Chapter 3, Part I: Body Tissues

1. Histology: ◦ the study of tissues. 2. Tissues: ◦ group of cells which are similar in structure and perform common or related functions.

1. Epithelial Tissue 2. Connective Tissue 3. Muscle Tissue 4. Nervous Tissue

Objectives: ◦ Describe the general characteristics and functions of epithelial tissue ◦ Name the major types of epithelial tissue and relate each one to a particular organ

1. Cells are tightly packed 2. Externally- protect the body from drying out, from injury, and from bacterial invasion 3. Internally- specific function to the organ structure. Example: in the respiratory tract the tissue sweeps up impurities by means of the cilia 4. Readily divide to produce new cells that replace lost or damaged ones 5. Lacks blood vessels and must get its nutrients from the connective tissue

1. Covers the body 2. Lines the cavities, tubes, ducts and blood vessels inside the body, 3. Forms the epidermal membranes 4. Covers the organs inside body cavities

1. Protection from physical & chemical injury, 2. Protection against microbial invasion, 3. Contains receptors which respond to stimuli, 4. Filters, secretes & reabsorbs materials, and 5. Secretes serous fluids to lubricate structures.

4 Specific tissue types (classified according to their shape): 1.Squamous 2.Cuboidal 3.Columnar 4.Transitional

*Simple – one cell thick *Stratified- many cell layers (protection) 1. Forms solid, single layer of cells which line blood vessels, body cavities & cover organs in body cavities 2. Stratified = multiple layers 3. Forms epidermis, good for areas under friction

4. Forms membranes where filtration or exchange of substances by rapid diffusion. For example- found in the air sacs of the lungs where gas exchange occurs.

 Simple – one cell thick  Roughly cube shaped 1. Line ducts in kidneys, etc, where reabsorption and secretory activities take place. 2. Produces secretions in digestive tract, respiratory tract, urinary system, and reproductive system Duct Cuboid Cells Duct Cuboid Cells

1. Simple – one cell thick 2. Column shaped (long & narrow) 3. Line digestive tract where reabsorption & secretion occurs. Pseudostratified: gives the appearance Of more than one layer of columnar epithelial cells

1. Tissue changes in response to tension 2. Found in organs that need to stretch 3. Forms the bladder lining, ureters, and part of the urethra 4. Unusual cells that slide over each other