ANA 113 1stEdition Lecture 3 Outline of Last Lecture THE LIFE OF A CELLOutline of Current LectureTISSUE 1A. Tissue: A group of cells which act together to perform a specific function Histology: study of tissuesB. General Composition: cells and intercellular matrix.Current LectureC. There are four basic types of tissue classified according to their function and structural characteristics. 1. epithelium: consists of cells held closely together by cellular adhesions resting on a basement membrane. 2. connective tissue: (CT)3. muscle:4. nervous tissue: EPITHELIUM1. General Characteristicsa. consists of cell held together by cellular adhesions resting on a basement membrane. *Apical side faces outside*b. Highly cellular, very little intercellular material.c. Avascular (not penetrated by blood vessels.) Receives nutrients by diffusion from underlying tissue.)2. Functions of EpitheliumA. Membranous 1. Protects: covers body surfaces2. Lines body cavities (i.e. digestive tract, blood vessels)3. Contains cells for sensory perception (receptors for pain, temperature, touch)4. Absorption and secretion of nutrients and other products.5. Filtration (i.e. kidney)B. Glandular: production and secretion of various hormones and substances.3. Epithelium is further classified on the basis of:A. number of cell layers1. simple- one cell layer (i.e. lungs)2. stratified- many cell layers (i.e. parts of digestive tract)3. pseudostratified- considered a “single” layer of cells since each cell contacts the basement membrane. Gives the appearance of multiple layers since cells aren’t the same size.B. shape of the cells1. squamous- flat cells (thin) ◊ simple squamous- a thin layer of cells used for exchange. (found in blood vessels and alveoli) used to transport something, biggest cell.2. cuboidal- cube shaped □3. columnar- rectangular shaped (found in stomach) C. special characteristicse.g. cilia- keratin- cells contain a tough, waterproof protein.4. Classification of glandsA. Endocrine glands- secrete hormone directly into the bloodstream.B. Exocrine glands: secret their products through a duct to the site of action.1. unicellular2. multicellulara. simple tubularb. simple alveolarc. compound tubular of alveolarExamples of types of Epithelium:Type Appearance Locationsimple squamous - one thin layer of cells- used for exchange- blood vessels (used as lining)- alveolisimple cuboidal - glandular - glandssimple columnar - single layer of cell for exchange - room for organelles- digestive tract (intestine and stomach)stratified squamous (most protective)- tubes for transport in and out - begins at mouth, ends at anus: esophagus, skin, vagina, anus)stratified cuboidal - glandular epithelium - glandsstratified columnar - - larynxpseudostratified ciliated columnar- respiratory epithelium- bronchi- nasal cavity- tracheatransitional - used for “stretching” organs- cells change shape- bladder- uterusClassification of Glands: Endocrine: secretes hormones directly into bloodstreamVSExocrine: secretes product through duct, NOT bloodstream*Bloodstream is ideal way to transport hormones*Nervous Tissue (Note: Details for this type of tissue will be covered under the Neurohistology Lecture)A. General Characteristics1. specialized for the initiation and conduction of electrical signals overlong distances.2. highly cellulara. neuron (nerve cell)1. cell body2. processesaxon-dendrite- c. Neurons are classified according to number of processes and function.B. Neuroglia- supporting cellsExamples: CNS- oligodendrocyteastrocytemicrogliaPNS- schwann