Download Introduction to Anatomy & Physiology

Cardiovascular System
 Blood
 The Heart
 Blood Vessels &
Circulation
The Heart
 Introduction
 Overview of
Cardiovascular System
 Anatomy of the Heart
 The Heartbeat
 Cardiodynamics
Introduction & Overview
• Cardiovascular Circuits
• Blood Vessel Designations
• Location of the Heart
Learning Objectives
• Cardiovascular Circuits:
 Distinguish btw the pulmonary &
systemic circuits of blood flow in
terms of general anatomy & O2 &
CO2 content of the blood
• Blood Vessel Designations:
 Distinguish btw afferent & efferent
blood vessels & relate these terms
to the arterial & venous systems of
vessels
Learning Objectives
• Heart Location:
 Describe the location & general
features of the heart
 Explain what organs are found
w/in the mediastinum
CV Circuitry
• Pulmonary Circuit
 transports blood to & from the gas
exchange surfaces of the lungs
• Systemic Circuit
 transports blood to & from all parts
of the body except the gas
exchange surfaces of the lungs
• Heart
 each circuit begins and ends at the
Note: Pulmonary
veins are red [↑O2]
heart
Pulmonary arteries are blue [↓O2]
Blood Vessels
• Arteries
 efferent vessels – carry blood away
from heart
• Veins
 afferent vessels – carry blood
toward the heart
• Capillaries
 exchange vessels – release
nutrients, O2; absorb CO2, waste
Heart Location
• Mediastinum




