Biology project

Topic: circulatory system and cardiac

disorder
Introduction
The circulatory system is a system of organs that
includes the heart, blood vessels, and blood which is
circulated throughout the entire body of a human or
other vertebrate.[1] [2] It includes the cardiovascular
system, or vascular system, that consists of the heart
and blood vessels (from Greek kardia meaning heart,
and from Latin vascula meaning vessels). The
circulatory system has two divisions, a systemic
circulation or circuit, and a pulmonary circulation or
circuit.[3] Some sources use the terms cardiovascular
system and vascular system interchangeably
with circulatory system.[4]
Cardiovascular diseases (CVDs) are a group of
disorders of the heart and blood vessels. They include:
 coronary heart disease – a disease of the blood vessels

supplying the heart muscle;

 cerebrovascular disease – a disease of the blood vessels

supplying the brain;

 peripheral arterial disease – a disease of blood vessels

supplying the arms and legs;

  rheumatic heart disease – damage to the heart muscle and
heart valves from rheumatic fever, caused by
streptococcal bacteria;
 congenital heart disease – birth defects that affect the

normal development and functioning of the heart caused

by malformations of the heart structure from birth; and
 Deep vein thrombosis and pulmonary embolism – blood

clots in the leg veins, which can dislodge and move to

the heart and lungs.
https://www.who.int/

Anatomy
The parts of your heart are like the parts of a building.
Your heart anatomy includes:
 Walls.

 Chambers that are like rooms.

 Valves that open and close like doors to the rooms.

 Blood vessels like plumbing pipes that run through

a building.
 An electrical conduction system like electrical power

that runs through a building.

Heart walls
Your heart walls are the muscles that contract (squeeze)
and relax to send blood throughout your body. A layer of
muscular tissue called the septum divides your heart
walls into the left and right sides.
Your heart walls have three layers:
 Endocardium: Inner layer.

 Myocardium: Muscular middle layer.

 Epicardium: Protective outer layer.

The epicardium is one layer of your pericardium. The
pericardium is a protective sac that covers your entire
heart. It produces fluid to lubricate your heart and keep it
from rubbing against other organs.
Heart chambers
Your heart has four separate chambers. You have two
chambers on the top (atrium, plural atria) and two on the
bottom (ventricles), one on each side of your heart.
 Right atrium: Two large veins deliver oxygen-poor

blood to your right atrium. The superior vena

cava carries blood from your upper body. The
inferior vena cava brings blood from your lower
body. Then the right atrium pumps the blood to your
right ventricle.
 Right ventricle: The lower right chamber pumps

the oxygen-poor blood to your lungs through the

pulmonary artery. The lungs reload the blood with
oxygen.
 Left atrium: After the lungs fill your blood with

oxygen, the pulmonary veins carry the blood to the

left atrium. This upper chamber pumps the blood to
your left ventricle.
 Left ventricle: The left ventricle is slightly larger

than the right. It pumps oxygen-rich blood to the

rest of your body.
Heart valves
Your heart valves are like doors between your heart
chambers. They open and close to allow blood to flow
through. They also keep your blood from moving in the
wrong direction.
Atrioventricular valves
The atrioventricular (AV) valves open between your
upper and lower heart chambers. They include:
 Tricuspid valve: Door between your right atrium

and right ventricle.

 Mitral valve: Door between your left atrium and left

ventricle.
Semilunar valves
Semilunar (SL) valves open when blood flows out of
your ventricles. They include:
 Aortic valve: Opens when blood flows out of your

