Body Systems (Circulatory) PDF

Body Systems (Circulatory) Types of Body systems ​ Circulatory ​ Hormonal ​ Digestive ​ Excretory ​ Respiratory ​ Immune ​ Nervous ​ Skeletal ​ Muscular ​ Reproductive Circulatory system ​ Consists of the heart and blood vessels of 3 types: art...

Body Systems (Circulatory) Types of Body systems ​ Circulatory ​ Hormonal ​ Digestive ​ Excretory ​ Respiratory ​ Immune ​ Nervous ​ Skeletal ​ Muscular ​ Reproductive Circulatory system ​ Consists of the heart and blood vessels of 3 types: arteries, capillaries, veins ​ Arteries carry blood from the heart and veins take it back ​ Capillaries are where two-way exchange of materials between blood and cells happens ​ Generally nutrients and oxygen pass from blood to cells and wastes pass from cells to blood for removal, keeping cells alive ​ If blood flow ceases even temporarily, irreversible cell death is the consequence The heart ​ Two sides – right and left ​ Upper & lower chambers – atria & ventricles ​ More muscle in ventricle walls, more in the left than right ​ Two arteries and two veins ​ Two sets of valves, to ensure one way blood flow ​ Atrio-ventricular valves close when ventricles contract, semi-lunar valves close when they relax causing the lub-dub heart sounds Cardiac muscle and the pacemaker ​ In the wall of the right atrium is a specialized tissue which sends out an electrical signal every second causing the atria and then the ventricles to contract (the pacemaker/SAN) ​ The setting of the pacemaker can be adjusted, for example to less than a second during exercise when more blood is needed by the muscles ​ Cardiac muscle in the heart wall allows the rapid spread of the electrical signal to produce coordinated contraction Coronary heart disease (CHD) ​ Fatty deposits/plaque are gradually laid down on the inside of arteries ​ Arteries are narrowed & lose elasticity (causing high BP) ​ Eventually blood supply is reduced by the narrowing or cut off by a blood clot blocking the artery (thrombosis) ​ If this happens in the coronary artery heart muscle cells are deprived of oxygen and die, leading to a heart attack Risk factors for CHD  ​ Smoking ​ Lack of exercise ​ Prolonged stress ​ Genetic factors ​ Diet with bad fat ​ Obesity ​ Diabetes Comparing arteries, capillaries, and veins Observation Reason Pulse points can be felt in certain parts of the Most arteries are deep within the body (unlike veins) body (wrist, ankle, neck) but a few pass near the surface Artery walls have large amounts of elastic Blood pressure in arteries is pulsatile, constantly fibres allowing them to stretch and recoil rising and falling (120/80) Arteries have thick walls Blood pressure in arteries is much higher than in veins Veins have thin walls Blood pressure in veins is low so there is no need to withstand high pressure Capillaries repeatedly branch to form Creates high surface area for the exchange of extensive networks materials between blood and body cells Veins have a wide lumen (the space blood Minimum resistance to blood flow in veins required flows through) compared to arteries to maintain flow at low pressure Smooth lining on the inner wall in both Reduces friction between the blood and vessel wall arteries and veins as blood flows through Capillary walls are one cell thick Small distance for efficient diffusion of materials between blood and body cells Veins have valves Prevents backflow of blood which happens easily due to low pressure Arteries have contractile muscles fibres in Vasodilation/constriction of vessels allows control of their walls blood flow to different body parts Changes to heart rate ​ Blood flow needs to adjust according to the body’s needs ​ Heart rate and stroke volume (volume pumped per beat) both increase in response to exercise to increase blood flow ​ Arteries supplying the muscles widen to divert blood flow to actively respiring muscles ​ Additional blood flow supplies extra oxygen & glucose for and removes the extra waste carbon dioxide from respiration Components of the blood ​ Blood plasma (55% of blood volume) carries dissolved proteins, nutrients & most carbon dioxide (10% in RBCs) ​ Blood cells (45% of blood volume) suspended in plasma 1.​ Red blood cells transport oxygen bound to Hb 2.​ Platelets trigger blood clots in response to injury 3.​ White blood cells engulf bacteria (phagocytes) or produce antibodies (lymphocytes) for protection