Tissues of the Body Notes (Anatomy and Physiology)

Histology

Scientific name for the study of Tissues in the body

Tissues

A group of cells that are similar in structure and perform related functions

Epithelial Tissue

A body tissue that covers the surfaces of the body, inside and out.

Characteristics:

Cellularity: Closely packed cells of the body

Specialized Connections: Continuous sheet held together by tight junctions OR desmosomes

Polarity: Apical top and basal bottom

Supported by connective tissue: Resists tearing forces

Contains nerves but no blood vessels. Avascular!

Highly regenerative

Epithelial Tissue: Proper

Covers and lines inner and outer body

Epithelial Tissue: Glandular

Forms glands and secretes hormones and other substances

Connective Tissues

Provide support

Nervous Tissues

Provide control

Muscle Tissues

Provide movement

Tight Junctions

Impermeable connection (can't go through). Keeps enzymes within the proper tissue

Desmosomes

Allows some permeability. Helps resist tearing stresses

(only opens when stressed)

Gap Junctions

Fully permeable. Allows transmission of small molecules. (Nervous)

Number of Cells: Simple

One way to classify coverings and linings. It is a single layer of cells.

Number of Cells: Stratified

One way to classify coverings and linings. It is multiple layers of cells

Shape: Squamous

One way to classify coverings and linings. Cells are flattened and scaly

Shape: Cuboidal

One way to classify coverings and linings. Cells are box/cube like

Shape: Columnal

One way to classify coverings and linings. Cells are tall/column shaped

Glands

Cells that make and secrete a product called a secretion or hormone

Endocrine

DUCTLESS glands that produce hormones and release them into the extracellular space (IN)

Exocrine

Secretes onto body surfaces. (OUT)

4 Types of Connective Tissues

Proper connective tissues, cartilage, bone, and blood.

Common Characteristics:

Common Origin: Derived from same embryonic tissue: Mesenchyme

# of blood vessels varies from tissue to tissue

Adipose

Fat tissues

Collagen

Fiber. Gives strength

Elastic

Fiber. Stretching/recoiling

Reticular fibers

Fiber. Surrounds small blood vessels

Fibroblast --> Fibrocyte

Cells. Loose and dense connective tissue

Chondroblast --> Chondrocute

Cells. Cartilage

Osteoblast --> Osteocyte

Cells. Bone

hematopoietic stem cells

Cells. Blood cells

Loose Connective Tissue

One type of proper connective tissue. Has soft packing around organs, adipose (fat tissue), and supports free blood cells

Dense (thick) Connective Tissue

One type of proper connective tissue.

Dense Regular: Used for tense elastic situations. Very fibrous

Dense Irregular: Able to resist twisting. Fibers in many directions

Hyaline

A type of cartilage.

- Most abundant

- Glassy in appearance

- Absorbs compression of joints

Elastic Cartilage

A type of cartilage.

- Flexible support. Can repeatedly bend

Fibrocartilage

A type of cartilage.

- Supportive. Can withstand a lot of pressure