BLOOD COMPONENTS

Overview There are 4 main components within

blood that we are concerned with:

1. Red Blood Cells2. White Blood Cells3. Blood Plasma4. Platelets

Blood Blood = a collection of specialized cells

that perform specific functions for an organism

Even though it appears liquid, blood is considered a tissue like skin, muscle, bone, etc

Consists of two distinct elements:1. Fluid plasma portion2. Solid or “formed” portion

Blood About 55% of blood is

plasma, Water Dissolved gases Proteins, sugars, vitamins,

minerals, and waste products.

The remaining 45% of the blood is composed of cells White Blood Cells Red Blood Cells

Red Blood Cells (RBCs) Also called erythrocytes

Make up 44% of the total volume of your blood. The average male has 5.5 million RBCs/mL of

blood the average female has 4.5 million RBCs/mL of

blood

The shape of a RBC is described as a biconcave disk

RBCs The red blood cell is specialized for oxygen

transport Only 2% of the oxygen that enters the blood stream

is transported by the fluid portion of the blood. The remainder is transported by RBCs

these cells vastly increase the oxygen carrying capacity of the blood.

A mature red blood cell has no nucleus but is packed with 280 million molecules of hemoglobin an iron-containing molecule Has several binding sites for oxygen

Hemoglobin Hemoglobin is a pigment molecule, which gives

blood its red color (when bound to oxygen) in humans

RBCs Hemoglobin is specially designed to

perform two opposite functions: Pick up dissolved oxygen from the lungs

and carry it to the cells of the body. Release this oxygen, but only in the

presence of the cells that require it.

This ability is dependent on the structure of hemoglobin

RBCs A hemoglobin molecule contains four iron (Fe) atoms

Each represents a separate binding site (heme group) When the concentration of oxygen is high, each heme

group may form a loose bond with oxygen e.g. In the capillaries of the lungs

When the concentration of O2 is low, this loose bond is broken e.g. in the cells of working muscles

Theoretically, four molecules of oxygen can become attached to one molecule of hemoglobin.

In reality, not all of the possible heme positions will be occupied by oxygen.

Capillaries in the Lungs

Working muscle cells in the body

Oxygen binds to Hb

Oxygen is released from Hb

White Blood Cells (WBCs)

also called leucocytes make up only 1% of your total blood volume.

may increase to more than double normal levels, however, when your body is fighting an infection.

Have a number of different roles that help protect the body from disease-causing agents, or pathogens.

In contrast to red blood cells, all white blood cells have nuclei and appear colourless.

WBCs There are several types of WBCs

1. Macrophages can pass through the walls of the capillaries

to engulf and digest pathogens (phagocytosis = “cell eating”)

part of the body’s innate immune response which is the body’s generalized, automatic

response to infection.

WBCs2. Lymphocytes are non-phagocytic cells involved in the body’s acquired immune

response the body’s ability to recognize and fend off specific

pathogens.

There are two main types of lymphocytes: T cells & B cells Each contribute a specific part of the response that

allows the body to become immune to certain toxins.

WBCs In addition to their role in fighting

disease, lymphocytes can (under particular conditions) undergo changes to become a variety of cell types. Converted into red blood cells the bone

marrow Help construct different kinds of connective

tissue fibres throughout the body.

Platelets Also called thrombocytes They are only fragments of cells that were

created when larger cells in the bone marrow break apart.

Do not contain a nucleus Break down quickly in the blood

each platelet lasts only about a week to 10 days Platelets play an important role in clotting

blood and preventing excessive blood loss after an injury

Blood Clotting Process is not completely understood Clotting is first triggered by the injury.

Does not occur until a blood vessel is brokenA. Platelets are attracted to the site of the damaged

vessels and combine with other clotting agents in the plasma

produces the enzyme thromboplastinB. Thromboplastin reacts with prothrombin to produce

thrombin.C. Thrombin is an enzyme that reacts with a plasma

protein to produce fibrin. Insoluble, forms a mesh of strands that traps escaping

blood and forms the clot

Blood Plasma

The fluid portion of the blood in which the blood cells are suspended.

Also contains substances that play an important role in maintaining the body’s well-being. Fibrinogen (blood clotting) Serum albumin: maintaining the blood volume and blood

pressure. Serum globulin: protein antibodies to defend against

disease. Plasma also plays a role in the transport of carbon

dioxide in the blood. carried in the plasma from tissues to the lungs for gas

exchange.

Plasma Serum = The straw-coloured liquid

that remains when the clotting agents are removed contains cellular nutrients, hormones,

electrolytes, enzymes, hormones, antibodies, and waste materials.

Serum from an animal or a person immune to a particular disease can be injected into a patient to provide temporary immunity from that disease.

Summary Using a full page, copy table 9.2 into

your notebook For each component of blood you are

responsible for knowing: the relative amounts (% or cells per mL

blood) sizes compared to each other lifespan important function(s)