Page 123 - 84 human physiolofy part-1

Blood Physiology

Transport of Oxygen

Oxygen (O2) Is carried throughout the body by the blood circulation. Pulmonary circulation
happens when blood leaves the heart, enters the lungs, and becomes saturated with oxygen. Once this
saturated blood exits the heart, it delivers the oxygen to all organs throughout the body. This oxygen
depleted blood is then delivered back to the lungs to be renewed with fresh oxygen.

Blood Composition

Blood is a circulating tissue composed of fluid plasma and cells (red blood cells, white blood cells,
platelets). Anatomically, blood is considered a connective tissue, due to its origin in the bones and its
function. Blood is the means and transport system of the body used in carrying elements (e.g. nutrition,
waste, heat) from one location in the body to another, by way of blood vessels.

Blood is made of two parts:

1. Plasma which makes up 45-55% of blood volume.
2. Formed cellular elements (red and white blood cells, and platelets) which combine to make
the remaining blood volume.

Plasma makeup

Plasma is made up of 90% water, 7-8% soluble proteins (albumin maintains bloods osmotic
integrity, others clot, etc), 1% electrolytes, and 1% elements in transit. One percent of the plasma is
salt, which helps with the pH of the blood. The largest group of solutes in plasma contains three
important proteins to be discussed. There are: albumins, globulins, and clotting proteins.

Albumins are the most common group of proteins in plasma and consist of nearly two-thirds of
them (60-80%). They are produced in the liver. The main function of albumins is to maintain the
osmotic balance between the blood and tissue fluids and is called colloid osmotic pressure. In addition,
albumins assist in transport of different materials, such as vitamins and certain molecules and drugs
(e.g. bilirubin, fatty acids, and penicillin).

Globulins are a diverse group of proteins, designated into three groups: gamma, alpha, and beta.
Their main function is to transport various substances in the blood. Gamma gobulins assist the body's
immune system in defense against infections and illness.

Clotting proteins are mainly produced in the liver as well. There are at least 12 substances, known
as "clotting factors" that participate in the clotting process. One important clotting protein that is part of
this group is fibrinogen, one of the main component in the formation of blood clots. In response to
tissue damage, fibrinogen makes fibrin threads, which serve as adhesive in binding platelets, red blood
cells, and other molecules together, to stop the blood flow. (This will be discussed in more detail later
on in the chapter.)

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