Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Tissues  Groups of cells similar in structure and function  Most organs contain all 4 types  Tissue has non-living extracellular material between its cells  The four types of tissues  Epithelial  Connective  Muscle  Nerve

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Epithelial Tissue  Cellularity – composed almost entirely of cells; little or no extracellular matrix  Polarity – apical and basal surfaces  Special contacts – form continuous sheets held together by tight junctions and desmosomes  Supported by connective tissue – reticular and basal laminae  Avascular but innervated – contains no blood vessels but supplied by nerve fibers  Regenerative – rapidly replaces lost cells by cell division

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Key cell structures at each surface Microvilli, Cilia, Stereocilia Specialized junctions Basement membrane - Sheet between the epithelial and connective tissue layers

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Classification of Epithelia Figure 4.1a Number of layers Shape

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Epithelia: Glandular  A gland is one or more cells that makes and secretes an a particular product (secretion)  Two groups – endocrine and exocrine  Endocrine glands are ductless glands that produce hormones and secrete into the blood stream  Exocrine glands Secrete their products onto body surfaces (skin) or into body cavities through ducts

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Exocrine Glands  More numerous than endocrine glands  Examples include mucous, sweat, oil, and salivary glands  Exocrine glands are classified according to number of cells:  The only important unicellular gland is the goblet cell that produce mucin (glycoprotein) that when dissolved in water forms mucus.  Multicellular exocrine glands are composed of a duct and secretory unit

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Connective Tissue Functions  Support – bone, cartilage, ligaments, tendons, capsules encasing organs, organ stroma  Medium for exchange of metabolic waste, nutrients, oxygen – between blood and many cells.  Defense and protection – blood cells, physical barrier.  Storage of fat.

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Structural Elements of Connective Tissue  Have 3 main elements:  Ground substance – unstructured material that fills the space between cells  Fibers – collagen, elastic, or reticular  Cells – fibroblasts, chondroblasts, osteoblasts, and hematopoietic stem cells Extracellular matrix

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Fibers  Collagen –  Built primarily from the protein collagen  Tough fibers  Provides high tensile strength*  Elastic  Long fibers  Contain the protein elastin that allows stretch and recoil.  Found in place that need elasticity: lungs, blood vessels  Reticular  Short branch collagenous fibers that form delicate networks  Support soft tissue of organs (ex. Around blood vessels)

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cells  Fibroblasts –  Can be found connective tissue proper.  The most common resident cells in ordinary connective tissue.  Fibroblasts are responsible for secreting collagen  Chondroblasts – cartilage  Osteoblasts – bone  Hematopoietic stem cells – blood  Immune system cells - White blood cells, plasma cells, macrophages, and mast cells

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Areolar Connective Tissue: Model Figure 4.8

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Types of connective tissue

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings membranes  Membranes are a combination of more than one tissue  They all are multicellular sheets composed of at least 2 primary tissue types: epithelium that is bound to an underlying connective tissue proper.  There are 3 types:  cutaneous  mucous  serous  The synovial membrane is composed of connective tissue only

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Epithelial Membranes:Cutaneous Membrane  Cutaneous – skin Figure 4.12a

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Epithelial Membranes: Mucous Membrane  Mucous – lines body cavities open to the exterior e.g., digestive and respiratory tracts)  Moist membranes  Most ET are simple columnar or stratified squamous  The underlying CT – lamina propria  Absorption and secretion Figure 4.12b

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Epithelial Membranes: Serous Membranes Figure 4.12c  Serous – moist membranes found in closed ventral body cavity  Consists of squamous ET resting on loose CT  Serous membrane is named according to the site and organ: lungs – pleura; heart – pericardium; abdomen - peritoneum