Module 8 Intro

Module 8—Circulation, Immunity, and Excretion

Lesson Summary

 

In this lesson you explored the following essential questions:

• What are the main components of blood? How do these components contribute to transporting, clotting, and resisting the influence of pathogens?
  
  

• How does blood help to regulate body temperature?

Blood is a multifaceted component of your circulatory system. Specialized cells in blood each serve a function.

 

Red blood cells carry oxygen and carbon dioxide. There are five kinds of white blood cells.

 

Lymphocytes produce antibodies and regulate the production of antibodies. Eosiniophils release toxic granules, which kill pathogens. Neutrophils are macrophages that engulf and destroy invading pathogens, while basophils release granules that will increase blood flow to an area of infection, thus increasing inflammation.

 

Monocytes are also macrophages and engulf and destroy invading pathogens. Platelets are the cellular component in blood that ensure blood clotting occurs in the event of a ruptured blood vessel. Plasma, the fluid portion of blood, is key in transporting nutrients, hormones, and exchanging heat. Since plasma is mostly water, the heat capacity of water allows plasma to absorb and release large amounts of energy created during cellular respiration.

 

Your body is designed to balance heat production with heat loss via a countercurrent heat exchange mechanism. The close proximity of blood vessels allows transfer of thermal energy from warmer areas to cooler areas. This heat exchange system allows your body to adapt to varying internal and external conditions.

 

Finally, the movement of blood through the capillaries is essential to the transport of matter. Because of concentration and pressure gradients, the movement of wastes, essential nutrients, and fluids is possible. A disruption to these gradients can cause dysfunction in the body.

 

Lesson Glossary

 

antibody: a protein in the blood that identifies and neutralizes foreign invaders, such as bacteria or viruses

Each antibody is specific to a particular invader.

 

coagulation: the process where a damaged blood vessel wall is covered by a platelet and

fibrin-containing clot to stop bleeding and begin repair of the damaged vessel

 

connective tissue: the material between the cells of the body that gives tissues form and strength

 

This tissue is also involved in delivering nutrients.

 

countercurrent heat exchange: a mechanism used to transfer heat from one flowing current of fluid to another across a semi-permeable membrane

Birds use countercurrent heat exchange between blood vessels in their legs to keep heat concentrated within their bodies.

 

fibrin: a mesh-like protein involved in the clotting of blood

 

pathogen: a germ or foreign-invading substance that can cause illness/disease

 

shock: a serious, life-threatening condition where insufficient blood flow reaches the body tissues

As the blood carries nutrients and oxygen around the body, reduced flow hinders the delivery of these components to the tissues, and can stop the tissues from functioning properly.

 

stem cells: undifferentiated cells that can theoretically divide without limit to replenish other cells

When a stem cell divides, each new cell has the potential to either remain a stem cell or become another type of cell with a more specialized function. This can be, for example, a muscle cell, a red blood cell, or a brain cell.

 

undifferentiated cells: cells that have not yet reached the stage where specific biological roles are formed

These cells show no visible separation into their different structural parts.

 

vasoconstriction: the constriction of blood vessels resulting from muscular contraction in blood vessel walls

 

When blood vessels constrict, the flow of blood is restricted or slowed. It is the opposite of vasodilation, the widening of blood vessels.

Biology 20 © 2008 Alberta Education