The Heart and Coronary Arteries Flashcards
how many layers does the pericardium have? what are they?
function? (5)
- *- 3 layered sac:**
i) fibrous pericardium
ii) visceral layer - attached to surface of the heart
iii) parietal layer - attached to fibrous layer - *- function:**
i) protec from infections from other organs
ii) attached to great vessels
iii) attached to diaphragm: anchors heart in place & limits movement
iv) prevents excessive dilation of heart in cases of acute volume overload
v) lubrication: allows free movement of heart within the pericardial sac
what is pericardial effusion?
what does it lead to?
difference between acute and chronic pericardial effusion?
- is the buildup of too much fluid between the viseral and parietal pericardium
- leads to pericardial tamponade (when it cant beat)
- the heart normall fills the pericardial sac with a small amount of fluid and doesnt need much space to expand. but when get pericardial effusion, heart has no where to go - cant beat as efficiently: might get collapse of chambers of heart.
acute pericardial effusion: can only accumulate about 150ml before cardiac output is reduced
chronic pericardial effusion: can accumlate about a litre before compromised
when cardiac tamponade occurs - which ventricle is effected?
what can result in ?
- impairs diastolic filling of both ventricles. BUT: the right ventricle is more severely effected bc has thinner ventricle wall
- reduces cardiac output, which can lead to: hypotension / shock
- also causes an increase in venous pressures, pulmonary congestion (blood pools in lungs)
how do you manage cardiac tamponade?
management: pericardiocentesis Pericardiocentesis is a procedure done to remove fluid that has built up in the sac around the heart (pericardium). It’s done using a needle and small catheter to drain excess fluid.
what is difference in cardiac output when have cardiac tamponade, for inspiration and exhlation?
amount of blood that leaves the heart is improved during expiration
during inspiration, diaphragm goes down = less space available. cardiac output is worsened
DURING CARDIAC TAMPONADE, CARDIAC OUTPUT IS WORSENED IN INSPIRATION C.F. EXPIRATION
what are the dfferent layers of heart wall?
epicardium: visercal layer of serous pericardium
myocardium: cardiac muscle fibers. arrnaged in bundles. squeezes blood out of heart
endocardium: continious with endothelium. line chambers and the heart
is the volume of the blood propelled by the right ventricle the same as that propelled by left ventricle in one heart beat?
within a few mls: YES
label the different heart chambers pls xox
on external surface of the heart, what seperates the atria from the ventricles?
whats in them?
where do u find the anterior and posterior interventricular sulcus?
- *coronary groove (aka atrioventricular sulcus)**
contains: coronary arteries and veins
anterior and posterior interventricular sulcus: seperates the right and left ventricles
which BV go into the right atrium and left atrium?
(which BV go leave the right ventricle and left ventricle?)
this is wrong lol
right atrium: SVC, IVC and coronary sinus
left atrium: 4 pulmonary veins - back from lungs to heart, left auricle
right ventricle: 2/3 anterior, pulmonary trunk leaves it
left ventricle: apex (left border), inferior surface (2/3 post), aorta leaves
what are the internal landmarks of the right atrium?
- posterior wall: smooth. thumb sized depression: fossa ovalis
- *- anterior wall:** rough, due to pectinate muscle
- *- sino atrial node:** base of SVC (*)
- atrioventricular node: inferior to coronary sinus (#)
what is the function, location and appearance of the moderator band?
moderator band: Function: provides a shortcut between the anterior and posterior papillary muscles : gives them coordinated contraction during systole and efficient closing of the tricuspid valve.
- Location*: spans between the interventricular septum and the anterior wall of the right ventricle.
- Appearance*: does not seem to be attached to one single side, but rather crossing the lower portion of the right ventricular chamber.
what are the walls of the left atria like compared to the right atria?
- left atria walls are entirely smooth, apart from left auricle, where have pectinate muscle
- right atria: only the posterior wall is smooth, non smooth has pectinate muscle
describe important structures of the left atrium and ventricle xo
where does it go to?
- *left atrium**
- fossa ovalis (?)
- between left atrium and left ventricle: mitrial valve. attached by chordae tendineae and papillary muscles
- *left ventricle**
- thicker myocardium
- tranbeculae carnae: irregular muscular columns which project from the whole of the inner surface of the ventricle
- goes into ascending aorta and aortic semilunar valve
which are the first vessels to branch off the aorta?
what do they branch off into and supply? - what determines dominance between them?
left and right coronary arteries - supply atria and ventricles with o2 blood fo
- Left coronary arteries: supplies / turns into left anterior descending, supplies the left ventricle
- right coronary artery: supplies the posterior descending and posterior lateral
- dominance determined on the posterior lateral and posterior descending artereis and whether come from left or right coronary arteries
what are aortic sinuses?
what is located next to the RCA?
