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Functional Organization
of the Cardiovascular
System
Objectives





Describe the functional organization of cardiovascular
system
List the functions of cardiovascular system.
Describe the main function of arteries, capillaries and
veins
Describe the flow of blood through the chambers of the
heart and through the systemic and pulmonary
circulations.
Compare and contrast the systemic and pulmonary
circulation.
Functional Organization of Cardiovascular
system
HEART
(PUMP)
CARDIOVASCULAR
SYSTEM
VESSELS
(DISTRIBUTION
SYSTEM)
Blood
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 (continued)
II. Secondary functions:
1. Transportation:




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.
2. Regulation:
 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:

Positioned between two
bony structures – sternum
and vertebrae
(CPR)

Hollow, muscular organ.
Heart: Two sided pump
Vena cava
Pulmonary
trunk
pulmonary veins
(Aorta)
Atrium: weak primer pump for the ventricle
Ventricle: the main pumping force


Rt. Ventricle
Lt. ventricle
Pulmonary circulation
Systemic circulation
Blood Flow Through and Pump Action of the Heart
Pulmonary circulation
Starts at right
ventricle
Ends at left atrium
Receives blood
from right side of
heart
Carries blood
between heart and
lungs
Blood perfusing the
lungs is partially
deoxygenated
systemic circulation
Starts at left ventricle
Ends at right atrium
Receives blood from
left side of heart
Carries blood
between heart and
other organ systems
Blood perfusing the
organ systems is
oxygenated
All blood flows
through lungs
Part of the blood go
to different organ
systems
Low pressure, low
resistance
High pressure, high
resistance
Valves of the heart:
♥ 2 atrioventricular
(AV) valves:
■ One way valves.
■ Allow blood 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.
Heart Valves

One way flow in heart is
ensured by heart valves

Valves open & close
passively
- open  by forward P
by blood
- close  by backward P
by blood
Atrioventricular Valve Function
Semilunar Valve Function

No valves between atria and
veins
 Reasons
 Atrial pressures usually
are not much higher
than venous pressures
 Sites where venae cavae
enter atria are partially
compressed during
atrial contraction
The fibrous skeleton of the heart
Serves 3 roles:
 A mechanical base:
atria anchored above
and ventricles below
 Perforated by 4
apertures, each
containing a valve
 Insulates the
ventricles
Vascular Tree


Closed system of vessels
Consists of
 Arteries
 Carry blood away from heart to tissues
 Arterioles
 Smaller branches of arteries
 Capillaries
 Smaller branches of arterioles
 Smallest of vessels across which all
exchanges are made with surrounding
cells
 Venules
 Formed when capillaries rejoin
 Return blood to heart
 Veins
 Formed when venules merge
 Return blood to heart
Arteries
Structure of arterial wall
 Plentiful of elastic
fibers….high
compliance
Function:
Rapid transit passage-ways
for blood from heart to
tissues
Pressure reservoir
Arteries as a Pressure Reservoir
Arterioles (resistance vessels)

Very small arteries that
delivers blood to
capillaries

Structure
 Very little elastic tissue
but thick layer of smooth
muscle
Function Regulating

blood flow from arteries
to capillaries by
regulating resistance
according to tissue
metabolic needs.
Capillaries



Microscopic vessels that connects
arterioles to venules
Structure
 Single wall layered vessels
(endothelial cells)
 Undergoes extensive branching
 Maximized surface area and
minimized diffusion distance
 Velocity of blood flow through
capillaries is relatively slow
 Provides adequate exchange
time
Function:
 Exchange of nutrients and wastes
between blood and tissue cells
Capillaries cont.
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Under resting conditions many capillaries are not open
Capillaries surrounded by precapillary sphincters
Contraction of sphincters reduces blood flowing into capillaries in an
organ
Relaxation of sphincters has opposite effect
Veins

Carry blood from tissues to
heart

Structure:
 Thin wall
 Less smooth muscle and
considerable amount of
collagen
 Less elastic fibers

Function:
 Passage ways back to
heart
 Blood reservoir
(capacitance vessels)