Zoology: Structural Organisation in Animals (Animal Tissues)

Flashcards covering the fundamentals of animal tissues, including histology history, epithelial structures, cellular junctions, glandular types, and connective tissue classifications based on the lecture notes.

Marie François Xavier Bichat (14 November 1771 - 22 July 1802)

French anatomist and physiologist known as the father of modern histology and descriptive anatomy; he introduced the notion of tissues as distinct entities without using a microscope.

Tissue

A group of similar cells along with intercellular substances that perform a specific function in multicellular animals.

Morphology

The study of form or externally visible features; in case of animals, it refers to the external appearance of the organs or parts of the body.

Anatomy

The study of morphology of internal organs in animals.

Epithelial Tissue

A tissue composed of compactly packed cells with little intercellular matrix that grows upon another tissue (connective tissue) and provides a covering or lining for some part of the body.

Basement Membrane

A thin, non-living, non-cellular, and highly permeable layer secreted by both epithelium and connective tissue, composed of glycoproteins, mucopolysaccharides, and protein fibres.

Tight Junctions

Specialised links in animal tissues that help to stop substances from leaking across a tissue.

Adhering Junctions

Cell junctions that perform cementing to keep neighbouring cells together.

Gap Junctions

Junctions that facilitate communication between cells by connecting the cytoplasm of adjoining cells for the rapid transfer of ions, small molecules, and sometimes big molecules.

Microvilli

Minute, non-motile processes of the plasma membrane that increase surface area for absorption and secretion.

Cilia (Kinocilia)

Long, cylindrical, motile processes that help in movement and locomotion.

Simple Squamous Epithelium

A compactly packed single thin layer of flattened cells with irregular boundaries involved in forming diffusion boundaries in the blood vessels and air sacs of lungs.

Simple Cuboidal Epithelium

A single layer of cube-like cells found in the ducts of glands and tubular parts of kidney nephrons, specialized for absorption and secretion.

Simple Columnar Epithelium

A single layer of tall and slender cells with nuclei located at the base, present in the inner surface of hollow organs like bronchioles and fallopian tubes.

Pseudostratified Epithelium

A modification of columnar epithelium containing long and short cells that appears bilayered because nuclei are at different levels, even though all cells rest on a single basement membrane.

Compound Epithelium

A multilayered tissue with a limited role in secretion and absorption, primarily functioning to provide protection against chemical and mechanical stresses.

Transitional Epithelium (Urothelium)

A stretchable compound epithelium where the basement membrane becomes invisible during stretching; found in the renal pelvis, ureter, and urinary bladder.

Goblet Cells

Unicellular mucous-secreting glandular cells present in the alimentary canal.

Endocrine Glands

Ductless glands whose products, called hormones, are secreted directly into the fluid bathing the gland.

Heterocrine Glands

Mixed glands that contain both endocrine and exocrine parts, such as the pancreas, gonads, and liver.

Connective Tissue

The most abundant and widely distributed tissue in complex animals, responsible for linking and supporting other tissues and organs; it originates from the mesoderm.

Fibroblasts

Chief matrix-producing cells of connective tissue proper that produce and secrete protein fibres.

Macrophages (Histeocytes)

Amoeboid, phagocytic cells with kidney-shaped nuclei that act as scavengers by destroying bacteria and dead cells.

Mast Cells

Small amoeboid cells with S-shaped nuclei that secrete histamine, serotonin, heparin, and the matrix of connective tissue proper.

Collagen Fibres (White-Fibres)

Wavy, inelastic, and tough fibres made of collagen protein, which is the most abundant protein in the animal kingdom.

Elastic Fibres (Yellow-Fibres)

Branched fibres composed of elastin proteins that provide maximum elasticity and are highly resistant to chemicals.

Areolar Connective Tissue

A type of loose connective tissue, also known as spongy tissue, that is widely distributed and serves as a support framework for epithelium.

Adipose Connective Tissue

A type of loose connective tissue located mainly beneath the skin that contains adipocytes specialized for storing fats.

Tendon

A dense regular connective tissue structure that connects muscles to bones.

Ligaments

A dense regular connective tissue structure that connects one bone to another bone.

Chondrocytes

Mature cartilage cells enclosed in small cavities called lacunae within the solid and pliable matrix.

Osteocyte

A mature bone cell found in a lacuna; only one cell is found per lacuna.

Bone

A hard and non-pliable skeletal connective tissue rich in $Ca^{+2}$ salts and collagen fibres that provide structural strength to the body.