- The aortic sinus, or bulb of the aorta (sinus of Valsalva), is a dilation of the aorta at its origin, from which the coronary arteries arise.
- Get right, posterior and left aortic sinus. left and right go into left and right CA.
- the atrioventricular node is located close (and supplied by the) RCA .
describe the paths of th coronary arteries - what do they both anastmose with?
RCA: anastomoses with circumflex branch of LCA: gives rise to posterior interventricular artery
LCA: loops around apex and branches into left anterior descending (LAD). anastamoses with posterir interventricular artery
what is the first branch of the RCA?
what is another important thing supplied by the RCA?
why is this imporant
sinus node artery - goes to the sinus atrial node
also supplies the atrio-ventrocular node
RCA is important bc it supplies the two parts of the conducting system: the sino atrial and atrioventricular nodes
what need to know about coronary veins? where does it drain into ? (2)
- coronary veins drains into the coronary sinus on posterior surface of heart
- THEN, coronary sinus drains into right atria
when do the atrioventricular valves open?
name for this?
which valves are cloesd when this happens?
- *diastole**
- when ventricles are relaxed, chordae tendinae are slack and papillary muscles are relaxed
- ventricular pressure is lower than atrial pressure
- semi-lunar valves are closed
what is systole and when / how does it occur?
systole: ventricular emptying
- AV valves close
- ventricles contract: pushes the valve cusps closed, chordae tendinae are pulled taut and papillary muscles contract to pull cords and prevent cusps from everting
- semi-lunar valves are open
what is the role of the semilunar valves?
what are they and where found
Pulmonary valve – located between the right ventricle and the pulmonary trunk (pulmonary orifice).
Aortic valve – located between the left ventricle and the ascending aorta (aortic orifice).
- have three cusps
- *function:**
i) prevent backflow from aorta and pulm. trunk into ventricles
ii) work by passive action
the cardiac muscle fibres form two networks from two different types of fibres.
a) what direction are the atrial fibres like? what about the ventricles?
b) how does this influence how blood moves in each ?
Cardiac muscle fibres form 2 networks via gap junctions at intercalated discs.
There are two types of fibres
- the atria have a circular arrangement to squash the blood down
- the ventricles have a spiralling arrangement to push the blood up and out.
These fibres are, regardless, still separated by the fibrous skeleton of the heart.
which plexus innervates the heart? where do fibres from this plexus go to?
^ what does this get innervation from?
cadiac plexus - lies anterior to the bifurcation of the trachea and posterior the the arch of aorta
- *contains:**
- parasympathetic (from vagus)
- sympathertic (from sym. trunk)
- viseceral sensory afferents (VGA)
fibres extend from the plexus to the coronary vascularure and the components of the conducing system of the heart, esp the SA node
where do you find preganglionic and postganglionic
i) sympathetic neurons
ii) parasympathetic neurons
in the heart?
cardioacceletory centre: medullary reticular formation
preganglionic sympathetic neurons: thoracic spinal cord
postganglionic sympathetic neurons: SA & AV node, & coronary vasuclar smooth muscle
preganglionic parasympathetic neurons: vagus nerve
postganglionic parasympathetic neurons: SA & AV node,
explain why is cardiac pain called referred pain?
pain not felt in the heart - referred
- because viseceral afferent nerve fibres can only measure stretch / pH / o2 / Co2
- SO, viseceral afferent nerve fibres ascend to the CNS through sym. branches
- organ and skin pain fibres travel together to spinal cord
- therefore: pain occurs in skin supplied to T1-5 and L side of chest, neck and face
- infarct on **inferior wall is also referred
- toepigastrium (T7, 8 & 9)**
explain how the does conduction of the heart system occurs :)
The sino-atrial node is where the conducting system begins: natural pacemaker of the heart and is where electrical conduction will begin and spread across the atria to cause synchronous contraction.
The impulse will pause when it reaches the AV node, in order to ensure the atria have fully contracted.
The atrioventricular bundle connects the atria to the ventricles.
The AV bundle branches conduct the impulses through the interventricular septum, and the purkinjie fibres stimulate both the contractile cells of both ventricles, starting at the apex and moving superiorly
