Heart Anatomy

Pericardium and types

double serous membrane

Visceral pericardium- next to the heart

Parietal pericardium- outside layer

What fills space between layers of pericardium?

Serous fluid

3 Heart Walls

Epicardium

Myocardium

Endocardium

Epicardium

Epicardium

Outside layer (visceral pericardium)

Connective tissue layer

Myocardium

Middle layer (cardiac muscle)

Endocardium

Inner layer (endocardium)

Continuous within linings of blood vessels leaving and entering the heart

How many Chambers are there?

4, right and left sides act as seperate pumps

Atria

recieving chambers

Right and left ventricle

discharging chambers

Interventricular septum

longitudinal separaion

How may valves and function

4, allows blood to flow in one direction

Atrioventricular valves

- between atria and ventricles

Bicuspid (left)

Tricuspid (right)

Semilunar valves

between ventricle and artery

Pulmonary and aortic semilunar valve

• valves open as blood pumped through

• Held in place by chordae tendineae

(Heart strings)

• close to prevent back flow

Heart Strings

chordae tendineae

Aorta

leaves left ventricle; oxygenated blood

Pulmonary artery

leaves right ventricle detox blood to lungs

Vena Cava

enters right atrium

Pulmonary veins (4)

Enter left atrium oxygenated blood from lungs

Coronary circulation

nourshing the circulatory system- involves coronary arteries, cardiac veins, blood empties into the right atrium via coronary sinus

2 types of Crornary circulation

Pulmonary circulation - heart to lungs

Systemic Circuit- heart to body

Conduction System

intrinsic conduction system (nodal) system heart muscles, cells contract, without nerve impulses, in a regular, continuous way

• special tissue sets the pace

Sinoatrial node (pacemaker maker)

Atrioventricular node

Atrioventricular bundle

Bundle branches

Purkinje fibers

Cardiac Cycle

Atria contract simultaneously

• Atria relax, then ventricles contract

• Systole = contraction

• Diastole = relaxation

Systole

contraction

Diastole

relaxation

Ventricular systole

blood pressure builds before ventricle contracts pushing out blood

Early diastole Ventricular systole

atria finish re-filling, ventricular pressure is low

ECG EKG

P Wave - atrial depolarization (Contraction)

QRS - ventricular depolarization (Contraction)

T wave - ventricular repolarization (Relaxation)

U wave - repolarization of the purkinje fibers (Relaxation)

P Wave

P Wave - atrial depolarization (Contraction)

QRS

QRS - ventricular depolarization (Contraction)

T wave

T wave - ventricular repolarization (Relaxation)

U wave

U wave - repolarization of the purkinje fibers (Relaxation)

cardiac output (CO)

Amount of blood pumped by each side of the heart in one minute

stroke volume

volume of blood put out by each ventricle in one contraction

healthy heart pumps out about ___ of blood present ventricles ___

healthy heart pumps out about 60% of blood present ventricles (2oz)

Starling’s law of the heart

the more that the cardiac muscle is stretched, the stronger the contraction

What increase stretching

Venous return increases stretching

Exercise and muscular pump

tachycardia

tachycardia- 100+ pm

Bradycardia

Bradycardia- -60 pm

Fribrillation

Fribrillation- lack of blood supply to the heart muscle

shuddering

Useless pump

stroke volume constant

declines when blood volume suddenly drops or weakened heart rate

How can you modify Basic heart rate?

Cardiac output is maintained by faster heartbeat

• HR is also modified by chemicals, hormones and ions

Neural controls that control heart rate

• physical and emotional stress

stimulates SA and AV nodes

Heart rate increases

• congestive heart failure

”worn out” or weak

Prescription meds can enhance contractile force and stroke volume

• hormones and ions (electrolytes)

epinephrine and thyroxine increases HR

Ion calcium in blood

Depresses and slows the heart

Physical Factors of HR

• Age, gender, exercise, body temperature

• Fetus resting HR- 140-160

• Females 72-80