1. Chapter 11 The Cardiovascular System

2. The Cardiovascular System
Closed system of the heart and blood vessels
Heart pumps blood
Blood vessels allow blood to circulate to all parts of the body
Blood is the transport vehicle
Carries oxygen, nutrients, cell wastes, & hormones, to and from the cells to maintain homeostasis
Function of the cardiovascular system
To deliver oxygen and nutrients and to remove carbon dioxide and other waste products

3. The Heart Location About the size of your fist Mediastinum
Middle cavity of the thorax, between the lungs
Pointed apex directed toward left hip
The great vessels of the heart emerge from the base which points toward the right shoulder and lies beneath the second rib
About the size of your fist
Less than 1 lb.
Apex- Approximately at the level of the 5th intercostal space  where one would place a stethoscope to count the heart rate for an apical pulse

4. The Heart

5. The Heart: Coverings Pericardium – a double serous membrane
Visceral pericardium
Hugs the external surface of the heart & is part of the heart wall
Parietal pericardium
Outside layer
Serous fluid fills the space between the layers of pericardium
Pericarditis- Inflammation of the pericardium  results in an decrease in the amt of serous fluid. This causes the pericardial layers to bind and stick to each other, forming painful adhesions that interfere with heart movements.

6. The Heart: Heart Wall Three layers Epicardium Myocardium Endocardium
Outside layer
This layer is the visceral pericardium
Connective tissue layer
Myocardium
Middle layer
Mostly cardiac muscle – Allows contraction
Endocardium
Inner layer
Endothelium

7. External Heart Anatomy

8. The Heart: Chambers Right & left sides act as separate pumps
Four chambers
Atria
Receiving chambers
Right atrium
Left atrium
Ventricles
Discharging chambers
Right ventricle
Left ventricle

9. Blood Circulation

11. The Heart: Associated Great Vessels
Aorta
Leaves left ventricle
Pulmonary arteries
Leave right ventricle
Vena cava
Enters right atrium
Pulmonary veins (four)
Enter left atrium

12. The Heart: Valves Allows blood to flow in only one direction
Four valves
Atrioventricular valves – between atria and ventricles
Bicuspid (mitral) valve (left)
Tricuspid valve (right)
Semilunar valves between ventricle and artery
Pulmonary semilunar valve
Aortic semilunar valve

13. The Heart: Valves Valves open as blood is pumped through
Held in place by chordae tendineae (“heart strings”)
Close to prevent backflow
Aortic Valve Replacement Surgery

14. Operation of Heart Valves

15. Coronary Circulation
Blood in the heart chambers does not nourish the myocardium
The heart has its own nourishing circulatory system
Right and left coronary arteries & their major branches
Are compressed when the ventricles are contracting and fill when the heart is relaxed
Cardiac veins
Drain the myocardium
Blood empties into the right atrium via the coronary sinus

16. Angina & Myocardial Infarction website

17. Bypass Surgery
Website
Coronary Bypass Surgery

18. Balloon Angioplasty Coronary Angioplasty & Stenting

19. Heart View

21. The Heart: Conduction System
Autonomic Nervous system
Nerves = brakes & accelerators to decrease or increase heart rate
Accelerators = Sympathetic Nervous system
Brakes = Parasympathetic Nervous system
Intrinsic conduction system- Nodal system
Heart muscle cells contract, without nerve impulses, in a regular, continuous fashion
Built into the heart tissue & sets its basic rhythm
Causes heart muscle depolarization in only 1 direction (From the atria to the ventricles)
Enforces a contraction rate of 75 beats/minute
Heart beats as a coordinated unit

22. Intrinsic Conduction System
Special type of tissue  Sets the pace
Sinoatrial (SA) node
Located within the right atrium
Pacemaker  Starts each heartbeat
Atrioventricular (AV) node
Located at the junction of the right & left atria and ventricles
Atrioventricular bundle (Bundle of His)
Bundle branches (right and left)
Purkinje fibers
Spread within the muscle of the ventricle walls

23. Heart Contractions

24. Electrocardiograms (EKG/ECG)
Three formations
P wave:
Small & signals the depolarization of the atria immediately before they contract
QRS complex:
Complicated shape
Depolarization of the ventricles
T wave:
Repolarization of the ventricles

25. Electrocardiograms (EKG/ECG)

26. Abnormal EKG

27. Pathology of the Heart Abnormal ECG: Heart Block:
Damage to AV node  Ventricles are partially or totally released from the control of the SA node  Result = slower heart beat
Other conditions can damage the SA node resulting in a slower heart rate
Surgically installation of an artificial pacemaker
Fibrillation
Results from a lack of blood flow to the heart (ischemia)
Rapid uncoordinated heartbeat that makes the heart useless as a pump  Major cause of death from heart attacks in adults
Tachycardia (If prolonged, can lead to fibrillation)
+100 beats/min
Bradycardia
Less than 60 beats/min

