Chapter 12- the heart Flashcards
which cavity contains the heart. where is it?
located in the thoracic cavity between the lungs, called the mediastrinum.
what membrane encloses the heart, name its 3 layers
pericardial membranes,
1. outter layer fibrous pericaridum
2/3 - the serous pericardium is a folded membrane- the folds gives rise to two layers:
- perietal pericardium, (lining of fibrous pericardium)
——serous fluid——(prevents friction——–
-visceral/epicardium pericadium (surface of heart muscle)
what is the name of the heart muscle
myocardium
what lines the chambers, valces, and continues into the vessels as their lining of the heart and why
endocardium,
-smoothness- prevents abnormal blood clotting.
name the four chambers of the heart and the valves between (described in blood flow manerism)
caval viens > R atrium > Tricuspid valve (AtrioVentricular)> R ventricle > pulmonary semilunar valve > pulmonary artery > lung > pulmonary veins > L atrium > mitral valve > L ventricle > aortic semilunar valve >aorta
the superior vena cava carries blood from the ____ body
the inferior vena cava carries blood from the ___ body.
- upper
2. lower
what hormone is produced by the atria, how is it regulated?
when the walls of the atria are stretched by ^ blood volume or BP, the cells produce ANP (peptide), or ANH (hormone)) > decreased reabsorption of Na+ by kidneys, which increases elimination of water to decrease Blood volume, and pressure.
how is the inversion of the tricuspid valve preventeD?
in the lower part of the R ventricle are column of myocardium called papillary muscles. strands of chordae tendineae extend from the papillary muscles to the flaps of tricuspid valve. when the heart contracts it prevents the back flow.
the hormone ANP (or ANH) is an antagonist to which hormone, and what does it do?
aldosterone, which raises BP (ANP decreases BP)
what is unique about the walls of the L ventricle?
they are thicker to enable the L ventricle to contract more forcefully, to get blood to the whole body/.
what is the purpose of the firbous skeleton of the heart?
anchors the outer edges of the flaps and keeps the valve’s opennings from stretching.
also seperates the myocardium of the atria and ventricles and prevents contraction of the atria from reaching the ventricles.
what is the name of the large muscle of the heart between the L and R ventricle?
inter-ventricular septum
what is the name for the tip of the heart?
apex
what are the first branches of the ascending aorta, and what is their purpose?
L and R coronary arteries circulate blood through the myocardium itself.
define ischemic, what happends after prolonged ischemia?
when parts of they myocardium is deprived of its blood supply. prolonged leads to infarct (death)
what is the medical name for heart attack
myocardial infarction
define cardiac cycle
sequence of events in one heart beat.
contraction of the two atria, followed a fraction of a second later by the stimultaneous contraction of the two ventricles.
define systol and diastole
systol = contraction diastol = relaxation
in the heart, when is blood moving passively and when is blood moving actively?
passively from atria to venticles
actively from venticles to arteries
describe the “lub-dup”
lub: first sound, longest + loudest ,caused by ventricular systole closing the AV valves
dup: second sound, caused by closure of the aortic and pulmonary semilunar valves.
what is a heart murmur
- valves do not close properly, and causes an extra sound.
- regurgitation of blood, (creates turbulance)
- some valve defects involve narrowing (stenosis) and are congenital (born with it)
how do cells of the myocardium generate their own electrical action potentials faster than others?
signals spread quick electrical signals to adjacent muscle cells by means of the intercalated discs that form end-to-end junctions, which allows for electrical impulses to travel so fast that two atria contract as a unit in the cardiac cycle, followed by simultaneous contraction of the two ventricles.
define atherosclerosis
- most common cause of CAD
- plaque forms in the wals of a coronary artery, this narrows the lumen (cavity), and creates a rough surface, where a clot (thrombus) may form.
- increased risk with genetics, men, smoking, DM, and HTN (cause damaging to linings of arteries)
what are CRP ( C-reactive proteins) and homocysteine, and why is it crutial?
Chemical markers that signal the presence of inflammation, (possible risk factor for MI)
describe the steps of a heart contraction
SA node (group of specialized Na+ permeable cells, that depolarize faster in wall of R atrium) > impulse > Antrioventricula (AV) node ( located in L interatrial septum)> AV bundle (bundle of his) > R/ L bundle branch > [R bundle branch > R ventricle ] / [L bundle branch > L ventricle > purkinje fibres > L atrium]
which fibres in the electrical pulse pathway of the heart are respnsible for the ventricular systole?
purkinje fibers
what are arrhythmias
irregular HP
what are heart palpitations
increase heart rate
what is ventricular fibrillation
very rapid and uncoordinated ventricular beat that is ineffective for pumping blood
what 3 distinguishable waves or deflections are readable in an typical ECG?
- P wave (depolarization of atria)
- QRS wave (depolarization of ventricles)
- T wave (repolarization of ventricles)
what is bradycardia?
HR less than 60
what is tachycardia?
prolonged or consistent rate > 100 BPM
what is cardiac output, and how is it calculated?
blood pumped by a ventricle in 1 minute
cardiac output = stroke volume x pulse
(average is approx 5-6 liters/min)
what is starlings law of the heart?
the more the cardiac muscles are stretched the more forcefully they contract. = ^ stroke volume.
what is ejection fraction?
% of the blood within a ventricle that is pumped out per beat, should be 60-70%
what is cardiac reserve?
the difference between resting cardiac output and maximum cardiac output during exercies. should be 15L or more.
what two cardiac centers are contained in the medulla, and send impulses to the heart via autonomic nerves?
- accelerator center > sympathetic nerves > norepinephrine> ^ HR and force of contraction
- inhibitory center. > parasympathetic nerves > acetylcholine > decrease HR.
what stimulates the medulla to activate the impulse centers? (describe the reflex arc to increase HR and force when BP or O2 to the brain decreases).
Blood pressure, and oxygen levels via: pressoreceptors (in carotid sinuses and aortic sinus - they detect changes in BP and send signal to medulla via the vagus nerve) and chemoreceptors (in carotid bodies and aortic body, detect changes in O2 content and send signal to medulla via glossopharyngeal nerve).
