EKg, cardiac output, fetal development

Two types of myocytes (muscle cells)

1. Contractile- for contraction

2. Pacemaker cells- cells that spontaneously depolarize, initiate depolarization of the entire heart

P-wave

Depolarization of SA node and atria (atria contracts around here)

QRS complex

Ventricular depolarization and atrial repolarization relax (small dip, big peak, bigger dip)

T wave

Ventricular repolarization relax

P-R interval

Beginning of atrial excitation to beginning of ventricular excitation ( takes actual place around Q)

S-T segment

Flat line. Entire ventricular myocardium depolarized

Q-T interval

Large, Beginning of ventricular depolarization through ventricular repolarization

Systole

Contraction

Diastole

Relaxation-heart is filling with blood

What are the heart sounds from? (Lubb Dubb)

from the closure of valves

Which valves causes the Lubb sound from closing

from the Tricuspid and bicuspid(mitral) valve

Which valves causes the Dubb sound from closing

From the Pulmonary and aortic semilunar valve

Define cardiac output

Is the volume of blood ejected from L or R ventricle into the aorta or pulmonary trunk each minute

Stroke Volume (SV) • HR (bpm) = CO

Two main factors that affect cardiac output

1. stroke volume – amount of blood pumped out of ventricle and one beat.

2.) heart rate (bpm)

What is preload? (factor that affects cardiac output.)

The stretch that blood places on ventricle walls when filled. (End diastolic volume)

Factors that affect stroke volume

1.venous return- exercise causes muscle to squeeze veins increasing return

2.Contraction- need Ca, Noradrenaline + thyroid hormone increases Ca

3.blood leaving heart (after load)- resistance that blood experiences as it leaves ventricle, wider artery= less resistance,if after load decreases, stroke volume and CO goes up(inversely related)

Factors that effect heart rate

1. Vagus nerve (parasympathetic nerve fibers) decreases HR back to normal

2. Sympathetic increases HR by incr contraction rate

What 4 bulges represent earliest chambers of fetal heart

1. Sinus venosus

2. Atrium

3. Ventricle

4. Bulbous cordis

What sinus venosus gives rise to

Right atrium, coronary sinus, and SA node

What primitive atrium gives rise to

Pectinate muscles of atria

Primitive Ventricle gives rise to…

Left ventricle

Foramen ovale in fetal heart

Opening between atria, becomes fossa ovalis

Bulbous cordis gives rise to

Aorta, pulmonary trunk, Right ventricle

Ductus arteriosus in fetal heart

Connects pulmonary trunk to aorta. Becomes ligamentum arteriosum in adult (ligament basically)

Three branches of aortic arch in order

Brachiocephalic trunk

Left Common carotid artery

Left Subclavian Artery

B,C,S

Muscle called in atrial walls

Pectinate muscles

The muscle inner lining the ventricles

Trabeculae carnae