Heart Structure and Function Explained

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1.12. Heart Structure

 Heart is a hollow organ.
 Situated slightly towards left side
in the middle of the thoracic cavity.
 It is made up of CARDIC
MUSCLE.
 It is conical shape with apex
facing downwards and broad base
directed upwards.
 It is the size of the fist of the
person.
 It protected on all sides by rib
case and by vertebral Coolum on
the back side.
External features

Pericardium

Pericardium
 Heart is enclosed in a double layered,
Transparent, Thin sac called “ PERICARDIUM”
The Space between the inner and outer layers
is called “PERICARDIAL SPACE”
Pericardial space filled with a fluid called
“PERICARDIAL FLUID”
 Pericardium and Pericardial fluid protects the
heart from physical shocks or blows.

Pericardium
 Heart is enclosed in a double layered,
Transparent, Thin sac called “
PERICARDIUM”
The Space between the inner and outer
layers is called “PERICARDIAL SPACE”
Pericardial space filled with a fluid called
“PERICARDIAL FLUID”
 Pericardium and Pericardial fluid protects
the heart from physical shocks or blows.
Fluid.

 Heart is internally divided in to Four
chambers.
Two upper chambers called
“AURICLES”
Two lower chambers called
“VENTRICLES”
 The verticle groove indicates the
presence of right and left chambers.
Left V
Right Auricle.
Left Auric
Right Ventricle

 Very large vein that brings the blood to
heart from all parts of the body are called
“ Vena Cavae” or Caval Veins.
Very large Arteries that brings the blood
away from heart to all parts of the body
are called “ AORTAE” (Aorta = singular)
Left V
Right Auricle.
Left Auric
Right Ventricle
Vena Cavae
Aorta

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Blood Vessels that bring Blood to heart

 3 large veins that bring blood to all parts
of the body.
 SUPERIOR VENA CAVA
 INFERIOR VENA CAVA
 PULMONARY VEINS
 SUPERIOR VENA CAVA; Collects
deoxygenated blood from upper parts of
the body ( Head and Neck)
INFERIOR VENA CAVA; Collects
deoxygenated blood from lower parts of
the body ( Abdomen, Hands and Legs)
PULMONARY VEIN; Brings
oxygenated blood from lungs and opens
in to the left Auricle.
Blood Vessels that bring Blood to heart
In addition to this CORONARY
VEINS bring deoxygenated
blood from the walls of the
heart. These also opens into
right auricle

Blood Vessels that carry Blood away
from heart
systemic
Or Pulmonary
Aorta

 Heart receive oxygenated blood and
supply to all parts of the body
 2 large aortae that send blood to all parts
of the body.
 SYSTEMIC AORTA or SYSTEMIC TRUNK
 PULMONARY AORTA
 SYSTEMIC AORTA or SYSTEMIC TRUNK
Arises from left ventricle and carries
blood to all parts of the body except
lungs.
PULMONARY AORTA; Originates in
the right ventricle.
Out side the heart it divides in to 2
branches – RIGHT & LEFT PULMONARY
ARTERIES. Which carry blood to left and
right Lungs.
A pair of CORONARY ARTERIES
carry oxygenated blood to the heart
muscle.
In some people coronary arteries
get blocked, when this happen
muscle cells do not receive
oxygenated blood and stop
working. This is called Heart Attack.
Patient may die due to failure of
heart muscle.
Blood Vessels that carry Blood away from heart

 Heart has 4 chambers .
2 upper – Auricles.
2 lower - ventricles
 These 4 chambers are separated by
WALLS or SEPTAE ( Septum = Singular).
 Rt and Lt Auricles – Vertical Inter
Auricular Septum.
This wall prevents the mixing of
deoxygenated and oxygenated blood
(rt auricle , Lt auricle)
Rt and Lt Ventricles – Vertical Inter
Ventricular Septum
This wall prevents the mixing of
deoxygenated and oxygenated blood (rt
ventricle , Lt ventricle)
1.12.2. INTERNAL STRUCTURE OF HEART
Inter
Auricular
Septum.
Inter
Ventricular
Septum.

 Walls of ventricles thicker and muscular because it pumps blood to various
parts of the body.
Wall of Lt ventricle is thicker then
rt ventricle. (Pumps more distence i;e fingers
Auricles and Ventricles separated from
each other by transverse ( Horizontal)
Septum – AURICULO - VENTRICULAR
SEPTUM.
 There are 2 openings in this septum
called Auriculo ventricular Apertures
Rt auricle opens in to Rt ventricle through – Rt Auriculo ventricular Apertures
Lt auricle opens in to Lt ventricle through – Lt Auriculo ventricular Apertures
1.12.2. INTERNAL STRUCTURE OF HEART
Rt Auriculo
ventricular
Apertures.
Lt Auriculo
ventricular
Apertures

 Heart has valves which allow the blood
flow in one direction And prevents its
flowing back.
The valves held in position by tough
connective Tissue strands.
These strands are called
“CHORDAETENDINAE”
VALVES IN THE HEART

VALVES IN THE HEART
Sno Name of the Valve Location Allows blood to flow
from
1 Tricuspid Valve
(3 flaps or Cups )
Right Auriculo Ventricular
Aperture
Right Auricle to Right
Ventricle
2 Bicuspid (Mitral ) Valve
(2 flaps or Cups)
Left Auriculo Ventricular
Aperture
Left Auricle to Left
Ventricle
3 Pulmunary Valve
(3 half moon shape or
semilunar valves)
At the origin of pulmonary
aorta in the right ventricle.
Allows blood to flow
right ventricle in to
pulmonary aorta
4 Aortic Valve
( 3 semilunar valves)
At the origin of aorta in the
left ventricle
Allows blood to flow
from left ventricle in to
the aorta.

