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Four Principle Types of Tissue
  1. Epithelial
  2. Connective
  3. Muscular
  4. Nervous
Extracellular Matrix (ECM)
Comples, nonliving material b/w cells in tissues
  • some tissues have large amount; some little.
  • different components provide different characteristics in tissues
Components of ECM
  • Water
  • Proteins
    (collagen & elastic)
    - includes glycoproteins (fibronectin & laminins help connect ECM components to cell by binding w/ integrins in plasma membrane)
    (glycoprotein attachments also allow local communication w/in tissue)
  • Proteoglycans
    - hybrid molecules; mostly carbohydrates attached to protein backbone
    ex - chondroitin sulfate, heparin, hyaluronate
    - different proteoglycans give different characteristics to ECM, (thickness, shock absorption.)
Functions of ECM
  • Helps binds tissues together structurally
- ECM components bind together & to integrins in plasma membrane.
- in some tissues, it is primarily intercellular junctions that hold cells together
  • Allows local communication among ECM and various cells - through connection via integrins in plasma membrane
Embryonic Development of Tissues
  • Primary Germ Layers:
    - Endoderm
    - Mesoderm
    - Ectoderm\
  • Gastrulation - process of cell movement & differentiation, which results in development of primary germ layers
  • Histogenesis - process by which primary germ layers differentiate into different kinds of tisses (formation of tissues)
Epithelial Tissue Types & Locations
2 types
  • Membranous (covering/lining) epithelium - surface
  • Glandular epithelium (creates glands)
  • membranous - covers body & some of it's parts; likes serous cavities, blood & lymphatic vessels, & respiratory, digestive, & genitourinary tracts
  • Glandular - secretory units of endocrine and exocrine glands
Epithelial Tissue Functions
  • Protection
  • Sensory functions
  • Secretion - endo/exocrine
  • Absorption - line respiratory tract
  • Excretion - refers to not needed material (waste products)
Epithelial Tissue Generalizations
  • limited amount of matrix material
  • membranous type attached to basement membrane
  • avascular (no blood vessels - splinter example)
  • cells are in close proximity, with many desomosomes & tight junctions
  • capable of reproducing itself
Epithelial Tissue Classification
Membranous (covering/lining) epithelium - classification based on cell shape
  • Squamous (irregular shape)
  • Cuboidal (cubes)
  • Columnar (columns)
  • Pseudostratified Columnar
Epithelial Tissue Classifications (cont'd) - classifications based on layers of cell
Simple Epithelium
  • Simple Squamous Epithelium
  • One-cell layer of flat cells
  • Permeable to many substances
  • Examples: endothelium (lines blood vessels) & mesothelium (pleura)
  • Simple cuboidal epithelium
  • One-cell layer of cuboidal cells
  • Found in many glands & ducts
Epithelial Tissue Classifications (cont'd) - classifications based on layers of cell
Simple Epithelium Continued
  • Simple columnar epithelium
  • Single layer of tall, column shaped cells
  • cells often modified for special functions - goblet cells (secretion), cilia (movement), microvilli (absorption)
  • Often lines hollow visceral structures (internal organs)
  • Pseudostratified columnar epithelium
  • Columnar cells of different heights
  • all cells rest on basement membrane but may not reach free surface above
  • cell nuclei @ odd and irregular levels
  • found lining air passages & segments of male reproductive system
  • Motile cilia and mucus are important modifications
Epithelial Tissue Classifications (cont'd) classifications based on layers of cell
Stratified Epithelium
  • Stratified squamous (keratinized) epithelium
  • multiple layers of flat, squamous cells
  • cells filled with keratin (protein)
  • covers outer skin on body surface
  • Stratified squamous (nonkeratinized) epithelium
