Anatomy of the Heart Flashcards
where does the apex of the heart rest during maximal inspiration
fibrous tendon of the diaphragm
how does the phrenic nerve innervate the diaphragm
pierces the diaphragm and innervates it from beneath
what might irritatoin of the pericardial sac to?
why?
cause referred pain in the C3, 4, 5 dermatomes
-phrenic nerve also traverses the pericardial sac
where are the heart and esophagus located in the mediastinum
heart is in the middle mediastinum and esophagus is in the post mediastinum
what is the boundary btwn the sup and middle mediastinum?
manubrium-sternal junction and 4-5 intervertebral disk
where does the post mediastinum run from?
T5-T12
where are the esophagus and descending aorta located
post mediastinum
what is located at T8? T10? T12?
inf vena cava
esophagus and vagus
descending aorta
what are the layers of the sac (pericardium)
outer, thick fibrous layer
inner serous layer
what is the structure and role of the pericardium?
simililar to pleura and peritoneal lining
- protects the organ and lines the body wall
- fluid btwn layers
what kind of cells are in the serous layer?
what do they produce?
monolayer of mesothelial cells which produces a small amount of fluid
what does the pericardial cavity contain
what kind of tissue is aggregated here
small amount of fluid which lubricates the heart as it contracts
brown adipose tissue
the outer fibrous coat loosely is around the heart and on the outer surface of the great vessels except the what?
inf vena cava
what does each layers of the double inner serous coat do
one layer is closely adherent to the heart and the other lines the inner surface of the outer coat w/ the intervening space being filled w/ pericardial fluid
what does brown fat in the serous space provide? how does it differ from white adipose tissue
energy source and heat
white is only for energy storage
what is a cardiac tamponade
what may one experience from this?
too much fluid btwn the serous layers in the pericardial sac
-may experience mechanical compression of the heart, restricting its movements
why is brown fat cool to have in the serous space
having heat generating material next to the heart is helpful in spreading warmth throughout the body
when may pericardidtis appear
after bypass surgery in which the pericardial sac has been cut to reveal vessels
what may the inflammation from pericarditis produce?
an exudate, which is an ultrafiltration of plasma
-the exudate is called the pericardial effusion
what are the 5 layers of heart tissue
- epicardium
- sub-epicardium
- myocardium
- sub-endocardium
- endocardium -lines atrium or ventricles
what does sub-epicardium contain
arteries, veins, coronary sinus
what does sub-endocardium contain
veins, nerves, purkinje fibers
which layer of the heart is most prone to ischemia (lack of blood flow) and infarctions (necrosis as a result of ischemia)
sub-endocardium
why can an infarction of the sub-endocardium cause a lot of damage
purrkinje fibers spread the electrical signals from the SA/VA nodes
-may damage the electrical conduction system, requiring a pacemaker
why is the sub-endocardium more prone to ischemic damage
bc there is no blood flow during systole in subendocardium
what is the ligamentum arteriosum?
remains of ductus arteriosus(bypassed the lungs) btwn pulmonary trunk and aortic arch
what is the conus arteriosis
fetal structure which gives rise to the pulmonary trunk
what is the blood flow within the heart
sup and inf vena cava, RA, RV, pulmonary trunk, pul arteries, lungs, LA, LV, aortic valve, body
what is tricuspid and what is bicuspid
tricuspid: pulmonary valve (RV to PA), aortic valve (LV to aorta), AV valve (RA to RV)
bicuspic: mitrial (LA to ventricle)
when does the descending aorta pierce the diaphragm?
when does it branch into the common iliac arteries?
T12
L4
what does the external iliac go under? what does it become?
under the inguinal ligament and becomes the femoral artery
what does the internal iliac nourish
pelvic region
where does the common iliac vein join the inf vena cava?
at about the same level the ciliac artery bifurcates
why can the venous system keep the iliac vein open on the left side?
what happens on the right side
- enough negative pressure in the venous system to keep the vein open
- right side, the artery (right common illiac) crosses the vein
why can venous pressure be compromised during pregnancy
bc of increased abdominal pressure, left artery and vein are compressed against the body wall side by side.
