Histology: Types of Tissue Overview

Tissue is a group of cells that share a common embryonic origin and work together to fulfill specific functions.
Histoogy is the microscopic study of tissue structure, organization, and function.

Epithelial Tissue (Epithelium)
- Covers exterior body surfaces and lines internal cavities and passageways.
- Forms certain glands involved in secretion.
Connective Tissue
- Binds cells and organs, providing support, protection, and integration of body parts.
Muscle Tissue
- Excitable and responsive to stimulation.
- Has three main types:
  - Skeletal (voluntary)
  - Smooth
  - Cardiac (found in the heart)
Nervous Tissue
- Also excitable, facilitating the propagation of nerve impulses for communication within the body.

Originates from the zygote, which undergoes rapid cell division to form the embryo.
Early embryonic cells are totipotent, meaning they can differentiate into any cell type.
Three main cell lineages develop as cell proliferation progresses.

Tissue membranes are thin layers covering body surfaces, organs, and internal passageways.
Two main types:
- Connective Tissue Membranes: Include synovial membranes and encapsulate organs, providing a protective layer.
- Epithelial Membranes: Composed of epithelium over a connective tissue layer.

Formed solely from connective tissue, lining movable joints and organs such as the kidneys.
Synovial Membrane: A type of connective tissue membrane that produces synovial fluid to reduce friction in joints.

Composed of epithelial tissue and a surrounding layer of connective tissue.
Mucous Membrane: Composite of connective and epithelial tissues, containing lamina propria for support.
Serous Membrane: Composed of mesothelium supported by connective tissue; lines cavities and covers organs.
Cutaneous Membrane (Skin): A stratified squamous epithelial layer that protects against environmental threats.

Epithelial cells originate from all three embryonic layers:
- Ectoderm: Forms the epithelia of skin and mucosal lining of mouth, nose, and anus.
- Endoderm: Lining of airways and most parts of the digestive system.
- Mesoderm: Vascular systems' lining (endothelium).
Specialized structures called cell junctions form connections between adjacent cells.
Epithelial cells are polarized, with the apical surface facing the external environment and a basal surface adjacent to underlying tissues.