medical

1. Fundamentals of
Cardiovascular system
By
Sujoy Tontubay
B.Sc.(C.U),M.Sc.(V.U), Post Graduate Diploma in Epidemiology and Public
Health.
Assistant Professor in Medical Laboratory Technology, ILEAD.

2. Cardiovascular system
• The cardiovascular system consists of the heart, blood vessels,
and blood. Its primary function is to transport nutrients and
oxygen-rich blood to all parts of the body and to carry
deoxygenated blood back to the lungs.

3. Components of the cardiovascular system
• The cardiovascular system is the system responsible for
delivering blood to different parts of the body. It consists of the
following organs and tissues:
• The heart: A muscular pump that forces blood around the body.
• A closed system of blood vessels: These vessels include:
• Arteries: Vessels that carry blood away from the heart.
• Veins: Vessels that bring blood back to the heart.
• Capillaries: Tiny vessels that branch off from arteries to deliver blood
to all body tissues .

4. Layers of the Heart
Walls
• The heart wall consists of three
layers enclosed in the pericardium
1.Epicardium - the outer layer of the
wall of the heart and is formed by
the visceral layer of the serous
pericardium.
2.Myocardium - the muscular middle
layer of the wall of the heart and
has excitable tissue and the
conducting system.
3.Endocardium .

5. Structure and
Function
• The heart is subdivided by septa
into right and left halves, and a
constriction subdivides each half
of the organ into two cavities,
the upper cavity being called the
atrium, the lower the ventricle.
The heart, therefore, consists of
four chambers:
• The right atrium
• The right ventricle
• The left atrium
• The left ventricle

6. Heart
Valves
• The heart has four valves. All four
valves of the heart have a singular
purpose: allowing forward flow of
blood but preventing backward
flow. The outflow of each chamber
is guarded by a heart valve:
• Atrioventricular valves between the
atrial and ventricles
1.tricuspid valve (R side of the
heart)
2.mitral valve/bicuspid valve (left
side of the heart)
• Semilunar valves which are
located in the outflow tracts of the
ventricles
1.aortic valve (L side heart)

7. Functions 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.

9. PATHWAY OF BLOOD THROUGH HEART
• There are two blood circulatory systems in the body. The first is the systemic circulatory system.
This is the main blood circulatory system that transports blood to the organs, tissues, and cells
throughout the body.
• The second is the pulmonary circulatory system. This circulatory system moves blood between
the heart and lungs. It is where oxygen enters the blood and carbon dioxide leaves the blood.
• There are four chambers in the human heart. The pathway of blood through the heart is as follows:
• The deoxygenated blood from the body is received in the right atrium from the vena cava and enters
the right ventricle through a tricuspid valve. It enters the pulmonary artery through the semilunar
valve and goes to pulmonary circulation.
• The oxygenated blood from the lungs is received in the left atrium from the pulmonary veins and
enters the left ventricle through the bicuspid valve. It enters the aorta through a semilunar valve and
goes to the systemic circulation.

10. Circulation of blood through the heart

12. Blood follows the following through the heart:
1.Blood lacking oxygen returns from the body and enters the right atrium (upper right
chamber) via the inferior vena cava and superior vena cava veins.
2.Blood flows through the tricuspid valve and enters the right ventricle (lower right
chamber).
3.The right ventricle pumps blood through the pulmonary valve and out of the heart via
the main pulmonary artery.
4.The blood then flows through the left and right pulmonary arteries into the lungs. Here,
the process of breathing draws oxygen into the blood and removes carbon dioxide. As a
result, the blood is now rich in oxygen.
5.The blood returns to the heart and flows into the left atrium (upper left chamber) via
four pulmonary veins.
6.Blood flows through the mitral valve and enters the left ventricle (lower left chamber).
7.The left ventricle pumps the blood through the aortic valve into a large artery called the
“aorta.” This artery delivers blood to the rest of the body.

13. Cardiac Cycle
“Cardiac cycle refers to the sequence of events that take place when the
heart beats.”

14. Cardiac Cycle Phases
• Following are the different phases that occur in a cardiac cycle:
• Atrial Diastole: In this stage, chambers of the heart are calmed. That is when the aortic valve and
pulmonary artery closes and atrioventricular valves open, thus causing chambers of the heart to
relax.
• Atrial Systole: At this phase, blood cells flow from atrium to ventricle and at this period, atrium
contracts.
• Isovolumic Contraction: At this stage, ventricles begin to contract. The atrioventricular valves,
valve, and pulmonary artery valves close, but there won’t be any transformation in volume.
• Ventricular Ejection: Here ventricles contract and emptying. Pulmonary artery and aortic valve
close.
• Isovolumic Relaxation: In this phase, no blood enters the ventricles and consequently, pressure
decreases, ventricles stop contracting and begin to relax. Now due to the pressure in the aorta –
pulmonary artery and aortic valve close.
• Ventricular Filling Stage: In this stage, blood flows from atria into the ventricles. It is altogether
known as one stage (first and second stage). After that, they are three phases that involve the
flow of blood to the pulmonary artery from ventricles.