  • lines vagina, mouth, & esophagus
  • Free surface is moist
  • primary funtion is protection
Epithelial Tissue Classifications (cont'd) classifications based on layers of cell
Stratified Epithelium (cont'd)
  • Stratified cuboidal epithelium
  • 2/more rows of cells are typical
  • basement membrane is indistinct
  • located in sweat gland ducts and pharynx
  • Stratified columnar epithelium
  • multiple layers of columnar cells
  • only most superficial cells are typical in shape
  • rare
  • located in segments of male urethra and near anus
  • Stratified transitional epithelium
  • located in lining of hollow viscera subjected to stress (ex: urinary bladder)
  • Often 10/more layers thick
  • protects organ walls from tearing
example - holding urine on bus
Epithelial Tissue Glandular Epithelium
  • Speciallized for secretory activity
  • Exocrine glands - discharge secretions into ducts
  • Endocrine glands - "ductless" glands; discharge secretions directly into the blood or interstitial fluid
  • Structural classification of exocrine glands.  Multicellular exocrine glands are classified by the shape of their ducts and the complexity of their duct system
    - shapes include tubular and aveolar
    - simple exocrine glands - only 1 duct leads to surface
    - compound exocrine glands - have 2/more ducts
Epithelial Tissue
Glandular Epithelium
Functional classification of exocrine glands
Apocrine Glands
  • secretory products collect near apex of cell and are secreted by pinching off the distended end
  • Secretion process results in some damage to cell wall and some loss of cytoplasm
  • Mammary glands are good examples of secretory type
Holocrine Glands
  • secretion products, when released, cause rupture and death of cell
  • sebaceous glands are holocrine
Merocrine Glands
  • Secrete directly thru cell membrane
  • secretion proceeds w/ no damage to cell wall and no loss of cytoplasm
  • most prevalent gland type
Connective Tissue Functions, Characteristics, & Types
General Function - connects, supports, transports, and protects General Characteristics - ECM predominates most of connective tissue and determines characteristics, consists of fluid, gel, or solid matrix, with or without extracellular fibers (collagenous, reticular, and elastic) and proteoglycans or other compounds that thicken and hold together the tissue
connective Tissue Four Main Types
  • loose, ordinary (areolar)
  • adipose
  • reticular
  • dense (irregular/regular)
  • Compact
  • Cancellous
  • Hyaline
  • Fibrocartilage
  • Elastic
Connective Tissue Fibrous Connective Tissue
Loose, ordiary (areolar) connective tissue
  • 1 of the most widely distributed of all tissues
  • intercellular substances is prominent & consists of collagenous and elastic fivers loosely interwove and embedded in soft, viscious ground substance
  • several kinds of cells present:  notable, fibroblasts and macrophages, also mast cells, plasma cells, fat cells, and some white blood cells
  • Function-stretchy, flexible connection
Connective Tissue Adipose Tissue
Similar to loose connective tissue but contains mainly fat cells Functions-protection, insulation, support, and food reserve
Connective Tissue Reticular Tissue
Forms framework of spleen, lymph nodes, and bone marrow
  • consists of netwok of branching reticular fibers with reticular cells overlying them
  • Functions-defense against microorganisms and other injurious substances; reticular meshwork filters out injurious particles, and reticular cells phagocytose them
Connective Tissue Dense Fibrous Tissue
Matrix consists mainly of fibers packed densely and relatively few fibroblast cells
  • irregular - fibers interwine irregularly to form thick mat
  • reular - bundles of fibers are arranged in regular, parallel rows
    (collagenous & elastic)
    Locations:  composes structures that need great tensile strength such as tendons and ligaments, also dermis and outer capsule of kidney and spleen.
