Ch 19: heart

pulmonary circulation

Blood flow from the heart to the lungs.

systemic circulation

Blood flow from the heart to the body.

heart function

• generates blood pressure

• routes blood to/fro circuits

• ensures one-way blood flow

• regulates blood supply

coronary sulcus

• around the heart, separating the atria from the ventricles

anterior interventricular sulcus

inferiorly from the coronary sulcus on the anterior surface of the heart

• divide right and left ventricles

posterior interventricular sulcus

extends inferiorly from the coronary sulcus

superior and inferior vena cava

• carry blood from the body to the right atrium

• 4 pulmonary veins carry blood from lungs to the right atrium

pulmonary trunk

from the right ventricle, into the right & left pulmonary arteries, to the lungs

aorta

carry blood to whole body

atrioventricular valves (AV) and semilunar valves

valves between atria and ventricle

• prevent backflow when ventricle contract

• chordae tendineae

• papillary muscles

semilunar valves

• pulmonary

• aortic

right atrium

• ridged walls

• receive deoxy blood from systemic circuit

  • superior vena cava

  • interior vena cava

• tricuspid valve

right ventricle

• pump deoxy blood to pulmonary circuit

  • pulmonary valve and trunk

• moderator band

left atrium

• smooth walls

• separated by right atrium by interatrial septum

• receives oxygenated blood from pulmonary circuit

  • pulmonary veins

• bicuspid valve

left ventricle

• separated by right ventricle by interventricular septum

• pumps oxygenated blood to systemic circuit

  • aortic valve

  • ascending aorta

ventricular diastole (relaxed)

• av valve opens, ventricles filling

• semilunar valve closes (dub)

ventricular systole (contraction)

• av valves closes (lub)

• semilunar valves open, blood ejected

cardiac skeleton

• plate of connective tissue

• serves as electrical insulation between the atria and ventricles

• rigid attachment site for cardiac muscle

epicardium

surface of the heart

myocardium

think, middle layer composed of cardiac muscle

endocardium

smooth, inner layer surface, consists of simple squamous epithelial tissue

cardiac muscle tissue

• branching cells with one centrally located nucleus

• rich in mitochondria

• intercalated disc connect cells structurally and electrically

• striated

• excitable

• shorter, branched, and have a single nucleus

cardiac muscle action potentials in contractile cells

1. depolarization

   1. fast VG- Na+ channels open

   2. slow VG-Ca2+ channels open

2. Plateau

   1. fast VG-Na+ channels close

   2. some VG-K+ channels open

   3. slow VG-Ca2+ channels remain open (prolong action potential)

3. repolarization

   1. K+ channels open

   2. Ca2+ channels close

excitation in cardiac muscle tissue in order

SA node (pacemaker) → AV node (delay impulse by 0.1 sec) → AV bundle (conduct AP from atria to ventricles) → bundle branches (L&R, conduct AP towards apex) → purkinje fibers (spread AP to contractile cells in ventricles)

pacemaker potentials allow inherent rhythmicity

• change in membrane permeability of conducting cells are responsible for producing spontaneous action potential called pacemaker poteneial

prepotential phase

• funny Na+ channels open

• slow influx of Na+ to threshold

Depolarization

• fast VG-Ca2+ open, rapid influx of Ca2+ reverse membrane polarity

Repolarization

• VG-K+ open, rapid efflux (outflow) of K+ repolarizes membrane

components of the ECG

ECG

• uses electrodes called leads to record electrical events in heart

• diagnoses of cardiac abnormalitites

P-wave

• atrial depolarization, procedes atrial systole

QRS complex

• composed of Q,R,S waves

• ventricular depolarization precedes ventricular systole

T-waves

• repolarization of ventricles

cardiac output

• volume of blood pumped by a ventricle in 1 minute

CO = SV x HR

Stroke Volume: volume of blood pumped per ventricle per contraction

Heart Rate: number of heat beats in 1 min

blood supply to the heart

Coronary arterises: orginate from base of aorta

• left coronary artery: supply blood to anterior heart wall and left ventricle

• right coronary artery: originates on right side of aorta, supplies blood to right ventricle

Cardiac veins: parallel to the coronary arteries, drain blood from the cardiac muscle

• drain blood into the coronary sinus that leads into the right atrium

Coronary Artery Disease

• decreases blood supply to the heart

• coronary arteries are narrowed, most often due to the atherosclerosis

Myocardial Infarction (Heart Attack)

• closure of one or more coronary arteries

• area of cardiac muscle lacking adequate blood supply die, and scars

heart procedures

bypass: procedure reroutes blood past the blockage

balloon angioplasty: open blocked blood vessels

stent: mech inserted to keep vessels open