-right artery presses on the vein, compromising venous return resulting to venous stasis
-greater/sooner on RIGHT
in venous drainage into the RA, where do internal jugular veins end
subclavians
what is the anterior wall of the RA made of? what is the ridge along the lateral side of the RA called?
pectinate muscles
crista terminales
why is the arrangement of trabeculae carnae good
good for generating significant force w/o much muscle weight
where is the SA node located
on the post wall of the R
-close to entry point of SVC
what is the fossa ovalis the remnant of
-when does this clsoe
of the foramen ovale-fetal opening btwn the right and left atrium which floses/fibroses upon the 1st breath
how are the walls of the right and left ventricles compared
wall of left is twice as thick as the right
what happens in RV failure
RV works harder to pump blood through the lungs and consequently there’s pressure backup into the RA and vena cavas
-caused by lung disease
what do valves have on all sides? what is in the middle?
endocardium on all sides
fibrous tissue in the middle
what edema? what happens when standing and lying down
venous system begins to leak fluid
-when standing, fluid acculmulates in lower lets, when lying down, it redistributes
how is chordae tendinae and papillary muscles connected
one papillary muscle has linkages (also made of endocardium and fibrous tissue) to 2 separate valves
how many papillary muscles are on the left and right
2 on left and 3 on right
what is trabeculae carnae
muscle lining the ventricles
papillary muscles are an extension of what
myocardium
how is blood flow back to the atria prevented
a split second before the ventricles contract, papillary muscles contract, so valvle leaflets can be tightly held closed against the pressure from ventricle contraction
in what disesases does mitrial valve prolapse occur
marfan syndrome
graves disease
hypertension
what happens in mitral valve prolapse
some blood in the LV gets regurgiated/squirted back into the LA
-audibly detectable as a heart murmur
how do poeple w/ marfan syndrome look like `
tall, long limbs, long and thin fingers
-thin women w/ minor chest wall deformities, scoliosis
what causes marfan syndrome
dominant mutation in the fibrillin-1 gene
-found in elastic/non elastic fibers in connective tissues
where is fibrillin-1 found in
elastic/non elastic fibers in connective tissues
what are patients more prone to when they have marfan syndrome
lung problems (spont pneumothroax), aortic dilation or aortic aneurysm, scoliosis, eye problems
- subluxation (dislocation) of the cyrstalline lens (lens suspended from ciliary body by elastic fibers) in one or both eyes (ectopia lentis) occurs in 80% pts
- nearsightedness
- astig
when does mitral stenosis occur
occurs following group A beta hemolytic streptococcal (GABHS) paryngitis in children-rheumatic fever
what is the problem in mitral stenosis
what can this cause
problem getting blood into the left ventricle
-fast, turbulent blood flow btwn left atria and ventricle
- can cause left atrial fibrillation bc atrium must work much harder to get blood into the ventricle
- fluid may be backed up into the lungs leading to respiratory distress and pulmonary edema
what did pathologic examination of the mitral valve in mitral stenosis reveal
scarring: proliferation of fibroblasts and macrophages
what do the serum of the patients with mitral stenosis from strep throat, leading to rheumatic fever contain
antibodies which cross-react w/ myocardial tissue
- antibodies to type 5 streptococcal M protein
- cross react w/ myosin in myocardial tissue
why can different parts of the heart fail?
