structure and function of blood vessels and heart Flashcards
ventricular fibrillation
irregular heartbeat
spasm
heart not pumping blood around the body
infarction
dead tissue in the heart from lack of oxygen/nutrients (ischaema)
due to obstruction of coronary artery
Diffusion speed relation to distance
fast over short distances, slow over 1mm
Function of CVS in relation to efficiency
speeds up gas and solute transport over long distances
reduces DD for O2 and nutrients
Other functions of CVS
delivers O2 and nutrients to cells, removal of CO2 and waste
Communication between organs via transport of hormones
Temp regulation
Hydrodynamic device in sexual reproduction
what drives movement of blood (excluding the heart)
Pressure differences
What is blood pressure determined by
CO
blood volume
peripheral resistance
2 circuits in cardiovascular circulation
systemic and pulmonary
Composition of blood
plasma 55% (water, ions, proteins, nutrients, hormones, metabolic wastes etc)
Hematocrit 45%
Leucocytes (WBCs) and platelets make up the buffy coat
Order of pumping blood around the body
RHS heart, lungs (oxy), LHS heart, body (deoxy), back to RHS
Where is most blood distributed
veins and venules- acts as reservoir
61%, slow moving
Blood flow (at rest)
Most blood flowing through abdominal organs and kidneys
Majority of pumping in parallel, so most organs supplied separately
Means blocking supply to one organ doesn’t mean supply blocked to rest of the body
Components of BVS
lumen
endothelial cells (tunica intima)
smooth muscle cells (tunica media)
connective tissue (tunica adventita)
arteries
large lumen
thick layer smooth muscle and connective tissue
function of thick elastic smooth muscle in arteries
stretches to absorb pressure coming out of the heart during systole
Prevents pressure buildup and huge release of pressure- instead pressure passed slowly onto rest of the body
During diastole smooth muscle undergoes passive recoil (releasing pressure)
arterioles
thin muscular wall and small lumen
contraction of thin smooth muscle regulates diameter of the lumen to control flow of blood to different organs
Major determinant of mean arterial pressure
capillaries
single layer endothelial cells
Exchange of O2, nutrients and waste across capillary walls but not proteins
Only 1 RBC can pass at a time
Exchange facilitated by slow movement of blood and large SA within the capilaries
Exchange occurs by
diffusion down gradients
venules/veins
thin walls large lumen valves thin smooth muscle layer low pressure skeletal muscle contraction driving force for blood back to heart low resistance
muscle layers in the heart
pericardium (outermost)
Epicardium
Myocardium (innermost)
Septum
divides left and RHS of heart
What are valves held in place by
chordae tendineae and papillary muscle
2 SL valves
pulmonary and aortic
2 AV valves
left- bicuspid
right-tricuspid
blood supply to the heart
supplied with oxygenated blood via coronary arteries
which branch off the aorta
How does deoxy blood from the heart muscle back into the right atrium
via coronary sinus vein
coronary arterial disease
insufficient blood flow (ischemia) associated with chest pains (angina), radiates down left arm
Severe blockage leads to death of heart region and myocardial infarction
Ventricular fibrillation and death
Causes of coronary arterial disease
atherosclerosis
blood clot
drugs, surgery
Function of CSF
protects brain against brain damage
How does fluid pass into vein at the top of the skull
via arachnoid villi (valves)
Where is CSF produced
specialised epithelial cell called choroid plexus
BBB
capillaries contain tight junction and less permeable to many substances- drugs and proteins can’t get into the brain
exceptions that can cross BBB
lipophilic molecules eg anaesthetics, alcohol
why can brain damage occur so quickly
Blood needs constant supply of O2 and glucose- has no stored glycogen
stroke
loss of supply and death of neurons
exchange in brain
by diffusion down gradients
facilitated by slow blood and large SA
