D1) Structure of the cardiovascular system Flashcards
Heart general facts
4 chambers
Left hand side- oxygenated
Right hand side- deoxygenated
Arteries- away from the heart (oxygenated)
Veins- towards the heart (deoxygenated)
EXCEPT- Pulmonary artery & Pulmonary vein
Heart structure
Double pump
Found under sternum
Size of closed fist
Surrounded by a twin layered sac- pericardium
Layers between 2 sacs- pericardial fluid
Fluid- prevents friction between heart beats
Left & right separated- septum
Function of the heart
To drive blood through the arteries to working muscles
Walls of the heart
Epicardium- outer wall
Myocardium- strong middle layer
Endocardium- inner layer
Pulmonary circulation
Carries blood from: heart-lungs-heart
Top loop
Systematic circulation
Carries blood from: heart- body-heart
Bottom loop
Arteries
Blood- away from the heart
Thick muscular walls
Carries blood at high pressure & high speed
No valves
Elasticity & contractility
Smooth muscle around arteries- contract to increase or decrease diameter as required- maintains pressure
Located deep in body at pulse points
Veins
Facilitate venous return
Thinner walls & larger diameter
Blood- travelling slower & under lower pressure
Muscle contracts around the veins to squeeze the blood back to the heart
Valves in the veins- prevent backflow when the muscles relax
Mainly close to the skin
Capillaries
Connect arteries & veins by uniting arterioles & venules
Capillary numbers can be increased through regular exercise
Allow diffusion of oxygen & nutrients needed in body cells
1 cell thick
Pressure of blood- higher than veins, lower than arteries
Arterioles
Thinner walls than arteries
Control blood distribution by changing diameter
Adjust blood flow to the capillaries in response to oxygen demand
During exercise- they will increase to provide extra oxygen; t compensate increased blood demand, other muscles will have it reduced where arterioles will decrease
Responsible for controlling blood flow to the capillaries
Venules
Connect capillaries to veins
Transport de-oxygenated blood under low pressure to the veins & then to the heart
Blood
Constantly moving
Collects chemicals from one part of the body & delivers them to other parts, for use or disposal
Plasma
Liquid part of blood
Straw coloured
90% water as well as electrolytes (sodium, potassium & proteins)
CO2 away from cells to the lungs for removal from the body
Dissolves carbonic acid (H2CO3) (H2O + CO2)
Leucocytes/ White blood cells
Identify, destroy & remove pathogens
Originate in the bone marrow
Erythrocytes/ Red blood cells
Collect & carry oxygen to all cells of the body so they create energy
Red blood cells contain haemoglobin, which combines to oxygen to become oxyhaemoglobin
Flattened, round discs, large surface area
Platelets
Tiny pieces of disc shaped cell
Produced in bone marrow
Clump together when blood vessels are damaged & help to clog a ‘meshwork’ of fibres- create a clot, to help stop bleeding
Stimulates fibrin