near anterior thoracic wall
medial to the lungs
superior to diaphragm
contains thymus, esophagus, trachea
• Base (of Heart)
 superior – location of major efferent &
afferent blood vessels
• Apex (of Heart)
 inferior – pointed
Anatomy of the Heart
• Pericardium
• Layers of the Heart
• External Anatomy
• Internal Anatomy
Learning Objectives
• Pericardium:
 Describe the structure & function
of the pericardium
• Heart Layers:
 Identify the 3 layers of the heart &
relate them to the pericardium &
lining of the blood vessels
Pericardium
Structure
• Serous membrane lining the
pericardial cavity
• Subdivisions:
 Visceral Pericardium
on outer surface of the heart
forms the epicardium (outer) layer of
the heart
 Parietal Pericardium
closer to lungs & body wall
lines inner surface of the pericardial
sac
Pericardium Function
• Pericardial cavity
 potential space btw visceral & parietal
pericardia
 pericardial fluid – lubricant reducing
friction during heartbeats
• Pericardial sac
 reinforced by dense collagen fiber
network
 stabilizes the position of the heart and
associated blood vessels w/in the
mediastinum
Layers of the Heart
• Epicardium
 outer layer
 continuous w/ visceral pericardium
• Myocardium
 middle layer
 muscular contraction
• Endocardium
 inner layer
 lines the heart chambers; continuous w/
endothelium of blood vessels
Learning Objectives
• Heart Valves:
 Distinguish btw the valves of the
heart in terms of structure, locus,
& function
• Heart Chambers:
 Describe the structure & function
of the chambers of the heart
Learning Objectives
• Coronary Vessels:
 Describe the location, structure,
& function of the coronary
arteries & cardiac veins
• Blood Flow Through the Heart:
 Trace the flow of blood through
the heart chambers & valves &
the associated blood vessels
going to & from the pulmonary &
systemic circuits
Heart Anatomy:
External
• Right Atrium
 auricle – expandable extension of the
atrium
 receives blood from superior & inferior
vena cava & coronary sinus
 pumps blood to R. ventricle
• Right Ventricle
 relatively thin-walled
 receives blood from the R. atrium
 pumps blood to lungs via the pulmonary
trunk & arteries
Great Vessels
• Superior Vena Cava
 drains blood into R atrium from upper
systemic circuit
• Inferior Vena Cava
 drains blood into R atrium from lower
systemic circuit
• Pulmonary Trunk
 directs blood out of R ventricle to
pulmonary circuit
 L pulmonary arteries (2)
 R pulmonary arteries (3)
Heart Anatomy:
External
• Left Atrium
 auricle – expandable extension of the
atrium
 receives blood from the pulmonary veins
 pumps blood to L. ventricle
• Left Ventricle
 relatively thick-walled
 receives blood from the L. atrium
 pumps blood to heart via coronary
arteries and to systemic circuit via aorta
Great Vessels
• Pulmonary Veins
 drain blood from pulmonary circuit
into the L atrium
 from L pulmonary veins (2)
 from R pulmonary veins (2)
• Aorta
 directs blood out of L ventricle to
systemic circuit
 ascending aorta  aortic arch 
descending aorta
Heart Anatomy:
Internal
• Interatrial septum
 divides R & L atria
• Interventricular septum
 divides R & L ventricles
Comparison of R & L
Ventricles
Pumps blood to
the lungs in the
thoracic cavity
Pumps blood to the
entire body
Contraction
of R & L Ventricles
Heart Valves
• Atrioventricular Valves
 control blood flow btw atria & ventricles
 prevent backflow of blood from
ventricles into atria during ventricular
contraction
• Semilunar Valves
 control blood flow btw ventricles &
efferent arteries
 prevent backflow of blood from
pulmonary trunk & aorta into the R & L
ventricles
Atrioventricular
Valves
• Tricuspid valve
 btw R atrium & R ventricle
 3 cusps
• Bicuspid (mitral) valve
 btw L atrium & L ventricle
 2 cusps
• Supported by chordae tendineae
attached to papillary muscles in
ventricle
Semilunar
Valves
• Pulmonary semilunar valve
 separates R ventricle from
pulmonary trunk
 3 symmetrical cusps
• Aortic semilunar valve
 separates L ventricle from aorta
 3 symmetrical cusps
• Do not require bracing because
arterial walls do not contract
Semilunar Valve:
Open & Closed
Coronary
Arteries
• Supply blood to heart
• Emerge from ascending aorta
• Right Coronary Artery
 follows coronary sulcus
 branches to form:
 marginal branches
 posterior interventricular branch
 supplies blood to:
 right atrium
 portions of both ventricles
 part of heart conduction system - SA & AV
nodes
Coronary
Arteries
• Left Coronary Artery
 branches to form:
 circumflex branch
 anterior interventricular branch
 supplies blood to:
 left atrium
 interventricular septum
 left ventricle
Cardiac
Veins
• Great Cardiac Vein
 drains:
 anterior surface of R & L ventricles
 L atrium
 drains into coronary sinus
• Posterior Cardiac Vein
 drains:
 posterior surface of L ventricle
 drains into coronary sinus
Cardiac
Veins
• Middle Cardiac Vein
 drains:
 posterior surface of R & L ventricles
 drains into coronary sinus
• Small Cardiac & Anterior Cardiac
Veins
 drains:
 R atrium
 drains into coronary sinus
Cardiac
Veins
• Coronary Sinus
 drains all the cardiac veins
 drains into R atrium
Superficial Anatomy
Sequence of Blood Flow
Through the Heart
1) Superior & inferior vena cava
2)
3)
4)
5)
6)
7)
a) Coronary sinus
Right atrium
Tricuspid valve
Right ventricle
Pulmonary semilunar valve
Pulmonary trunk
R & L pulmonary arteries
a) Capillaries of the lungs
Sequence of Blood Flow
Through the Heart
b) Capillaries of the lungs
8) R & L Pulmonary veins
9) Left atrium
10) Bicuspid (mitral) valve
11) Left ventricle
12) Aortic semilunar valve
13) Ascending aorta
a) Coronary arteries
Right
Blood Flow
Left
Superior
Through the Heart
Right
Left
Pulmonary
Tricuspid
Inferior
Aortic
Bicuspid
(mitral)
Circulatory System
• To View Video:
– Move mouse cursor over slide titlelink
– When hand appears, click once
• ASX Video plays about 23 min
• A Video Quiz is included in the
presentation – 10 Questions
Heartbeat
• Innervation
• Contractile Cells
• The Conduction System
• The Cardiac Cycle
Learning Objectives
• Heart Innervation:
 Describe how the heartbeat is
regulated by the central nervous
system
• Heart Conduction:
 Explain the sequence of heart
conduction & relate it to the
heartbeat
Heart Innervation
• Medulla oblongata (brain stem)
 cardiac centers
• Autonomic Nervous System
 innervates SA & AV nodes
 controls heart rate
Heart Innervation
• Sympathetic N.S.
 sympathetic nerves from spinal cord
increase heart rate & strength of
contraction in response to stress
• Parasympathetic N.S.
 parasympathetic nerves from brain
(vagus nerve; CN X) decrease heart rate
& strength of contraction during calming
period
The Heartbeat
• Contractile Cells