15. Duration of Cardiac Cycle
• In a normal person, a heartbeat is 72 beats/minute. So, the duration of one
cardiac cycle can be calculated as:
• 1/72 beats/minute=.0139 minutes/beat
• At a heartbeat 72 beats/minute, duration of each cardiac cycle will be 0.8
seconds.
• Duration of different stages of the cardiac cycle is given below:
• Atrial systole: continues for about 0.1 seconds
• Ventricular systole: continues for about 0.3 seconds
• Atrial diastole: continues for about 0.7 seconds
• Ventricular diastole: continues for about 0.5 seconds

17. What is the cardiac cycle?
• The cardiac cycle consists of two phases.
• The first phase is diastole, in which the ventricles fill with blood. It begins
when the aortic or pulmonary valve closes and ends when the mitral or
tricuspid valve closes. During diastole, blood vessels return blood to the
heart in preparation for the next contraction of the ventricles.
• Normally, the diastolic blood pressure when sitting quietly is 80 mmHg or
below
• The second phase is systole, in which the ventricles contract and eject
blood. It begins when the mitral or tricuspid valve closes and ends when
the aortic or pulmonary valve closes. The pressure inside the ventricles
becomes greater than the pressure inside adjacent blood vessels, thereby
forcing the blood from the ventricles to the vessels.
• Normally, the systolic blood pressure in an individual quietly sitting is 120
mmHg or below.

18. HEART SOUNDS
Heart sounds are made when
these two sets of valves close in
response to pressure
changes within the heart
• The first heart sound is caused
by the closure of the
atrioventricular valves at the
start of ventricular systole
• The second heart sound is
caused by the closure of the
semilunar valves at the start of
ventricular diastole

20. HEART RATE
• A normal resting heart rate for adults ranges from 60 to 100
beats per minute.
• To measure your heart rate, simply check your pulse. To check
your pulse at your wrist, place two fingers between the bone
and the tendon over your radial artery — which is located on the
thumb side of your wrist.
• When you feel your pulse, count the number of beats in 15
seconds. Multiply this number by four to calculate your beats
per minute.

21. HEART RATE MEASUREMENT

22. BLOOD PRESSURE
• Blood pressure is the force that moves blood through the circulatory
system. It is an important force because oxygen and nutrients would
not be pushed around the circulatory system to nourish tissues and
organs without blood pressure.
• Blood pressure is also vital because it delivers white blood cells
and antibodies for immunity and hormones such as insulin.
• Your blood pressure normally rises and falls throughout the day.

23. Ranges of normal blood pressure readings
• The National Institutes of Health Trusted Source and the American
Heart Association (AHA)Trusted Source cite normal blood pressure
to be below 120 mm Hg systolic and 80 mm Hg diastolic.
However, blood pressure changes naturally for many reasons.
Category Systolic and/or Diastolic
Normal < 120 mm Hg and < 80 mm Hg
Elevated (at risk, or
prehypertension)
120-129 mm Hg and < 80 mm Hg
Hypertension stage 1 130-139 mm Hg or 80-89 mm Hg
Hypertension stage 2 > 140 mm Hg or > 90 mm Hg
Hypertensive crisis
(emergency situation)
> 180 mm Hg and/or > 120 mm Hg

24. Cause of Fluctuations of blood pressure
Fluctuating blood pressure can be caused by several issues.
• Stress
Emotional stress and anxiety can temporarily increase blood pressure.
• Medication
Both over-the-counter and prescription medications can impact your blood
pressure.
• Food and drink
What you eat or drink might impact your blood pressure reading. Foods high in
tyramine, a substance found in aged foods, can increase blood pressure. This
includes foods that are:
• fermented
• pickled

25. Risk factors
• These factors may put you at greater risk for experiencing fluctuating
blood pressure:
• High levels of stress
• Anxiety
• taking blood pressure pills that aren’t effective or don’t last until your
next dose
• tobacco use
• excessive alcohol consumption
• night-shift work