Cardiovascular System: General Circulation & Heart Anatomy & Physiology II Tony Serino, Ph.D. Biology Department Misericordia University

General Circulatory System Cardiovascular Consists of a closed system of vessels which transport blood Two circuits: Systemic and Pulmonary Arteries move blood away from the heart Veins move blood toward the heart

General Circulatory System Lymphvascular –moves lymph Consist of blind end tubes which collect interstitial fluid (now called lymph) and returns it to circulation The lymph is cleaned before returned to the blood vessels

Heart as a Dual Pump Cardiac muscle arranged as whorls that squeeze the blood Twin pumps: systemic and pulmonary Four chambers: 2 atria and 2 ventricles

Cardiac Muscle Cells

Cardiac Muscle Depolarization

Conductance of Ions during Depolarization

Heart Development

Fetal Circulation

Selected Heart Defects

Heart: Location

Heart in Relation to other Organs

Layers of the Heart and Pericardium

Heart: Anterior View

Heart: Posterior View

Heart: Internal Anatomy

Differences in Ventricular Wall

Coronary Arteries

Angioplasty Fig. 12.66 12.66.jpg

Coronary Veins

Major Cardiac Valves

Heart Murmurs 12.22.jpg

Diastole: Period of Ventricular Filling Cardiac cycle Diastole: Period of Ventricular Filling

Systole: Isovolumetric Contraction

Systole: Ventricular Ejection

Diastole: Isovolumetric Relaxation

Conduction System of Heart

Pacemaker Potential

Einthoven’s Triangle (bipolar lead placement) Depolarizations are positive in front and negative behind wave. Repolarization is negative in front and positive behind wave Direction and type of wave within heart influences whether machine records an upward or downward deflection

ECG and electrical changes

Normal ECG Segments are the time between wave forms; Intervals include the space and the wave form.

ECG Normal Sinus Rhythm Junctional Rhythm (AV node rhythm)

Second Degree Heart Block Ventricular Fibrillation (V-fib)

PR interval increased with each beat until a QRS is skipped. First-Degree Heart Block In first-degree heart block, the heart's electrical signals are slowed as they move from the atria to the ventricles (the heart's upper and lower chambers, respectively). This results in a longer, flatter line between the P and the R waves on the EKG (electrocardiogram). First-degree heart block may not cause any symptoms or require treatment. Second-Degree Heart Block In this type of heart block, electrical signals between the atria and ventricles are slowed to a large degree. Some signals don't reach the ventricles. On an EKG, the pattern of QRS waves doesn't follow each P wave as it normally would. If an electrical signal is blocked before it reaches the ventricles, they won't contract and pump blood to the lungs and the rest of the body. Second-degree heart block is divided into two types: Mobitz type I and Mobitz type II. Mobitz Type I In this type (also known as Wenckebach's block), the electrical signals are delayed more and more with each heartbeat, until the heart skips a beat. On the EKG, the delay is shown as a line (called the PR interval) between the P and QRS waves. The line gets longer and longer until the QRS waves don't follow the next P wave. Sometimes people who have Mobitz type I feel dizzy or have other symptoms. This type of second-degree heart block is less serious than Mobitz type II. The animation below shows how your heart's electrical system works. It also shows what happens during second-degree Mobitz type I heart block. Click the "start" button to play the animation. Written and spoken explanations are provided with each frame. Use the buttons in the lower right corner to pause, restart, or replay the animation, or use the scroll bar below the buttons to move through the frames. Mobitz Type II In second-degree Mobitz type II heart block, some of the electrical signals don't reach the ventricles. However, the pattern is less regular than it is in Mobitz type I. Some signals move between the atria and ventricles normally, while others are blocked. On an EKG, the QRS wave follows the P wave at a normal speed. Sometimes, though, the QRS wave is missing (when a signal is blocked). Mobitz type II is less common than type I, but it's usually more severe. Some people who have type II need medical devices called pacemakers to maintain their heart rates. Third-Degree Heart Block In this type of heart block, none of the electrical signals reach the ventricles. This type also is called complete heart block or complete AV block. When complete heart block occurs, special areas in the ventricles may create electrical signals to cause the ventricles to contract. This natural backup system is slower than the normal heart rate and isn't coordinated with the contraction of the atria. On an EKG, the normal pattern is disrupted. The P waves occur at a faster rate, and it isn't coordinated with the QRS waves. Complete heart block can result in sudden cardiac arrest and death. This type of heart block often requires emergency treatment. A temporary pacemaker might be used to keep the heart beating until you get a long-term pacemaker. Depolarization delayed between atria and ventricle; PR interval is prolonged. PR interval increased with each beat until a QRS is skipped. No ration between ventricle and atria rhythm; P maybe buried in QRS complex 2:1, 3:1 ratio between ventricle and atria rhythm

Heart Sounds “Lub-dub” Sound associated with valve closing producing turbulent blood flow

Cardiac Cycle

(ml/min)

Factors Affecting SV Stroke Volume (SV) = End Diastolic Volume – End Systolic Volume SV = EDV – ESV (ml/beat) EDV affected by: Venous return which is dependent on venous tone, skeletal muscle pumps, etc. ESV As the heart fills it is stretched which allows for better overlap of the contractile proteins which will affect the force of contraction and the ESV (Starling’s Law of the Heart) Increasing the force of contraction at any EDV will decrease the ESV and increase the SV (sympathetic stimulation and epinephrine)

Sympathetic Stimulation Leads to increase HR Increases in Ca++ release from SR, increase Ca++ through membrane and increase myosin crossbridge cycling Increases force of contraction

Heart Rate Control Sinus Rhythm = normal SA node control Autonomic Activity Sympathetic = accelerator (tachycardia) Parasympathetic = brake (bradycardia) Hormones epinephrine Drugs -caffeine, nicotine, atropine, etc.

Exercise Effects