1. Cardiovascular System and Disorders
BIO 238

2. Heart and blood vessels are part of the cardiovascular system
Heart pumps blood
Arteries carry blood away from the heart to capillaries
Veins carry blood from capillaries to heart

5. Heart Chambers 2 atria 2 ventricles Atrial septum
Receive blood from veins
2 ventricles
Pump blood to arteries
Atrial septum
Interventricular septum

6. Heart is a double pump
Left atria and ventricle: left pump
Right atria and ventricle: right pump
Differences in wall thickness depend upon work performed by the chamber
Ventricles have more muscle then atria: atria pump to ventricle, ventricles pump out to body areas
Left ventricle is most muscular: pumps blood to body
Right ventricle has less muscle: pumps blood to lungs only

8. Heart Valves:
Allows blood to flow in one directionAtrioventricular valves
Allows flow from atria to ventricles
Tricuspid valve: between R atrium and ventricle
Bicuspid (mitral) valve: between L atrium and ventricle
Semilunar valves
Located at base of blood vessels attached to ventricles
Pulmonary semilunar valve: between R ventricle and pulmonary trunk
Aortic semilunar valve: between L ventricle and aorta

10. Cardiac Cycle Includes:
Systole: contraction phase
Diastole: relaxation phase
When atria and ventricles are relaxed, blood flows into atria, then through open AV valves into ventricles
Semilunar valves closed due to greater pressure in arteries than in ventricles

11. Atrial systole forces more blood into relaxed ventricles

12. Ventricular systole (atrial diastole) increases blood pressure in ventricles
Closes AV valves, opens semilunar valves
Blood moves from ventricles and into arteries

13. Ventricular diastole (atrial diastole) follows
Allows AV valves to open and semilunar valves close
Cycle repeats

14. Heart Sounds Lub-dup (pause) lub-dup
Lub: closing of AV valves during ventricular diastole
Dup: closing of semilunar valves during ventricular systole

15. Flow of Blood Through the Heart
Two basic circuits of blood flow
Pulmonary circuit
Deoxygenated blood flows from R ventricle to lungs
Oxygenated blood flows from lungs to L atrium
Systemic Circuit
Oxygenated blood flows L ventricle to body
Deoxygenated blood flows from body to R atrium

16. Steps of heart circulation
Superior and inferior vena cava return blood from body to R atrium
Pulmonary veins return blood from lungs to L atrium
Atria push blood into ventricles
R ventricle pumps blood into pulmonary trunk
Blood moves into R and L pulmonary arteries, which head to lungs
L ventricle pumps blood into the aorta, which carries blood out to body

18. Heart Conduction System
Conduction system consists of specialized muscle tissue that acts as neural tissue
Spontaneously form impulses
Impulses cause myocardium to contract

19. Components include Sinoatrial (SA) node Atrioventricular (AV) node
AV bundle
Purkinje fibers

20. Atrioventricular node
Sinoatrial node
Pacemaker of the heart
Rhythmically forms impulses to initiate each heartbeat
Impulses cause simultaneous contraction of atria
Atrioventricular node
Receives impulse from SA node
Delay in passing through node allows time for ventricular filling and the completion or atrial contraction
Passes impulse to the AV bundle

21. AV bundle Purkinje fibers Divides into L and R branches
Carries impulse down ventricular septum and up lateral ventricle walls
Forms Purkinje fibers
Purkinje fibers
Carry impulse to myocardium of ventricles
Contraction occurs from the apex upward

22. Electrocardiogram (ECG or EKG)
Recording of the electrical current generated during heart contraction
Performed by an electrocardiograph

23. Electrocardiogram has three distinct waves
P wave: atrial depolarization
QRS wave: ventricular depolarization
T wave: ventricular repolarization

24. Regulation of Heart Function
Numerous factors can act on the SA node to increase or decrease heart rate
Autonomic Regulation
Cardiac center in the medulla oblongata
Stimulated by excessive blood pressure and emotional factors, such as grief and depression
Sympathetic neurons in the cardiac center cause an increase in heart rate
Parasympathetic neurons in the cardiac center cause a decrease in heart rate

25. Other factors affecting heart rate
Age: resting rate declines with age
Sex: females slightly faster than males
Physical condition: good condition means lower heart rate
Temperature: increase in temperature increases rate
Epinephrine: increases strengthens heart rate
Thyroxine: produces a lesser but longer lasting increase in heart rate

26. Blood potassium levels
Blood calcium levels
Low levels slow heart rate
Increased levels increase heart rate and prolong contraction
Blood potassium levels
Increased levels decrease both heart rate and force of contraction
Low levels can cause abnormal heart rhythms

