Chapter 12- the heart

Question 1

which cavity contains the heart. where is it?

Answer 1

located in the thoracic cavity between the lungs, called the mediastrinum.

Question 2

what membrane encloses the heart, name its 3 layers

Answer 2

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)

Question 3

what is the name of the heart muscle

Answer 3

myocardium

Question 4

what lines the chambers, valces, and continues into the vessels as their lining of the heart and why

Answer 4

endocardium,

-smoothness- prevents abnormal blood clotting.

Question 5

name the four chambers of the heart and the valves between (described in blood flow manerism)

Answer 5

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

Question 6

the superior vena cava carries blood from the ____ body

the inferior vena cava carries blood from the ___ body.

Answer 6

1. upper

2. lower

Question 7

what hormone is produced by the atria, how is it regulated?

Answer 7

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.

Question 8

how is the inversion of the tricuspid valve preventeD?

Answer 8

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.

Question 9

the hormone ANP (or ANH) is an antagonist to which hormone, and what does it do?

Answer 9

aldosterone, which raises BP (ANP decreases BP)

Question 10

what is unique about the walls of the L ventricle?

Answer 10

they are thicker to enable the L ventricle to contract more forcefully, to get blood to the whole body/.

Question 11

what is the purpose of the firbous skeleton of the heart?

Answer 11

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.

Question 12

what is the name of the large muscle of the heart between the L and R ventricle?

Answer 12

inter-ventricular septum

Question 13

what is the name for the tip of the heart?

Answer 13

apex

Question 14

what are the first branches of the ascending aorta, and what is their purpose?

Answer 14

L and R coronary arteries circulate blood through the myocardium itself.

Question 15

define ischemic, what happends after prolonged ischemia?

Answer 15

when parts of they myocardium is deprived of its blood supply. prolonged leads to infarct (death)

Question 16

what is the medical name for heart attack

Answer 16

myocardial infarction

Question 17

define cardiac cycle

Answer 17

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.

Question 18

define systol and diastole

Answer 18

systol = contraction
diastol = relaxation

Question 19

in the heart, when is blood moving passively and when is blood moving actively?

Answer 19

passively from atria to venticles

actively from venticles to arteries

Question 20

describe the “lub-dup”

Answer 20

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.

Question 21

what is a heart murmur

Answer 21

• 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)

Question 22

how do cells of the myocardium generate their own electrical action potentials faster than others?

Answer 22

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.

Question 23

define atherosclerosis

Answer 23

• 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)

Question 24

what are CRP ( C-reactive proteins) and homocysteine, and why is it crutial?

Answer 24

Chemical markers that signal the presence of inflammation, (possible risk factor for MI)

Question 25

describe the steps of a heart contraction

Answer 25

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]

Question 26

which fibres in the electrical pulse pathway of the heart are respnsible for the ventricular systole?

Answer 26

purkinje fibers

Question 27

what are arrhythmias

Answer 27

irregular HP

Question 28

what are heart palpitations

Answer 28

increase heart rate

Question 29

what is ventricular fibrillation

Answer 29

very rapid and uncoordinated ventricular beat that is ineffective for pumping blood

Question 30

what 3 distinguishable waves or deflections are readable in an typical ECG?

Answer 30

1. P wave (depolarization of atria)
2. QRS wave (depolarization of ventricles)
3. T wave (repolarization of ventricles)

Question 31

what is bradycardia?

Answer 31

HR less than 60

Question 32

what is tachycardia?

Answer 32

prolonged or consistent rate > 100 BPM

Question 33

what is cardiac output, and how is it calculated?

Answer 33

blood pumped by a ventricle in 1 minute
cardiac output = stroke volume x pulse
(average is approx 5-6 liters/min)

Question 34

what is starlings law of the heart?

Answer 34

the more the cardiac muscles are stretched the more forcefully they contract. = ^ stroke volume.

Question 35

what is ejection fraction?

Answer 35

% of the blood within a ventricle that is pumped out per beat, should be 60-70%

Question 36

what is cardiac reserve?

Answer 36

the difference between resting cardiac output and maximum cardiac output during exercies. should be 15L or more.

Question 37

what two cardiac centers are contained in the medulla, and send impulses to the heart via autonomic nerves?

Answer 37

1. accelerator center > sympathetic nerves > norepinephrine> ^ HR and force of contraction
2. inhibitory center. > parasympathetic nerves > acetylcholine > decrease HR.

Question 38

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).

Answer 38

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).