The circulatory system transports blood around the body which contains red blood cells, white blood cells, platelets suspended in plasma. Red blood cells contain hemoglobin and carry oxygen, while white blood cells help fight infection and platelets help with clotting. The heart pumps blood through arteries and veins with a dual circulation system. Blood vessels have valves to prevent backflow. The circulatory and lymphatic systems work together to fight infection, transport nutrients and remove waste throughout the body.
5. RED BLOOD CELLS Biconcave discs No nuclei Spongycytoplasmenclosed in anelasticcellmembrane Red pigmentcalledhaemoglobin Are madebythe red bonemarrow of certainbones in theskeleton: ribs, vertebrae and breastbone
12. WHITE CELLS Differenttypes Largerthan red cells Theyhavenuclei They are made in thesamebonemarrowthat red cells Thetwo more numeroustypes are: - Phagocytes - Lymphocytes
15. White bloodcells: Phagocytes Theycollect at thesite of aninfection, engulfing (ingesting) and digestingharmful bacteria. Theypreventthe spread of infectionthroughthebody.
27. CONTROL OF THE HEART BEAT At rest: normal heartrate, 50-100 beats per minutes. Duringexercise: 200 beats/min Theheart beat isinitiatedbythepacemaker, a smallgroup of specializedmusclescells at the top of therightatrium.
28. Control of theheart beat Bloodpressure↑ ↓ heartrate Bloodpressure↓ ↑ heartrate ↓ O₂ concentration ↑ CO₂ concentration Hormone adrenaline
35. Lymphaticsystem Thin-walledvesselscalledlymphatics. Theyemptytheircontentsintothebloodsystem. The fluid iscalledlymph. Most of thelymphflowresultsfromthevesselsbeingcompressedwhenthebodymusclescontract in movementssuch as walkingorbreathing. There are valves, whichforcethe fluid in onedirection: towardstheheart. Lymphnodes: storage of lymphocytes. There are alsophagocytes. Lymphaticorgans:Spleenandthymus
39. THYMUS: functions Particularlyimportantlymphoidorgan in thenewborn: - controlsthedevelopment of thespleen and thelymphnodes. - produces lymphocytes (immunity) Afterpuberty, importantimmunologicalorgan, althoughitbecomessmaller. - storage of whitecells - production of a largepopulation of lymphocytes T.
40. Bloodfunctions: DEFENCE AGAINST INFECTIONS WHITE CELLS: - Phagocytes: - at thesites of a wound - in thebloodcapillaries - in lymphnodes ingestharmful bacteria and stop thementeringthe general circulation - Lymphocytes:Production of antibodies CLOTTING
41. CLOTTING Whentissueisdamaged and bloodvesselscut Plateletsclumptogether and block thesmallercapillaries. Fibrinogenfibrin(network of fibresacross thewound) Red cellsbecometrapped in thisnetwork and form a bloodclot. ↓ entry of harmful bacteria prevents furtherloss of blood