module 3 - 8.5 the heart Flashcards
what is the heart?
a muscular organ that pumps blood through the circulatory system by increasing blood pressure relative to lowest blood pressure in blood vessels - difference in pressure causes blood to flow
what 3 layers is the wall of the heart made up of?
- epicardium - outer layer of the heart wall and inner pericardial membrane
- myocardium - cardiac muscle
- endocardium - lines the chambers and covers the heart valves, joins with endothelium that lines blood vessels
what is the heart enclosed by and why?
- enclosed by pericardium for protection of the heart
- fluid between inner and outer pericardial membranes lubricates movement of the heart
what is the pericardium?
double walled sac for protection of the heart
why does blood not separate when pumped?
due to hydrogen bonds between water molecules in blood
where is the heart beat initiated?
right atrium
where does the tricuspid valve prevent backflow of blood?
from right ventricle to right atrium
which pressure increases during ventricular systole in a mammalian heart?
ventricular pressure
when listening to the heart on a stethoscope, what contributes to the first ‘lub’ sound?
closing of the bicuspid valve
when listening to the heart on a stethoscope, what contributes to the second ‘dub’ sound?
closing of semi lunar valves
what are the 3 types of vertebrate muscle?
skeletal , cardiac, smooth
what are cadriac muscles made from?
cardiomyoctyes joined together by intercalated discs
why do cardiomyocytes need to contract in coordination with its neighboring cells?
to efficiently pump blood from the heart, if this coordination breaks down, the heart may not pump blood
what are intercalated discs?
a type of cell junction/cytoplasm bridge
what do intercalated discs allow?
allows cardiomyocytes to contract in coordinated manner
