Zoology Lesson 4: Animal Tissues

Comprehensive vocabulary flashcards covering the types, characteristics, and functions of animal tissues from Zoology Lesson 4.

Tissue

A group of cells with similar structure and function, plus the extracellular substance surrounding them.

Histology

The study of tissues.

Epithelium

A covering or lining tissue that forms the outer layer of body surfaces, lines internal organs, and makes up glands.

Avascular

A characteristic of epithelial tissue meaning it has no blood supply.

Simple Epithelium

Epithelial tissue composed of one single layer of cells, used for absorption, secretion, filtration, and diffusion.

Stratified Epithelium

Epithelial tissue composed of multiple layers of cells stacked on top of each other, providing protection against abrasion and friction.

Pseudostratified Epithelium

A single layer of cells with nuclei at different levels, giving a multilayered appearance; often has cilia and goblet cells.

Transitional Epithelium

A special type of stratified epithelium that can stretch and change shape depending on the degree of distension of the organ it lines.

Squamous

Epithelial cells that are flat and scale-like in shape.

Cuboidal

Epithelial cells that are cube-shaped.

Columnar

Epithelial cells that are tall and thin.

Goblet cells

Specialized cells found in pseudostratified columnar epithelium that secrete mucus.

Keratinized Stratified Squamous Epithelium

Tissue where surface cells are dead, contain no nuclei, and are filled with keratin to be dry and resistant to friction; found in the skin.

Non-keratinized Stratified Squamous Epithelium

Tissue where surface cells remain alive and moist; providing protection in areas like the mouth, esophagus, and vagina.

Cilia

Free surface modifications that move substances across surfaces, such as in the respiratory tract.

Microvilli

Free surface modifications that increase surface area for absorption.

Tight Junctions

Cell connections that act as a barrier to prevent leakage, located in the stomach, intestines, and bladder.

Desmosomes

Cell connections that provide strength against mechanical stress, found in the skin, heart, and cervix.

Hemidesmosomes

Cell connections that anchor epithelial cells to the basement membrane.

Gap Junctions

Connexin protein channels that provide a mechanism for intercellular communication and coordination.

Exocrine glands

Secretory organs that secrete substances through ducts onto a surface or into a cavity.

Endocrine glands

Ductless glands that secrete hormones directly into the blood.

Merocrine

A mode of secretion where cells release products via exocytosis and the cell remains intact.

Apocrine

A mode of secretion where the apical cytoplasm of the cell pinches off; the cell then repairs itself.

Holocrine

A mode of secretion where the entire cell ruptures and is destroyed to release its secretory products.

Connective Tissue

A diverse group of tissues made of cells, protein fibers, and extracellular matrix that support, connect, and protect other tissues.

Fibroblasts

Connective tissue cells that form fibrous connective tissue.

Macrophages

Large connective tissue cells capable of moving and ingesting foreign substances and microorganisms.

Mast cells

Nonmotile cells that release chemicals, such as histamine, which promote inflammation.

Collagen fibers

Protein fibers in the extracellular matrix that provide strength.

Elastic fibers

Protein fibers in the extracellular matrix that allow for stretch.

Reticular fibers

Protein fibers in the extracellular matrix that form a supportive mesh or framework.

Areolar tissue

A type of loose connective tissue primarily consisting of collagen and a few elastic fibers that acts as packing material.

Adipose tissue

Loose connective tissue composed mostly of adipocytes specialized for energy storage, cushioning, and insulation.

Hyaline cartilage

The most common type of cartilage; providing support with flexibility at the ends of long bones.

Fibrocartilage

A specialized connective tissue with more collagen than hyaline, able to withstand compression and resist tearing.

Erythrocytes

Red blood cells that are biconcave, lack a nucleus, and transport $O_2$ and $CO_2$.

Leukocytes

White blood cells that contain a nucleus and fight infections via phagocytosis.

Thrombocytes

Also called platelets; small cell fragments derived from megakaryocytes that aid in blood clot formation.

Skeletal Muscle

Muscle tissue under voluntary control that appears striated and moves bones of the skeleton.

Cardiac Muscle

Striated muscle tissue under involuntary control, featuring intercalated discs and found only in the heart.

Smooth Muscle

Non-striated muscle tissue under involuntary control found in the walls of hollow organs like the stomach and intestines.

Neurons

Functional units of nervous tissue that transmit electrical impulses; consisting of dendrites, a cell body, and an axon.

Neuroglia

Also known as glial cells; these support, nourish, and protect neurons.