Muscular System: The Cardiac Muscle (Heart)

1. Muscular System:
Cardiac Muscle

2. 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

4. 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.

5. 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

6. The Human Heart
Description
Weight: 250-300g
Approximately the size of
your fist.
Pumps: 70ml/beat
Works: 70 beats/minute

8. 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

9. 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)

11. Fibrous Pericardium
Serous Pericardium
(Parietal Layer)
Pericardial Cavity
(Pericardial Fluid)
Myocardium
Serous Pericardium
(Parietal Layer)
Endocardium
Epicardium

12. 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.

13. Right Atrium Left Atrium
Right Ventricle
Left Ventricle
Atrioventricular Valves
Tricuspid Valve
Mitral Valve
Semilunar Valves
Pulmonary Valve
Aortic Valve

14. 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.

15. 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.

16. 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:

17. 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

18. 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:

19. 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.

20. 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.

21. 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

22. Inferior Vena Cava
Superior Vena Cava
Right Atrium
Right Ventricle
Pulmonary Arteries
Pulmonary
Veins
Left Atrium
Left
Ventricle
Aorta

23. Circulation of Blood through the Heart