cardio Flashcards
where does the heart lie
mediastinum in thoracic cavity
right atrium …..
receives de-oxygenated from s and i vc and cs
right ventricle …….
waiting entry halls, primer pumps (thin walled)
left atrium …..
receives oxygenated blood from 4 branches of pulmonary pv’s
left ventricle ……..
generally 1/3 bigger than right ventricle
entry halls primer pumps (thin walled)
what are the 3 principal coronary arteries
left anterior descending
left circumflex
right coronary artery
what are coronary arteries
provide an intermittent pulsating flow to the myocardium, actively delivering blood when the heart is relaxed
ineffective during contraction
heart requires 1/20 of the bodys blood supply
what are the 3 blood vessel distinct layers
tunica interna
tunica media
tunica external
structure of blood vessels
arteries and veins lie side by side
have a narrow band of connective tissue
capillary beds ..
they are interconnected network of capillaries
dozens of capillaries form from a single arteriole
blood collects in several venules
what are myocardial cells
myofibrils with their myofilaments (actin and myosin)
they are surrounded by mitochondria (red) and the sarcoplasmic reticulum (blue) which are the intracellular calcium stores
what is electromechanical coupling
the stimulation of a cell membrane results in an action potential
this is converted to the activation of the sliding filament system of the contractile apparatus of the sarcomeres
during contraction, actin filaments slide together, therefore shortening the fibre length and generating contraction
action potential …..
membrane potential- difference in charge across a cell membrane
inside of the cell is negatively charged where the outside of the cell which is positively charged
more sodium outside of the cell in comparison to potassium inside the cell
when the potential difference between the inside and outside moves towards 0 and the cell is depolarised and when its returning back to its resting value its said to be repolarised
sensory control
vasomotor centre: brainstem integration of input
baroreceptor: detect amount of stretch on vessel walls
chemoreceptors: stimulated by excessive plasma co2 sympathetic system responds accordingly
anatomical nervous system (sympathetic)
neurotransmitter: alpha receptors- noradrenaline
beta receptors- noradrenaline or adrenaline
stimulation,excitation
high heart rate
high blood pressure
high respiration dilates pupils
low GI motility (inhibits urination)
