Cardiovascular System (CVS)
Cardiac
(heart)
Right sided:
(volume pump)
Left sided:
(Pressure pump)
Vascular
-
Arteries
Arterioles
Capillaries
Venules
Veins
Functions of Cardiovascular System
I. Primary (main) Function of the Heart:
♥ Acts as a muscular pump:
in order to maintain adequate level of blood flow
throughout CVS by pumping blood under press into
vascular system.
♥ Responsible for the mass movement of fluid in
body.
Functions of Cardiovascular System
II. Secondary functions:
1. Transportation:
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Delivers O2 to tissues, & brings back CO2 to lungs.
Carries absorbed digestion products to liver &
tissues.
Carries metabolic wastes to kidneys to be excreted.
Distribution of body fluids.
Functions of Cardiovascular System
II. Secondary functions:
2. Regulation:
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Hormonal: carries hormones to target tissues to
produce their effects.
Immune: carries antibodies, leukocytes (WBCs),
cytokines, & complement to aid body defense
mechanism against pathogens.
Protection: carries platelets, & clotting factors to aid
protection of the body in blood clotting mechanism.
Temperature: helps in regulation of body
temperature, by diverting blood to cool or warm the
body.
Anatomy of the Heart
Position:
located behind
sternum.
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
Hollow, muscular organ.
Anatomy of the Heart
♥ Consists of 2 separate pumps that maintain
unidirectional flow of blood; the Lt & Rt hts.
♥ Left heart pumps oxygenated blood  Systemic
circulation.
♥ Right heart pumps deoxygenated blood  Pulmonary
circulation.
♥ Each pump contains 2 chambers: an atrium &
a ventricle.
♥ 2 Atria:
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Chambers of the Heart
♥ 2 Ventricles:
Thin-walled chambers.
Receive blood returning to
heart.
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Thicker, muscular walls.
Pump blood from heart.
Each has same capacity
& pumps same volume of
bl in a given period of time.
Chambers of the Heart
♥ Atria & ventricles are separated into 2 functional units
by a sheet of fibrous connective tissue, which gives
attachment to the valves.
Valves of the Heart
♥ 2 Atrioventricular (AV)
valves:
■ One way valves.
■ Allow bl to flow from
atria into ventricles.
■ Tricuspid (Rt) & Mitral (Lt).
♥ 2 Semilunar valves :
■ One way valves.
■ At origin of pulmonary artery
& aorta.
■ Pulmonary (Rt) & Aortic (Lt).
■ Open during ventricular
contraction.
Valves of the Heart: Remember
■ Vs are at entrance & exit
of each ventricle.
■ Vs allow bl to flow in only
ONE direction.
■ When AV-vs open, semilunar-vs
close & vice versa.
■ Opening & closing of
vs occur as a result of press
differences.
■ AV cusps are held by chordae
tendineae to papillary muscles.
Atrioventricular & Semilunar Valves
Types of Circulations
Pulmonary and Systemic Circulations
■ Pulmonary circulation:
– Bl pumped from RV
through the lungs & back
to the ht.
■ Systemic circulation:
– Oxygen-rich bl pumped to
all organ systems to supply
nutrients from LV
■ Rate of bl flow through
systemic circulation = flow
rate through pulmonary
circulation.
Pulmonary Circulation
• Moves blood to and from the lungs
• Pulmonary trunk
– Arises from right ventricle
• Pulmonary arteries
– Branches of pulmonary trunk which project to
lungs
• Pulmonary veins
– Exit each lung and enter left atrium
Systemic Circulation: Arteries
• Aorta
– From which all arteries are derived either directly
or indirectly
– Parts
• Ascending, descending, thoracic, abdominal
• Coronary arteries
– Supply the heart
Systemic Circulation: Veins
• Return blood from body to right atrium
• Major veins
– Coronary sinus (heart)
– Superior vena cava (head, neck, thorax, upper
limbs)
– Inferior vena cava (abdomen, pelvis, lower
limbs)
• Types of veins
– Superficial, deep, sinuses
Fetal Circulation
Heart Walls: 3 Distinct Layers
1. Endocardium:
the innermost layer of the ht.
2. Myocardium:
the thickest main layer,
consists of cardiac ms.
3. Pericardium (epicardium):
the thin, outer covering or
external membrane around
the ht.
Physiology of Cardiac Muscle
■ Cardiac muscle tissue forms 2 functional syncytia:

atria, & ventricles.
The heart is composed of 2 major types of cardiac
muscle:
1: Contractile cells.
2: Autorhythmic (or automatic) cells.
Contractile cells: Contract when stimulated, in same
way as skeletal ms except for longer duration.
Heart : Conducting Tissues
1.
2.
3.
4.
5.
6.
Sinoatrial (SA) node.
Internodal pathways.
Atrioventricular (AV) node.
Bundle of His.
Rt & Lt bundle branches.
Purkinje fibers.
Heart : Conducting Tissues
♥ Conduction pathway:
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Sinoatrial (SA) node.
Internodal pathways.
Atrioventricular (AV) node.
Bundle of His.
Rt & Lt bundle branches.
Purkinje fibers.
♥ Stimulation of Purkinje
fibers cause both ventricles
to contract simultaneously.
Heart : Conducting Tissues
■ SA- node & to a lesser extent AVnode contain small round cells
called ‘P cells’ which are probably
the actual pacemaker cells.
■ At AV- node, very small no. of
intercalated discs & gap junctions
 delay transmission of impulse.
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
Cardiac Cycle
Regulation of the Heart
• Intrinsic regulation: Results from normal functional
characteristics, not on neural or hormonal regulation
– Starling’s 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
Cardiac Innervations
■ Autonomic Nervous System:
I: Sympathetic Nervous System division.
II: Parasympathetic Nervous System division.
Cardiac Innervations
I: Sympathetic Nervous
System:
■ Sympathetic nerves that
reaches heart originates from
POSTGANGLIONIC FIBERS
(upper thoracic, paravertebral, ganglia) 
releases NORADRENALINE.
■ Mainly supplies:
– SA-node,
– Atrial myocardium,
– AV-node,
– Ventricular myocardium.
Cardiac Innervations
II: Parasympathetic Nervous
System:
■ Parasympathetic nerve (vagus)
that reaches ht originates from
PREGANGLIONIC FIBERS (T1
to T5) 
releases ACETYLCHOLINE.
■ Mainly supplies:
– SA-node,
– Atrial myocardium,
– AV-node.
EKG
EKG
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