Anatomy and the Importance of the Coronary Circulation
Introduction
The circulatory system
is responsible for the movement of blood and other body fluids within the body.
These body fluids are within the confines of special structures called the
blood vessels. Following the pumping of the blood by the heart, blood flows to all
parts of the body through systemic, pulmonary and portal circulation. The heart
has special muscles called the cardiac muscles whose major role is to contract
and relax thus pumping and receiving blood from all parts of the body. The
pumping activity of the heart is continuous thus the cardiac muscles require
constant supply of oxygen and other nutrients and removal of the waste
products. The cardiac muscles receive blood through the coronary artery while
the coronary vein drains blood back to the heart chambers. This movement of
blood within the heart muscles is called coronary circulation. Understanding
circulation requires the understanding of the structure of the heart that shows
how the blood vessels are ramified. The study of the body structures in
relation to their functions is called anatomy.
This essay seeks to introduce the anatomy of
the heart in relation to its contraction and relaxation thus pumping and
receiving blood from other parts of the body. It will also address the
importance of coronary circulation in relation to the whole body and in the
process show the anatomical changes that may affect the heart and the whole
body systems.
The
Anatomy of the Heart
The anatomy of the
heart is very vital in the explanation of the movement of blood to all parts of
the body as it shows the exact structures involved and how effects on the
structures affect other body organs. Located in the chest cavity and just
posterior to the breast bone, between the lungs and superior to the diaphragm
is the heart.
Heart walls
Forming the heart walls
are the cardiac muscles whose pumping activity and heart beat enables constant
flow of blood to and from other body parts. The cardiac muscles are dividing
into three layers epicardium the outer covering layer of the heart, myocardium
the middle layer made up of muscles and the endocardium; the inner layer. The
endocardium is continuous with the inner lining of the coronary blood vessels. The
coronary blood vessels ramify the walls of the heart.
Heart chambers
The heart is divided
into four chambers namely; the left and the right ventricles, the left and the
right atria. The walls of these chambers are made of the cardiac muscles and
are supplied by the coronary blood vessels. Also subdividing the heart
vertically is the septum made of the purkinje tissues.
The hearts blood
vessels
The blood vessels are
hollow tubes that form a network that transports blood throughout the body. From
the heart are two types of blood vessels namely the arteries and the veins, The
arteries transport oxygenated blood away from the heart except the pulmonary
artery that transports deoxygenated blood from the lungs back to the heart. All
veins carry deoxygenated blood back to the heart except the pulmonary vein that
carries oxygenated blood away from the heart to the lungs. Among the arteries is the aorta which forms
the largest artery in the body and from which branch several arteries including
the coronary artery (Seiler, 2009).
Once blood is pumped from the heart, it leaves
the heart through the aorta which now branches down to various arteries
supplying the other body organs. Among the branches are the carotid arteries
which supply blood to the head region, the subclavian arteries which supply
blood to the upper limbs and the coronary artery which supply blood to the
heart muscles. The movement of blood through these blood vessels is called
systemic circulation.
The coronary blood
vessels
These are the blood
vessels that supply the heart muscles. They include the coronary arteries and
the coronary veins.
The coronary arteries
Source:
Gaziano, Ridker and Libby (2011)
These are the first
branches of the aorta and are further divided into the left coronary artery and
the right coronary artery. The left coronary artery branches further into the Left
Anterior Descending Artery that supplies oxygenated blood to the septum and the
walls of the ventricles and the left atrium on the front side of the heart and
the Left Circumflex Artery that supplies oxygenated blood to the walls of the
ventricles and the left atrium in the back region of the heart.
The Right Coronary Artery branches supplies
oxygenated blood to the walls of the ventricles and the right atrium and it
branches into the Posterior Descending Artery that supplies oxygenated blood to
the inferior walls of the left ventricle and the septum. (Gaziano et al 2011)
Coronary veins
The
supply of blood rich in oxygen and nutrients to the heart muscles also leaves
with the waste products due to physiological processes like respiration. The
ramification of the coronary arteries in the heart walls eventually branch into
fine capillary beds that join to form coronary veins that drain blood back into
right atrium of the heart.
Importance of the coronary circulation
The
heart is a vital organ of the body whose major function is to transport blood
and required nutrients to all body parts through its pumping activity. This
means that the heart supplies must be kept constant. To facilitate this blood
moves to the heart muscles through the coronary circulation. Coronary
circulation therefore promotes the working of the heart through provision of
the oxygen and nutrients and removing accumulating waste products.
When
there is lack of oxygen reaching the heart muscles, the resulting effect are
that the muscles die thus losing their basic function. This is very dangerous
as it could cause a heart attack and in severe cases death. Therefore
continuous coronary supply helps in promoting good health of the heart thus
reducing heart complications.
