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USC - BIOL 244 - Class Notes - Week 5

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USC - BIOL 244 - Class Notes - Week 5

School: University of South Carolina
Department: Biology
Course: Anatomy and Physiology II
Professor: Anil Datt
Term: Winter 2016
Tags: anatomy and cardiovascular system
Name: Class notes Cardiovascular system
Description: Summary of lectures on cardiovascular system
Uploaded: 03/12/2018
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background image The Cardiovascular System Blood Flow: Right ventricle    lungs  → left atrium  left ventricle    aorta  → body tissues    vena cava   right  atrium    right ventricle Systole­ The contraction, or pumping, phase
Diastole­ The relaxation, or filling, phase
Pulmonary circuit­ Right side receives oxygen­poor blood from tissues then Pumps blood to 
lungs to get rid of CO2, pick up O2
Systemic circuit­ Left side receives oxygenated blood from lungs and pumps blood to body 
tissues
Right atrium ­ Receives blood returning from systemic circuit
Left atrium ­ Receives blood returning from pulmonary circuit
Right ventricle ­Pumps blood through pulmonary circuit
Left ventricle ­Pumps blood through systemic circuit
Pericardium: double­walled sac that surrounds heart; made up of two layers
1. Superficial  fibrous pericardium: functions to protect, anchor heart to  surrounding structures, and prevent overfilling 2. Deep two­layered  serous pericardium Parietal layer lines internal surface of fibrous pericardium Visceral layer (epicardium) on external surface of heart Three layers of heart wall: 3.   Epicardium: visceral layer of serous   pericardium 4.   Myocardium: circular or spiral bundles of   contractile cardiac muscle cells  Cardiac skeleton: crisscrossing, interlacing layer of connective tissue • Anchors cardiac muscle fibers 
• Supports great vessels and valves
• Limits spread of action potentials to specific paths
5.   Endocardium: innermost layer; is continuous   with endothelial lining of blood vessels • Lines heart chambers and covers cardiac skeleton of valves Interatrial septum­ separates atria
Interventricular septum­ separates ventricles
Superior vena cava­ returns blood from body regions above the diaphragm
Inferior vena cava­ returns blood from body regions below the diaphragm
Coronary sinus­ returns blood from coronary veins
Trabeculae carneae: irregular ridges of muscle on ventricular walls
Papillary muscles: project into ventricular cavity
– Anchor  chordae tendineae that are attached to heart valves
background image 1.  Two Atrioventricular (AV) valves prevent backflow into atria when ventricles contract with 
the help of 
Chordae tendineae a) Tricuspid valve (right AV valve): made up of three cusps and lies between right 
atria and ventricle
b) Mitral valve (left AV valve, bicuspid valve): made up of two cusps and lies 
between left atria and ventricle
2. Two Semilunar (SL) valves  – Prevent backflow from major arteries back into ventricles
– Open and close in response to pressure changes
– Each valve consists of three cusps that roughly resemble a half moon
Pulmonary semilunar valve: located between right ventricle and pulmonary 
trunk
Aortic semilunar valve: located between left ventricle and aorta Equal volumes of blood are pumped to pulmonary and systemic circuits
Left ventricle walls are 3× thicker than right­ Pumps with greater pressure
Coronary circulation 
• Functional blood supply to heart muscle itself
• Shortest circulation in body
• Delivered when heart is relaxed
• Left ventricle receives most of coronary blood supply
• Both left and right coronary arteries arise from base of aorta and supply arterial blood to 
heart Left coronary artery supplies interventricular septum, anterior ventricular walls, left 
atrium, and posterior wall of left ventricle
Right coronary artery supplies right atrium and most of right ventricle Heart depolarizes and contracts without nervous system stimulation
Coordinated heartbeat is a function of:
1.  Presence of gap junctions
2.  
Intrinsic cardiac conduction system • Network of noncontractile (autorhythmic) cells
• Initiate and distribute impulses to coordinate depolarization and 
contraction of heart Action potential initiation by pacemaker cells
Cardiac pacemaker cells have unstable resting membrane potentials called pacemaker 
potentials or prepotentials
Three parts of action potential:
1.   Pacemaker potential: K +  channels are closed,   but slow Na +  channels are open, causing   interior to become more positive

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School: University of South Carolina
Department: Biology
Course: Anatomy and Physiology II
Professor: Anil Datt
Term: Winter 2016
Tags: anatomy and cardiovascular system
Name: Class notes Cardiovascular system
Description: Summary of lectures on cardiovascular system
Uploaded: 03/12/2018
3 Pages 19 Views 15 Unlocks
  • Better Grades Guarantee
  • 24/7 Homework help
  • Notes, Study Guides, Flashcards + More!
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