99% of muscle cells in heart
myocardium of atria & ventricles
• Action Potentials


differs from skeletal muscle
has plateau w/ relatively long
refractory period
Features of Cardiac
Contractile Cells
• Single nucleus
 ovoid
• Striated
 myofibrils organized into sarcomeres
• Branched
 one cell contacts 3 or more others
• Intercalated discs
 btw/ cells - speeds cell-cell propagation
of contraction
The Heartbeat
•
Cardiac Action Potential
1) Rapid depolarization: Na+ influx via fast
channels in sarcolemma ~3 – 5 msec;
ends w/ closure of Na-channels
2) The plateau: Ca2+ influx via slow
channels in sarcolemma – maintains
depolarization ~175 msec; ends w/
closure of Ca-channels
3) Repolarization: K+ outflow via slow
potassium channels ~ 75 msec
Cardiac Conduction
System
• Sinoatrial (SA) Node
 locus: wall of R atrium
 called pacemaker – initiates
contraction of the atria
• Internodal Pathways
 locus: walls of R atrium
 conducting cells
 brings contraction stimulus from
SA node to AV node
Cardiac Conduction
System
• Atrioventricular (AV) Node
 locus: junction btw/ atria &
ventricles
 delays conduction to ventricles
allowing atria to finish contraction
• Av Bundle (bundle of His)
 locus: superior to interventricular
septum
 conducting cells
 brings contractile stimulus from atria
to ventricles
Cardiac Conduction
System
• R & L Bundle Branches
 locus: interventricular septum
 conducting cells
 branch from AV bundle down septum
to apex
 during conduction, atria relax
• Purkinje Fibers
 locus: walls of the R & L ventricles
 conducting cells
 induce rapid contraction of ventricles
Conduction
System
Impulse Conduction
Through the Heart
Impulse Conduction
Through the Heart
Impulse Conduction
Through the Heart
Electrocardiogram
(ECG or EKG)
• P wave
 atrial depolarization
• QRS Complex
 ventricular depolarization
 atria repolarize at this time
• T wave
 ventricular repolarization
Electrocardiogram
• P – R Interval
 from start of atrial depolarization
to start of QRS complex
 extension of P – R interval to >0.2
sec can indicate damage to
conducting pathways or AV node
Electrocardiogram
• Q – T Interval
 time required for ventricles to
undergo single cycle of
depolarization & repolarization
 lengthening of time can indicate
conduction problems, coronary
ischemia (reduced blood flow to
heart muscle) or myocardial
damage
Cardiac Cycle
• Systole
 contraction
 atrial systole & ventricular systole
do not occur at same time
• Diastole
 relaxation
 atrial diastole & ventricular
diastole differ in duration
Phases of the
Cardiac Cycle
• Atrial Systole




atria contract
ventricles fill w/ blood
100 msec
atrial pressure exceeds venous
pressure
• Atrial Diastole
 atria relax
 begins w/ ventricular systole
Phases of the
Cardiac Cycle
• Ventricular Systole
 concurrent w/ atrial diastole
 ventricles contract
 blood forced into pulmonary trunk
& aorta
 blood from pulmonary & systemic
circuits pushed into atria
 270 msec
Phases of the
Cardiac Cycle
• Ventricular Diastole
 ventricles relax
 atria still relaxed
 all chambers fill passively with
blood
Phases of the
Cardiac Cycle
Heart Sounds
• Lubb-dupp
 “lubb” sound - S1
 start of ventricular contraction
 sound of AV valves closing
 “dupp” sound – S2
 start of ventricular filling at beginning of
ventricular diastole
 sound of semilunar valves closing
• S3 & S4 sounds
 very faint
 often inaudible in healthy adults
Detecting
Heart Sounds
Cardiodynamics
• Chamber Volumes
• Stroke Volume
• Heart Rate
Learning Objectives
• Cardiodynamics:
 Describe the movements & forces
generated during cardiac
contractions
Chamber Volumes
• End-diastolic volume (EDV)
 the amount of blood in each
ventricle at the end of
ventricular diastole (the start
of ventricular systole
• End-systolic volume (ESV)
 the amount of blood remaining
in each ventricle at the end of
ventricular systole (the start of
ventricular diastole)
Chamber Volumes
• Stroke volume (SV)
 the amount of blood pumped
out of each ventricle during a
single beat
 SV = EDV – ESV
• Ejection fraction
 % of the EDV represented by
the SV
Chamber Volumes
• Cardiac output (CO)
 the amount of blood pumped by
each ventricle in 1 min
CO
(ml/min)
= SV
(ml/beat)
 HR (beats/min)
Factors Controlling
Stroke Volume
• The EDV
 filing time – dependent on heart rate
 venous return – dependent on CO, blood
volume, peripheral circulation patterns, skeletal
muscle activity, other factors affecting blood
flow through venae cavae
• The ESV
 preload – degree of stretching during
ventricular diastole
 contractility – amount of force produced
during contraction
 afterload – amount of tension necessary to
force open semilunar valves
Factors Affecting
Heart Rate
• Autonomic activity
•
•
•
•
Hormones
Drugs
Changes in ion concentrations
Alterations in body temperature
Abnormal
Heart Rate
• Normal heart rate (HR)
 70 – 80 beats/min
 resting adult
• Bradycardia
 slower than normal heart rate
• Tachycardia
 faster than normal heart rate
Parasympathetic
Stimulation
Sympathetic
Stimulation
Cardiac Output