish re-filling, ventricular pressure is low

  11. Blood • Plasma – fluid • Red blood cells or erythrocytes – produced in the bone marrow of large bones / transport O2 and CO2 • White blood cells (lymphocytes and phagocytes) – produced in the bone marrow / belong to immune system • Platelets - cell fragments that help blood clotting

  12. (antibodies) urea + HEAT

  13. Blood Vessels • Arteries • carry blood Away from heart; strong thick walls; smooth muscle (elastic); fibrous coat; small lumen = ↑ pressure • Veins • carry blood back to heart; large lumen; thin wall/muscle; ↓ elastic; valves • Capillaries • connect arteries and veins; no valves; pores; no muscle/not elastic extremely thin (1 cell thick) = fast exchange

  14. Blood Pressure • Blood applies pressure to the walls • If it is too low - cells might not get enough O2 • If it is too high - vessels can rupture (heart attack, stroke) • Salt can increase blood pressure • Normal blood pressure: 120/80 mm Hg

  15. Coronary Heart Disease • Slow build up of plaque (lipids, cholesterol) = ATHEROSCLEROSIS • Arteries become harder, less flexible • Less space for blood • Coronary arteries supply O2 to heart cells • Thrombosis = clot = heart attack = heart cells die • Factors affecting coronary heart disease (CHD): • Age, race, heredity, gender, cholesterol levels, blood pressure, obesity, diabetes, smoking, sedentary lifestyle, stress

  16. Heartbeat Control • Myogenic muscle contraction: • Sino-Atrial Node (SA) – specialized cells generate electrical impulse on their own with regular frequency (PACEMAKER) • Impulse spreads to both atria → atria contract together • Atrio-Ventricular node (AV) picks up the impulse in lower right atrium septum and conduces to the ventricles through fibers • Ventricles contract: AV valves close / semi-lunar valves open (SYSTOLE) • Contraction stops – ventricles relax (DIASTOLE)

  17. Heartbeat Control • Autonomic Nervous System and hormones can modify myogenic rhythm: • Nerves from brain stem (medulla) have involuntary control over heart rate = affect SA node • Exercise = ↑CO2 / ↓O2 = medulla oblongata (brainstem) takes over • Chemoreceptors detect ↑CO2 = H+ causes decrease in pH • Adrenaline targets sino-atrial node (SAN): stimulant

  18. Cardiac Cycle • One whole heartbeat • Systole = contraction / Diastole = relaxation • Valves prevent backflow • Sound = valves closing • 1st = atrio-ventricular valves (mitral, tricuspid) • 2nd = semilunar valves (aortic, pulmonary) • Important = valves open and close depending on pressure inside chambers/blood vessels • Atria systole = pressure not too great (thin walls, most blood already moved to ventricles) • Ventricular systole = pressure great inside both ventricles

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