Tissue Level of Organization and Embryology

These flashcards cover key terms and concepts related to the tissue level of organization and embryology, providing definitions and explanations for easier study and comprehension.

Blastocyst

A structure formed in the early development of mammals, consisting of a hollow ball of cells that implants into the uterine wall.

Trophoblast

The outer layer of cells in the blastocyst that will develop into the placenta.

Germ layers

The three primary layers of cells (ectoderm, mesoderm, endoderm) that form during embryonic development.

Ectoderm

The outermost germ layer that forms neural tissues and epidermis.

Mesoderm

The middle germ layer that forms muscles, skeleton, and cardiovascular systems.

Endoderm

The innermost germ layer that forms internal epithelial tissues.

Epithelial tissue

A type of tissue characterized by tightly packed cells with minimal matrix, forming protective layers and surfaces.

Avascular

Lacking blood vessels; a characteristic of epithelial tissues.

Basal Lamina

A thin layer of extracellular matrix upon which epithelial cells sit, consisting of proteins made by both epithelial and connective tissues.

Keratin

An internal protein that strengthens cells, particularly in keratinized epithelial tissues.

Exocrine glands

Glands that secrete substances through ducts onto surfaces or into cavities.

Merocrine secretion

A method of secretion where substances are released via exocytosis, such as in salivary glands.

Apocrine secretion

A method of secretion where the apical part of the cell pinches off to release substances, such as in mammary glands.

Holocrine secretion

A method of secretion where the entire cell disintegrates to release its contents, as seen in sebaceous glands.

Connective Tissue

A group of tissues that support, bind together, and protect tissues and organs of the body.

Matrix

The extracellular substance in connective tissue, consisting of fibers and ground substance.

Collagen fibers

Strong and thick protein fibers that provide strength to connective tissues, particularly tendons and ligaments.

Adipose tissue

A type of loose connective tissue that stores fat.

Neurons

Specialized cells responsible for transmitting electrical impulses in the nervous system.

Metaplasia

The transformation of one type of mature epithelial cell into another under certain conditions, often due to environmental changes.

Hypertrophy

An increase in cell size.

Hyperplasia

An increase in the number of cells, which may lead to neoplasia (abnormal tissue growth).