Function - furnishes flexible connections that are strong or stretchy
Connective Tissue Bone Tissue
Highly specialized connective tissue type
  • cells - osteocytes - embedded in calcified matrix
  • inorganic component of matrix accounts for 65% of total bone tissue
  • support
  • protect
  • poing of attachment for muscles
  • reservoir for minerals (calcium)
  • supports blood-forming tissue
Connective Tissue Compact Bone
Osteon (Haversian system)
  • structural unit of bone
  • spaces for osteocytes called lacunae
  • matrix present in concentric rings called lamellae
  • canaliculi are canals that join lacunae with central haversian canal
Cell Types
  • Osteocyte - mature, inactive bone cell
  • Osteoblast - active, bone-forming cell
  • Osteoclast - bone-destroying cell
Formation (ossification)
  • in membranes - flat bones or skulls
  • from cartiilage (endochondral) - long bones (humerus)
Connective Tissue Cancellous Bone (Spongy bone)
  • Trabeculae - thin beams of bone
  • supports red bone marrow (myeloid tissue - type of reticular tissue), (produces blood cells)
  • called spongy bone because of it's spongelike appearance
Connective Tissue Cartilage
  • Chondrocyte is only cell type present
  • Lacunae house cells, as in bones
  • Avascular - nutrition of cells depends on diffusion of nutrients thru matrix
  • heals slowly after injury because of slow nutrient transfer to the cells
  • perichondrium is membrane that surrounds cartialge
Connective Tissue Types
  • appearance is shiny and translucent
  • most prevalent type of cartilage
  • located on side of articulating bones (joints)
  • astrongest and most durable type of cartlage
  • matrix is semirigid and filled with strong, white fibers
  • found in intervertebral disks and pubic symphysis
  • serves as shock-absorbing material between bones at the knee (menisci)
  • contains many fine, elastic fibers
  • provides strength and flexibility
  • located in external ear and larynx
Connective Tissue Blood
  • Liquid tissue
  • contains neither ground substance nor fibers
  • composition of whole blood
    - liquid fraction (plasma in matrix): 55% of total blood volume
    - formed elements contribute 45% of total blood volume:  RBC (erythrocytes) WBC (leukocytes) Platelets (thrombocytes)
Connective Tissue Blood (cont'd)
  • transportation
  • regulation of body temp
  • regulation of body pH
  • WBC destroy bacteria
Circulation blood tissue is forbed in red bone marrow by process called hematopoiesis; the blood-forming tissue is sometimes called hematopoietic tissue
Muscle Tissue
  • Skeletal, or striated voluntary
    - smooth, or nonstriated involuntary, or visceral
    - Cardiac, or striated voluntary
  • Microscopic Characteristics
    skeletal muscle - threadlike cells w/ many cross striations and many nuclei per cell
    - smooth muscle - elongated, narrow cells, no cross striations, one nucleus per cell
    - Cardiac Muscle - branching cells w/ intercalated disks (formed by abutment of plasma membrane of 2 cells)
Nervous Tissue Functions
  • rapid regulation and integration of body activities
Nervous Tissue Specialized characteristics and organs
  1. excitability
  2. conductivity
  1. brain
  2. spinal cord
  3. nerves
Nervous Tissue cell types
  • Neuron - conducting unit of system
  • cell body, or soma
    - processes:  axon (single process) transmits nerve impulse away from the cell body
    - dendrites (one or more) transmits nerve impulse toward the cell body and axon
  • Neuroglia - speecial connecting, supporting, coordinating cells that surround the neurons
Tissue Repair
  • tissues have varying capacity to repair themselves; damaged tissue regenerates or is replaced by scar tissue
  • regeneration - growth of new tissue
  • scar - dense fibrous mass; unusually thick scar is a keloid
  • epithelial and connective tissues have greatest ability to regenerate
  • muscle and nervous tissues have limited capacity to regenerate
body membranes
Thin tissue layers that cover surfaces, like cavities, and divide spaces or organs epithelial membranes are most common type
  • cutaneous membrane (skin): primary organ of integumentary system, one of the most important organs, coposes approx 16% of body weight
primary organ of integumentary system, one of the most important organs, coposes approx 16% of body weight ry system, one of the most important organs, coposes approx 16% of body weight Serious membrane (serosa):  parietal membranes line closed body cavities, visceral membranes cover visceral organs, pleura surrounds lung and lines thoracic cavity, peritoneum covers abdominal viscera and lines abdominal cavity Mucous membrane (mucosa):  lines and protects organs that open to exterior of body, found lining ducts and passageways of respiratory, digestive, other tracts, lamina propria fibrous connective tissue underlying mucous epithelium.  mucus is made up of mostly water and mucine.  proteoglycans that form double layer protection against environmental microbes
Connective Tissue Membranes
  • do not contain epithelial components
  • synovial membranes - line spaces b/w bone in joints
  • have smooth and slick membranes that secrete synovial fluid
  • help reduce friction b/w opposing surfaces in moveable joint
  • synovial membranes also line bursae
THE BIG PICTURE tissues, membranes, and the whole body
tissues & membranes maintain homeostasis
  • epithelial tissues:  form membranes that contain and protect internal fluid environment, absorb nutrients, and secrete products that regulate functions involved in homeostasis
  • connective tissues:  hold organs and systems together and form structures that support body and permit movement
THE BIG PICTURE tissues, membranes, and the whole body (cont'd)
tissues and membranes maintain homeostasis (cont'd)
  • muscle tissues:  work with connective tissues to permit movement
  • nervous tissues:  work with glandular epithelial tissue to regulate body function
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