left ventricle to your aorta (artery that carries

oxygen-rich blood to your body).
 Pulmonary valve: Opens when blood flows from

your right ventricle to your pulmonary arteries (the

only arteries that carry oxygen-poor blood to your
lungs).
https://my.clevelandclinic.org/
Working of heart
The four chambers of the heart are attached to major
veins or arteries that either bring blood into or carry
blood away from the heart.
 The two largest veins in the body, the superior and
inferior vena cava, bring the oxygen-poor (blue) blood
to the heart into the right atrium.
 This oxygen-poor blood then passes through the
tricuspid valve into the right ventricle. The tricuspid
valve closes after the blood passes through to prevent
it from flowing back into the right atrium.
 The right ventricle fills and contracts to pump blood to
the lungs.
 The right ventricle pumps blood through the
pulmonary valve into the pulmonary artery. Once
blood passes into the pulmonary artery the pulmonary
valve closes to prevent backflow of blood into the right
ventricle.
 The two branches of the pulmonary artery carry blood
to both lungs.
 In the lungs, the blood picks up oxygen and expels
carbon dioxide.
 Reoxygenated blood (red blood) leaving the lungs
enters the heart through the pulmonary veins and is
carried into the left atrium.
 The reoxygenated blood then flows through the mitral
valve and into the left ventricle. The mitral valve
closes after the blood passes through to prevent
backflow.
 The left ventricle, the most muscular chamber of the
heart, then contracts with enough pressure to send the
blood through the aortic valve and into the aorta.
After the blood passes through the aortic valve it
closes to prevent backflow of blood into the left
ventricle.
 The aorta branches into arteries, arterioles and
capillaries as it delivers blood throughout the body.
 At the capillaries the blood delivers its supply of
oxygen and picks up carbon dioxide. It then begins its
 journey back to the heart, through the veins, and back
into the inferior and superior vena cava for the
process to begin again.
The heart's control system
A heartbeat is caused by an electrical impulse traveling through the heart. The
heart's built-in electrical system controls the speed of its pumping. The
electrical impulse originates in the sinus node which functions as the heart's
natural pacemaker. The sinus node is most often located in the top of the right
atrium. The electrical signals travel through the heart tissue causing the atria
and ventricles to contract and relax and the blood to be pumped to the body.

https://www.chop.edu/

Blood vessels
Blood vessels

Your heart pumps blood through three types of blood

vessels:
 Arteries carry oxygen-rich blood from your heart to

your body’s tissues. The exception is your

pulmonary arteries, which go to your lungs.
 Veins carry oxygen-poor blood back to your heart.

 Capillaries are small blood vessels where your body

exchanges oxygen-rich and oxygen-poor blood.

Coronary arteries
Your heart receives nutrients through a network
of coronary arteries. These arteries run along your
heart’s surface. They serve the heart itself and include
the:
  Left coronary artery: Divides into two branches
(the circumflex artery and the left anterior
descending artery).
 Circumflex artery: Supplies blood to the left atrium
and the side and back of the left ventricle.
 Left anterior descending artery (LAD): Supplies
blood to the front and bottom of the left ventricle
and the front of the septum.
 Right coronary artery (RCA): Supplies blood to
the right atrium, right ventricle, and bottom portion
of the left ventricle and back of the septum.
Cardiac disorders
Heart failure
Heart failure (HF), also known as congestive heart
failure (CHF), is a syndrome caused by an impairment
in the heart's ability to fill with and pump blood. Although
symptoms vary based on which side of the heart is
affected, HF typically presents with shortness of
breath, excessive fatigue, and bilateral leg swelling.[3]
The severity of the heart failure is mainly decided based
on ejection fraction and also measured by the severity of
symptoms.[7] Other conditions that have symptoms
similar to heart failure include obesity, kidney failure,
liver disease, anaemia, and thyroid disease.[7]
Common causes of heart failure include coronary artery
disease, heart attack, high blood pressure, atrial
fibrillation, valvular heart disease, excessive alcohol
consumption, infection, and cardiomyopathy. These
cause heart failure by altering the structure or the
function of the heart or in some cases both.[6] There are
different types of heart failure: right-sided heart failure,
which affects the right heart, left-sided heart failure,
which affects the left heart, and biventricular heart
failure, which affects both sides of the heart.[11] Left-
sided heart failure may be present with a
reduced ejection fraction or with a preserved ejection
fraction.[10] Heart failure is not the same as cardiac
arrest, in which blood flow stops completely due to the
failure of the heart to pump.[12] [13]
Diagnosis is based on symptoms, physical findings,
and echocardiography.[6] Blood tests, and a chest x-
ray may be useful to determine the underlying cause.
[14]
Treatment depends on severity and case.[15] For
people with chronic, stable, mild heart failure, treatment
usually consists of lifestyle changes, such as not
smoking, physical exercise, and dietary changes, as well
as medications.[16][17][18][needs update] In heart failure due to left
ventricular dysfunction, angiotensin-converting-enzyme
inhibitors, angiotensin receptor blockers, or angiotensin
receptor-neprilysin inhibitors, along with beta
blockers, mineralocorticoid receptor
antagonists and SGLT2 inhibitors are recommended.
[6]
Diuretics may also be prescribed to prevent fluid
retention and the resulting shortness of breath.
[19]
Depending on the case, an implanted device such as
a pacemaker or implantable cardiac defibrillator may
sometimes be recommended.[15] In some moderate or
more severe cases, cardiac resynchronization
therapy (CRT)[20] or cardiac contractility modulation may
be beneficial.[21] In severe disease that persists despite
all other measures, a cardiac assist device ventricular
assist device, or, occasionally, heart transplantation may
be recommended.[19]
Heart failure is a common, costly, and potentially fatal
condition, [22] and is the leading cause of hospitalization
and readmission in older adults.[23][24] Heart failure often
leads to more drastic health impairments than failure of
other, similarly complex organs such as the kidneys or
liver.[25] In 2015, it affected about 40 million people
worldwide.[8] Overall, heart failure affects about 2% of
adults, [22] and more than 10% of those over the age of
70.[6] Rates are predicted to increase.[22] The risk of
death in the first year after diagnosis is about 35%, while
the risk of death in the second year is less than 10% in
those still alive.[10] The risk of death is comparable to that
of some cancers.[10] In the United Kingdom, the disease
is the reason for 5% of emergency hospital admissions.
[10]
Heart failure has been known since ancient times; it
is mentioned in the Ebers Papyrus around 1550 BCE.[26]
Congestive heart failure is
a pathophysiological condition in which the heart's
output is insufficient to meet the needs of the body and
lungs.[10] The term "congestive heart failure" is often
used because one of the most common symptoms
is congestion or fluid accumulation in the tissues and
veins of the lungs or other parts of a person's body.
[10]
Congestion manifests itself particularly in the form
of fluid accumulation and swelling (edema), in the form
of peripheral edema (causing swollen limbs and feet)
and pulmonary edema (causing difficulty breathing)
and ascites (swollen abdomen).[28] Pulse pressure,
which is the difference between the systolic ("top
number") and diastolic ("bottom number") blood
pressures, is often low/narrow (i.e. 25% or less of the
level of the systolic) in people with heart failure, and this
can be an early warning sign.[29]
Symptoms of heart failure are traditionally divided into
left-sided and right-sided because the left and right
ventricles supply different parts of the circulation. In
biventricular heart failure, both sides of the heart are
affected. Left-sided heart failure is the more common.
Peripheral artery disease
Peripheral artery disease (PAD) is a vascular
disorder that causes abnormal narrowing
of arteries other than those that supply
the heart or brain.[5] [15] PAD can happen in any blood
vessel, but it is more common in the legs than the arms.
[16]

