Uploaded by Jordan Amorado


Cardiovascular System
Function: to pump blood to all parts of the body
Location of the Heart in the Thoracic Cavity
-> Mediastinum (“midway”) – central compartment of the thoracic
2. Aortic Valve – controls the blood flow from the left
ventricle to the aorta
3. Atrio-Ventricular Valve
 Tricuspid Valve – right Atrio-Ventricular Valve
 Bicuspid Valve or Mitral Valve – left AtrioVentricular Valve
1. Heart – anatomical pump; pressure gradient;
2. Blood vessels - passageways
 Arteries – largest
 Veins
 Capillaries – smallest
3. Blood – transport medium (oxygen, carbon dioxide, nutrients,
wastes, electrolytes, and hormones)
Circulations – forms a figure 8
Pulmonary circulation – heart and lungs
Systemic circulation – heart and organ systems
Anatomy of the heart
 Upper chambers
 RECEIVES blood
 Lower chamber
 More muscle fibers; pumps blood from the heart
Pulmonary arteries – carry blood away from the ventricles
Pulmonary veins – return blood from tissues to the atria
Valves – controls the blood flow from atrium to ventricle and
prevents backflow
1. Pulmonary Valve – controls the blood flow from the
right ventricle to the pulmonary arteries
Organization of Cardiac Muscles
Cardiac walls – composed of spirally arranged cardiac muscle
1. Endocardium (thin inner) – unique type of epithelial tissue
that lines the chambers of the heart
2. Myocardium (thick middle layer) – cardiac muscles that
consists of interlacing bundles -> intercalated disc)
3. Epicardium (thin external layer) – covers the heart
4. Pericardium (outermost later)
 Protects the heart against infection
 Provides lubrication
 Fixes the heart to mediastinum
2 layers of pericardium
 Serous layer
 Fibrous layer
2 Types of membrane junctions are present within intercalated disc
Intercalated disc – composed of cell adhesion molecules that
connects cardiac muscle to another by fusion:
1. Gap junctions - connect and facilitate communication
between the two muscle cells (electrical signals)
2. Desmosomes – to hold together the two muscles
Pericarditis - pericardial sac inflammation
 Effect: painful friction between two pericardial layers
 Cause: viral or bacterial infection
Electrical Activity of the Heart
Autorhythmicity (or automaticity) - the heart rhythmically
contracts because of action potentials that it generates by itself
2 specialized types of cardiac muscle cells
Electrical activity -> Mechanical activity
1. Contractile cells (99%) “working cells”
 Do mechanical work of pumping
 these cells normally do not initiate their action
 atria, ventricles, valves
2. Autorhythmic cells
 Non-contractile cardiac cells specialized for initiating
and conducting the action potentials responsible for
contraction of the working cells
 Receive electrical signal that initiates action potential
for contraction
a. Sinoatrial node (SA node)
 PACEMAKER of the heart
 Start of the initial electrical activity
 Interatrial pathway (Bachmann’s) - spreads
throughout both atria
 a group of autorhythmic cells that are located
between vena cava and the right atrium
b. Atrioventricular node (AV)
 Located at the base of the right atrium near
the septum above between the atria and
 Internodal pathways - action potential spread
from the atria to the ventricles
c. Bundle of His (atrioventricular bundle)
 Divides to form the bundle branches that
curves around the ventricular chambers
d. Purkinje fibers (looks like small twigs of a tree
 Small terminal fibers that extend from the
bundle of His
 Spread throughout the ventricular myocardium
Pacemaker Potential in Autorhythmic Cells
Pacemaker activity - cardiac autorhythmic cells do not have a
resting potential
D: Lowest Point
K+ : close channels
Na+ : open channels
Action Potential in Cardiac Contractile Cells
Occurs at the ventricular to contract cardiac muscles
E: Pacemaker potential (slow depolarization)
 K+ : closed channels
 Na+ : opened channels, leak or funny channels (influx)
 T-type Ca2+ [Tiny channels] : open channels (influx)
A: Threshold (fast depolarization)
 L-type Ca2+ channels [Large channels] open channels
 Na+ : close channels
B: Peak of the Pacemaker potential
 Ca2+: close channels
 K+: open channels
C: Repolarization
K+ : goes outside the cell
4: Resting potential
 K+ : open channels (goes outside the cells)
0: Depolarization
 Na+ : open channels (influx)
1: Repolarization
 Na+ : close channels (influx)
 K+ : open channels (fast efflux)
2: Slow entry of Ca2+
 K+ : open channels (slow efflux)
 L-type Ca2+ : open channels (influx)
3: Repolarization
 K+ : open channels (goes outside the cells)
 L-type Ca2+ : close channels (influx)
Autorhythmic and Contractile Cells
Actin and Myosin – responsible for contraction
Electrocardiogram (ECG)
 Biomedical device that records the electrical activity present in
body fluids from the cardiac impulse that reaches the body
 Indirect recording of the actual electrical activity of the heart.
