Heart

Cardiac= heart.  delivery of nutrients to and the removal of wastes from the body tissues.

 Myocardium: the muscular wall of the heart/cardiac muscle

Cardiac Chambers Four chambers. Two chambers at superior aspect two at inferior aspect. 

Interventricular septum thick, muscular wall that separate the inferior chambers

Interatrial septum separates the two upper chambers.

Atria (singular atrium) the superior thin-walled collecting chambers. All blood returning to the heart from elsewhere in the body must enter one of these two chambers. 

right atrium Blood returning to the heart from the body organs

left atrium: blood returning to the heart from the lungs

ventricles. Inferior, thick-walled pumping chambers. right ventricle pumps blood to the lungs.  left ventricle pumps blood to the body.  nearly twice as thick /pumps with significantly greater force.

Cardiac Valves valves ensure blood always flows proper direction. atrioventricular (A-V) style valves: separate the atrium from the ventricle on the same side of the heart.

Cardiac Valves have a flap and string-like design. Pressures on these valves are quite high.  string-like structures help to anchor the valve flap when the ventricle is contracting.   

Tricuspid valve valve on the right side of the heart Bicuspid or mitral valve valve on the left side under very high pressures more likely to weaken and fail as an individual ages.

semilunar style valves separate the ventricle from its major artery. pocket-type design.  Pressures not quite as strong as those on the A-V valves.   

pulmonic valve: semilunar valve / right side heart/ separating the right ventricle from the pulmonary artery. 

aortic valve: semilunar valve /left side heart/ separating the left ventricle from the aorta

Cardiac Vessels arteries blood vessels that transport blood AWAY from the heart.  typically transport highly oxygenated blood the body. 

Cardiac Vessels Veins: blood vessels that transport blood TOWARDS the heart.  typically transport very low oxygen blood, returning from the body.

Aorta emerges from the superior part of the left ventricle. very large diameter tube/ curves around above the heart and then travels behind the heart towards the lower portions of the body.  Branches of the aorta deliver blood to the body  

Pulmonary artery emerges from the superior portion of the right ventricle, at the very front of the heart.  transporting blood with a very low oxygen content.  traveling to the lungs to pick up a new supply of oxygen.

Superior vena cava: merge from veins of the head, arms, and torso that lie superior to the heart.  Goes to right atrium

Inferior vena cava : merge from veins legs and torso areas that lie inferior to the heart. Goes to right atrium

pulmonary veins: left atrium pulmonary veins: left atrium.  are returning blood to the heart from the lungs. 

Divisions of the Circulation Pulmonic Systemic Coronary  It takes the entire blood volume of your body only about one minute to make the complete circuit.

Pulmonary (pulmonic) Circulation  Transports blood from the heart to the lungs and back. 

Systemic Circulation From the heart to the body and back. 

Coronary Circulation Small branch of the systemic circulation Coronary arteries first tiny branches off of the aorta. These vessels supply nutrients and remove wastes from the myocardial muscle layer of the heart Blood recollects into the cardiac veins that join to form the coronary sinus, a large vein, and then returns to the right atrium. Obstruction of these vessels can result in a heart attack. 

 Cardiac Muscle  cardiac muscle cells of the atria are interconnected with one another and function as a unit.  cardiac muscle cells of the ventricles are also interconnected with one another and function as a unit. 

Intercalated discs between adjacent cardiac cells/ allow rapid signal transmission.

no direct interconnection between the atrial and ventricular muscle groups.  intricate communication pathway to communicate between the two areas

Autorhythmic : cells capable of self-stimulation Autorhythmic : cells capable of self-stimulation.  They can contract on their own without being told to do so by the nervous system. All cardiac muscle cells

Cardiac Conduction Sequence Sinoatrial (SA) node beginning of all normal contractions of the heart This is pacemaker of the heart. 

Cardiac Conduction Sequence Special group of cardiac muscle cells that are autorhythmic at about 70 times per minute.  located in the right atrium where the superior vena cava attaches to that chamber.

The signal spreads from the SA node through the right atria and on to the left atrium, being passed cell-to-cell via the intercalated discs. The atria then contract and push some blood into the ventricles (most blood enters strictly by gravity prior to that, however).

The atrial cells then signal the atrioventricular (AV) node, a second group of special cardiac muscle cells that are also autorhythmic, but at a slower rate, about 40 times per minute. located near the septum in the lower portion of the right atrium. 

The AV node is the only electrical connection between the atrial and ventricular muscle masses.  The only way in which the atrial and ventricular muscle masses can communicate. 

A-V Node Conducts the message that it is time to contract from the sinoatrial node to the ventricles.

A-V Node As long as the AV node receives a message from the SA node, it does not contract on its own.  If there is a communication problem and the message is not received, the atrioventricular node may assume the role of pacemaker.  The heart rate is often about half of the normal heart rate person will generally have difficulty doing anything which requires more blood to be pumped by the heart,

A-V Node Screens out excessive contractions of the heart muscle. The message is then sent via special conduction tissue, the AV Bundle and its branches to the ventricular cells, stimulating the ventricles to contract. The ventricles then relax.

A-V Node Screens out excessive contractions of the heart muscle. Heart rates over 180 beats/minute are life-threatening.  Because the heart is contracting so rapidly, there is too little time for the ventricles to fill; therefore no blood is being pumped from the heart.  The AV node will eliminate some of the beats and only pass on a reasonable number to the ventricles if an excessive number are coming from the atria.