cvs part 1 abd 2 ppt

Surface Anatomy of the Heart (How to Locate the Heart from the Outside)

• Heart is located in the mediastinum of the thoracic cavity.

• Lies between the lungs.

• Located behind the sternum and rests on the diaphragm.

• About 2/3 of the heart lies left of the midline.

What is mediastinum

The central compartment of the thoracic cavity between the lungs.

Where is the heart located in relation to the sternum?

Posterior (behind) the sternum.

The pulmonary circuit

Carries blood to and from gas exchange surface of lungs

The systemic circuit

Carries blood to and from the body

Function of the heart

Acts as a pump that circulates blood, delivering oxygen and nutrients while removing wastes.

The heart

is a muscular pump that generates pressure to circulate blood through the pulmonary and systemic circuits.

Right Atrium

Receives blood from body/Deoxygenated

Right Ventricle

Pumps blood to lungs/ deoxygenated blood

Left Atrium

Receives blood from lungs/ Oxygenated

Left ventricle

Pumps blood to body / oxygenated blood

Covering of the heart

Covering: Pericardium

Inner layer : serious pericardium

Outer layer : Fibrous Pericardium

What is the pericardial cavity?

The space between the parietal and visceral layers of the serous pericardium that contains pericardial fluid to reduce friction.

What is pericarditis?

Inflammation of the pericardium causing pain and friction between pericardial layers.

What is cardiac tamponade

Accumulation of fluid in the pericardial cavity that compresses the heart and impairs filling and pumping

Epicardium(protection)

• Outer layer of the heart wall.

• visceral pericardium.

Myocardium(contraction/pumping)

• Middle and thickest layer.

• Made of cardiac muscle tissue.

• Responsible for the pumping action of the heart.

Endocardium(smooth inner lining)

• Inner layer lining the heart chambers and valves.

• Formed by simple squamous epithelium (endothelium) and connective tissue.

What are the auricles of the heart and what is their importance?

• Auricles are ear-like extensions of the right and left atria.

• They increase the volume/capacity of the atria, allowing them to hold more blood.

What are the grooves (sulci) of the heart and what do they contain?

• Grooves (sulci) are external depressions on the surface of the heart.

• They contain coronary blood vessels and fat.

Coronary Sulcus

• Between atria and ventricles

• Contains coronary vessels

Thickness of the walls of the heart and why they differ in different chambers.

• Heart wall thickness depends on the amount of work and pressure required.

• Atria have the thinnest walls because they only move blood into the ventricles.

• Right ventricle is thicker because it pumps blood to the lungs.

• Left ventricle is the thickest because it pumps blood to the entire body and generates the highest pressure.

Tricuspid valve loction and function

• Between right atrium and right ventricle.

• Prevents backflow into the right atrium.

Pulmonary Semilunar Valve Location and function

• Between right ventricle and pulmonary trunk.

• Prevents backflow into the right ventricle.

Mitral (biscuspid)Valve

• Between left atrium and left ventricle.

• Prevents backflow into the left atrium.

Aortic Semilunar Valve

• Between left ventricle and aorta.

• Prevents backflow into the left ventricle.

Blood flow

RA → Tricuspid → RV → Pulmonary Valve → Pulmonary Trunk → Lungs → LA → Mitral Valve → LV → Aortic Valve → Aorta

What is valvular stenosis

• Narrowing of a heart valve.

• Makes it harder for blood to flow through the valve.

• Causes the heart to work harder.

Heart murmur

• Abnormal heart sound caused by turbulent blood flow.

• Often results from defective or stenotic valves.

Distinguish between arteriosclerosis and atherosclerosis.

Arteriosclerosis

• General hardening and loss of elasticity of arteries.

Atherosclerosis

• Specific type of arteriosclerosis.

• Caused by buildup of fatty plaques (atheromas) in artery walls.

What is angina pectoris?

• Chest pain caused by reduced blood flow to the heart muscle.

• Usually temporary.

• No permanent heart muscle death occurs.

What is myocardial infarction (MI) and how is it different from angina pectoris

Myocardial Infarction (Heart Attack)

• Prolonged blockage of coronary blood flow.

• Causes death of heart muscle tissue.

🫀 Angina Pectoris

• Temporary reduction in blood flow.

• Causes chest pain but no permanent tissue death.

What is the cardiac cycle and what are its two basic phases?

The cardiac cycle is one complete heartbeat, including contraction and relaxation of the heart chambers. The two basic phases are:

• Systole = contraction phase

• Diastole = relaxation phase

What is systole?

Systole is the contraction phase of the cardiac cycle when blood is pumped out of the heart.

What is diastole?

Diastole is the relaxation phase of the cardiac cycle when the heart chambers fill with blood.

What is the cardiac conducting system

The cardiac conducting system is a network of specialized cardiac muscle cells that generate and conduct electrical impulses through the heart.

What is the cardiac conducting role

• Initiates the heartbeat

• Coordinates atrial and ventricular contractions

• Maintains a regular heart rhythm

• Ensures efficient pumping of blood

List the structures of the cardiac conducting system in order.

