Cardiovascular system
The cardiovascular system contains the Heart,
Blood vessels and blood. There is approximately 5 liters of blood
that courses through these blood vessels as it’s pumped by the Heart. The
cardiovascular system transports nutrients, oxygen, cellular waste products and
hormones to the rest of the body. The heart pumps blood throughout the
body every minute.
The Heart
The heart is a fist sized organ located in the
thoracic region. The great blood vessels (aorta, pulmonary trunk, vena cava and
pulmonary veins) are connected at the top of the heart.
There are two circulatory loops, the systemic
circulatory loop and the pulmonary
circulatory loop.
The systemic loop carries oxygenated blood from the left side of the heart to the body
tissues and organs (except to the heart and lungs) and returns deoxygenated
blood to the right side of the heart. The systemic circulatory loop also gets
rid of waste from body tissues.
The pulmonary circulation loop carries deoxygenated oxygen from the right side of the heart to the
lungs where it picks up oxygen and returns it to the left side of the heart.
The heart contains four chambers: right
atrium, right ventricle, left atrium, left ventricle.
Blood vessels
Blood vessels are the blood ‘highways’ of our
body. The size of the vessel corresponds to the quantity of blood that goes
through (arteries are thick and capillaries thin). The hollow portion of the
blood vessel through which blood passes is called the lumen. Blood
vessels are lined with a thin layer of epithelium known as endothelium. the
endothelium prevents blood clots and protects blood cells.
There are three types of blood vessels: arteries,
veins and capillaries. Blood vessels are usually named according to the
region they carry blood or nearby body structures.
Arteries- They carry blood away from the heart. All
arteries except the pulmonary trunk and arteries of the pulmonary circulation
loop carry highly oxygenated blood to tall parts of the body. Due to the
pressure of blood going through arteries they are usually thick walled, muscular
and elastic.
Arterioles are small arteries that branch off from the main
arteries and carry blood to
capillaries.
Capillaries- They are the smallest,
thinnest and most common vessels in the body. Capillaries connect to arterioles
on one end and to venules on the other. Capillaries help in the exchange of
gases, nutrients and waste products. The endothelium of the capillaries is very
thin , it acts as a filter to allow for gases, liquids and nutrients to go
through while keeping the blood cells inside the capillaries.
Veins- they carry deoxygenated blood to the
heart. They usually undergo low blood pressure and their walls are
therefore thin, less elastic and less muscular. Since veins do not rely on the
heart to pump blood back, they rely on gravity, inertia and skeletal muscle
contractions to help in blood flow. Vein contain one-way valves to prevent the
blood from flowing away from the heart.
Venules are like
arterioles but connect to veins.
Coronary Circulation
The heart has blood vessels that provide the
myocardium with oxygen and nutrients. The left and right coronary arteries
provide blood to the left and right sides of the heart. The coronary sinus is a
vein that returns deoxygenated blood from the myocardium to the vena cava
Hepatic Portal Circulation
The hepatic portal vein carries blood from the
stomach and small intestines to the liver. The liver removes toxins, stores
sugars and processes the products of digestion before they reach other body
tissues. Blood from the liver then returns to the heart through the Vena Cava.
Blood
The body carries about 5 liters of blood. Blood
carries nutrients, wast and gases throughout the body. Blood is made up of red
blood cells, white blood cells, platelets,
and liquid plasma.
Red blood cells- They make up 45% of blood
volume. Red blood cells are produced in the red bone marrow. About 2 million
are produced every second! Red blood cells look like a concave disk. This shape
gives them a high surface are and helps them squeeze through the capillaries.
The high surface area to volume ratio allows oxygen to be easily transferred
into and out of the cells. Red bloods cells contain no DNA and are unable to
repair themselves.
Red blood cells transport oxygen throughout the body through the red
pigment hemoglobin. Hemoglobin contains iron and proteins.
White blood cells- white blood
cells make a small percentage of blood. They help with immunity. There are two
classes of white blood cells: granular leukocytes and agranular leukocytes.
Granular leukocytes- There are three types: neutrophils,
eosinophils, and basophils. Neutrophils contain digestive enzymes
that neutralize bacteria. Eosinophils contain digestive enzymes for digesting
viruses that have been bound to by antibodies in the blood. Basophils release
histamine to intensify allergic reactions and help protect the body from
parasites.
