March 17, 2016: Conduction System of the Heart (Chapter 20)

Dub

Semi-Lunar Valves Snapping Shut = Ventricular Relaxation

Lub

Sound of AV Valves Snapping Shut = Ventricular Contraction

Step 1: SA Node (Pacemaker)

Step 1

Step 2: AV Node

Step 2

Step 3: AV Bundles

Step 3

Step 4: Purkinje Fibers V(Ventricular Conduction Fibers)

Step 4

What is the function of the atrioventricular node?

The AV Node takes the signal from the Sinoatrial (SA) Node, slows the signal down and regulates it, and then sends the electrical impulses from the atria to the ventricles (bundle of His).

Re-polarized

Re-ploarzation = Recharging after a complete discharge

T Wave

Replarization of Ventricular = Ventricular Relazation

Standard AVG

120/80

ECG

3 patterns (should see four)

P Wave

Atrial Contraction No Re-polarzation Signal Visible

Atrio-Ventricular Node

Atrio-

Diastolic Pressure

Bottom Number (approx 800 Min Pressure in the Brachial artery during Ventricle Diastole (relaxation)

Systolic Pressure

Contraction Measuring Ventricular Contraction

Depolarized

Depolarization = Discharging, release of electrical energy

Diastolic Pressure

Dialating Measuring Ventricular Relaxation

Pace Maker Potential Voltage

Directly Stimulation of Atria (both)

Paper - on the Heart

Don't need to do AP of Heart Need to address in Paper WHOLE CARDIAC CYCLE! Start anywhere - R. Atrium and go though EKG Explain Conduction System - EKG Lecture, letter, presentation, make sense to another

Electrocardiogram

ECG/EKG

Structure

Electrical signals arising in the SA node (located in the right atrium) stimulate the atria to contract, and travel to the atrioventricular node (AV node), which is located in the interatrial septum. After a delay, the stimulus diverges and is conducted through the left and right bundle of His to the respective Purkinje fibers for each side of the heart, as well as to the endocardium at the apex of the heart, then finally to the ventricular epicardium.[1] On the microscopic level, the wave of depolarization propagates to adjacent cells via gap junctions located on the intercalated disk. The heart is a functional syncytium (not to be confused with a true "syncytium" in which all the cells are fused together, sharing the same plasma membrane as in skeletal muscle). In a functional syncytium, electrical impulses propagate freely between cells in every direction, so that the myocardium functions as a single contractile unit. This property allows rapid, synchronous depolarization of the myocardium. While advantageous under normal circumstances, this property can be detrimental, as it has potential to allow the propagation of incorrect electrical signals. These gap junctions can close to isolate damaged or dying tissue, as in a myocardial infarction (heart attack). - Source: Wiki

Heart Sounds

Lub-Dub....Lub-Dub....Lub-Dub.... All Valve Sounds All associated with the Ventricular Cycle. Lub: Tricuspid and Bicuspid Valves Closes (AV Valves) Atrio Ventricule Valve (AV Valve) Dub: Semi-Lunar Valve Close

Heart: Types of Tissue

Natural Rate of Pacemaker is 100 BPM Nervous Tissue - Parasympathetic keeps in check to lower BPM, and backs off when needs the heart beat to rise i.e. when stand up and blood pressure lowers.

Polarized

Polarization = Charged up like a battery

What supplies blood to the AV node?

The blood supply of the AV node is via the AV nodal artery. The origin of this artery is most commonly (about 90% of hearts) a branch of the right coronary artery, with the remainder originating from the left circumflex artery.

What is the conduction system of the heart?

The cardiac conduction system is a group of specialized cardiac muscle cells in the walls of the heart that send signals to the heart muscle causing it to contract. The main components of the cardiac conduction system are the SA node, AV node, bundle of His, bundle branches, and Purkinje fibers.

What is the use of nodal tissue?

The heart's rhythm of contraction is controlled by the sinoatrial node (SA node), often called the pacemaker. This node is part of the heart's intrinsic conduction system, which is made up of specialized myocardial cells called nodal cells.

Electrical conduction system of the heart

The normal electrical conduction in the heart allows the impulse that is generated by the sinoatrial node (SA node) of the heart to be propagated to, and stimulate, the cardiac muscle (myocardium). The myocardium contracts after stimulation. It is the ordered, rhythmic stimulation of the myocardium during the cardiac cycle that allows efficient contraction of the heart, thereby allowing blood to be pumped throughout the body. Source: Wiki

Systolic Pressure

Top Number (approx 120) Max Pressure in the Brachial artery during Ventricle Systole (contraction)

Measuring BP

Ventricle Somatic (body, not pulmonary) pressure Usually about 40 * Difference between Systolic Pressure and Diastolic Pressure

QRS

Ventricular Depolarization = Ventricular Contraction

Anatomy of the Heart Paper!!!

http://www.biosbcc.net/b100cardio/htm/heartant.htm