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