 Representing the overall spread of activity throughout the
heart during depolarization and repolarization
P wave rate 60-100 bpm with 10% variation – Normal = 75
Sinus Bradicardycardia: Rate < 60 bpm slow heartbeat
Sinus Tachychardia: Rate > 100 bpm fast heartbeat
Results from:
- Pain/Anxiety
- Volume depletion
- Pericarditis
- Chronotropic drugs (dopamine)
Abnormalities in Heart Rhythm
Arrhythmia – Any variation from the normal rhythm and sequence
of excitation of the heart
ECG Waves
3 distinct wave-forms:
1. P wave – ATRIAL depolarization
 Filling of blood in the atria
 PR segment (AV nodal delay) – opening the valve
2. QRS wave – VENTRICULAR depolarization
 Blood is pumped out of the atrium
 ST SEGMENT– contraction of ventricles;
3. T wave – VENTRICULAR repolarization
 K+ goes out repolarizing the cell
 TP segment – relaxing and filling
Hearth Rhythm and Heart Rate
Normal sinus rhythm – heart rhythm
Formula: 1500/(small x big boxes)
Other method: 60/0.2 x big box
Atrial fibrillation has irregular distance while atrial flutter has
equal distance
Thromboembolism – blood clot; clogging of vessels
Cardio version – small plates with lower voltage input compared
to defibrillator
Mechanical Events of the Cardiac Cycle
Heart Murmurs
Resultant changes in blood flow through the heart
Cardiac cycle alternate periods
Systole – contraction and emptying
Diastole – relaxation and filling
Stages of Cardiac Cycle
1. Filling phase – ventricles fill during diastole and atrial
2. Isovolumetric contraction – ventricles contract, building up
pressure ready to pump blood into the aorta/pulmonary
3. Outflow phase (ventricular systole) – the ventricles
continue to contract, pushing blood into the aorta and the
pulmonary trunk
4. Isovolumetric relaxation (ventricular diastole) – the
ventricles relax, ready to re-fill with blood in the next filling
Laminar (layer) flow
normal flow of the blood in which layers of the fluid slide
smoothly over one another
does not produce an audible sound
Turbulent flow
a turbulent sound/murmurs can be heart from the heart
Cardiac Output (CO)
the volume of blood pumped by each ventricle per minute
depends on heart rate (HR) and stroke volume (SV)
Cardiac Output = Average HR x Average SV
Determined by stroke volume
Cardiac Reserve
Difference between the cardiac output at rest and the
max volume of blood the heart can pump per minute
Stroke Volume = EDV - ESV
1. Intrinsic control related to the extent of venous return
2. Extrinsic control related to the extent of sympathetic
stimulation of the heart
Ejection Fraction = SV/EDV
Healthy heart – EF= 50% - 70%
Heart during strenuous exercise – EF = 90%
Failing heart – EF= 30% or less
Heart failure (HF) – the inability of CO to keep pace with the
body’s demands for supplies and removal of wastes
Heart Diseases associated with Coronary circulation (Coronary
Artery Disease)
1. Vascular Spasm
Abnormal spastic constriction that transiently narrows
the coronary vessels
Vasoconstriction of blood vessel because of damaged
blood vessel to prevent the leakage of blood
2. Atherosclerosis
3. Thromboembolism
formation in a blood vessel of a clot (thrombus) that
breaks loose and is carried by the blood stream to
plug another vessel
embolus – piece of clot
thrombus – blood clot