Pulmonary veins

Veins are types of blood vessels which carry blood towards the heart. These carry deoxygenated blood from tissues back to the heart. Pulmonary veins are blood vessels that carry oxygen-rich blood from lungs to the left atrium where it is returned to the systemic circulation.

Pulmonary veins are the only veins in the adult human body, which contain a higher percentage of oxygenation of blood than their arterial counterpart, the pulmonary arteries. All other veins carry oxygen-poor blood.

Pulmonary veins are located between lungs and the heart. Pulmonary veins play an important role in respiration by receiving oxygenated blood in the alveoli and draining it into the left atrium.

Many smaller blood vessels converge in each of lungs (right and left) to form a pair of pulmonary veins. Each pair leaves its respective lung through a spot known as the hilum, or root. From there, pulmonary veins travel to the heart and connect with left atrium.

The pulmonary veins can become distended in congestive heart failure (left-sided heart failure), resulting in pulmonary edema. Damage to the pulmonary veins epithelial lining can cause pleural effusions as well.

There are typically four pulmonary veins, two draining each lung:
*Right superior: drains the right upper and middle lobes
*Right inferior: drains the right lower lobe
*Left superior: drains the left upper lobe
*Left inferior: drains the left lower lobe
Pulmonary veins

What are the components of blood?

The total blood volume in an adult is about 5.5 liters. The blood consists of a fluid and formed elements.

Formed elements include:
Red blood cells
White blood cells
Platelets

Of the total volume in the human body, 50% - 60% is plasma or the liquid portion of the blood.

Various components of blood each play a role.  In humans, blood cells are produced by stem cells in the bone marrow.

Plasma is a protein-rich solution. It is the fluid portion of the blood in which electrolytes, nutrients, metabolites, vitamins, hormones, gases and parties are dissolved.

Red blood cells or erythrocytes transport O2 and play an important role in pH regulation. The cells deliver hemoglobin, which is the iron-bearing protein that makes the transportation of oxygen possible.

Hemoglobin also gives human blood and that of many other animals, its red color. The red blood cells normally make-up 40%-50% of the total blood volume.

White blood cells can be divided into neutrophilic, eosinophilic, and basophilic granulocytes, monocytes and lymphocytes.

Neutrophils play a role nonspecific immune defense, whereas monocytes and lymphocytes participate in specific immune response.

Eosinophil is an important defense against parasitic infections. It will increase in allergic states such as hay fever, asthma.

Platelets are needed for hemostasis. Platelets or thrombocytes are cell fragments without nuclei that work with blood clotting chemicals at the site of wounds.

The research has shown that platelets help fight infections by releasing proteins that kill invading bacteria and some other microorganisms.
What are the components of blood?

What is high blood cholesterol?

Chemically, cholesterol is a fatlike compound – actually an alcohol – in which in its pure form appears as pearly flakes.

A high blood cholesterol level means that the person has more cholesterol in the bloodstream than the body needs.

A high level of cholesterol in the bloodstream is recognized as a major risk factor for the development of atherosclerosis and is therefore also a risk factor for coronary artery disease.

In atherosclerosis, which deposits of cholesterol and other lipids, along with cellular reactions, thicken artery walls. This process gradually reduces the caliber of the artery and restricts blood flow.

In adequate blood flow may cause injury to or death of tissue beyond the site of reduced flow. In the coronary arteries, this leads to myocardial infarction or sudden death.

In general, the causes of high blood cholesterol or hypercholesterolemia, can be regroup into two major categories:
*Life style factors
*Genetic factors

Lifestyles factors that can contribute to high blood cholesterol include; obesity, lack of physical activity or exercise and consuming an unhealthy diet that contains excessive cholesterol.

The principal nutritional factors identified with high blood cholesterol and the development of coronary heart disease are dietary fat, approximately saturated fatty acids and cholesterol and energy imbalance leading to obesity.
What is high blood cholesterol?

