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Title: Anatomy and Physiology by Rod R Seeley 6th edition chapter 20 power-point


1
Anatomy and Physiology, Sixth Edition
Rod R. SeeleyIdaho State University Trent D.
StephensIdaho State University Philip
TatePhoenix College
Chapter 20 Lecture Outline
See PowerPoint Image Slides for all figures and
tables pre-inserted into PowerPoint without notes.
Copyright The McGraw-Hill Companies, Inc.
Permission required for reproduction or display.
2
Chapter 20
  • Cardiovascular System
  • The Heart

3
Functions of the Heart
  • Generating blood pressure
  • Routing blood
  • Heart separates pulmonary and systemic
    circulations
  • Ensuring one-way blood flow
  • Heart valves ensure one-way flow
  • Regulating blood supply
  • Changes in contraction rate and force match blood
    delivery to changing metabolic needs

4
Size, Shape, Location of the Heart
  • Size of a closed fist
  • Shape
  • Apex Blunt rounded point of cone
  • Base Flat part at opposite of end of cone
  • Located in thoracic cavity in mediastinum

5
Heart Cross Section
6
Pericardium
7
Heart Wall
  • Three layers of tissue
  • Epicardium This serous membrane of smooth outer
    surface of heart
  • Myocardium Middle layer composed of cardiac
    muscle cell and responsibility for heart
    contracting
  • Endocardium Smooth inner surface of heart
    chambers

8
Heart Wall
9
External Anatomy
  • Four chambers
  • 2 atria
  • 2 ventricles
  • Auricles
  • Major veins
  • Superior vena cava
  • Pulmonary veins
  • Major arteries
  • Aorta
  • Pulmonary trunk

10
External Anatomy
11
Coronary Circulation
12
Heart Valves
  • Atrioventricular
  • Tricuspid
  • Bicuspid or mitral
  • Semilunar
  • Aortic
  • Pulmonary
  • Prevent blood from flowing back

13
Heart Valves
14
Function of the Heart Valves
15
Blood Flow Through Heart
16
Systemic and PulmonaryCirculation
17
Heart Skeleton
  • Consists of plate of fibrous connective tissue
    between atria and ventricles
  • Fibrous rings around valves to support
  • Serves as electrical insulation between atria and
    ventricles
  • Provides site for muscle attachment

18
Cardiac Muscle
  • Elongated, branching cells containing 1-2
    centrally located nuclei
  • Contains actin and myosin myofilaments
  • Intercalated disks Specialized cell-cell
    contacts
  • Desmosomes hold cells together and gap junctions
    allow action potentials
  • Electrically, cardiac muscle behaves as single
    unit

19
Conducting System of Heart
20
Electrical Properties
  • Resting membrane potential (RMP) present
  • Action potentials
  • Rapid depolarization followed by rapid, partial
    early repolarization. Prolonged period of slow
    repolarization which is plateau phase and a rapid
    final repolarization phase
  • Voltage-gated channels

21
Action Potentials inSkeletal and Cardiac Muscle
22
SA Node Action Potential
23
Refractory Period
  • Absolute Cardiac muscle cell completely
    insensitive to further stimulation
  • Relative Cell exhibits reduced sensitivity to
    additional stimulation
  • Long refractory period prevents tetanic
    contractions

24
Electrocardiogram
  • Action potentials through myocardium during
    cardiac cycle produces electric currents than can
    be measured
  • Pattern
  • P wave
  • Atria depolarization
  • QRS complex
  • Ventricle depolarization
  • Atria repolarization
  • T wave
  • Ventricle repolarization

25
Cardiac Arrhythmias
  • Tachycardia Heart rate in excess of 100bpm
  • Bradycardia Heart rate less than 60 bpm
  • Sinus arrhythmia Heart rate varies 5 during
    respiratory cycle and up to 30 during deep
    respiration
  • Premature atrial contractions Occasional
    shortened intervals between one contraction and
    succeeding, frequently occurs in healthy people

26
Alterations in Electrocardiogram
27
Cardiac Cycle
  • Heart is two pumps that work together, right and
    left half
  • Repetitive contraction (systole) and relaxation
    (diastole) of heart chambers
  • Blood moves through circulatory system from areas
    of higher to lower pressure.
  • Contraction of heart produces the pressure

28
Cardiac Cycle
29
Events during Cardiac Cycle
30
Heart Sounds
  • First heart sound or lubb
  • Atrioventricular valves and surrounding fluid
    vibrations as valves close at beginning of
    ventricular systole
  • Second heart sound or dupp
  • Results from closure of aortic and pulmonary
    semilunar valves at beginning of ventricular
    diastole, lasts longer
  • Third heart sound (occasional)
  • Caused by turbulent blood flow into ventricles
    and detected near end of first one-third of
    diastole

31
Location of Heart Valves
32
Mean Arterial Pressure (MAP)
  • Average blood pressure in aorta
  • MAPCO x PR
  • CO is amount of blood pumped by heart per minute
  • COSV x HR
  • SV Stroke volume of blood pumped during each
    heart beat
  • HR Heart rate or number of times heart beats per
    minute
  • Cardiac reserve Difference between CO at rest
    and maximum CO
  • PR is total resistance against which blood must
    be pumped

33
Factors Affecting MAP
34
Regulation of the Heart
  • Intrinsic regulation Results from normal
    functional characteristics, not on neural or
    hormonal regulation
  • Starlings law of the heart
  • Extrinsic regulation Involves neural and
    hormonal control
  • Parasympathetic stimulation
  • Supplied by vagus nerve, decreases heart rate,
    acetylcholine secreted
  • Sympathetic stimulation
  • Supplied by cardiac nerves, increases heart rate
    and force of contraction, epinephrine and
    norepinephrine released

35
Heart Homeostasis
  • Effect of blood pressure
  • Baroreceptors monitor blood pressure
  • Effect of pH, carbon dioxide, oxygen
  • Chemoreceptors monitor
  • Effect of extracellular ion concentration
  • Increase or decrease in extracellular K
    decreases heart rate
  • Effect of body temperature
  • Heart rate increases when body temperature
    increases, heart rate decreases when body
    temperature decreases

36
Baroreceptor and ChemoreceptorReflexes
37
Baroreceptor Reflex
38
Chemoreceptor Reflex-pH
39
Effects of Aging on the Heart
  • Gradual changes in heart function, minor under
    resting condition, more significant during
    exercise
  • Hypertrophy of left ventricle
  • Maximum heart rate decreases
  • Increased tendency for valves to function
    abnormally and arrhythmias to occur
  • Increased oxygen consumption required to pump
    same amount of blood
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