17-2: Pathway of circulation Flashcards
The right atrium receives __ blood through __ pathways: _.
deoxygenated blood; three pathways; superior vena cava, inferior vena cava, coronary sinus
superior vena cava
returns deoxy blood from organs above the heart and empties into R atrium
inferior vena cava
returns deoxy blood from organs below the heart and empties into R atrium
coronary sinus
returns deoxy blood from vessels supplying the myocardium and empties into R atrium
The right ventricle receives _ blood from __; then pumps it through _.
deoxy; tricuspid valve; pulmonary SL valve into pulmonary trunk
Deoxy blood entering the pulmonary trunk goes: __.
into right and left pulmonary arteries that carry the blood to the lungs, dropping off CO2 and picking up O2
The left atrium receives _ blood from __.
oxy blood from the lungs through 4 pulmonary veins
The left ventricle receives _ blood from _; then pumps it through _.
oxy; mitral/bicuspid valve; the aortic SL valve into aorta
Oxy blood entering the aorta goes _.
into many major arteries supplying all body tissues with oxygen.
Which ventricle has thicker walls?
left ventricle - pumping blood to a longer route through the whole body
coronary circulation
heart tissues need their own blood vessels, because food and O2 can’t diffuse from blood inside the heart through the myocardium
The coronary circulation originates as ___ branches off of the ___.
2 main branches; ascending aorta
left coronary artery
runs to left side of heart and divides into two major branches: anterior interventricular artery and circumflex artery
right coronary artery
runs to right side of heart and divdes into two major branches: marginal artery and the posterior interventricular artery
anterior interventricular artery
branches from the left coronary artery
posterior interventricular artery
branches from the right coronary artery
marginal artery
branches from the right coronary artery
circumflex artery
branches from the left coronary artery
As blood delivers O2/nutrients and picks up CO2/waste from the cardiac cells, it is collected by ___ which empty into ___.
cardiac veins; coronary sinus
coronary sinus
large vein on posterior surface of the heart where cardiac veins empty; it empties into the right atrium
anastomosis
where several arteries supplying the same region merge; these fusing networks provide collateral routes for blood delivery to the myocardium
conduction system
internal regulating system of the heart (even out of the body, the heart continues to beat)
autorhythmicity
specialized cardiac cells spontaneously and rhythmically generate electrical impulses that stimulate the cardiac muscles to contract (unstable resting potential)
syncytia
the cardiac muscle cells are so tightly connected at the intercalated discs, that when 1 fiber is stimulated, they all contract simultaneously as a unit
The heart is divided into two syncytia: ___ and ___.
atrial syncytium and ventricular syncytium, separated by a wall of insulating connective tissue
The conduction pathway consists of __ regions of ___ cells.
5; autorhythmic
sinoatrial node
mass of self excitable cells in the wall of the right atrium, just below opening to SVC
pacemaker cells
SA node - these cells set the pace for heart rate because they’re faster than other areas
normal sinus rhythem
~75 bpm, but may be altered by nerve impulses from autonomic nervous system or chemicals
The impulse generated by the SA node does what?
spreads rapidly over the atrial syncytium, causing the atria to contract simultaneously
atrioventricular node
2nd mass of self excitable cells, at the base of the inter atrial septum; last part of atria to depolarize
bundle of His
electrical bridge between the atria and ventricles, in the interventricular septem
The bundle of His splits __, which terminate into __.
into right and left bundle branches; many Purkinje fibers
What causes ventricular contraction?
stimulation of the ventricular syncytium by the Purkinje fibers
What are the steps in the conduction pathway?
- SA node sets the pace;
- impulse travels through atrial syncythium, causing both atria to contract
- impulse travels to the AV node
- impulse travels down the bundle of His and interventricular septum, which branches into right and left bundle branches
- impulse travels from bundle branches to many Purkinje fibers, which stimulate the ventricular syncythium, causing both ventricles to contract
