Chapter 18: Cardiovascular System (Heart)

The heart is approximately the size of a ___

Closed fist

Heart location

• In mediastinum between second rib & fifth intercostal space

• Enclosed in pericardium, a double walled sac

Apex

Anything that comes to a point

Pericardium

1. Fibrous Pericardium (superficial)

2. Serous Pericardium (deep)

1. Fibrous Pericardium (superficial)

Protects, anchors, and prevents overfilling

2. Serous Pericardium (deep)

• Parietal layer line internal surface of fibrous pericardium 

• Visceral layer (epicardium) is on external surface of the heart

• Separated by fluid- filled pericardial cavity 

The layers of the heart

• Pericardium (Fibrous & Serous)

  • Serous = Parietal + Visceral

1. Epicardium

2. Myocardium

3. Endocardium 

1. Epicardium 

Visceral layer of serous pericardium 

2. Myocardium

• Spiral bundles of cardiac muscle cells

• Fibrous skeleton of heart: crisscrossing, interlacing layer of CT (anchors & supports)

3. Endocardium 

Continuous with endothelial lining of blood vessels 

Cardiac muscle cells are…

Striated, short, fat, branched, and interconnected

• Rich in mitochondria (heart needs to beat for a long time without getting fatigued) 

• Contain intercalated discs with gap junctions that allow rapid passage of ions and electrical signals between adjacent cardiac muscle cells

The heart has ___ chambers

4 (Right & Left atrium, Right & Left ventricle)

The heart has ___ atria

2 (Right & Left atria)

The upper chambers of the heart are separated by…

The interatial septum

Coronary sulcus (atrioventricular groove)

Separates the atria from the ventricles

The ________ separates the 2 lower chambers of the heart (the ventricles) 

Interventricular septum  

Anterior & posterior ___________ mark the positon of the interventricular septum externally

Interventricular sulci

Vessels entering the right atrium

• Superior vena cava

• Inferior vena cava

• Coronary sinus

Vessels entering the left atrium

Right & left pulmonary veins 

Papillary muscles

• Project into ventricular cavities 

• Attach to the tricuspid and mitral valves via cordae tendineae (heart strings) and contract to prevent the valves from flipping backward into the atria during ventricular systole (contraction)

Vessels leaving the right ventricle

Pulmonary trunk

Vessel leaving the left ventricle

Aorta

Main function of the heart valves

Ensure unidirectional flow through the heart (prevents blood from flowing backwards)

Atrioventricular valves

• AKA “AV” valves

• Located between atria and ventricles

• Prevents back flow into atria when ventricles contract

The 2 atrioventricular valves

• Tricuspid valve (right) 

• Mitral (bicuspid) valve (left) 

“Tri before you Bi”

What anchors AV valve cusps to papillary muscles?

Chordae Tendineae (heart strings)

Semilunar valves

Located at the exits of the left and right ventricles

• Prevent back flow into ventricles when ventricles relax 

1. Aortic semilunar valve (left)

2. Pulmonary semilunar valve (right)

Pulmonary Circuit is pumped by the ______ side of the heart

Right side

Systemic circuit is pumped by the _____ side of the heart

Left

Pulmonary Circuit

Path blood takes to the lungs and back to the heart (by right side of heart)

• Carries oxygen-poor blood to the lungs and receives oxygen rich blood back

• Short, low pressure circulation

Systemic Circuit

Path blood takes from the heart to the rest of the body (from the left side of the heart) 

• Carries oxygen rich blood to body and returns deoxygenated blood back to heart

• A long resistance filled pathway of blood

T or F Equal volumes of blood are pumped into each circuit?

True

Definiton of an artery

Carries blood AWAY from the heart

Definition of a vein

Carries blood TO the heart

The _____ ventricle of the heart is much thicker due to pumping blood through the entire body

Left