bc of a direct myocardial infarction as opposed to some systemic disease
how can a pt with atherosclerosis (plaque build up in vessels) lead to left ventricular failur
leads to increased peripheral vascular resistance
- LV works much harder which leads to hypertrophy, weakening the mucsle
- left heart failure inevitably leads to right failure leading to death
what do right and left coronary arteris arise from
right coronary artery arises from an aortic sinus
left coronary artery arises from left post sinus
where is the apex of the heart located
5th intercostal space ~9cm left of the sternum
-roughly aligned w/ the xiphoid process of the sternum
where are th eopenings for the coronary artiers
at the base of the (right) ant and left post aortic valves
what grooves do the left coronary artery and right coronary artery lie in
left: interventricular groove
right: coronary groove
when do the left and right coronary artiers fill
during diastole (relaxation)
what are symptoms of a heart attack
crushing chest pain anxiety difficulty breathing nausea, vomiting sweating pallor
what is atherosclerosis
a disease of large and medium muscular arteries w/ several indications:
- endothelial dysfunction
- vascular inflammation
- clotting: buildup of lipids, Ca, and cellular debris in the tunica intima
what is arteriosclerosis
similar to atherosclerosis but w/o fatty plaque buildup
what can happen if atherosclerosis comes on slowly
why can a fast blockage be more dangerous
collateral branches of coronary arteries (few) may sprout around the clot
-a fast blockage can be more dangerous bc there are normally so few branches
what can be used in a coronary artery bypass graft
internal mammary vessels
in coronary bypass surgery, what can some stents (tubular support) be coated w/
-what can happen when uncoated
compounds which inhibit cellular proliferation and inflammation
-with uncoated stents, vessels may revert to original level of blockage w/in a year
what is an angina
referred pain as a result of an exertional decrease in blood flow to the heart
-not a heart attack
what does the coronary sinus open up into
where does it lie
right atrium coronary groove (alone coronary artery)
what are cardiac muscles linked by
why
gap junctions
-as a result, electrical excitement will discharge across many cardiac muscle cells
what is the bundle of His (atrioventricular bundle)
connects SA Node to the AV node
- SA node in RA
- AV node is in RA but close to the valve leading into the RV
what are the left and right bundle branches located? what are they made of
interventricular system
made of purkinje fibers: specilaized cardiac muscle cells which look like nerves
-conducting elements for the electrical current
what does an SA Node produce
how is it related to the AV node
autorhythmic function
-beats on its own
-must faster than AV node (~80 beats per min vs 40 bpm) purkinje is 20bpm
what is important for both atria to work in series
discharge of SA node permeates both right and left atria muscle cells
-slight dysfunction btwn them could lead to rapid draining of blood from the lungs
what ist he preferential pathway for the SA node
bachman’s bundles
where are the purkinje fibers located? what happens here often?
interventricular septum
-infarct
what will myocytes do to the electrical current as it comes down to the tip of the heart
as electrical current comes down to the tip of the heart, it curves back up, moving the purkinje fibers into the cardiac myocytes
-myocytes will activate it in a particular pattern
how do ventricles contract after electrical discharge from the tip of the ventricles upward towards the valves
from the bottom (apex) up in a twisting fashion
-as though blood is being rung out toward the valve
where does the great cardiac vein run in
ant interventricular sulcus
what is the moderator band
a band of muscular tissue which contains the purkinje right bundle branch (conveys right branch of the AV bundle)
where does the moderator band extend from
from the interventricular septum across the lumen of the RV to the papillary muscles
what does the moderator band ensure
the 2 ventricules contract at the same time
what dermatomes are invovled with the innervation of the heart
what nerves innervate the heart
T1 and sometimes T2 dermatomes
T1 and T2 nerves (sympathetic innervation)
where are the sympathetic ganglia near
what are parasympathetic ganglia near
the CNS origin, not the organ being innervated
close to the organ being innervated
what are the sympathetic ganglia that send post-ganglionic fibers to innervate the heart?
superior cervical ganglion and T2 ganglion
what are cardiac plexi
ganglia that are close to or w/in the heart
- superfial
- deep
what does the cardiac skeleton, the reinforced fibrocartilaginous “skeleton” do?
where is it located
helps to support the heart when it contracts
-around the location of the valves, absorb pressure when the muscle contracts (points of greatest stress)