27. Types of Blood Vessels Arteries Capillaries
Carry blood away from the heart
Branch into smaller arteries, eventually forming arterioles
Play an important role in controlling blood flow and blood pressure
Capillaries
Most numerous and smallest vessels
RBCs pass through one at a time
Thin walls allow exchange of materials between blood and cells

29. Veins Blood flows from capillaries into venules
Venules unite to form larger veins, which in turn unite to form even larger veins
Valves exist in large veins to prevent blood backflow and aid in venous blood return
Veins hold ~60% of blood volume at any instant
Reducing venous volume can compensate for blood loss or increase in muscle activity

30. Blood Flow Blood flows from high pressure areas to low pressure areas
Greatest in ventricles and lowest in atria
Ventricles create the pressure

31. Pressure decreases with increased distance from the heart
Due to increase in overall cross-sectional area of vessels due to branching

32. Due to low pressure, veins require assistance to return blood to the heart
Skeletal muscle contractions
Contraction compresses veins, forcing blood from one valved segment to another
Important in arms and legs

33. Respiratory movements
Downward contraction of diaphragm during inspiration
Decreases thoracic pressure and increases abdominal pressure
High pressure in abdominal veins forces blood into low pressure thoracic veins

34. Blood Pressure Arterial blood pressure in the systemic circuit
Systolic blood pressure
Highest pressure during ventricular systole
Diastolic blood pressure
Lowest pressure during ventricular diastole
Pulse pressure is difference between systolic and diastolic blood pressures
Causes the pulse: expansion and contraction of arterial walls

36. Factors Affecting Blood Pressure
Cardiac output
Volume of blood pumped by heart in one minute
Determined by heart rate and blood volume pumped in contraction
Increase cardiac output, increase blood pressure
Decrease cardiac output, decrease blood pressure
Blood volume
Decrease in blood volume, decrease in blood pressure
Increase in blood volume, increase in blood pressure

37. Peripheral resistance
Friction of blood against blood vessel walls
Constriction of arterioles increase both resistance and blood pressure
Dilation of arterioles decreases both resistance and blood pressure
Viscosity
Thickness of blood
Determined by blood cell concentration and plasma proteins
Increase viscosity increases blood pressure
Decrease viscosity decreases blood pressure

38. Control of Peripheral Resistance
Vasomotor center in the medulla
Increases frequency of sympathetic impulses to cause vasoconstriction
Increases blood pressure and velocity
Accelerates oxygen and carbon dioxide transport rates
Decreases frequency of sympathetic impulses to cause vasodilation
Lowers blood pressure and velocity
Activity of vasomotor area can be modified
Affected by epinephrine, impulses from higher brain area, impulses from pressure and chemoreceptors
Decrease in pressure, pH, or oxygen causes vasoconstriction

39. Autoregulation
Blood vessels are affected by localized changes in blood composition
Oxygen, carbon dioxide, pH
Effects can override vasomotor control
Increases rate of exchange of materials between cells and capillaries
Example: decrease in oxygen and increase in carbon dioxide causes vasodilation to increase blood flow

42. Heart Disorders Arrhythmia Bradycardia Tachycardia Heart flutter
Abnormal heart beat
Caused by factors such as damage to conduction system and drugs
Bradycardia
Heart rate less then 60 beats/min
Tachycardia
Heart rate over 100 beats/min
Heart flutter
Heart rate over beats/min
Fibrillation
Very rapid heart rate with uncoordinated contraction
Blood is not pumped from ventricles

43. Congestive heart failure (CHF)
Acute or chronic inability of hear to pump out returned to it
Symptoms include fatigue, edema, accumulation of blood in organs
Possible cause is atherosclerosis
Heart murmurs
Unusual heart sounds associated with defective heart valves
Myocardial infarction
Death of myocardium due to coronary artery blockage
Heart attack
Pericarditis
Inflammation of pericardium due to viral or bacterial infection

44. Blood Vessel Disorders
Aneurysm
Weakened vessel wall bulges, forming balloon-like sac filled with blood
Rupture can be fatal
Arteriosclerosis
Hardening of the arteries
Due to calcium deposits accumulating in tunica media
Atherosclerosis
Formation of fatty deposits in the tunica interna of arteries
Plagues reduce lumen size and increase probability of blood clot formation

45. Hypertension Phlebitis Varicose veins Chronic high blood pressure
Pressure exceeds 140/90
Pre-hypertension
A systolic pressure between and diastolic pressure between 80-89
Phlebitis
Inflammation of a vein
Most common in the legs
Thrombophlebitis involves the formation of blood clots at the inflammation site
Varicose veins
Dilated, swollen veins due to malfunctioning valves
Causes include heredity, pregnancy, and lack of physical activity
Hemorrhoids