When narrowing occurs in the heart, it is called coronary

artery disease (CAD), and in the brain, it is
called cerebrovascular disease.[4] Peripheral artery
disease most commonly affects the legs, but other
arteries may also be involved, such as those of the
arms, neck, or kidneys.[4] [17]
Peripheral artery disease (PAD) is a form of
peripheral vascular disease. Vascular refers to both the
arteries and veins within the body. PAD differs from
peripheral veinous disease. PAD means the arteries are
narrowed or blocked—the vessels that carry oxygen-rich
blood as it moves away from the heart to other parts of
the body. Peripheral veinous disease, on the other hand,
refers to problems with veins—the vessels that bring the
blood back to the heart.[18]
The classic symptom is leg pain when walking, which
resolves with rest and is known as intermittent
claudication.[2] Other symptoms include skin
ulcers, bluish skin, cold skin, or abnormal nail and hair
growth in the affected leg.[3] Complications may include
an infection or tissue death, which may
require amputation; coronary artery disease; or stroke.
[4]
Up to 50% of people with PAD do not have symptoms.
[2]

The greatest risk factor for PAD is cigarette smoking.

[4]
Other risk factors include diabetes, high blood
pressure, kidney problems, and high blood cholesterol.[7]
[19]
PAD is primarily caused by the build-up of fatty
plaque in the arteries, which is called atherosclerosis,
especially in individuals over 40 years old.[6][20][16] Other
mechanisms include artery spasm, blood clots,
trauma, fibro muscular dysplasia, and vasculitis.[5]
[19]
PAD is typically diagnosed by finding an ankle-
brachial index (ABI) less than 0.90, which is the systolic
blood pressure at the ankle divided by the systolic blood
pressure of the arm.[9] Duplex
ultrasonography and angiography may also be used.
[8]
Angiography is more accurate and allows for
treatment at the same time; however, it is associated
with greater risks.[9]
It is unclear if screening for peripheral artery disease in
people without symptoms is useful, as it has not been
properly studied.[21][22][20] For those with intermittent
claudication from PAD, stopping smoking and
supervised exercise therapy may improve outcomes.[11]
[12]
Medications, including statins, ACE inhibitors,
and cilostazol, may also help.[12][23] Aspirin, which helps
with thinning the blood and thus improving blood flow,
does not appear to help those with mild disease but is
usually recommended for those with more significant
disease due to the increased risk of heart attacks.[20][24]
[25]
Anticoagulants (blood thinners) such
as warfarin show no definitive scientific evidence of
benefit in PAD.[26] Surgical procedures used to treat PAD
include bypass grafting, angioplasty, and atherectomy.
[10]

In 2015, about 155 million people had PAD worldwide.

