chapter 11 part a

Chapter 11

Part A:  The Heart

1.     Where is it?

a.    Location- thorax between the lungs in the inferior mediastinum

b.    Orientation-pointed apex directed toward left hip

c.    Size-about the size of your fist

2.    Coverings

a.    Pericardium (around the heart)= double wall sac

                                          i.    Fibrous pericardium- is loosed and superficial

                                        ii.    Serous pericardium- is deep to the fibrous pericardium and composed of two layers

1.     Visceral pericardium(actually on the heart)= next to heart; also known as the epicardium

2.    Parietal pericardium

a.    Outside layer that lines the inner surface of the fibrous pericardium…secretes serous fluid

b.    Serous fluid fills the space between the layers of pericardium… lubricates to prevent friction and irritation

3.    Heart Structure

a.    The heart wall:

                                          i.    Epicardium

1.     Outside layer= visceral pericardium, connective tissue.

                                        ii.    Myocardium

1.     Middle layer= mostly cardiac muscle

                                       iii.    Endocardium

1.     Inside layer= endothelium

b.    Heart Chambers

                                          i.    Double pump= right and left side act as separate pumps

                                        ii.    Four chambers

1.     Two atria: upper chambers, receiving chambers(where blood comes into heart), right and left atrium

2.    Two ventricles: discharging chambers(where blood leaves the heart), right and left ventricle

c.    Heart septa

                                          i.    Interventricular septum: separates the two ventricles

                                        ii.    Interatrial septum: separates two atria

d.    Heart valves

                                          i.    Purpose= allow blood to flow in only one direction to prevent backflow

                                        ii.    Four valves

1.     Atrioventricular (AV) valves- between atria and ventricles:

a.    Bicuspid (mitral) valve- left side of heart

b.    Tricuspid valve- right side of heart

2.    Semilunar valves-between ventricle and artery:

a.    Pulmonary semilunar valve

b.    Aortic semilunar valve

3.    AV valve details

a.    Chordae tendineae= anchor AV valves in place(heart strings)

b.    Open during heart relaxation and closed during ventricular contraction

4.    Semilunar valve details

a.    Open during ventricular contraction and closed during heart relaxation

b.    Valve sequence= operate opposite of one another to force a one way path of blood through the heart

4.    Systemic and pulmonary circulations

a.    Systemic circulation: blood flows from the left side of the heart, through all body tissues, and back to the right side of the heart

b.    Pulmonary circulation: blood flows from the right side of the heart, to the lungs, and back to the left side of the heart

5.    Great vessels

a.    Arteries

                                          i.    Aorta

                                        ii.    Pulmonary artery

b.    Veins

                                          i.    Superior/inferior venae cavae

                                        ii.    Pulmonary veins

6.    Blood flow through the heart

a.    From venae cavae

b.    From right atrium

c.    From right ventricle

d.    From pulmonary trunk

e.    In the lungs

f.    From the lungs

g.    From left atrium

h.    From left ventricle

7.    Coronary circulation

a.    Own nourishing system for heart walls

b.    Coronary arteries

c.    Cardiac veins

d.    Coronary sinus

8.    Heart conduction system

a.    Intrinsic

b.    No nerve impulses

c.    Sinoatrial (SA) node

d.    Atrioventricular (AV) node

e.    AV bundle

f.    Purkinje fibers

g.    Heart contractions

                                          i.    Initiation

                                        ii.    Autorhythmic cells

                                       iii.    Cardiac depolarization

                                       iv.    Irregularities

1.     Tachycardia

2.    Bradycardia

9.    Cardiac cycle

a.    Sequence

b.    Systole

c.    Diastole

d.    Lubb dupp = heart sounds

                                          i.    Lubb

                                        ii.    Dupp