2. Agranular
Leukocytes- There are two types: lymphocytes and monocytes.
Lymphocytes include T cells and natural killer cells that fight off viral
infections and B cells that produce antibodies against infections by pathogens.
Monocytes develop into cells called macrophages . They ingest pathogens and the
dead cells from wounds or infections.
Platelets- They are responsible for clotting. Platelets form
in the red bone marrow. They have a short lifespan, usually about a week.
Plasma- This is the liquid part of the blood. It
contains water, proteins and dissolved substances. Plasma makes about 55% of
the blood volume. The proteins in the plasma include antibodies and albumin. O
dissolved in the plasma, including her substances dissolved in plasma
include: oxygen, carbon dioxide, electrolytes,
nutrients, and cellular waste products. The plasma functions as a
transportation medium for these substances.
Functions of the cardiovascular System
The cardiovascular system has three
functions: transportation, regulation
and protection.
Transportation- It transports blood
throughout the body. The blood transports nutrients, hormones and oxygen and
removes waste materials and carbon dioxide to be processed or removed from the
body.
Protection- The cardiovascular system protects the body
through its white blood cells. The platelets and red blood cells create
protection against outside infection by creating scabs. Blood lso carries
antibodies that provide immunity.
Regulation- Blood vessels help maintain a stable body
temperature by controlling the blood flow to the surface of the skin. Blood
also helps maintain the body’s pH. The albumins in the blood help balance the
osmotic concentration of the body’s cells.
Cardiovascular conditions/Diseases
Coronary artery disease ( also known
as coronary heart disease and ischaemic heart disease)- Coronary artery disease
(CAD) is the most common type of heart disease and cause of heart attacks. CAD
is caused by plaque building up along the inner walls of the arteries of the
heart, which narrows the arteries and reduces blood flow to the heart.
Signs and symptoms:
Chest pain
Decreased exercise tolerance
Heartburn
Difficulty in breathing
Swelling of the extremities
Risks:
Smoking
Lack of exercise
Hypertension
Hyperglycemia
Genetics
Alcohol consumption
Stress
Age (men over 60, women over 65)
Obesity
Diet rich in saturated fats, low in antioxidants
Low hemoglobin
Diagnosis:
EKG
Stress test
Coronary angiography
Intravascular ultrasound
MRI
Treatment:
Medical treatment - drugs (e.g. cholesterol lowering medications,
beta-blockers, nitroglycerin, calcium antagonists, etc.);
Coronary interventions- angioplasty and coronary stent-implantation;
Coronary artery bypass grafting (CABG - coronary artery bypass
surgery).
Stem cell therapy
Angiogenesis
Cardiomyopathy - is the
deterioration of the function of the myocardium (the heart muscle), usually
leading to heart failure
Signs and Symptoms:
Breathlessness
Swelling of the legs
Irregular heartbeat
Chest pain
Treatment:
Medications
Pacemaker
Defibrillators
Ventricular assist devices
Hypertensive heart disease - diseases of
the heart secondary to high blood pressure
Signs and symptoms:
Fatigue
Irregular pulse or palpitations
Swelling of feet and ankles
Weight gain
Nausea
Shortness of breath
Difficulty sleeping flat in bed (orthopnea)
Bloating and abdominal pain
Greater need to urinate at night
An enlarged heart (cardiomegaly)
Heart failure
Cor pulmonale - a failure at the right
side of the heart with respiratory system involvement
Cardiac dysrhythmias -
abnormalities of heart rhythm
Inflammatory heart disease
Endocarditis – inflammation of the inner layer of the heart,
the endocardium. The structures most commonly involved are the heart valves.
Inflammatory cardiomegaly
Myocarditis – inflammation of the myocardium, the muscular
part of the heart.
Valvular heart disease
Cerebrovascular disease - disease of
blood vessels that supplies to the brain such as stroke
Peripheral arterial disease - disease of
blood vessels that supplies to the arms and legs
Congenital heart disease - heart structure
malformations existing at birth
Rheumatic heart disease - heart
muscles and valves damage due to rheumatic fever caused by streptococcal
bacteria infections
