lect 1

primary role of cardiovascular system

distribution of essential substances to repair tissues, remove by-products of metabolism

secondary role of the CV system

circulation of H and NT, heat dissipation, mediation of defense responses

circulation of H and Nt allows

chemical signaling among cells (humoral communication)

heat dissipation is the

transfer from core to body surface

mediation of defense responses works

against invading microorganisms

3 basic functional parts of the circulatory system

heart, blood, vessels

heart consists of 2 pumps in series

right heart, left heart

right heart propels

oxygen-poor blood thru the lungs (pulmonary circulation)

left heart propels

oxygen-rich blood to all other tissues (systemic/peripheral circulation)

flow thru the heart is made

unidirectional by the presence of one-way valves

cardiac output is

pulsatile, meaning ventricles generate pressure pulses

parts that contain oxygen-rich blood

left atrium, left ventricle, arteries, arterioles

parts that work with gas exchange

capillaries, venules

parts that work with oxygen-poor blood

veins, right atrium, right ventricle, pulmonary arteries

each side of the heart is a 2-chamber pump comprised of

a thin-walled atrium, a thick-walled ventricle

atrium is the

receiving chamber and primer pump

ventricle is the

main pumping chamber

2 major types of cardiac myocytes

contractile cells, myoconductive cells

contractile cells are

atrial and ventricular myocytes

myoconductive cells are

nodal and purkinje cells

myoconductive cells are specialized

excitatory/conductive cells that spontaneously generate/conduct electrical signals thru the heart so that it beats rhythmically

myoconductive cells only contain

a few contractile elements, contracting weakly

cardiac muscle is

striated, filled w/repeating units of highly organized contractile protein arrays (sarcomeres)

cardiac muscle is arranged in

a lattice that behaves like a synctium

cardiac muscle cells are

short, branched, interconnected

cells are connected by

intercalated discs

intercalated discs are

specialized jxns that fuse neighboring cells

2 components of intercalated discs

desmosomes, gap jxns

desmosomes provide

physical connection (mechanical coupling)

gap jxns provide

electrical connection (electrical coupling)

myocytes can be activated almost

instantaneously by a wave of electrical stimulation

myocytes can contract

as one to generate a coordinated heartbeat

2 muscular functional syncytia

atrial syncytium, ventricular syncytium

atrial syncytium is the

right atrium, left atrium

ventricular syncytium is the

right ventricle, left ventricle

fibrous skeleton separates

atrial and ventricular muscle physically and electrically

fibrous skeleton lies along

atrioventricular (coronary groove)

fibrous skeleton blocks

electrical comm btwn atria and ventricles except where penetrated by AV bundle (bundle of His)

electrical insulation allows

atrial and ventricular syncytia to be activated separately and sequentially w/a time delay btwn

myocardium is the

thickest layer of the heart wall

atrial walls are

thinner than ventricular walls

left ventricular wall is

twice as thick as the right ventricular wall (even tho these chambers pump same V of blood per beat)

2 valves in the right heart

tricuspid, pulmonary/pulmonic valves

2 valves in the left heart

mitral, aortic valves

tricuspid valve is aka

right atrioventricular AV

pulmonary/pulmonic valve is aka

right semilunar

mitral valve is aka

left atrioventricular bicuspid

aortic valve is aka

left semilunar

right and left sides of heart are separated by two walls called

septa

2 types of septa

interventricular septum, interatrial septum

no valves exist btwn

cranial/caudal vena cava and right atrium, pulmonary veins and left atrium

thin flaps of flexible endothelium-covered fibrous tissue open and close to

maintain unidirectional blood flow

valve motion is

passive, moved by pressure exerted by flowing blood

AV valves separate

each atrium from its corresponding ventricle

AV valves position varies

according to phase of cardiac cycle

AV valves open when

ventricles relax to allow blood to drop from atria above

AV valves close when

ventricles contract to prevent backflow of blood into atria

chordae tendinae tether edges of sheet-like valve to

ventricular papillary muscles below

during ejection, papillary muscles

contract, tensing chordae to prevent valve eversion and backflow of blood