NUTR 366: Lecture 3; Tissue Level of Organization and Cellular Differentiation

Vocabulary practice flashcards covering cell differentiation, stem cell potency, transcription factor regulation, embryonic germ layers, primary body tissues, and specialized characteristics and classifications of epithelial tissue.

Differentiation

The process by which unspecialized cells become specialized to carry out distinct functions in the body.

Stem Cell Potency Hierarchy

The progression of differentiation potential from totipotent zygotic cells down to fully specialized unipotent stem cells.

Totipotent Stem Cell

An embryonic cell arising from the first division of the zygote that has the potential to differentiate into any cell needed to form an entire organism.

Pluripotent Stem Cell

An embryonic cell derived from totipotent cells that can differentiate into any tissue type in the human body, but cannot support the full development of an organism.

Multipotent Stem Cell

A stem cell that has the potential to differentiate into multiple cell types within a specific cell lineage or a small number of lineages.

Oligopotent Stem Cell

A progenitor stem cell that is limited to differentiating into only one of a few specific cell types.

Unipotent Stem Cell

A fully specialized stem cell that can only reproduce to generate more of its own specific cell type, such as a satellite cell.

Transcription Factors

Proteins that bind to specific genes on a DNA molecule and regulate gene expression by promoting or inhibiting the binding of RNA polymerase.

Cell-based Therapy

A medical treatment in which stem cells are induced to differentiate in a culture dish and injected into a patient to repair or replace damaged tissues.

Induced Pluripotent Stem Cells (iPSCs)

Pluripotent cells created by reprogramming adult differentiated cells using specific transcription factors, avoiding legal, ethical, and immunological issues of embryonic stem cells.

Embryonic Germ Layers

The three distinct cell lineages established in the early embryo—ectoderm, mesoderm, and endoderm—from which all body tissues and organs originate.

Ectoderm

The outermost germ layer that gives rise to the epidermis, cutaneous glands, nervous system, pituitary, adrenal medulla, mouth lining between cheek and gums, and anus.

Mesoderm

The middle germ layer that gives rise to connective tissues proper, bone, cartilage, blood, blood vessel endothelium, muscle, synovial and serous membranes, kidneys, and gonadal linings.

Endoderm

The innermost germ layer that forms the lining of the airways and digestive tract (except mouth and distal rectum/anal canal) as well as digestive and endocrine glands.

Histology

The microscopic study of tissue appearance, structural organization, and biological function.

Primary Tissue Types

The four fundamental tissue categories of the human body: epithelial, connective, muscle, and nervous tissues.

Epithelial Tissue

A cellular tissue that covers external and internal body surfaces, lines organs, and forms glands to provide physical protection, control permeability, provide sensation, and produce secretions.

Endothelium

The simple squamous epithelial tissue lining hollow organs and internal cavities, such as blood vessels and serous membranes.

Basal Lamina

A layer composed of glycoproteins and collagen within the basement membrane that attaches epithelial tissue to underlying connective tissue.

Cilia vs Microvilli

Cilia are motile apical cell structures supported by microtubules that beat in unison to propel fluids, whereas microvilli are non-motile structures supported by actin filaments that increase apical surface area for absorption.

Cell Junctions

Specialized intercellular connection structures that maintain epithelial integrity by forming tight seals, mechanical anchorages, or channel communications between adjacent cells.

Tight Junctions

Cell junctions between plasma membranes that create an impermeable barrier to block water, solutes, acids, and enzymes from leaking between cells.

Desmosomes

Anchoring junctions that attach neighboring cells together through cadherin glycoproteins connected to keratin intermediate filaments.

Hemidesmosomes

Anchoring junctions that secure epithelial cells to the extracellular basal lamina using integrin proteins.

Adherens Junctions

Anchoring junctions that connect adjacent cells using cadherins linked internally to contractile actin filaments.

Gap Junctions

Channel junctions composed of interlocking connexin proteins that allow direct passing of ions and small molecules for electrical and metabolic coupling between cells.

Classification of Epithelia

The categorization of epithelial tissues based on cell shape (squamous, cuboidal, columnar) and layer arrangement (simple, stratified, pseudostratified, transitional).

Pseudostratified Columnar Epithelium

A tissue comprising a single layer of irregularly shaped cells of varying heights that gives the false appearance of having multiple layers.

Transitional Epithelium

A specialized stratified epithelium designed to stretch and change cell shape as fluid volume within organs like the bladder changes.