Chapter 4 - Chapter 4 - Types of Tissues

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 4 - Types of Tissues Tissues are collections of cells and cell products that perform specific, limited functions Types of Tissue i. Epithelial tissue: ii. Connective tissue: iii. Muscle tissue: iv. Neural tissue - carries electrical signals from one part of the body to another 1. Epithelial Tissues 0. Epithelia  - layers of cells covering internal or external surfaces a. Glands  - structures that produce secretions Characteristics of Epithelia i. Cellularity (cell junctions) ii. Polarity (apical and basal surfaces) iii. Attachment (basal lamina) iv. Avascularity  v. Regeneration Functions of Epithelial Tissue i. Provide physical protection ii. Control permeability iii. Provide sensation iv. Produce specialized secretions (glandular epithelium) Specializations of Epithelial Cells i. Move fluids over the epithelium (protection) ii. Move fluids through the epithelium (permeability) iii. Produce secretions (protection and messengers) Free Surface and Attached Surface - Polarity  Apical surfaces:  microvilli   cilia  (ciliated epithelium) move fluid Basolateral surfaces Maintaining the Integrity of Epithelia i. Intercellular connections ii. Attachment to basal lamina iii. Epithelial maintenance and repair A. Intercellular Connections v. Support and communication 1. CAMs (cell adhesion molecules):  transmembrane proteins   2. Intercellular cement:  proteoglycans  3. Hyaluronan (hyaluronic acid) : glycosaminoglycans vi. Cell junctions - form bonds with other cells or extracellular material: a. occluding (tight) junctions b. gap junctions c. macula adherens (desmosomes) i. Occluding (Tight) junctions— between two plasma membranes Adhesion belt attaches to terminal web & prevents passage of water & solutes; isolates wastes in the lumen ii. Gap junctions— allow rapid communication 4. Held together by channel proteins (junctional proteins, connexons); allow ions to pass and coordinates contractions in heart  muscle iii. Macula adherens (Desmosomes) 5. CAMs, dense areas, and intercellular cement Spot desmosomes - tie cells together and allow bending and twisting Hemidesmosomes - attach cells to the basal lamina Attachment to the Basal Lamina i. Clear layer (Lamina lucida) - thin layer, secreted by epithelia and a barrier to proteins ii. Dense layer Epithelial Maintenance and Repair - epithelia are replaced by division of  germinative cells  (stem cells) (near basal  lamina) 1
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 07/13/2011 for the course BIOL 2401 taught by Professor Watson during the Summer '10 term at Richland Community College.

Page1 / 5

Chapter 4 - Chapter 4 - Types of Tissues

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online