Cardiovascular System (Heart) - Lec

• Heart

• Blood vesselsCirculatory System

• Circulatory System

Cardiovascular System

• Heart

• Blood Vessels

• Blood

Circulatory System

• Approximately the size of a fist

• Located

  • In the mediastinum between the second rib and fifth intercostal space

  • On the superior surface of the diaphragm

  • Two-thirds to the left of the midline

  • Anterior to the vertebral column, posterior to the sternum

Heart Anatomy

Location of Heart - Image

Heart - Image

1. Right ventricle

2. Interventricular septum

3. Left ventricle

• Double-Walled Sac

  • Superficial fibrous pericardium

Pericardium—Fibrous

• Loosely surrounds heart

• DICT sac – thick, tough white

• Attached to the diaphragm and Great Vessels of the Heart

• Protects, anchors, and prevents
  overfilling

Superficial fibrous pericardium

Pericardium—Fibrous - Image

Pericardium - Image

Pericardial fluid - Image

• Deep two-layered serous pericardium

  • The parietal layer lines the internal
    surface of the fibrous pericardium

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

  • Separated by fluid-filled
    pericardial cavity (decreases
    friction)

Pericardium—Serous

Visceral and Parietal Pericardium - Image (A)

1. Outer balloon wall (comparable to parietal serosa)

2. Air (comparable to serous fluid)

3. Inner balloon wall (comparable to visceral serosa)

Visceral and Parietal Pericardium - Image (B)

1. Heart

2. Parietal pericardium

3. Pericardial space (Has serous fluid)

4. Visceral pericardium

Heart - Image

1. Heart

2. Visceral pericardium

3. Parietal pericardium (Fibrous?)

4. Serous

5. Pericardial cavity

Heart - Image (Pt. 1)

1. Pericardium

2. Myocardium

3. Pulmonary trunk

4. Fibrous pericardium

5. The parietal layer of the serous pericardium

Heart - Image (Pt. 2)

6. Pericardial cavity

7. Epicardium (visceral layer of serous pericardium) HEART

8. Myocardium WALL

9. Endocardium

10. Heart chamber

• Epicardium

• Myocardium

• Endocardium

Heart Wall

Same thing as the visceral layer of the serous pericardium

• Simple Squamous Epithelium

• Shiny

• Produces pericardial fluid

Epicardium

The cardiac muscle layer forms the bulk of the heart.

• Spiral bundles of cardiac muscle cells

• Fibrous skeleton of the heart: crisscrossing, the interlacing layer of connective tissue

Myocardium

• Anchors cardiac muscle fibers

• Supports great vessels and valves

• Limits spread of action potentials to
  specific paths

Fibrous skeleton (Heart)

Myocardium - Image

Endothelial layer of the inner myocardial surface

• Lines the chambers of the heart

• Simple Squamous Epithelium

• Is in direct contact with Blood

  • It provides a smooth, slick surface for blood to “slide” against

• Is continuous with endothelial lining of blood
  vessels

Endocardium

Ventricular Endocardium - Image

• (2) Atria

• (2) Ventricles

Chambers of Heart

• Receiving Chambers

• Thin-Walled

• VERY little musculature

• Low pressure

Atria )Pt. 1)

• Pumping chambers

• Thick-Walled

• Heavily muscularized

• High pressure

Ventricles (Pt. 1)

Chambers - Image

• Left and Right

• Separated internally by the interatrial septum (wall)

• Auricles (ears) increase atrial volume

Atria (Pt. 2)

Atria - Image

Auricles

1. Right

2. Left

◦ Left and Right
◦ Separated by the interventricular
septum
◦ Anterior and posterior
interventricular sulci mark the
position of the septum external

Ventricles (Pt. 2)

Ventricles - Image

Thin walls ridged by pectinate muscles

Atria - The Receiving Chambers

◦ Superior vena cava
◦ Inferior vena cava
◦ Coronary sinus

Atria - Vessels emptying into the right atrium

Right and left pulmonary veins

Atria - Vessels emptying into the left atrium

Atria (Emptying vessels) - Image (Frontal section)

Heart - Image

1. Superior vena cava

2. Right pulmonary veins

3. Right atrium

4. Right ventricle

Heart - Image

5. Inferior vena cava

6. Left ventricle

7. Left atrium

8. Left pulmonary veins

Heart - Image

1. Superior vena cava

2. Right pulmonary veins

3. Inferior vena cava

4. Coronary Sinus

5. Left pulmonary veins

Heart - Image

1. Superior vena cava

2. Right atrium

3. Right ventricle

4. Inferior vena cava

5. Left atrium

Heart - Image

6. Left pulmonary veins

7. Left ventricle

8. Epicardium

9. Myocardium

10. Endocardium

Thick walls ridged by trabeculae carneae

Ventricles: The Pumping Chambers

Pulmonary trunk

Ventricles: Vessel leaving the right ventricle

Aorta

Ventricles: Vessel leaving the left ventricle

Trabeculae carneae - Image

Heart - Image

1. Pulmonary Artery

2. Pulmonary Trunk

3. Aorta

• Ensure unidirectional blood flow through the heart (prevent backflow of blood)