[13]
It becomes more common with age.[27] In the
developed world, it affects about 5.3% of 45- to 50-year-
olds and 18.6% of 85- to 90-year-olds.[7] In the
developing world, it affects 4.6% of people between the
ages of 45 and 50 and 15% of people between the ages
of 85 and 90.[7] PAD in the developed world is equally
common among men and women, though in the
developing world, women are more commonly affected.
[7]
In 2015, PAD resulted in about 52,500 deaths, which
is an increase from the 16,000 deaths in 1990.

Coronary artery disease

Coronary artery disease (CAD), also called coronary

heart disease (CHD), ischemic heart disease (IHD),
[13]
myocardial ischemia,[14] or simply heart disease,
involves the reduction of blood flow to the cardiac
muscle due to build-up of atherosclerotic plaque in
the arteries of the heart.[5] [6] [15] It is the most common of
the cardiovascular diseases.[16] Types include stable
angina, unstable angina, and myocardial infarction.[17]
A common symptom is chest pain or discomfort which
may travel into the shoulder, arm, back, neck, or jaw.
[4]
Occasionally it may feel like heartburn. Usually
symptoms occur with exercise or emotional stress, last
less than a few minutes, and improve with rest.
[4]
Shortness of breath may also occur and sometimes
no symptoms are present.[4] In many cases, the first sign
is a heart attack.[5] Other complications include heart
failure or an abnormal heartbeat.[5]
Risk factors include high blood
pressure, smoking, diabetes, lack of
exercise, obesity, high blood cholesterol, poor
diet, depression, and excessive alcohol consumption.[6][7]
[18]
A number of tests may help with diagnoses
including: electrocardiogram, cardiac stress
testing, coronary computed tomographic angiography,
biomarkers (high-sensitivity cardiac troponins)
and coronary angiogram, among others.[8] [19] Ways to
reduce CAD risk include eating a healthy diet,
regularly exercising, maintaining a healthy weight, and
not smoking.[20] [9] Medications for diabetes, high
cholesterol, or high blood pressure are sometimes used.
[9]
There is limited evidence for screening people who
are at low risk and do not have symptoms.[21] Treatment
involves the same measures as prevention.[10]
[22]
Additional medications such
as antiplatelets (including aspirin), beta blockers,
or nitro-glycerine may be recommended.[10] Procedures
such as percutaneous coronary intervention (PCI)
or coronary artery bypass surgery (CABG) may be used
in severe disease.[10][23] In those with stable CAD it is
unclear if PCI or CABG in addition to the other
treatments improves life expectancy or decreases heart
attack risk.[24]
In 2015, CAD affected 110 million people and resulted in
8.9 million deaths. it makes up 15.6% of all deaths,
making it the most common cause of death globally.
[12]
The risk of death from CAD for a given age
decreased between 1980 and 2010, especially
in developed countries.[25] The number of cases of CAD
for a given age also decreased between 1990 and 2010.
[26]
In the United States in 2010, about 20% of those over
65 had CAD, while it was present in 7% of those 45 to
64, and 1.3% of those 18 to 45; [27] rates were higher
among males than females of a given age.

The most common symptom is chest pain or discomfort

that occurs regularly with activity, after eating, or at other
predictable times; this phenomenon is termed
stable angina and is associated with narrowing of
the arteries of the heart. Angina also includes chest
tightness, heaviness, pressure, numbness, fullness, or
squeezing.[28] Angina that changes in intensity, character
or frequency is termed unstable. Unstable angina may
precede myocardial infarction. In adults who go to the
emergency department with an unclear cause of pain,
about 30% have pain due to coronary artery disease.
[29]
Angina, shortness of breath, sweating, nausea or
vomiting, and light-headedness are signs of a heart
attack, or myocardial infarction, and immediate
emergency medical services are crucial.
https://en.wikipedia.org/

Conclusion

The heart and blood vessels form an intricate network

throughout the human body. The anatomy of the four-
chambered heart is central to the network and functions
to maintain blood moving throughout the body. Arteries,
capillaries, and veins work in conjunction to keep all
tissues healthy by providing oxygen and other nutrients
while removing carbon dioxide and other waste through
continuous blood flow. As the body encounters
parasites or infections, the immune response is
triggered and the appropriate blood components initiate
a response to remove the undesirable items. In cases
of mutations or injuries to the circulatory system, other
systems in the body can be affected, thus demonstrating
the importance of how the body requires the interaction
of all the systems to maintain proper function.
Chronic diseases are now the dominant contributors to the
global burden of disease, and CVD is the largest contributor
to the chronic disease cluster. Although CVD death rates are
declining in most high income countries, trends are increasing
in most low and middle income countries.