1. NOTES: UNIT 6- The Circulatory System The Heart

2. The circulatory system…
The cardiovascular system delivers oxygen and nutrients to tissues and removes wastes.

3. STRUCTURE OF THE HEART Size: ● about 14 cm long and 9 cm wide
Location:
● 2/3 left of midline
● below 2nd rib and rests on diaphragm
Location allows for CPR
● divided into right and left sides
Divided by interventricular septum

5. STRUCTURE OF THE HEART
Heart Covering: the heart is enclosed in a double-walled sac called the pericardium (protects against friction)
● loosely fitting superficial part of the sac: fibrous pericardium
● deep to the fibrous pericardium: serous pericardium
*composed of 2 layers
*space between the layers = pericardial cavity (cushions and lubricates heart)

7. STRUCTURE OF THE HEART Heart Wall
● epicardium = outermost layer; in contact with pericardium (older people= infiltrated with FAT  )
● myocardium = middle layer; thick, muscular (mainly cardiac muscle tissue!)
● endocardium = inner layer; lines the heart chambers

8. one-way valves to prevent “backflow” as blood moves through the heart
each side is divided into an atrium and a ventricle (blood always flows from atrium to ventricle)
ATRIA: chambers that receive blood returning to the heart
VENTRICLES: chambers that pump blood out of the heart
one-way valves to prevent “backflow” as blood moves through the heart
R and L AV valves (tricuspid/bicuspid)
Pulmonary & aortic semilunar valves

9. Left AV valve (bicuspid)
Right AV valve

10. ● Structure of AV valves:
-CHORDAE TENDINAE: strong fibrous structures (“heart strings”) that attach to the flaps of the valves  hold AV valves closed while ventricles contract
-PAPILLARY MUSCLES:
muscles embedded in the endocardium; attach to the
chordae tendineae  contract to hold valves closed
*serve to anchor flaps in their closed
position so pressure doesn’t blow them
into atria like an umbrella on a windy day

12. Blood Vessels & Blood Flow
● RIGHT SIDE:
RIGHT ATRIUM receives deoxygenated blood from the superior and inferior vena cava and coronary veins (sinus)
pumps blood into the RIGHT VENTRICLE
 right ventricle pumps blood out of the heart into the PULMONARY ARTERIES (takes blood to the lungs to get O2)

14. ● LEFT SIDE:
 LEFT ATRIUM receives oxygenated blood from the pulmonary veins (coming from the lungs)
 pumps blood into the LEFT VENTRICLE
 left ventricle pumps blood out of the heart into the AORTA (takes blood to all of the body)

16. SEMILUNAR VALVES: prevent backflow from arteries leaving the heart
-PULMONARY VALVE: separates pulmonary arteries from R ventricle
-AORTIC VALVE: separates aorta from L ventricle
*ventricle contraction forces these valves open until contraction is over; blood flowing backwards closes valves

18. 2 Types of Circulation blood leaves from right side of heart
● pulmonary circulation: to the lungs & back
blood leaves from right side of heart

19. 2 Types of Circulation: ● systemic circulation: out to the body & back
blood leaves from the left side of the heart
*coronary circulation: supplies the heart muscle (myocardium)
shortest systemic circuit: blood branches off aorta to coronary arteries, supplies oxygen to myocardium, and then returns through coronary veins & coronary sinus to Right atrium

21. **500,000 Americans die per year of coronary artery disease
**3.5 million Americans have coronary problems

22. Path of Blood Flow Through the Heart Right side
Deoxygenated blood enters the right atrium through the superior and inferior vena cava  through right atrioventricular (tricuspid) valve  right ventricle  through pulmonary semilunar valve  pulmonary artery  arterioles  capillaries of lungs
Left Side
Oxygenated blood returns from the capillaries of the lungs through venules  pulmonary veins  left atrium  left atrioventricular (bicuspid, mitral) valve  left ventricle  aortic semilunar valve  aorta

25. Let’s label!

26. Cardiac Cycle: *systole: contract *diastole: relax
●When the whole heart is in diastole, in Ventricular filling: blood returning to heart passively & flows into atria & through the open AV valves
● ATRIAL SYSTOLE: atria contract (propels residual blood into ventricles) while the ventricles relax (VENTRICULAR DIASTOLE)
● VENTRICULAR SYSTOLE: ventricles contract while the atria relax (ATRIAL DIASTOLE); blood leaves heart
● all chambers relax for a brief period; cycle repeats!

28. Heart Poster- start Label the anatomy of the heart
Then color code blood flow using arrows through the heart
BLUE: deoxygenated blood
RED: oxygenated blood

29. Conduction System of the Heart
The conduction system of the heart is composed of 4 structures
Sinoatrial Node (SA Node): initiates contraction; PACEMAKER
Electrical message passes throughout R & L atria  atrial systole
Atrioventricular Node (AV node): receives message from SA Node & slows it down for 1/10 second before passing it through AV bundle (bundle of His)

30. Conduction System of the Heart
Atrioventricular (AV) Bundle: passes electrical impulse to Purkinje fibers on left and right sides of ventricles
Purkinje Fibers: stimulates the right & left ventricles to contract together  ventricular systole

32. Animation!- click here

34. ELECTROCARDIOGRAM (ECG/EKG):
● records the electrical changes in the myocardium during a cardiac cycle
● the pattern has several characteristic waves:
1) P wave: depolarization wave from SA through atria
2) QRS complex: ventricular depolarization; precedes ventricle contraction
3) T wave: ventricular repolarization

37. Normal EKG/ECG

38. A 60 year old woman with 3 hours of chest pain.
Acute Myocardial Infarction

39. A 55 year old man with 4 hours of "crushing" chest pain.
Acute Myocardial Infarction

40. Regulation of Cardiac Cycle:
● Heartbeat is affected by:
-Physical exercise
-Body temperature
-Concentration of ions (calcium, potassium)
-Emotions

41. Heart Poster Color code blood flow using arrows through the heart
BLUE: deoxygenated blood
RED: oxygenated blood
Label heart Anatomy
Label the 4 structures in the conduction system on your heart
Use yellow highlighter to outline the flow of impulse conduction through the heart