Dr. Martin's notes

Thursday February 16, 2017

Blood and Circulation

The circulatory system is made up of the heart, veins, arteries, capillaries and the lymphatic system.
Blood that leaves the heart goes into the arteries, passes through the body into the small capillaires, then returns to the heart by the veins. It is re-oxygenated in the lungs then pumped by the heart back to the body.

The lymphatic system provides antibodies and macrophages for building immunity to disease.

The liquid portion of blood is called Plasma.

Every body must have an exact amount of blood in it to survive. This is called the blood volume. The blood volume is regulated by the spleen and to some extent by the liver. Every body has about 5 litres (almost 5 quarts) of blood. A blood loss of up to 15% of the total volume can be tolerated by a healthy adult, without any serious signs and symptoms. However, blood loss exceeding this limit can cause serious symptoms and complications, if immediate medical attention is not sought. An average human being can lose a maximum of 30 to 40% of the total blood volume and stay alive, provided he is given immediate treatment.

About seven to eight percent of the human body weight is made up of blood. A healthy adult with a body weight of 60 kilograms has approximately 4.2 to 4.8 liters of blood. Body weight is one of the factors that determine the quantity of blood in the human body. Other factors include age, gender, and health condition. Usually, females are found to have slightly lesser amount of blood, as compared to males. Adults have more blood in their body, than in kids.

When compared to those living in low altitude areas, people living in higher altitudes have more blood in their body. They are found to have about 1.8 liters more blood, than those living at sea level. Regions in higher altitudes have less atmospheric oxygen.So people living in such places have more blood to nourish the body cells with enough oxygen.

Blood carries oxygen to the cells in the RBC's (red blood cells). The amount of oxygen carried is regulated by the amount of hemoglobin in the blood cells. This is measured with a hematocrit test. (Lack of hemoglobin is often an iron deficiency)

WBC's (white blood cells) help to fight disease. They attack bacteria, viruses and other disease causing microbes.

There are also many different types of blood cells that are part of our immunity (see chart Page 279)

Blood has a clotting factor known as fibrinogen. This material "dams up" a blood vessel when it is injured or cut.

If the person has too much Low Density Lipoprotein (LDL cholesterol) it can build up in the arteries causing arteriosclerosis (aka hardening of the arteries). This condition when inflammed causes fibrinogen to attach to the cholesterol causing plaques. These plaques can clogg an artery or break off and go through the blood until they can no longer pass through the system. If they lodge in the coronary arteries (of the heart) they are called a coronary infarct. If this causes the blood in the vessel to stop flowing (causing a heart attack) it is called a myocardial infarction or MI.

Statin drugs are given to reduce LDL cholesterol, but often the side effects in the liver are worse than having the high cholesterol. It is better to increase your HDL and have a better ratio between the two.