Diff between Right and Left Auricles
Sno Right Auricle Left Auricle
1 Larger in size Smaller in size
2 Receives blood through superior
and inferior vena cave
Receives blood through pulmonary
vein
3 Receives deoxygenated blood from
all parts of the body except lungs.
Receives oxygenated blood from
lungs
4 Pumps blood in to right ventricle Pumps blood in to left ventricle

Sno Right Ventricle Left Ventricle
1 Smaller in Size Larger in size
2 Pulmonary aorta takes its origin Systemic aorta takes its origin
3 Receives deoxygenated blood from
right auricle
Receives oxygenated blood from left
auricle
4 Pumps deoxygenated blood to lungs Pumps oxygenated blood to all parts
of the body except lungs
5 Tricuspid valve guards the right
auriculo ventricular aperture
Bicuspid (Mitral) Value guards the
left ariculo-ventricular aperture.
Diff between Right and Left Ventricles

1.12.3. Heart – Mechanism of functioning
 Cardiac muscle responsible for Contraction and relaxation of Heart.
Heart contract and relaxes 70 – 80 times/ minute
HEART BEAT: Heart beat represent 1 contraction and 1 relaxation of the heart.
Contraction phase called SYSTOLE. Relaxation phase called DIASTOLE
One Heart beat has 3 stages.
1. Auricular Systole : Both auricles contract at the same time and
pump blood in to ventricles
2. Ventricular Systole: Both ventricles contract at the same time
and pump blood in to vessels. (Auricles
begin to relax during this stage)
3. Ventricular diastole : Both auricles and ventricles relax

Blood flow circuits
 There are two circuits for the flow of blood
 PULMONARY CIRCUTE: Blood flow from
Heart and Lungs.
SYSTEMIC CIRCUTE: Blood flow from
Heart and Organs of the body.
Heart pumps blood in to two circuits
called DOUBLE CIRCUTE HEART
P V
P A
AORTA
Vena cava

Pulmonary Circuit
 Deoxygenated blood from
organs is collected in to Rt auricle
and then sent in to Rt Ventricle.
From rt ventricle to lungs.
In the lungs blood is oxygenated
and returned to the left Auricle
by pulmonary veins.
P V
P A
AORTA
Vena cava

Systemic Circuit
 Oxygenated blood from left
Auricle is pumped in to left
ventricle
From left ventricle blood is
pumped into systemic aorta.
This aorta supplied blood to
various parts of the body.
The deoxygenated blood from
various parts of the body collected
in to superior , inferior venacava
and finally in to rt auricle.
P V
P A
AORTA
Vena cava

Blood Pressure
 The blood with which blood
flows in the blood vessel is called
BLOOD PRESSURE.
ARTERIES – Receive blood so
High BP in arteries.
The BP gradually decreases
when blood flows in to capillaries.
When this blood is collected in
veins BP greatly reduced.
BP high in Arteries. Less in Veins

Blood Pressure
BLOOD PRESSURE measured
by doctors by a instrument called
“SPHYGMOMANOMETER” and is
written as 120 / 80
(systolic/diastolic)

Hypertension or High Blood Pressure
In some people BLOOD
PRESSURE will be very high more
then the usual 120 / 80 such a
condition is called High Blood
Pressure.
Reason for high bp : Blocking of
arteries by cholesterol.

Coronary Angioplasty

Thank you

External view of the heart
pulmonary
artery
pulmonary
vein
coronary
artery
left
ventricle
right ventricle
inferior
vena cava
right atrium
pulmonary
vein
aorta
superior
vena cava

The vena cava carries deoxygenated
blood from the body to the right atrium
superior
vena cava
(transports blood
from the head)
inferior
vena cava
(transports blood
from rest of body)

The right atrium collects deoxygenated
blood and pumps it to the right ventricle
right atrium

The right ventricle pumps deoxygenated
blood to the lungs
right ventricle

The pulmonary artery carries deoxygenated
blood from the right ventricle to the lungs
aorta

The septum separates the left and right
sides of the heart
septum

The pulmonary veins carry oxygenated
blood from the lungs to the left atrium
Pulmonary
veins

The left atrium collects the oxygenated
blood and pumps it to the left ventricle
Left atrium

The left ventricle pumps oxygenated
blood to the body via the aorta
Left ventricle

The aorta carries the oxygenated from the
left ventricle to the rest of the body
Aorta
Aortic arch

Atrio-ventricular valves prevent backflow
of blood into the atria when ventricles
contract
Bicuspid valve
(mitral valve)
Tricuspid valves
Tendon

The semi-lunar valves prevent backflow of
blood from the arteries into the ventricles
Aortic semi-lunar
valve
Pulmonary
semi-lunar
valve

Summary Quiz
Identify the part of the heart indicated by an arrow .
There are 10 questions in total.

Question 1

Question 2

Question 3

Question 4

Question 5

Question 6

Question 7

Question 8

Question 9

Question 10

Answers
1 left ventricle
2 vena cava
3 right atrium
4 pulmonary artery
5 aorta
6 pulmonary vein
7 left atrium
8 atrio-ventricular (tricuspid) valve
9 semi-lunar (aortic) valve
10 right ventricle

Finish

Heart Structure and Function Explained

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