Cardiovascular System
Dr. Zabun Nahar
Associate Professor
Email: zabunnahar@uap-bd.edu
Cell: 01711033021
Cardiovascular System
Cardiovascular system: An organ system that distributes blood to all parts of the
body. sometimes referred to as the circulatory system, is a group of organs and tissues tasked
with circulating blood flow throughout the body.
Major function – transportation, using blood as the transport vehicle
Superior Vena Cava
 The superior vena cava is one of the two main veins bringing de-oxygenated
blood from the body to the heart. Veins from the head and upper body feed
into the superior vena cava, which empties into the right atrium of the heart.

Inferior Vena Cava
 The inferior vena cava is one of the two main veins bringing de-oxygenated
blood from the body to the heart. Veins from the legs and lower torso feed into
the inferior vena cava, which empties into the right atrium of the heart.

Pulmonary Artery
 The pulmonary artery is the vessel transporting de-oxygenated blood from the
right ventricle to the lungs.

Pulmonary Vein
 The pulmonary vein is the vessel transporting oxygen-rich blood from the lungs to
the left atrium.

The heart is roughly a
cone shaped hollow
muscular organ about
the size of 10 cm long
located in the thoracic
cavity
in
the
medianstinum. The heart
pump bloods through the
network of arteries and
veins
of
the
cardiovascular system.
Anatomy of Heart
The circulatory system refers to
how the body keeps blood
moving through the body.

It supplies oxygen and nutrients
to our body.

It helps carry waste and carbon
dioxide out of the body.
Anatomy of Heart



This system carries oxygen, nutrients,
cell wastes, hormones and other
substances vital for body homeostasis
to and from cells .
The force to move blood around the
body is provided by the pumping heart
and blood pressure.
The human heart is approximately the
size of a fist, and weighs less than a
pound. It is enclosed within the inferior
mediastinum, the medial cavity of the
thorax, and flanked on each side by the
lungs
Anatomy of Heart

The pointed apex is directed
toward the left hip and rests at
about the fifth intercostal
space .

The broad aspect, or base,
points toward the right
shoulder and lies beneath the
second rib.
Anatomy of Heart

The heart is enclosed by a
double-walled sac called the
pericardium .

The superficial loosely fitted
part is called the fibrous
pericardium .

Protects and anchors the heart
Anatomy of Heart
Pericardium (around the heart") is a triple-layered
fluid-filled sac that deep to the fibrous
pericardium is the slippery and surrounds the
heart.
Two-layer serous pericardium. The parietal layer
lines the interior of the fibrous pericardium
The parietal layer attaches to the large arteries
leaving the heart and then makes a U-turn and
continues inferiorly over the heart surface as the
visceral layer, or epicardium
A slippery lubricating fluid is produced by the
serous pericardial membranes which allows the
heart to beat easily in a relative frictionless
Anatomy of Heart
The heart walls are composed of three layers:
1.
outer epicardium
2.
myocardium
3.
endocardium

The myocardium consists of thick bundles of the cardiac muscle twisted
into ringlike arrangements . This is the layer of the heart that actually
contracts . Reinforced by dense, they are fibrous connective tissue
(“heart skeleton”).

The endocardium is a thin, glistening sheet of endothelium that lines the
heart chambers that continuous with the linings of the blood vessels
leaving and entering the heart
Heart
The heart has four hollow chambers:
2 atria – receiving chambers and 2 ventricles – filling chambers
 Blood flows into the atria under low pressure from the veins, and continues into
the ventricles
 The ventricles are thick- walled discharging chambers . They are the pumps of
the heart . When they contract, blood is propelled out of the heart and into
circulation.
 The right ventricle forms most of the heart’s anterior surface
 The left ventricle forms the apex
 The septum that divides the heart longitudinally is the interventricular septum
or the interatrial septum based on the chambers it separates
 The heart functions as a double pump
 The right side works as the pulmonary circuit pump. It receives relatively
oxygen-poor blood from the veins of the body through the large superior and
inferior vena cavae






