Cardiac Physiology Quiz

Course Information

• Lecture quizzes are included in exams
• Attendance is part of the grade
• Answer keys are posted after class
• Exam scantrons are not returned
• Office hours are for reviewing exams
• The syllabus is a contract; students should read it thoroughly
• No makeup exams are available
• Blackboard contains many guidelines and materials
• Check folders for additional material
• Recommended materials: Pencil and good eraser for scantrons, save blank scantrons
• No grade changes due to insufficient materials

Advanced AP Pathophysiology

• Apply anatomical and physiological knowledge to case studies, critical thinking questions, and clinical scenarios
• Understand and apply knowledge to clinical situations
• Integrate multiple systems of the human body

Medical Terminology

• Cardiovascular System: Deals with the heart and blood vessels
• Chapter 25: Discusses the structure and function of the cardiovascular system
• Review of Heart Structures and Function: Focuses on the pumping action necessary for blood circulation
• Functions of the Circulatory System: Blood's transport function (oxygen, nutrients, waste, electrolytes, hormones, immune) along with regulating body temperature

Heart Locations

• The heart is located in the mid-sternum area, with its point of maximal intensity (PMI) near the 2nd rib
• Anatomical references provide specific locations of heart parts and surrounding structures (lungs, diaphragm, etc)

Heart Conditions

• Dextrocardia: Congenital birth defect where the heart is positioned on the right side instead of the left.
• Hypoplastic Left Heart Syndrome: A rare congenital condition where the left side of the heart is severely underdeveloped.

Heart Anatomy

• Pericardium: Fibrous covering around the heart, offering protection and holding it in place
• Myocardium: Muscular portion of the heart forming the walls of the atria and ventricles
• Endocardium: Thin, three-layered membrane lining the inside of the heart

Heart Function

• Valves: Ensure one-way blood flow; atrioventricular valves (tricuspid and mitral/bicuspid) and semilunar valves (aortic and pulmonary) are crucial for proper heart function
• Fibrous Skeleton: Structural support and isolating force for electrical impulses in the heart

Heart Valves Functions

• AV valves: Prevent backflow into atria/open and close in response to pressure
• Tricuspid valve(right) and mitral valve (left)
• Chordae Tendineae: Anchor cusps to papillary muscles (special heart muscles) to prevent everting of flaps during contraction
• Semilunar valves: Prevent backflow into ventricles during heart relaxation/open and close in response to pressure changes
• Aortic valve and pulmonary semilunar valve
• No chordae tendineae

Heart Cycle Recall

• When the heart contracts, blood must fill the ventricle first. Thus, AV valves need to open first, followed by atrial contraction to fill the ventricle completely before sytole. The volume of blood filling up the ventricles is about 130ml.

Cardiac Cycle

• Describes rhythmic pumping action of heart
• Systole: Ventricular contraction and emptying
• Diastole: Ventricular relaxation and filling(with blood)
• Main atrial pressure waves (a, c & v waves) during cardiac cycle
• Four phases of cardiac cycle

Ejection Fraction

• Portion of end diastolic volume ejected during systole
• Normal ejection fraction is less than 55% of EDV

Cardiac Output

• Amount of blood pumped by the heart each minute
• Determined by stroke volume (amount pumped per beat) and heart rate (number of beats per minute)

Factors Affecting Stroke Volume

• Preload: Stretch of ventricular muscle from blood filling before contraction
• Contractility: Forcefulness of ventricular muscle contraction
• Afterload: Pressure in arteries that must be overcome for blood ejection
• Important: Increase in Afterload = Increased Cardiac workload

Local Control of Blood Flow

• Blood flow proportional to tissue metabolic needs
• Autoregulation: Each tissue controls its own blood flow.

Collateral Circulation

• Most organs receive blood from multiple branches
• Arterial anastomosis: Where arteries supplying the same area connect.
• Coronary collateral arteries: May prevent myocardial ischemia in healthy subjects and in some patients with coronary artery disease.
• Exercise often increases collateral blood flow.
• Important to note: Larger coronary arteries being blocked (occluded) may hinder the smaller coronary arteries from restoring blood flow.

Factors Affecting Heart Rate

• Parasympathetic activity (vagus nerve): Slows heart rate, no effect on contractility
• Sympathetic activity: Speeds heart rate, increases contractility

Nervous Control of BP

• Input to cardiovascular centers: Several structures in the brains communicate with the medulla oblongata for control and regulation of heart rate and contractility
• Output to Effectors: Medulla oblongata sends impulses to cause changes in cardiac rate and contractility and vascular resistance

Additional Information

• Digitalis (digoxin): Medication helpful for congestive heart failure and atrial fibrillation
• Definitions of ischemia, hypoxemia
• Questions for review:
  • Differences between cardiac and skeletal muscle (histology and physiology)
  • What maintains blood flow in Atria
  • What factors regulate right atrial pressure