28. The Heart: Cardiac Cycle
Events of 1 complete heartbeat
Both atria & ventricles contract and then relax
Atria contract simultaneously and then relax  ventricles then contract simultaneously and then relax
Systole
Contraction of the ventricles
Diastole
Relaxation of the ventricles

29. Filling of Heart Chambers – the Cardiac Cycle

30. The Heart: Cardiac Output
Cardiac output (CO)
Amount of blood pumped out by each side of the heart (each ventricle) in one minute
CO = (heart rate [HR]) x (stroke volume [SV])
Varies with the demands of the body
Stroke volume (SV)
Volume of blood pumped out by a ventricle with each heartbeat

31. The Heart: Regulation of Heart Rate
Stroke volume usually remains relatively constant
Starling’s law of the heart – the more that the cardiac muscle is stretched, the stronger the contraction
Changing heart rate is the most common way to change cardiac output

32. Regulation of Heart Rate
Increased heart rate
Sympathetic nervous system stimulation
Activated in times of “Fight or Flight”
Hormones
Epinephrine
Thyroxine
Exercise
Fever
Increases the metabolic rate of heart cells

33. The Heart: Regulation of Heart Rate
Decreased heart rate
Parasympathetic nervous system stimulation
Congestive heart failure
Heart is worn out and pumps weakly
Digoxin
Works to provide a slow, steady, but stronger beat

34. Cardiac Output Regulation

35. Congestive Heart Failure (CHF)
Decline in pumping efficiency of the heart  Leading to inadequate circulation
Progressive condition
Causes: Coronary atherosclerosis, high blood pressure and a history of multiple myocardial infarctions
Left side fails
Pulmonary congestion  suffocation
Right side fails
Peripheral congestion and edema

36. Blood Vessels: The Vascular System
Taking blood from the heart to the tissues and back
Arteries
Arterioles
Capillaries
Venules
Veins

37. Blood Vessels: Anatomy
Three layers (tunics)
Tunic intima
Lines the lumen or interior of the vessels
Endothelium  slick surface, decreases friction as blood flows through
Tunic media
Middle coat
Smooth muscle
Controlled by sympathetic nervous system
Changes the diameter of the vessels
Constriction  blood pressure increases
Dilation  blood pressure decreases
Tunic externa
Mostly fibrous connective tissue
Outermost tunic

38. The Vascular System

39. Differences Between Blood Vessel Types
Walls of arteries are the thickest
Lumens of veins are larger than arteries
Skeletal muscle “milks” blood in veins toward the heart
Walls of capillaries are only one cell layer thick to allow for exchanges between blood and tissue

40. Movement of Blood Through Vessels
Most arterial blood is pumped by the heart
Veins use the milking action of skeletal muscles to help move blood

41. Varicose Veins website

42. Capillary Beds Capillary beds consist of two types of vessels
Vascular shunt – directly connects an arteriole to a venule

43. Capillary Beds True capillaries – exchange vessels
Oxygen and nutrients cross to cells
Carbon dioxide and metabolic waste products cross into blood

44. Diffusion at Capillary Beds

45. Vital Signs Arterial pulse Blood pressure Respiratory Rate
Body Temperature

46. Pulse Pulse – pressure wave of blood
Monitored at “pressure points” where pulse is easily palpated

47. Blood Pressure
Measurements by health professionals are made on the pressure in large arteries
Systolic – pressure at the peak of ventricular contraction
Diastolic – pressure when ventricles relax
Pressure in blood vessels decreases as the distance away from the heart increases

48. Blood Pressure Changes

49. Measuring Arterial Blood Pressure

50. Blood Pressure: Effects of Factors
Neural factors
Autonomic nervous system adjustments (sympathetic division)
Renal factors
Regulation by altering blood volume
Renin – hormonal control

51. Blood Pressure: Effects of Factors
Temperature
Heat has a vasodilation effect
Cold has a vasoconstricting effect
Chemicals
Various substances can cause increases or decreases
Diet

52. Variations in Blood Pressure
Human normal range is variable
Normal
140–110 mm Hg systolic
80–75 mm Hg diastolic
Hypotension
Low systolic (below 110 mm Hg)
Often associated with illness
Hypertension
High systolic (above 140 mm Hg)
High diastolic (above 90)
Can be dangerous if it is chronic

54. Varicose Veins website

55. Blood Distribution