Muscular System:Cardiac Muscle

Muscular System

Cardiac Muscle • Only found in the HEART.• Involuntary (Autonomic Nervous System)• Moderate Contraction• Striated• Nuclei is centrally located

• Branched• Abundant in mitochondria• Each cell have and average

length o 50-100um and, 15um width

• Each fiber is envelope with ENDOMYSIUM

• The fascicle is surrounded by PERIMYSIUM

• Intercalated discs

Muscular System

Cardiac Muscle

• Purkinje fibers are non-contractile but are specialized to initiate and conduct the electrical impulse that controls cardiac contraction.

• The chain of events that occurs during contraction of cardiac muscle cells is identical to the skeletal muscle cells.

• Unlike skeletal muscle cells, cardiac muscle cells contract without neural impulse.

The Human Heart

Position and Location

• Lies within the pericardium in middle mediastinum

• Behind the body of sternum and the 2nd to 6th costal cartilages.

• In front of the 5th to 8th thoracic vertebrae

• A third of it lies to the right of median plane and 2/3 to the left

• Anterior to the vertebral column, posterior to the sternum

The Human Heart

Description

Weight: 250-300gApproximately the size of

your fist.Pumps: 70ml/beatWorks: 70 beats/minute

Layers of the Heart

Pericardium

Composed of:

• A superficial FIBROUS PERICARDIUM.• A deep two-layer serous pericardium.• The PARIETAL LAYER lines the internal surface of the fibrous

pericardium.• The VISCERAL LAYER or EPICARDIUM lines the surface of the

heart.• They are separated by the fluid-filled pericardial cavity called

the PERICARDIAL CAVITY.

Pericardium – a double-walled sac around the heart

Layers of the Heart

Myocardium

Endocardium

• Thickest layer of the heart• Thickest in left ventricle because must

pump hard to overcome high pressure of systemic circulation

• Right atrium the thinnest because of low resistance to back flow

• Consist of cardiac muscle cells = myocytes• Different from smooth or skeletal

muscle cells due to placement of nuclei, cross striations, and intercalated disks

• The myocardium‘s smooth inner lining, Innermost layer

• Composed of:Simple squamous epithelium (endothelium)

Fibrous Pericardium

Serous Pericardium(Parietal Layer)

Pericardial Cavity(Pericardial Fluid)

Myocardium

Serous Pericardium(Parietal Layer)

Endocardium

Epicardium

Parts of the Heart

Septum

Inter-atrial septum

Interventricular septum

• Located between right and left atria.• Contains

Fossa ovalis – remnant of foramen ovale• Foramen ovale – opening of

interatrial septum of fetus

• Located between right and left ventricles

• Upper membranous part • Thick lower muscular part

A thin partition or membrane that divides two cavities or soft masses of tissue in an organism.

Right Atrium Left Atrium

Right Ventricle

Left Ventricle

Atrioventricular Valves

Tricuspid Valve

Mitral Valve

Semilunar Valves

Pulmonary Valve

Aortic Valve

Parts of the Heart

Cardiac Muscle

Right Heart

Left Heart

Receives venous blood from systemic circulation via superior vena cava and inferior vena cava into right atrium.

Receives oxygenated blood from the pulmonary vein pumps blood into systemic circulation.

Parts of the Heart

Sulcus:

4 Sulcus/Grooves of the Heart

• Coronary sulcus (circular sulcus) – marks the division between atria and ventricles, contains the trunks of the coronary vessels and completely encircles the heart

• Interatrial groove － separates the two atria and is hidden by pulmonary trunk and aorta in front

• Interventricular grooves － anterior and posterior, mark the division between ventricles (which separates the RV from the LV), the two grooves extend from the base of the ventricular portion to a notch called: the cardiac apical incisures

a long narrow slit or groove that divides an organ into lobes.

Major Vessels of the Heart

Vena Cava

Superior Vena Cava

Inferior Vena Cava

One of the two main veins that bring deoxygenated blood from the body to the heart.

Carries blood from the lower part of the body to the heart.

Vessels returning blood to the heart include:

Major Vessels of the Heart

Coronary sinus

Right and left pulmonary

veins

• Opens into the right atrium• Returns deoxygenated blood

from heart muscle (coronary veins)

• Open into the left atrium• Return oxygenated blood from

lungs

Major Vessels of the Heart

Pulmonary trunk

Ascending Aorta

• Carries deoxygenated blood from right ventricle to lungs

• Splits into right and left pulmonary arteries

• Carries oxygenated blood away from left atrium to body organs

• Three major branches• Brachiocephalic• Left common carotid, • Left subclavian artery

Vessels conveying blood away from the heart include:

Parts of the Heart

Atria

Right Atrium

Left Atrium

The right upper chamber of the heart. The right atrium receives deoxygenated blood from the body through the vena cava and pumps it into the right ventricle which then sends it to the lungs to be oxygenated.

Left atrium receive oxygenated blood through the pulmonary vein. The blood is then pumped into the left ventricle chamber of the heart through the mitral valve.

Parts of the Heart

Ventricles

Right Ventricle

Left Ventricle

The right ventricle is the chamber within the heart that is responsible for pumping oxygen-depleted blood to the lungs. It is located in the lower right portion of the heart below the right atrium and opposite the left ventricle.

The left ventricle receives oxygenated blood from the left atrium via the mitral valve and pumps it through the aorta via the aortic valve, into the systemic circulation.

Parts of the Heart

Valves

Atrioventricular

Semi-lunar

• Tricuspid – found between Right Atrium and Right Ventricle

• Mitral – found between Left Atrium and Left Ventricle

• Pulmonic – located between the right ventricle and the pulmonary artery.

• Aortic

Inferior Vena Cava

Superior Vena Cava

Right Atrium

Right Ventricle

Pulmonary Arteries

Pulmonary Veins

Left Atrium

LeftVentricle

Aorta

Circulation of Blood through the Heart