1. SA (Sinoatrial) node – pacemaker of the heart

2. AV (Atrioventricular) node – delays the impulse

3. AV bundle (Bundle of His)

4. Right and Left Bundle Branches

5. Purkinje Fibers – distribute impulse throughout ventricles

What is an EKG (ECG)?

is a recording of the electrical activity of the heart.

• used to measure heart rate and rhythm

• Detects heart attack or heart damage

What occurs in the heart during the P wave, QRS complex, and T wave?

P Wave

• Atrial depolarization

• Atria contract (atrial systole)

📈 QRS Complex

• Ventricular depolarization

• Ventricles contract (ventricular systole)

📈 T Wave

• Ventricular repolarization

• Ventricles relax (ventricular diastole)

Define cardiac arrhythmia, tachycardia, bradycardia, fibrillation, and ectopic focus.

Cardiac Arrhythmia

• Any abnormal heart rhythm.

🫀 Tachycardia

• Heart rate greater than 100 beats/minute.

• Heart beats too fast.

🫀 Bradycardia

• Heart rate less than 60 beats/minute.

• Heart beats too slowly.

🫀 Fibrillation

• Rapid, uncoordinated, ineffective contractions of the heart muscle.

• Can prevent effective pumping of blood.

🫀 Ectopic Focus

• An abnormal pacemaker site outside the SA node.

• Produces abnormal electrical impulses and irregular rhythms.

First-Degree Heart Block

• Electrical impulse is delayed at the AV node.

• All impulses still reach the ventricles.

• Usually mild and often asymptomatic.

Second-Degree Heart Block

• Some electrical impulses from the atria fail to reach the ventricles.

• Some heartbeats are “dropped.

Third-Degree Heart Block (Complete Heart Block)

• No impulses pass from the atria to the ventricles.

• Atria and ventricles beat independently.

• Most severe form; often requires a pacemaker.

What are the physiological properties of the heart

Automaticity (Autorhythmicity)

• Ability to generate its own electrical impulses without nervous stimulation.

Excitability (Irritability)

• Ability to respond to a stimulus and generate an action potential.

Conductivity

•Ability to transmit electrical impulses from cell to cell.

Contractility

• Ability of cardiac muscle to contract and generate force.

Explain the Absolute Refractory Period

• Period during which cardiac muscle cells cannot be stimulated to contract again, no matter how strong the stimulus.

• Prevents tetanic (sustained) contractions of the heart.

• Allows the heart to relax and refill with blood.

Explain the Relative Refractory Period (RRP).

• Follows the ARP.

• A cardiac muscle cell can be stimulated, but only by a very strong stimulus.

• The cell is beginning to recover its excitability.

Explain syncytium and its significance in the heart.

Cardiac muscle cells connected by gap junctions that act as one functional unit, allowing coordinated contraction of the heart.

What is elasticity of the heart and what law explains it?

Elasticity: Ability of the heart to stretch and recoil.

Frank-Starling Law: The greater the stretch of cardiac muscle fibers, the greater the force of contraction.

What happens to the size and elasticity of the heart in heart failure?

the heart often enlarges and loses elasticity, making it harder to fill properly and pump blood effectively.

Cardiac muscle histology

Striated, branched, involuntary, central nucleus, intercalated discs.

What are the cardiac centers and where are they located?

Cardiac Centers

• Control heart rate and force of contraction.

• Located in the medulla oblongata of the brainstem.

Two Cardiac Centers:

• Cardioacceleratory Center → increases heart rate and force of contraction.

• Cardioinhibitory Center → decreases heart rate.

Name 5 important arteries in the wall of the heart (coronary circulation).

Right Coronary Artery (RCA)

Left Coronary Artery (LCA)

Anterior Interventricular Artery (LAD)

Circumflex Artery

Posterior Interventricular Artery

Blood supply of the heart

🫀 Right Coronary Artery (RCA)

• Supplies the right side of the heart.

• Major branch:

  • Posterior Interventricular Artery

🫀 Left Coronary Artery (LCA)

• Supplies most of the left side of the heart.

• Major branches:

  • Anterior Interventricular Artery (LAD)

  • Circumflex Artery

Which veins bring deoxygenated blood into the right atrium?

Superior Vena Cava – returns deoxygenated blood from the upper body.

🫀 Inferior Vena Cava – returns deoxygenated blood from the lower body.

🫀 Coronary Sinus – returns deoxygenated blood from the heart muscle itself.

How many pulmonary veins are there?

Four pulmonary veins

• Right Superior Pulmonary Vein

• Right Inferior Pulmonary Vein

• Left Superior Pulmonary Vein

• Left Inferior Pulmonary Vein

Define hepatic portal circulation

• special pathway that carries nutrient-rich blood from the digestive organs to the liver before returning it to the heart.

S1 (“Lub”)

• Caused by closure of the AV valves:

  • Tricuspid valve

  • Mitral (bicuspid) valve

• Marks the beginning of ventricular systole.

S2 (“Dub”)

• Caused by closure of the semilunar valves:

  • Pulmonary valve

  • Aortic valve

• Marks the beginning of ventricular diastole.

Junctional rhythm

Second degree heart block

Ventricular fibrillation