• 4 (2 AV & 2 SL)

Heart Valves

Heart Valves - Image

• Lie between the atria and the ventricles

• Prevent backflow into the atria when the ventricles contract

Atrioventricular (AV) Valves

AV Valves - Image

◦ Between the left atrium and left ventricle
◦ (2) flaps
◦ Bicuspid, Mitral
◦ Chordae tendons and papillary muscles

AV Valves - Left Valve

AV Valves (Left Valve) - Image

AV Valves (Left Valve) - Image

Heart - Image

◦ Between the right atrium and right ventricle
◦ (3) flaps
◦ Tricuspid
◦ Chordae tendons and papillary muscles

AV Valves - Right Valve

AV Valves (Right Valve) - Image

AV Valves (Right Valve) - Image

◦ Prevent backflow into the ventricles
when ventricles relax
◦ Aortic semilunar valve
◦ Pulmonary semilunar valve

Semilunar (SL) Valves (Pt. 1)

Semilunar (SL) Valves - Image (1)

Semilunar (SL) Valves - Image (2)

• Heart valves ensure unidirectional blood flow through the heart

• Semi-lunar valves are found in the large arteries that leave the ventricles
  ◦ Pulmonary SL valve
  ◦ Aortic SL valve

Semilunar (SL) Valves (Pt. 2)

• Prevent backflow into the
  ventricles

• Each has three flaps

Semilunar (SL) Valves (Pt. 3)

Pulmonary and aortic valves from above - Image

Image

1. Pulmonary valve

2. Aortic valve

3. Area of cutaway

4. Mitral valve

5. Tricuspid valve

Image (Anterior)

1. Fibrous skeleton

2. Myocardium

3. Tricuspid (right atrioventricular) valve

4. Mitral (left atrioventricular) valve

5. Aortic valve

6. Pulmonary valve

Semilunar valves open - Image

Semilunar valves closed - Image

• (Lub-dup) are associated with the closing of heart valves

• The first sound occurs as AV valves close

• The second sound occurs when SL valves close

Heart Sounds

Heart Sounds - Image

Vessels returning blood to the heart include

• Superior and inferior vena cavae

• Coronary Sinus

• Right and left pulmonary veins

External Heart: Major Vessels of the Heart (Anterior View)w)

External Heart: Major Vessels of the Heart (Anterior View) - Image

Vessels returning blood to the heart include:

• Right and left pulmonary veins

• Coronary Sinus

• Superior and inferior venae cavae

External Heart: Major Vessels of the Heart (Posterior View)

Vessels conveying blood away from the heart

• The pulmonary trunk, which splits into the right and left pulmonary arteries

• Ascending aorta (three branches) -brachiocephalic, left common carotid, and subclavian arteries

External Heart: Major Vessels of the Heart

Circulation - Image

Circulation - Image

• Cardiac muscle tissue
• Cardiac cycle
• Cardiac conduction system

?

Image

1. Nucleus

2. Intercalated discs

3. Cardiac muscle cell

4. Gap junctions

5. Desmosomes

• Cardiac muscle is striated, short, fat, branched, and interconnected

• The connective tissue endomysium acts as both the origin and insertion

Microscopic Anatomy: Heart Muscle (Pt. 1)

• Intercalated discs anchor cardiac cells together and allow free passage of ions

• Heart muscle behaves as a functional syncytium

Microscopic Anatomy: Heart Muscle (Pt. 2)

• Excitability

• Contractility

• Extensibility

• Elasticity

Properties of Muscle

•Automaticity

•Auto rhythmicity

Cardiac Muscle (+2) & Contraction

• Contracts automatically—no nervous stimulation required

Automaticity

• Contracts in a rhythm—very consistent over time

Auto rhythmicity

• Pulmonary Circuit (circulation)

• Systemic Circuit (circulation)

• Coronary Circuit (circulation)

Circuits

• Receives blood from organs (deoxygenated)
• Sends blood to lungs

Pulmonary Circuit (circulation) (Pt. 1)

• Receives blood from lungs (oxygenated)
• Sends blood to organs

Systemic Circuit (circulation)

Nourishes the myocardium

Coronary Circuit (circulation)

The right side of the heart is the pump for the pulmonary circuit

• Short-distance

• Low resistance through lungs

• Low-pressure pump

• Thinner walls (ventricles)

Pulmonary Circuit (circulation) (Pt. 2)

Pulmonary Circuit (circulation) - Image

Image

1. Right ventricle

2. Interventricular septum

3. Left ventricle

• Systole

• Diastole

Contraction & Relaxation

Contraction of the heart muscle

Systole

Relaxation of the heart muscle

Diastole

Diastole (filling) - Image

Systole (pumping) - Image

Diastole & Systole - Image

Cardiac cycle - Image

• When one cell undergoes an action potential, the action potential spreads to all connecting cells (they all contract together)

• Action potentials are all or nothing in the heart.

Functional Syncytium (Pt. 1)

• One heartbeat spreads to the whole heart
• Muscular contraction is followed after depolarization

Functional Syncytium (Pt. 2)

• Atria group/syncytium
• Ventricle group/syncytium

Functional Syncytium: Types (2)