Heart Anatomy

layers of pericardium

layers of pericardium

Superficial to deep

fibrous pericardium

serous pericardium

pericardial cavity (In between parietal and visceral layer in serous filled with pericardial fluid)

layers of heart wall

Superficial to deep

epicardium

myocardium

endocardium

epicardium function

protecting the heart

myocardium function

(cardiac muscle) pumping of the heart

muscle fibers are involuntary , striated, and branched

endocardium function

(squamous epithelium) lines the inside of myocardium and covers valves and large vessels

atria

2 upper chambers

interatrial septum

auricle: (dog ear) and allows blood to collect

fossa ovalis: remnant of opening fetus right to if blood was foramen ovale (by passes lungs)

ventricles

2 lower chambers

interventricular septum

atria is the thinnest (no pumping)

right ventricle a little bit thicker pumps to the lungs= pulmonary circulation

left ventricle is thickest muscle and pumps blood to the rest of the body

which chamber is the thinnest and why?

atria; no pumping

which chamber is medium sized and what does it do?

right ventricle; pumps to the lungs (pulmonary circulation)

which chamber is the thickest and why?

left ventricle; pumps to the rest of the body

valves function

function: allow blood to flow in one direction to prevent backflow

what are the 4 valves?

atrioventricular (AV) (2): between atria and ventricles

bicuspid (mitral) valves: left side of heart

tricuspid valves: right side of heart

semilunar valves (2): between ventricle and vessel/artery

pulmonary semilunar valves

aortic semilunar valves

AV valves

anchored in place by chordae tendineae (heart strings) and papillary muscles

Semi-lunar valves

closed during relaxation, opened during contraction

AV vales and semi-lunar valves work opposite of each other to force a one-way path of blood through the heart

lubb vs dubb

lubb: AV valves closing (ventricular systole begins)

dubb: semi-lunar valves closing (end of ventricular systole)

Systemic circulation

blood flows on left side of heart through body tissues and back to the right side of the heart (left vent to right atrium)

Pulmonary circulation

blood flows from the right side of the heart to the lungs and back to left side of the heart (right vent to left atrium)

Blood flow of heart order

1. SVC and IVC and coronary sinus dump blood into the right atrium from right atrium through the tricuspid valve, blood travels to right ventricle

2. from the right vent, blood leaves the heart as it passes through the pulmonary semi-lunar valve into the pulmonary trunk

3. pulmonary trunk splits into right and left pulmonary arteries that carry blood to the lungs

4. oxygen is picked up and CO2 is dropped off by blood capillaries in the lungs

5. oxygen-rich blood returns to the heart through the four pulmonary veins

6. blood eneters the left atrium and travels through the bicuspid valve into the left ventricle

7. from the left ventricle, blood leaves the heart via the aortic semi-lunar valve and on to the aorta

8. between pulmnary trunk and aortic arch is ligament arteriosum what was once a hole

   1. fetal ductus arteriosum remnant

ischemia

decreased flow of blood to vessel (low oxygen) which leads to angina pectoris

angina pectoris

chest pain

myocardial infarct

heart attack; death of cardiac muscle due to lack of blood supply. Caused by blockage of coronary artery usually due to plaque

cardiac arrest

heart stops pumping

coronary circulation

flow thru vessels in myocardium

coronary arteries

(left and right)

branch from aorta to carry oxygenated blood throughout cardiac muscle and drains into the coronary veins

coronary veins

carries de-oxygenated blood back to get oxygenated and drains into the coronary sinus

coronary sinus

(posterior) all de-oxygenated blood collected by coronary veins empties into one coronary sinus which drains into the right atrium

1. sinoatrial (SA) node

pacemaker; located in right atrium wall causes both atria contract “push” blood to ventricle

shortens=contracting=systole=depolarization

lengthens=relaxation=diastole=repolarization

2. AV (atrio-ventricular) node

(interatrial septum) slows conduction (0.1 sec) allows blood to empty to ventricle

3. AV bundle: Bundle of His

(interventrical septum) allows Action Potential to pass from atria to ventricles

4. right/left bundle branches

conducts impulses (left bundle to left atrium and right bundle to right atrium)

5. Purkinje fibers

(large conduction fibers)

quick to apex then up side walls

ventricles contract

Pacemaker

Controls irregular heart rhythm via electrical pulses to go back to normal

if SA node is damaged

heart beats too slow not enough blood to brain

artificial pacemaker

inherently SA node: 100 bpm

Average resting: 70/75 bpm

How does the AP spread throughout all the muscle fibers?

Gap junctions in intercalated discs

one cardiac cycle

one heart beat

typically:

2 atria contract while 2 ventricles relax then 2 ventricles contract and 2 atria relax

systole

contraction

diastole

relaxation

atrial systole

contraction both atria

ventricular systole

contraction both ventricles

resting state

cardiac cycle lasts 0.8 sec

AVE bpm at rest

70-75 bpm

when do atria contract/relax?

both atria contract at the same time and relax at the same time

when are ventricles relaxing?

when atria are contracting and vice versa

what is EKG (Electrocardiogram)

recording of currents from cardiac conduction on skin. Lets us infer what is happening in the muscle and conductive tissue

P wave

atrial depolarization —> contraction atria (contraction happens after peak)

QRS complex

onset of ventricular depolarization —> contraction of ventricles

T wave

ventricular repolarization —> ventricles start to relax

EKG is really only?

voltage over time

EKG easily measures?

heart rate

EKG infers?

abnormal rhythm and patterns, follow recovery post heart attack, and presence of living fetus

average bpm of adult

60-100 bpm

vein vs artery

Arteries carry blood away from the heart, and veins carry blood towards the heart

Mitral regurgitation

is a disorder in which the mitral valve on the left side of the heart does not close properly, leads to irregular sounds

what does it mean to have a pulse?

a measurement of the heart rate, or the number of times the heart beats per minute