Anatomy and physiology of the cardiovascular system

1. INTRODUCTION TO CVS
PHYSIOLOGY
DR WAIRIMU MWAURA

2. OBJECTIVES
Intro to the CVS and its components
Anatomy of the heart
Pulmonary and systemic circulation
Coronary circulation

3. INTRODUCTION
The CVS (circulatory system): organ system that
transports molecules to and from the cells of the body.
The molecules carried by the CVS include oxygen,
nutrients, hormones and waste products from cells
through out the body.
Transport of these materials is necessary to maintain
homeostasis of the body.
The CVS is made up of the heart, blood vessels and
blood.

4. THE HEART
Muscular pump that generates the force that moves
blood through blood vessels.
It is about the size of your clenched fist, 250 gms in
females, 300 gms in males.
While at rest it beats 60-100 times/ minute.
It will beat over 2 billion times in a lifetime.
Loss of its ability to pump blood results in death.

5. PERICARDIUM
Thin, two layered, fluid filled sac that surrounds the heart.
Functions: protects &lubricates the heart, contains the heart
within the mediastinum.
2 layers:
i. Outer fibrous pericardium
ii. Inner serous pericardium
Fibrous pericardium: made up of connective tissue, anchors the
heart within the mediastinum.
- Superiorly, it is continuous with the connective tissue coverings of
the great vessels, inferiorly it is attached to the diaphragm.

6. PERICARDIUM
Serous pericardium is further divided into 2: parietal&
visceral pericardium.
Parietal pericardium – lines the fibrous pericardium.
Visceral pericardium (epicardium) – covers the heart surface.
Space between the parietal &visceral pericardium is the
pericardial sac that contains pericardial fluid.
Pericardial fluid reduces friction as the heart contracts within
the pericardial sac.

7. PERICARDIUM

8. SEROUS PERICARDIUM

9. HEART WALL
Heart wall is composed of 3 layers of tissue:
i. Epicardium
ii. Myocardium
iii. Endocardium
Epicardium- superficial layer, thin serous membrane that
constitutes the smooth outer surface of the heart.
Myocardium- thick middle layer of the heart, composed of cardiac
muscle cells, responsible for the heart’s ability to contract.
Endocardium- forms the smooth inner surface of the heart
chambers, allows blood to move easily through the heart.
- Covers the surface of the heart valves.

10. HEART WALL

11. ANATOMY OF THE HEART
Heart consists of 4 chambers :2 atria and 2 ventricles.
The thin walled atria form the superior and posterior
parts of the heart.
Thick walled ventricles form the anterior & inferior
portions.
Auricles : flaplike extensions of the atria, seen anteriorly
between each atria and ventricle.

14. ATRIA
Right atria has 3 openings- superior vena cava, inferior vena
cava& coronary sinus.
The superior and inferior vena cava receive blood from the
body into the right atrium.
-Opening for the coronary sinus receives venous blood from the
heart.
The left atrium has 4 openings from the four pulmonary veins
that receive blood from the lungs.
Right and left atria are separated from each other by the
interatrial septum.

15. VENTRICLES
The atria open into the ventricles through the
atrioventricular valves.
The ventricles are separated by the interventricular septum.
Blood leaves the ventricles of the heart through 2 arteries
the pulmonary trunk &aorta.
Pulmonary trunk carries blood from the right ventricle to the
lungs.
Aorta carries blood from the left ventricle to the body.
Wall of the left ventricle is thicker than that of the right
ventricle-this allows for stronger contractions to pump blood
through the systemic circulation.

17. ATRIOVENTRICULAR VALVES
Ensure one way blood flow from the atria into the ventricles.
Prevent back flow of blood into the atria.
Tricuspid valve: consists of 3 cusps, is the AV between the RA
and RV.
Bicuspid (mitral) valve: 2 cusps, AV between the LA and LV.
Papillary muscles: cone shaped muscular pillars, found in the
ventricles.
The papillary muscles are attached to the cusps of the AV
valves by chordae tendineae.
Papillary muscles prevent the AV from opening into the atria
by pulling onto the chordae tendineae.

18. SEMILUNAR VALVES
Located between each ventricle & its associated great artery.
Aortic and pulmonary semilunar valves.
Each valve consists of 3 semilunar cusps whose free inner borders
meet in the center of the artery to block blood flow.
Contraction of the ventricles pushes blood against the semilunar
valves, forcing them to open.
Blood then enters the great arteries.
If there is backflow from the aorta/ pulmonary trunk towards the
ventricles it enters the pocket of the cusps causing them to meet in
the center closing the valve.

21. CIRCULATION THROUGH THE HEART
The heart is 2 pumps in one.
Blood flows through both sides simultaneously.
Right side of the heart pumps blood through the pulmonary
circulation.
Pulmonary circulation- carries blood to the lungs, CO2 diffuses
from the blood into the lungs & O2 diffuses from the lungs into the
blood.
The pulmonary circulation then returns blood to the left side of
the heart.
Left side of the heart pumps blood through the systemic
circulation, delivering O2 &nutrients to tissues, carries CO2 & waste
products back to the right side of the heart.

24. CIRCULATION THROUGH THE HEART

26. CORONARY CIRCULATION
The heart receives its oxygenated blood supply from the
coronary circulation.
Shortest circulation in the body.
The coronary arteries originate at the base of the aorta from
openings called the coronary ostia located behind the aortic
valve leaflets.
2 coronary arteries
i. Right coronary artery and
ii. Left coronary artery

27. CORONARY OSTIA

29. CORONARY CIRCULATION
The coronary arteries provide intermittent, pulsating blood
flow to the myocardium.
Actively deliver blood when the heart is relaxed (diastole).
Ineffective when the ventricles are contracting (systole) as:
i. They are compressed by contracting myocardium
ii. The entrance to the coronary ostia is blocked by the open
aortic valve.

30. RIGHT CORONARY ARTERY
The RCA divides into 2:
i. Marginal artery
ii. Posterior descending artery
Supplies the:
i. Right atrium & ventricle
ii. Inferior portion of the left ventricle
iii. Interventricular septum- posterior part
iv. Major portion of the conducting
system (SAN &AVN)

31. LEFT CORONARY ARTERY
Divides into two branches:
i. Anterior descending / anterior interventricular branch
-Reaches the apex of the heart
-Gives many septal branches
ii. Left circumflex branch
- Runs in the AV groove and proceeds as the posterior
descending branch

32. LEFT CORONARY ARTERY
Areas supplied:
i. Left atrium
ii. Greater part of the left ventricle
iii. Small portion of the right
ventricle
iv. Anterior part of the
interventricular septum
v. Part of the bundle of His

33. CORONARY CIRCULATION
75 % of the venous drainage of the heart is through the
coronary sinus.
Coronary sinus- large venous structure located on the
posterior aspect of the heart.
It empties into the tight atrium.
Main tributaries of the coronary sinus are: great cardiac vein,
small cardiac vein, middle cardiac vein & posterior cardiac
vein.
Remaining venous drainage is through the anterior coronary
vein and thebesian veins.

34. CORONARY CIRCULATION

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