Which of the following are formed elements of the blood? Select all that apply.
a. Platelet
b. Leukocyte
c. Plasma
d. Erythrocyte
e. Complement proteins

Verified step by step guidance

1. Understand that blood is composed of two main components: plasma (the liquid part) and formed elements (the cellular components).
2. Recall that formed elements include all the cells and cell fragments suspended in the plasma, such as erythrocytes (red blood cells), leukocytes (white blood cells), and platelets (cell fragments involved in clotting).
3. Identify each option: Platelets are cell fragments, so they are formed elements; Leukocytes are white blood cells, so they are formed elements; Plasma is the liquid portion, not a formed element; Erythrocytes are red blood cells, so they are formed elements; Complement proteins are part of the plasma and immune system proteins, not formed elements.
4. Select all options that are cellular components or cell fragments (formed elements): Platelet, Leukocyte, and Erythrocyte.
5. Exclude options that are not cellular components: Plasma and Complement proteins.

Key Concepts

Formed Elements of Blood

Formed elements are the cellular components of blood, including red blood cells (erythrocytes), white blood cells (leukocytes), and platelets. These elements are suspended in plasma and perform various functions such as oxygen transport, immune defense, and clotting.

Plasma Composition and Function

Plasma is the liquid portion of blood that carries water, electrolytes, nutrients, hormones, and proteins like complement proteins. It is not a formed element but serves as the medium in which formed elements are suspended and transported.

Complement Proteins

Complement proteins are part of the immune system found in plasma that help destroy pathogens by promoting inflammation and cell lysis. They are soluble proteins, not cellular formed elements, and play a role in innate immunity.