Part 1 Grade 8 Semester 1 Year 2011-2012 Circulatory System Part 1 Grade 8 Semester 1 Year 2011-2012

Blood as the Transport Medium To supply oxygen and glucose, as well as other substances, large organisms have a specialised transport system. This system has 4 parts: A medium-blood A system of tubes-arteries and veins A pump-heart Sites of exchange-capillaries

Blood Content

Types of Blood Cells Cell Type Appearance Function Structure Red blood Cells (erythrocytes) Transport O2 from lungs Contain haemoglobin Have no nucleus Cells are smalls and flexible White Blood Cells (Phagocytes) Remove microorganisms that invade the body and might cause infection by engulfing them. Irregular shaped nucleus Enzymes in cytoplasm digest microorganisms once engulfed Sensitive cell surface membrane (Lymphocytes) Produce antibodies-as defense against diseases Large nucleus contains may copies of genes for antibody production Platelets Involved in blood clotting Can release blood clotting enzyme

Blood Clotting Platelet plug Collagen fibers Platelet releases chemicals that make nearby platelets sticky Clotting factors from: Platelets Damaged cells Plasma (factors include calcium, vitamin K) Prothrombin Thrombin Fibrinogen Fibrin 5 µm Fibrin clot Red blood cell

Blood Plasma Our transport medium has watery liquid part that is called plasma. Plasma has transport function which carries dissolved food molecules, waste materials, and hormones. Plasma is also able to distribute heat around the various part of the body.

The Heart It is a double pump It contracts (systole) and relaxes (diastole) It has 4 chambers Each chamber pumps the same volume of blood Heart rate/pulse: 72 beats/min

Blood Vessels The blood flows away from the heart in vessels called arteries. The blood flows back towards the heart in vessels called veins. Joining the arteries and veins are the capillaries. Main artery: aorta Main veins: vena cava

Transverse Section of Vessels Narrow central tube (lumen) Wide central tube (lumen) Artery: Blood is rich in oxygen (except in the pulmonary artery); High pressure. Vein: Blood is low in oxygen (except in the pulmonary vein); Low pressure; has pocket valve. Capillary: One cell thick; large surface area

Arterial end of capillary Capillaries At the arterial end of a capillary, blood pressure is greater than osmotic pressure, and fluid flows out of the capillary into the interstitial fluid. Capillary Red blood cell 15 m Tissue cell INTERSTITIAL FLUID Net fluid movement out movement in Direction of blood flow Blood pressure Osmotic pressure Inward flow Outward flow Pressure Arterial end of capillary Venule end At the venule end of a capillary, blood pressure is less than osmotic pressure, and fluid flows from the interstitial fluid into the capillary.

The mammalian cardiovascular system Pulmonary vein Right atrium Right ventricle Posterior vena cava Capillaries of abdominal organs and hind limbs Aorta Left ventricle Left atrium artery Capillaries of left lung head and forelimbs Anterior of right lung 1 10 11 5 4 6 2 9 3 7 8