heart stuff Flashcards
what does blood transport?
respiratory gases, products of digestion, metabokic wastes & hormones
how does the circulatory system manage the pressure of blood flow?
blood flows through the lungs at a lower pressure, to prevent damage to the capillaries in the alveoli
+ this also reduces the speed at which blood flows, enabling more time for gas exchange
-oxygenated blood then goes back through the heart to be pumped out at a higher pressure to the rest of the body
arteries
carry blood from heart to rest of body
have thick muscular walls w elastic tissue to stretch + recoil to support high pressures + prevent vessels from bursting
folded endothelium to allow artery to stretch
- carry oxygenated blood, except pulmonary (heart –> lungs)
veins
carry blood back to the heart under low pressure
wider lumen than arteries w v little elastic tissue
have VALVES to prevent backflow of blood
contraction of body muckes surrounding the veins, help w bloodflow through them
- carry deoxygenated blood (O2 used up by body cells), except pulmonary (lungs –> heart)
arterioles
smaller vessels divided from arteries to connect to capillaries
muscles in arterioles direct blood to diff areas of demand in the body
- muscles contract to contrict the arteriole + restrict blood flow
+ relax to allow full blood flow
capillaries
• always found near exchange tissues - short diffusion distance
• walls = 1 cell thick - short diffusion distance
• networks of capillaries form capillary beds - large SA for gas exchange
importance of TF
cells can take in oxygen & nutrients + release metabokic wastes into ut
formation of TF
as blood enters capillaries from arteries, HSP increases due to smaller diameter
this causes ultrafiltration, forcing water & small molecules out the capillaures into the spaces surrounding the cells, forming TF
reabsorption of TF
as fluid leaves, HSP lowers
loss of fluid + increased conc of large molecules that remained in the capillary means water potential at the venule end is v low
so water from the TF reenters the capillary via osmosis
- this water contains dissolved waste molecules released from cells (Co2 + urea) to be removed from the body
cardiac musle
thick, muscular layer on walls of heart
• myogenic
• never fatigues
coronary arteries
what happens if they become blocked?
supply cardiac muscle w oxygenated blood
if become blocked, cardiac muscle won’t receive oxygen so cells will not be able to respire and will die, resulting in a heart attack
right vs left vertricles
right - pumps deoxyg blood to lungs at lower pressure to prevent damage to capillaries in lungs
left - pumps oxg blood to rest of bosy at higher pressures to ensure blood reaches all cells
- there4 have thicker muscular walls (than right ventricles) to enable larger contractions
atria vs ventricles
ventricles have thicker muscular walls than atria as they have to push blood out of the heart, whereas atria just have to push blood a short distance into the ventricles
vena cava
carries deoxyg blood from body into right atrium
pulmonary vein
carries oxyg blood from lungs into left atrium
aorta
carries oxyg blood from left ventricle to rest of body
pulmonary artery
carries deoxyg blood from right ventricle to lungs
septum
muscle running down middle of heart, separating oxygenated and deoxygenated blood
- maintains high conc of O2 in oxygenated blood
+ there4 maintains the conc grad to enable efficient diffusion into respiring cells
atrioventricular valves
av valves link atria to ventricles
- prevent backflow of blood from ventricles back into the atria when the ventricles contract
semilunar valves
SL link ventricles to the pulmonary artery + aorta
- prevent backflow of blood back into the heart after the ventricles contracts
how do valves prevent backflow of blood?
will only open when pressure is higher behind them compared to in front
forced shut when pressure is higher in front than behind
means blood can only flow in 1 direction through the heart
cardiac cycle
ongoing sequence of contraction + relaxation of atria & ventrickes thay keeps blood ciculating the body
involves:
• diastole
• atrial systole
• ventricular systole
diastole
- atria & ventricles are relaxed
- blood enters atria via VC and PV
- pressure in atria starts to increase
atrial systole
- atria contract, increasing the pressure further
+ decreasing the volume of the chambers - causes AV valves to open + blood flows into the ventricles
