1. The Blood System 6.2

2. Composition of Blood Blood is composed of plasma, erythrocytes, leukocytes and platelets. Plasma contains/transports dissolved substances ( wastes, nutrients) Erythrocytes(red) transfer oxygen and carbon dioxide Leucocytes (white) defend body from “invaders”(include lymphocyes and phagocytes) Platelets help with blood clotting

3. Blood cells

4. Leukemia Too many immature white blood cells Type of cancer Repeated rounds of cell division

5. Sickle cell anemia Abnormally shaped red blood cells due to abnormally shaped hemoglobin They cannot carry oxygen as efficiently Genetic disorder

6. Arteries carry blood away from the heart / to tissues have thick walls to withstand high pressure / prevent bursting have muscle fibers to generate the pulse / help pump blood / even out blood flow have elastic fibers to help generate pulse / allow artery wall to stretch/recoil Narrow lumen

7. Veins carry blood back to the heart / from the tissues have thinner walls because the pressure is low / to allow them to be squeezed have fewer muscle / elastic fibers because there is no pulse / because pressure is low have valves to prevent backflow Wide lumen

9. Artery vs. vein

10. Capillaries allow exchange of O2 / CO2 / nutrients / waste products from tissues/cells have a thin wall to allow (rapid) diffusion / movement in / out have pores / porous walls to allow phagocytes / tissue fluid to leave are narrow so can penetrate all parts of tissues / bigger total surface area

11. Capillaries

12. Blood vessels See Table 1 pg. 294

13. Atherosclerosis Occlusion (blockage) of coronary arteries Development of fatty tissue (atheroma) on the walls of the arteries LDL (low density lipoproteins) accumulate White blood cells engulf them and become large Smooth muscle forms a cap over the atheroma Narrows the lumen even more

14. Atherosclerosis

15. Structure of the Heart Aorta Vena cava (superior) Vena cava (inferior) Right atrium Left atrium Right ventricle Left ventricle Pulmonary veins Pulmonary artery Left Atrio-ventricular valve Right Atrio-ventricular valve Semilunar valves Septum

16. The Human Heart

17. Cross Section of the heart

18. Circulation 2 types in our bodies Pulmonary: heart to lungs and back Systemic: heart to body and back

19. Control of the heart beat Heart muscle tissue can contract without stimulation from a nerve. Cardiac muscle relaxes and contracts spontaneously (myogenic muscle contraction) The region of the heart that initiates the pulse is known as the pacemaker (SA node). Nerves and hormones can transmit messages to the pacemaker. (cranial nerves from the medulla) – One nerve can carry a message to slow down (vegus nerve) – One nerve can carry a message to speed up (cardiac nerve) – Epinephrine (hormone) speeds up the heart

20. Action of the Heart The atrium receives all the blood from the body and lungs. It comes in through veins. The ventricles are responsible for pumping the blood to body/lungs through arteries. Valves ensure that all blood moves in one direction.

21. Sequence of Heart Beats Pacemaker initiates a beat via electrical stimulus. Starts in the atrium and continues to the ventricles Atrium contracts forcing blood into ventricles. Atrio-ventricular valves close and ventricles contract forcing blood into arteries. Pressure in ventricles decreases allowing for blood to re-enter from the atrium.

22. The Cardiac Cycle

23. Heartbeat