1. THE HEART

2. Cardiovascular System
series of tubes-blood vessels
filled with a fluid-blood
connected to a pump-heart
Arteries
carry blood away from heart
Veins
carry blood to heart
pressure generated in heart pumps blood continuously through system
Blood flow
movement of blood through heart & around body to peripheral tissues
Circulation

3. Circulation right side of body- Pulmonary Circuit
carries blood to & from lungs for gas exchange
Systemic Circuit
carries newly oxygenated blood from lungs to body & back to heart
each circuit begins & ends at heart

4. Heart Anatomy hollow, small organ about size of clenched fist
weighs from grams
located in middle of chest in mediastinum
surrounded by pericardial cavity
lining of pericardial cavity is pericardium
visceral & parietal part
visceral pericardium -epicardium
superficial layer that covers surface of heart
parietal pericardium
lines inner surface of pericardial sac which surrounds heart
between these two-pericardial cavity
filled with pericardial fluid
to lubricate & reduce friction

5. Heart Wall 3 layers Epicardium-visceral pericardium
covers outer surface
Myocardium
muscular wall
Endocardium
simple squamous epithelium

6. Microscopic Anatomy different from skeletal muscle in several ways
cells are smaller
uninucleated
have branching interconnections between have intercalated discs
location of gap junctions & desmosomes
convey action potentials from cell to cell
ensure cells contract simultaneously

7. Heart Anatomy top of heart-base pointed, lower part-apex 4 chambers
2 atria & 2 ventricles
coronary sulcus (atrioventricular sulcus)
anterior & posterior interventricular sulci
mark external boundary of right & left ventricle
Coronary Sulcus

8. Heart Anatomy each atrium has expandable extensions- auricles
hold extra blood
right atrium receives blood from systemic circuit via superior & inferior vena cavae & coronary sinus
superior vena cava
returns blood from body areas superior to diaphragm
inferior vena cava
drains areas below diaphragm
coronary sinus
delivers blood from myocardium of heart

10. Internal Heart Anatomy
blood passes into right ventricle via right AV (atrioventricular) valve or tricuspid valve
keeps blood flowing in one direction from atrium to ventricle
prevents backflow into atrium
tiny, white collagen cords-chordae tendineae attach to each flap
originate at papillary muscles
help to close valves
chordae tendineae & papillary muscles anchor flaps in closed position

11. Internal Heart Anatomy
pectinate muscles-right atrium
fossa ovalis also found here
muscular ridges- ventricles- trabeculae carnae
moderator band extends horizontally from right ventricle wall
coordinates contraction of muscle cells
insures chordae tendinae tense before ventricles contract

12. Internal Anatomy
from right ventricle blood is pumped to pulmonary circuit
valves between ventricles & vessels-semilunar valves
prevent back flow into ventricles
each made of 3 pocket-like flaps shaped like crescent moons
blood travels via pulmonary semilunar valve into pulmonary trunk
start of pulmonary circuit
from pulmonary trunk, blood goes to left & right pulmonary arteries and to lungs for gas exchange
after being oxygenated, blood reenters heart via 2 left & 2 right pulmonary veins-open into left atrium
blood goes from left atrium to left ventricle via left AV valve
bicuspid or mitral valve
from here blood is ejected through aortic semi lunar valveinto aortic arch

13. Heart Anatomy left ventricle discharging chamber
Ligamentum arteriosum
left ventricle
discharging chamber
contractsblood propelled into circulation
equal volumes are pumped to both circuits
right pumps blood to pulmonary circuit through pulmonary trunk
short path with low pressure
left pumps blood through systemic circuit
long path-runs through entire body
5X more resistance to flow
functional difference between left & right ventricle is reflected in anatomy
left ventricle walls are 3X as thick as right ventricle wall
allows left ventricle to generate more pressure
pulmonary trunk is attached to aortic arch by ligamentum arteriosum

20. Coronary Circulation
heart muscle must have its own source of oxygenated blood
supplied by coronary arteries
originate at base of ascending aorta
blood pressure
right coronary artery follows coronary sulcus & supplies right atrium, parts of both ventricles & parts of conducting system
left coronary artery supplies: left ventricle, left atrium & interventricular septum
great cardiac vein
begins anterior surface of ventricles along interventriuclar sulcus
curves around left side of heart in coronary sulcus
empties into coronary sinus

21. Heart Beat myocytes-autorhythmic
depolarize spontaneously at regular time intervals
initiate contraction without signals from brain
each beat begins with action potential generated at SA node (sino-atrial)-pacemaker
generates impulses at regular intervals
to ensure four chambers of heart are coordinated electrical signals travel through cardiac conduction system
sympathetic & parasympathetic connections to heart can modify heart beat
not involved in normal contractions