Unit D

Module 7 ~ Lesson 3


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 multi-faceted component of your circulatory system. Specialized cells in the blood each serve a particular function.

Red blood cells carry oxygen and carbon dioxide. White blood cells are an important component of the immune system. Platelets are the cellular component in blood that ensures 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.

Your body is designed to balance heat production with heat loss via a countercurrent heat exchange mechanism. The close proximity of all blood vessels allows the 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.

Lesson Glossary

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

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

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

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

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

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.

hemoglobin: a protein that makes up the majority of the contents of a red blood cell

dissociate: to separate reversibly into smaller components


Complete Unit D: Section 4 Assignment now.