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The blood then pumps out through the pulmonary trunk which splits into the left
and right pulmonary arteries
The pulmonary arteries carry blood to the lungs, where oxygen is picked up and
carbon dioxide is unloaded
Oxygen-rich blood drains from the lungs and is returned to the left side of the heart
through the four pulmonary veins. This circuit is call pulmonary circulation. Its only
function is to carry blood to the lungs for gas exchange and then return it to the
heart
Blood returned to the left side of the heart is pumped out of the heart into the
aorta. The systemic arteries branch from the aorta to supply the body tissues with
blood
Oxygen-poor blood circulates from the tissues back to the right atrium via the
systemic veins, which empty their blood into either the superior or inferior vena
cava
This second circuit, from the left side of the heart through the body tissues and
back to the right side of the heart is called systemic circulation
It supplies oxygen and nutrient-rich blood to all body organs
Chambers of Heart

The right atrium receives blood from the
veins and pumps it to the right ventricle.

The right ventricle receives blood from the
right atrium and pumps it to the lungs,
where it is loaded with oxygen.

The left atrium receives oxygenated blood
from the lungs and pumps it to the left
ventricle.

The left ventricle (the strongest chamber)
pumps oxygen-rich blood to the rest of the
body. The left ventricle’s vigorous
contractions create our blood pressure.

Aorta

The aorta is the largest single blood vessel in the body. It is
approximately the diameter of your thumb. This vessel carries
oxygen-rich blood from the left ventricle to the various parts of the
body.

It is studied in the following three parts
1.
Ascending aorta.(5 cm long and is enclosed in the pericardium)
2.
Arch of the aorta.
3.
Descending aorta.
The Heart Valves
Like so many pumps, the heart depends on a series of valves to work properly.

There are two pairs of valves in the heart
a pair of atrioventricular valves
a pair of semilunar valves

The right atrioventricular valves is known as the tricuspid valve , because of three
cusps. The left atrioventricular valves

Is known as bicuspid valve, because of two cusps.
Position of valves:

On the right-hand side are the pulmonary and tricuspid valves;

on the left-hand side are the aortic and mitral valves.

The four valves open and close automatically to the chambers, so that it can flow
in only one direction
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1.
2.

1.
2.
3.
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1.
2.
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The heart also has four valves:
2 that separate the atria from the ventricles
2 that separate the ventricles from their arteries. All of these valves prevent back flow
The atrioventricular (AV) valves are between the atria and ventricles
On the left is the bicuspid or mitral valve
On the right is the tricuspid valve
They are all anchored by the chordae tendineae
When the heart is relaxed and blood is passively filling its chambers, the AV-valve flaps hang
limply into the ventricles. As the ventricles contract, they press on the blood in their
chamber, and the intraventricular pressure rises
The semilunar valves guard the bases of the large arteries leaving the ventricular chambers
On the right is the pulmonary valve
On the left is the aortic valve
When the ventricles are contracting these valves are forced open and flattened against the
arterial walls
When the ventricles are relaxed the blood flows back towards the heart. This prevents
arterial blood from reentering the heart
Blood Supply to the Heart

The heart is supplied with arterial blood by the right and left coronary arteries,
which branch from the aorta immediately distal to the aortic valve

The coronary arteries receive about 5% of the blood pumped from the heart

Because the heart is composed primarily of cardiac muscle tissue that
continuously contracts and relaxes, it must have a constant supply of oxygen
and nutrients. The coronary arteries are the network of blood vessels that carry
oxygen- and nutrient-rich blood to the cardiac muscle tissue.
Coronary Circulation

The heart muscle, like every other organ or tissue in our body, needs oxygen-rich
blood to survive. Blood is supplied to the heart by its own vascular system, called
coronary circulation

The aorta (the main blood supplier to the body) branches off into two main coronary
blood vessels (also called arteries). These coronary arteries branch off into smaller
arteries, which supply oxygen-rich blood to the entire heart muscle.
The right coronary artery supplies blood mainly to the right side of the heart. The
right side of the heart is smaller because it pumps blood only to the lungs.
The left coronary artery, which branches into the left anterior descending artery and
the circumflex artery, supplies blood to the left side of the heart. The left side of the
heart is larger and more muscular because it pumps blood to the rest of the body.


The coronary arteries supply
oxygenated and nutrient filled
blood to the heart muscle.
There are two main coronary
arteries: right coronary artery
and left coronary artery.

