Chapter 22: Stem Cells and Tissue Renewal

Epithelial tissues

They are essential for covering body surfaces, lining organs, and forming protective barriers throughout the body.

Stem cells

They are undifferentiated cells with the capacity for self-renewal and the ability to differentiate into multiple cell types.

Basal stem cells

They are located in the basal layer of epithelia and have the potential to give rise to differentiating cells.

Transit-amplifying cells

They are the immediate progeny of basal stem cells and undergo rapid proliferation before differentiating into specific cell types.

Asymmetric cell division

It is a common mechanism by which epithelial stem cells self-renew while generating differentiating progeny.

Fibroblasts

They are a type of connective tissue cell that plays a crucial role in the maintenance, repair, and remodeling of various tissues and organs.

Myofibroblasts

They are a specialized form of fibroblast that exhibit properties of both fibroblasts and smooth muscle cells.

Myoblasts

specialized muscle progenitor cells

Blood vessles

They are part of the circulatory system and play a crucial role in transporting blood throughout the body.

Arteries

They carry oxygenated blood away from the heart to various tissues and organs.

Veins

They return deoxygenated blood back to the heart.

Capillaries

They are tiny, thin-walled vessels that connect arteries and veins. They enable the exchange of nutrients, oxygen, waste products, and hormones between the blood and surrounding tissues.

Tunica intima

It is composed of a single layer of endothelial cells, supported by a thin layer of connective tissue.

Tunica media

It consists of smooth muscle cells and elastic fibers, which allow the blood vessels to constrict or dilate, regulating blood flow and blood pressure.

Tunica adventitia

It is a connective tissue layer that provides structural support and contains nerves and blood vessels that supply the blood vessel itself.

Lymphatics

They are a network of vessels that parallel the blood vessels and form the lymphatic system.

Lymphatic vessels

They collect excess interstitial fluid, called lymph, from tissues and transport it back to the bloodstream.

Lymph nodes

They are small structures located along the lymphatic vessels that filter lymph, removing pathogens, cellular debris, and foreign substances.

Lymphocytes

It is a type of white blood cell, reside within the lymphatic system and play a central role in immune responses.

Endothelial cells

They are specialized cells that line the interior surface of blood vessels and lymphatic vessels, forming a thin layer called the endothelium.

Hematopoiesis

It is the process by which new blood cells are formed in the body.

Hematopoietic lineage expansion

Specific progenitor cells are stimulated to undergo increased proliferation and differentiation.

Regeneration

It refers to the ability of an organism to replace lost or damaged tissue with newly formed tissue that restores the original structure and function.

Repair

It involves the formation of scar tissue to bridge gaps in tissue that cannot be regenerated fully.

Inflammation

It is the initial response to tissue injury, characterized by the recruitment of immune cells, release of cytokines, and activation of various signaling pathways.

Cell proliferation

It occurs as a result of the activation and division of existing cells or the recruitment of stem cells or progenitor cells to the site of injury.

Differentiation

It is the process by which newly generated cells become specialized and acquire the characteristics and functions of the damaged tissue.

Remodeling

It involves the restructuring and maturation of the newly formed tissue, including the organization of cells, deposition of extracellular matrix, and restoration of tissue architecture.

Cell reprogramming

It refers to the process of converting specialized cells into a more flexible state, often resembling embryonic stem cells, which have the ability to give rise to all cell types in the body.