1. Topic 2
The Heart

2. Objective 1 Function of the Heart
The function of the heart is to provide pressure for pumping blood into the arteries of systemic circulation. The heart functions as a pump by alternatively contracting and relaxing.
Diastole: relaxation phase; during diastole, the pressure in a chamber of the heart is reduced
Systole: contraction phase; during systole, the pressure in a chamber of the heart is increased
Ventricular Ventricular Pressure low, Ventricles fill Pressure elevated, Ventricles empty
Diastole
Systole

3. Objective 2 Size and Position of the Heart
Size of the Heart
♥ About the size of a fist
♥ Average dimensions of an adult heart: 12 cm X 9 cm X 6 cm
♥ Average weight of the adult heart
Males: grams
Females: grams

4. Location of the Adult Heart
♥ Lies in the mediastinum
♥ 2/3rds to the left of the midline
♥ Medial to the lungs
♥ Directly posterior to the sternum
♥ Anterior to the esophagus
♥ of the heart lies at T5-T8
♥ of the heart lies in the 5th intercostal space, about 9cm to the left of the body’s midline
Base
Apex
Note: The location of the base and apex of the heart are counter intuitive!

6. Objective 3 The Pericardium
The pericardium is a double walled sac that surrounds the heart.
A. Structure
Fibrous pericardium: superficial portion made of dense irregular connective tissue
Functions:
1. Protects the heart
2. Anchors the heart to surrounding structures
3. Prevents overfilling of the heart

7. Serous pericardium: deeper serous membrane, composed of
Serous pericardium: deeper serous membrane, composed of areolar connective tissue and mesothelium (simple squamous epithelium) which secretes pericardial fluid
Parietal layer: lines the internal surface of the fibrous pericardium
Visceral layer: adheres to the surface of the heart; is also called the epicardium
Pericardial cavity: space between the parietal and visceral layer that contains pericardial fluid
Functions:
pericardial fluid lubricates surfaces and reduces friction

8. Pericardial Sac Intact Sac Cut Away

9. Objective 4 Tissues of the Heart Wall
The tissues that make up the wall of the heart are organized into three layers:
Layer Location Structure Function(s)
Epicardium outer layer described in Cells secrete (Visceral pericardium) objective 3
serous fluid

10. Myocardium

11. Layer Location Structure Function(s)
Myocardium middle layer cardiac muscle cells Cardiac muscle: (myocytes) held in place by contracts to eject blood collagen and elastic fibers into arteries (called the fibrous skeleton)
Fibrous skeleton: stabilizes the position
of valves and myocytes
helps to distribute
the force of contraction
Adds strength and helps to prevent overdistention
Helps to maintain the shape of the heart
Provides elasticity
Isolates atrial muscle cells from ventricular muscle cells

12. Vascular Supply to the myocardium: vessels of coronary circulation
The heart is filled with blood, why does it need it’s own circulation?

13. Nerve Supply: Autonomic NS
SNS:
PNS:
Cardiac Nerves increases rate and strength of contraction
Vagus Nerve (X) decreases rate and strength of contraction

14. Layer Location Structure Function(s)
inner layer which endothelium (simple maintains a smooth lines the squamous epithelium/ surface for blood ventricles and areolar connective flow covers valves tissue
Endocardium

16. Objective 5 Structures of the Heart
The heart has four chambers:
Atria: superior chambers which receive deoxygenated blood from systemic circulation (right atrium) and oxygenated blood from the lungs (left atrium)
 The atria are separated from each other by an interatrial septum
Ventricles: inferior chambers which distribute deoxygenated blood to lungs (right ventricle) and oxygenated blood to systemic circulation (left ventricle)
 The ventricles are separated from each other by an interventricular septum

18. 8 of 39 : 18-04bGrossHeart_L.jpg
                                     
                                         
8 of 39 : 18-04bGrossHeart_L.jpg
Right and Left Atria: superior chambers
♥ are separated from each other by an interatrial septum What To Look For In The Atria:
Auricle
Crista terminalis
Pectinate Muscles
Fossa Ovalis
© 2006 Pearson Education, Inc., publishing as Benjamin Cummings

20. Crista terminalis: location of the SA node

21. Patent Foramen Ovale

22. Attached Vessels: Right Atrium Left Atrium SVC, IVC pulmonary veins
coronary sinus

23. Right Atrium: receives deoxygenated blood from systemic circulation
Left Atrium receives oxygenated blood from pulmonary circulation

24. Right and Left Ventricles:
♥ they are separated from each other by an interventricular septum
What to look for in the ventricles:
Papillary Muscles
Note: The left ventricular wall is thicker than the right ventricular wall
The apex lies in the floor of the left ventricle
Trabeculae Carneae

25. Right Ventricle
Left Ventricle

26. Attached Vessels:
Right Ventricle Left Ventricle
pulmonary trunk
aorta

27. Heart Valves
♥ The heart valves prevent blood from moving backwards
Mnemonic for remembering order of valves: Try Pulling My Aorta
(Tricuspid, Pulmonary, Mitral, Aortic)

28. Try before you buy! Tricuspid Valve Right Atrio-ventricular Valve
Left Atrio-ventricular Valve
Bicuspid Valve
                                                                                    
                                                                             
Tricuspid Valve
Lies between the right atrium Lies between the left atrium and the right ventricle and the left ventricle
Also called mitral
Try before you buy!

29. Mitral Valve

30. Valve Mechanism:

31. Semilunar Valves
Pulmonary: lies at the base of the pulmonary trunk Aortic lies at the base of the aorta

32. Semilunar Valves

34. C. External Features of the Heart
Base
Apex
Coronary Sulcus
Anterior Interventricular Sulcus
Posterior Interventricular Sulcus

35. Objective 6 Great Blood Vessels
Superior Vena Cava (SVC): Carries deoxygenated blood from areas of systemic circulation above the diaphragm to the right atrium
Inferior Vena Cava (IVC): Carries deoxygenated blood from areas of systemic circulation below the diaphragm to the right atrium

36. Pulmonary Trunk (Artery):. Carries deoxygenated blood from the
Pulmonary Trunk (Artery): Carries deoxygenated blood from the towards the lungs
Pulmonary Veins (4): Carries oxygenated blood from the lungs to the left atrium
Aorta: Carries oxygenated blood from the left ventricle to systems of the body
right ventricle

37. Objective 7 Circulation of Blood Through The Heart
Superior/Inferior Systemic Body Tissues Vena Cava Circulation
Right Atrium
Left Ventricle (Through the Mitral Valve)
Pulmonary Trunk/Arteries Left Atrium (Through the Semilunar Valve)
Lungs
Aorta (Through the Semilunar Valve)
Right Ventricle (Through the Tricuspid Valve)
Pulmonary Veins