Chapter 18 - Section 18.4 - Study Guide - Assess Your Learning Outcomes - Page 705: 5

White blood cells (WBCs), also known as leukocytes, have varying life spans and behaviors within the body. The relative length of time that WBCs spend in the bloodstream versus other tissues can vary among different types of WBCs. Additionally, some WBCs recirculate in the blood, while others do not. Here's an overview: **Neutrophils:** - **Time in Bloodstream vs. Tissues:** Neutrophils spend a relatively short time in the bloodstream, typically only a few hours. - **Recirculation:** Neutrophils actively recirculate between the bloodstream and tissues, particularly in response to infections and inflammation. - **Life Span:** Neutrophils have a relatively short life span of a few days. **Eosinophils:** - **Time in Bloodstream vs. Tissues:** Eosinophils also spend a relatively short time in the bloodstream. - **Recirculation:** Eosinophils recirculate between the bloodstream and tissues, especially in areas associated with allergic reactions and parasitic infections. - **Life Span:** Eosinophils have a life span of several days to a couple of weeks. **Basophils:** - **Time in Bloodstream vs. Tissues:** Basophils spend a relatively short time in the bloodstream. - **Recirculation:** Basophils do not recirculate as actively as other types of WBCs. - **Life Span:** Basophils have a life span of a few days to less than a week. **Lymphocytes:** - **Time in Bloodstream vs. Tissues:** Lymphocytes can spend varying lengths of time in the bloodstream and tissues, depending on their function. - **Recirculation:** Lymphocytes are highly mobile and recirculate actively between the bloodstream and lymphoid tissues (spleen, lymph nodes, etc.). - **Life Span:** The life span of lymphocytes varies greatly. Some live for a few days, while others can live for years, especially memory cells. **Monocytes:** - **Time in Bloodstream vs. Tissues:** Monocytes spend a relatively short time in the bloodstream before migrating into tissues. - **Recirculation:** Monocytes do not recirculate back into the bloodstream like other WBCs; instead, they transform into tissue-resident macrophages or dendritic cells. - **Life Span:** Monocytes have a life span of several days to a few weeks. In summary, the time WBCs spend in the bloodstream versus other tissues varies depending on the type of WBC. Neutrophils, eosinophils, and basophils spend relatively short times in the bloodstream and may actively recirculate, while monocytes differentiate into tissue-resident cells. Lymphocytes are highly mobile and recirculate actively between the bloodstream and lymphoid tissues. The life spans of WBCs can range from a few hours to several days or even years, with lymphocytes having some of the longest life spans due to the presence of memory cells.

White blood cells (WBCs), also known as leukocytes, have varying life spans and behaviors within the body. The relative length of time that WBCs spend in the bloodstream versus other tissues can vary among different types of WBCs. Additionally, some WBCs recirculate in the blood, while others do not. Here's an overview: **Neutrophils:** - **Time in Bloodstream vs. Tissues:** Neutrophils spend a relatively short time in the bloodstream, typically only a few hours. - **Recirculation:** Neutrophils actively recirculate between the bloodstream and tissues, particularly in response to infections and inflammation. - **Life Span:** Neutrophils have a relatively short life span of a few days. **Eosinophils:** - **Time in Bloodstream vs. Tissues:** Eosinophils also spend a relatively short time in the bloodstream. - **Recirculation:** Eosinophils recirculate between the bloodstream and tissues, especially in areas associated with allergic reactions and parasitic infections. - **Life Span:** Eosinophils have a life span of several days to a couple of weeks. **Basophils:** - **Time in Bloodstream vs. Tissues:** Basophils spend a relatively short time in the bloodstream. - **Recirculation:** Basophils do not recirculate as actively as other types of WBCs. - **Life Span:** Basophils have a life span of a few days to less than a week. **Lymphocytes:** - **Time in Bloodstream vs. Tissues:** Lymphocytes can spend varying lengths of time in the bloodstream and tissues, depending on their function. - **Recirculation:** Lymphocytes are highly mobile and recirculate actively between the bloodstream and lymphoid tissues (spleen, lymph nodes, etc.). - **Life Span:** The life span of lymphocytes varies greatly. Some live for a few days, while others can live for years, especially memory cells. **Monocytes:** - **Time in Bloodstream vs. Tissues:** Monocytes spend a relatively short time in the bloodstream before migrating into tissues. - **Recirculation:** Monocytes do not recirculate back into the bloodstream like other WBCs; instead, they transform into tissue-resident macrophages or dendritic cells. - **Life Span:** Monocytes have a life span of several days to a few weeks. In summary, the time WBCs spend in the bloodstream versus other tissues varies depending on the type of WBC. Neutrophils, eosinophils, and basophils spend relatively short times in the bloodstream and may actively recirculate, while monocytes differentiate into tissue-resident cells. Lymphocytes are highly mobile and recirculate actively between the bloodstream and lymphoid tissues. The life spans of WBCs can range from a few hours to several days or even years, with lymphocytes having some of the longest life spans due to the presence of memory cells.