The coronary arteries branch from the base of the aorta and encircle the heart in the
coronary sulcus (AV groove) at the junction of the atria and ventricles

The coronary arteries and their major branches are compressed when the ventricles
are contracting and fill when the heart is relaxed

The myocardium is drained by several cardiac veins, which empty into the coronary
sinus
1.
The coronary sinus, in turn, empties into the right atrium

When the heart beats rapidly the myocardium can received an inadequate amount of
blood. This can result in crushing chest pain called angina pectoris

Pain due to angina pectoris is a warning sign
1.
If angina is prolonged, oxygen-deprived heart cells may die forming an infarct
2.
The resulting myocardial infarction is a “heart attack”

The heart pumps the body’s 6 quart supply of blood through the blood vessels over
1000 times per day. In reality, the heart pumps about 6000 quarts of blood in a single
day
Conducting System of Heart

The conducting system is made up of myocardium that is specialised for initiation and
conduction of the cardiac impulse. It has following parts-

Sinoatrial node (SA node): it known as the pacemaker of the heart, it generates the
impulse at the rate of about 70/min and initiate the heartbeat

Atrioventricular node or AV node: its smaller than SA node and is capable of
generating impulse at a rate of about 60/min.

Atrioventricular bundle (AV bundle or bundle of His): it is the only muscular
connection between the atrial and ventricular musculatures, it divides into left & right
bundle branches.
The SA node has the highest rate of depolarization in the whole system. It starts
each heartbeat and sets the pace for the whole heart and is therefore called the
pacemaker
 The impulse travels from the SA node through the atria to the AV node, causing
the atria to contract
 At the AV node, the impulse is delayed to give the atria time to finish contracting.
It then passes rapidly through the AV bundle, the bundle branches, and the
Purkinje fibers, causing a “wringing” contraction of the ventricles that begins at
the apex and moves toward the atria
 This contraction effectively ejects blood superiorly into the large arteries leaving
the heart
 Tachycardia is a rapid heart rate (> 100 bpm)
1. Bradycardia is a slow heart rate (< 60 bpm)
2. Neither condition is pathological, but prolonged tachycardia may progress to
fibrillation

Components of the circulatory
system
Includes:
Blood: consisting of liquid plasma and cells,
 Blood vessels (vascular system): the "channels“
(arteries, veins, capillaries) which carry blood to/from
all tissues.
 Arteries carry blood away from the heart (oxygenated blood).
 Veins return blood to the heart (deoxygenated blood).
 Capillaries are thin-walled blood vessels in which gas/ nutrient/
waste exchange occurs.
 Heart: a muscular pump to move the blood
 Lymp nodes
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1.
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1.
2.
3.
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1.
2.
3.
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1.
2.
3.
Blood vessels create a closed transport system, or vascular system
Arteries. Arteries leave the heart. Smaller arteries called Arterioles
Arteries
Higher, changing blood pressure
Thicker walls
The middle section (tunica media) is especially thick, strong and stretchy
Capillaries
Capillaries are minute blood vessels that connect arterioles and venules. Form
capillary beds
Veins
Venules
Larger veins
Great veins (Vena cavae) return blood to the heart
Veins-- Lower, constant blood pressure.
Thinner walls
Blood often flows against gravity
Have valves
Veins and Arteries
Capillaries

They connect arteries and veins.

Enable the exchange of oxygen, water, nutrient, carbon dioxide
and other chemical substances.
Circulation


Blood flows through the heart in a cyclical manner.
Physiologically, there are two circulations operating together i.e. double
circulation.
They are i) the pulmonary circulation and ii) the systemic circulation.
 The right side of the heart is responsible for the pulmonary blood flow and
the left side of the heart participates in the systemic blood flow
Blood flows from the right atrium to the right ventricle, and
then is pumped to the lungs to receive oxygen.
 From the lungs, the blood flows to the left atrium, then to the left
ventricle.
 From there it is pumped to the systemic circulation.

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Amazing Heart Facts

Your heart is about the same size as your fist.

An average adult body contains about five quarts of
blood.

All the blood vessels in the body joined end to end would
stretch 62,000 miles or two and a half times around the
earth.

The heart circulates the body's blood supply about 1,000
times each day.

The heart pumps the equivalent of 5,000 to 6,000 quarts of
blood each day.