Coronary
circulation promotes the heart beat through contraction and relaxation of the
heart muscles. The waves of electrical excitations arising from the Sino Atrial
Node (SAN) located in the right atrium reach the base of the heart through the
contraction and relaxation of the heart muscles.
Coronary
circulation plays a crucial role in transportation of nutrients, oxygen and
other chemical substances like drugs to the heart patients targeting the
activities of the heart muscle. The drugs may be used to dissolve blood clots
within the coronary artery and if so the clots are removed through the coronary
veins.
The
major organs of the body require oxygen and nutrients that are transported
through blood and this is only possible with the effective contraction and
relaxation of the heart muscles that occurs when there is good supply of oxygen
to the heart muscles through coronary circulation. In essence coronary
circulation promotes the good health of the body organs and the body as a
whole.
Problems
arising from the coronary circulation
According to O'Connor, Brady, Brooks, et
al (2010) there are several conditions
that arise from the heart and whose effect to the human body and health are
worth discussion
Coronary Heart Disease
The
coronary artery transports oxygenated blood form the heart to the heart muscles
though sometimes, there is accumulation of fatty substances and other materials
forming a plaque along the artery walls. This plaque accumulation results in
the narrowing of the artery thus may cause slowing or stoppage of blood supply
to the heart causing heart complications and even death.
Congestive Cardiac
Failure
The Coronary Heart
Disease block sufficient blood flow to the heart and coupled with diseases like
the High Blood Pressure, there is inability of the heart to pump enough blood
to meet the body needs. This means that vital organs of the body may lack
important nutrients like oxygen and in return there is accumulation of the
wastes in the organs. This disease is characterized by edema shown by the
accumulation of the body fluid due to the lack of the pump action of the heart.
When these fluids accumulate in the lungs they move into the air spaces causing
difficulty inn breathing.
Heart attack
Also called myocardial infarction and occurs
when a section of the heart has no blood supply due to the blockage of the
coronary arteries. The accumulation of the plaque in the artery leads to the
narrowing of the vessel a condition called atherosclerosis. The section that
does not receive the blood may begin to die and if this spreads, the heart
ability is lowered. Heart attack can also be caused by coronary artery spasm
which involves the tightening of the coronary artery and characterizes blockage
of blood flow to the heart. The symptoms of the disease include chest pains,
shortness of breath and nausea among others (Zbinden & Meier, 2007)
Both Heart Attack and Coronary Heart Disease
can be illustrated by the diagram below.
Sources:
Valensi, Lorgis, Cottin (2011)
Factors
Affecting Coronary Circulation
Coronary circulation
can be improved through several factors.
Exercise
Exercise promotes blood
flow within the body thus consistent exercises improves the heart pumping
capability and eliminates the accumulation of the wastes in the body.
Diet
Foods rich in
cholesterol cause the accumulation of cholesterol in the arteries that cause atherosclerosis.
Thus by promoting a balanced diet with low cholesterol reduces the risk of
heart diseases. (Williams & Restieaux, 2002)
Conclusion
The anatomy of the
heart is important in the explanation of the circulation of blood to various
parts of the body. From the essay, it is evident that the coronary circulation
plays a guiding role in the performance of other vital body organs through the
regulation the supply of oxygen and nutrients to the heart muscles thus
regulating the heart pumping capacity. The human coronary circulation functions
to prevent various diseases of the heart including Coronary Heart Disease,
Heart Attach and Congestive Cardiac Failure. Therefore there is need to protect
the heart from damage.
References
Valensi P, Lorgis L, Cottin Y (March 2011). "Prevalence, incidence,
predictive factors and prognosis
of silent myocardial infarction: a review of the literature". Arch Cardiovascular Dis 104 (3): 178–88
Gaziano JM, Ridker PM, Libby P. Primary and secondary prevention of
coronary heart disease. In: Bonow RO,
Mann DL, Zipes DP, and Libby P, eds. Braunwald's Heart Disease: A Textbook
of Cardiovascular Medicine. 9th ed. Philadelphia, Pa: Saunders
Elsevier; 2011: chap 49.
O'Connor RE, Brady W, Brooks SC, et
al. (November 2010).
"Part 10: acute coronary syndromes:
2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency
Cardiovascular Care". Circulation 122 (18 Suppl 3): S787 817
Seiler C. Collateral Circulation of the Heart, 1st edn. Vol. 1. London:
Springer; 2009
Zbinden R, Meier P. Coronary collateral flow in response to endurance
exercise training. Eur J Cardiovascular
Prev Rehabil 2007; 14:250–7
Williams
MJ, Restieaux NJ, (February 2002). "Myocardial infarction in young people with normal coronary arteries". Heart79 (2):
191–4. PMC 1728590. PMID 9538315
No comments:
Post a Comment