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
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2Chapter 20
- Cardiovascular System
- The Heart
3Functions 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
4Size, 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
5Heart Cross Section
6Pericardium
7Heart 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
8Heart Wall
9External Anatomy
- Four chambers
- 2 atria
- 2 ventricles
- Auricles
- Major veins
- Superior vena cava
- Pulmonary veins
- Major arteries
- Aorta
- Pulmonary trunk
10External Anatomy
11Coronary Circulation
12Heart Valves
- Atrioventricular
- Tricuspid
- Bicuspid or mitral
- Semilunar
- Aortic
- Pulmonary
- Prevent blood from flowing back
13Heart Valves
14Function of the Heart Valves
15Blood Flow Through Heart
16Systemic and PulmonaryCirculation
17Heart 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
18Cardiac 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
19Conducting System of Heart
20Electrical 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
21Action Potentials inSkeletal and Cardiac Muscle
22SA Node Action Potential
23Refractory Period
- Absolute Cardiac muscle cell completely
insensitive to further stimulation - Relative Cell exhibits reduced sensitivity to
additional stimulation - Long refractory period prevents tetanic
contractions
24Electrocardiogram
- 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
25Cardiac 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
26Alterations in Electrocardiogram
27Cardiac 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
28Cardiac Cycle
29Events during Cardiac Cycle
30Heart 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
31Location of Heart Valves
32Mean 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
33Factors Affecting MAP
34Regulation 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
35Heart 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
36Baroreceptor and ChemoreceptorReflexes
37Baroreceptor Reflex
38Chemoreceptor Reflex-pH
39Effects 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