Human blood components

Blood is a very complex mixture of many types of components with very diverse properties and is often referred to as ‘liquid organ’. Blood consists of formed elements that include:

Blood cells 
*Erythrocytes or red blood cells –make up 45% of the blood volume
*Leucocytes or white blood cells
*Thrombocytes or platelets

Blood plasma 
The liquid part of blood, the blood plasma, represents approximately 55% of entire blood. Plasma means the liquid portion of the blood in which the cells are suspended. The blood plasma can be divided into several groups:
*Water
*Mineral salts and ions
*Low molecular weight
*High molecular weight components
*Gases in soluble form
*Metabolites

Red blood cells

Plasma contains three types of protein: albumin, globulin and fibrinogen.
Albumin: most abundant and maintains blood colloidal osmotic pressure
Globulin: participate in the transport of hormones, ion, metals and lipids
Fibrinogen: essential component for blood clotting
Human blood components

Hemoglobin as a carrier

Oxygen is carried in the blood mainly bound to hemoglobin; a minor fraction is dissolved in the plasma. Hemoglobin releases the oxygen that sustains every body cell.

There are about 2.5 billion red blood cells circulating at any one time. With some 280 million molecules of hemoglobin packed inside them – each of them capable of carrying four oxygen molecules.

The maximum oxygen that can be bound to the hemoglobin in the blood is the oxygen capacity. One gram of hemoglobin theoretically can carry up to 1.39 mL of oxygen. More commonly an oxygen binding capacity of 1.34 to 1.36 mL oxygen per gram hemoglobin is accepted.

Disturbances in oxygen uptake in the lungs, or in supply of adequate amounts of oxygen to the tissues, are common features of many congenital heart lesions.

Red blood cells can carry much larger quantities of carbon dioxide than they can carry oxygen. During rest 100 mL of blood carries an average of 4 mL of carbon dioxide from the tissue to the lungs.

While the oxygen-carrying hemoglobin imparts a red color to the blood, on its return to the lungs hemoglobin loaded with carbon dioxide loses its bright color and assumes a dark red-dish shade, akin to purple.
Hemoglobin as a carrier

Blood clots

Thrombosis is a condition in which a blood clot in the heart or in a blood vessel blocks circulation. In 90% of cases, the cause of a fatal or nonfatal heart attack is a blood clot in a coronary artery. The clot often occurs in the surface of a plaque of atheroma that is partially obstructing the lumen of the coronary artery.

Heart attacks, strokes, and varicose veins are all caused by blood clots, which may occur in different parts of the body.

Blood clots are believed to occur in the coronary arteries because of platelets that become sticky when they come in contact with the damaged lining of blood vessels, where atheroma formation had commenced.

A coronary thrombosis can block the blood supply to part of the heart muscle, causing breathlessness and a crushing chest pain. It is the most common cause of a heart attack.

Three coronary arteries supply the heart with blood; they are the right coronary artery and the two branches of the left coronary artery.

Their work is so important that it is dangerous if they are affected by a condition called atherosclerosis, on which fatty material builds up in the artery wall and narrows its blood –carrying channel.
Blood clots

What is meant by blood pressure?

Human body needs the nutrients and oxygen from blood. Blood is pumped from the heart and it travels around the body delivering oxygen and nutrients to the organs of the body and returns to the heart ready to be pumped back out again.

Blood pressure is needed so that the blood can travel from heart to other organs and muscles.

An adult has around five liters of blood that circulates around the body approximately once every minute. Blood pressure is the force of the blood pushing against the walls of those arteries.

Each times the heart beats (about 60-70 times a minute at rest), it pumps out blood into the arteries. Blood pressure monitoring is an important indicator of a wearer’s cardiovascular status.

Many devices allow blood pressure to be measured by manual or digital sphygmomanometer systems that utilize an inflatable cuff applied to a person’s arm.

The blood pressure is at its greatest when the heart contracts and is pumping the blood. This is called systolic pressure.

When the heart is at rest, in between beats, the blood pressure falls. This is the diastolic pressure.

When blood pressure stays too high for too long, it can damage the blood vessels. Organs such as kidneys, heart, brain and eyes can be affected.

High blood pressure is the leading risk factor for heart failure. It also increases the risk later for atherosclerosis or hardening of the arteries.
What is meant by blood pressure?