TISSUE ORGANIZATION
Histology - is the study
of tissues
EMBRYONIC GERM LAYERS
Ectoderm - epidermis of the
skin,nervous system
Endoderm - functional lining of the
digestive, respiratory tract; accessory
organs and glands such as lungs,
stomach,pancreas
Mesoderm - skeletal system, muscular
system, and circulatory system
MAIN TISSUE TYPES
Epithelial
Connective
Muscle
Nervous
EPITHELIAL TISSUE
Location
–sheets or layers lining body
tubes, cavities, or covering body
surfaces
–Form many glands
GENERAL
CHARACTERISTICS
 Form sheets, layers
 Cells fit together tightly
 One edge attached to basement membrane
 No blood supply
 Regenerate quickly
 Many are secretory
 Supported by connective tissue
FUNCTIONS
Protection
Absorption
Filtration
Secretion
Gas exchange
EPITHELIAL TISSUE TYPES
Number of layers
– simple epithelium
– stratified epithelium
– pseudostratified epithelium
Shape of cells
– squamous (flat)
– cuboidal ( cubed)
– columnar ( tall)
– transitional (varies)
Examples of Epithelial Tisuue
Simple squamous
Simple cuboidal
Simple columnar
Simple columnar
– ciliated
Pseudostratified
columnar
Stratified squamous
– keratinized
– non-keratinized
Stratified cuboidal
Stratified columnar
Transitional
Glandular
Glandular Epithelial Tissue Types
endocrine (ductless) - secrete hormones into blood
exocrine- secrete through ducts to specific
locations
• unicellular - “goblet cells”
• multicellular
–modes of secretion
»apocrine - apex pinches off
»holocrine - accumulate until rupture
»merocrine -most common;secrete by
exocytosis
CONNECTIVE TISSUE
Most abundant and widespread tissue
found in the body
GENERAL
CHARACTERISTICS
 Many types with great diversity
 Very good blood supply
 Cells usually spaced apart from each other
 Intercellular material (matrix) separating
cells
 No free surface
 Derived from mesenchyme
 Consist of ground substance, fibers, cells
Connective Tissue Functions
 Physical protection
 Support
 Binding
 Absorb shock
 Insulation
 Stores energy
 Blood production
 Immunity
Types of Fibers
Collagen - very tough and strong
– contains collagen protein
Elastic - very flexible and stretchable
– contains elastin protein
Reticular - forms network mesh
– contains collagen & glycoprotein
Types of Cells
 Fibroblast - “fiber-
 Plasma cells -
forming cells”
produce antibodies
 Macrophage - “big
eaters” phagocytic white  WBC - neutrophils,
blood cells
basophils,
 Mast cell - sentry cells;
eosinophils,
detect foreign substances;
lymphocytes,
produce inflammatory
monocytes
chemicals
– heparin; histamine
 Adipose - store fat
Connective Tissue Proper
 Loose Connective(Areolar) - attaches skin
to underlying body parts; superficial fascia
 Adipose - energy storage; insulation
 Reticular - binds smooth muscles together
Regular dense connective tissue(fibrous)
– tendon; ligaments
Irregular dense
– fascia, periosteum
Elastic connective
– blood vessels, lung tissue
Cartilage
 Hyaline cartilage (gristle)
– ends of long bone, nose tip, connects ribs to
sternum
 Elastic cartilage
– external ear
 Fibrocartilage
– between pubic symphysis
– discs between vertebrae
OSSEOUS TISSUE - BONE
MATRIX
30% collagen fibers
70% mineral salts
Osseous Tissue
Types of Cells
– osteocytes
– osteoblasts
– osteoclasts
Types of Bone
– Cancellous (Spongy) Bone - trabeculae
– Compact Bone - Haversian Canal System
Blood Tissue (Vascular)
 Hemopoietic Tissue (blood forming
tissue)
Types of Cells:
– erythrocytes (RBC’s)
– leukocytes (WBC’s)
– platelets (thrombocytes)
MUSCLE TISSUE
Contractile tissue
Responsible for movement
Skeletal Muscle - Voluntary
 Long, threadlike cells with parallel fibers
 Cells are multinucleate with nuclei located
peripherally; striated
 Usually attached to long bones
Smooth Muscle - Involuntary
Spindle shaped cells with single nucleus
per cell
No striations
Located in blood vessels, walls of hollow
organs, and the gastrointestinal tract
Cardiac Muscle - Involuntary
Branched cells with striated fibers
Intercalated discs
Only a single nucleus per cell
Only found in the heart
NERVE TISSUE
Characterized by the ability to
conduct electrical signals
Nervous Tissue
Located in the brain and spinal cord (CNS)
and in the nerves (PNS)
Sensitive to changes in the internal and
external environment
Conducts nerve impulses to other
neurons/body parts
NERVE TISSUE
Functions in coordinating, regulating,
and integrating body activities
Types of Cells:
– neuroglial cells - support cells
– neuron - cell body, axon, dendrites
MEMBRANES
Thin sheet or layer of tissue that
covers a structure or lines a
cavity
Epithelial Membranes
Cutaneous membrane - skin
Serous membrane - (serosa)
– found in closed cavities
• parietal membrane - lines inside of cavities
• visceral membrane - covers organs
Mucous membrane - mucosa
– line cavities that open to the exterior
Connective Tissue Membranes
Synovial Membrane
–line spaces between bones in joints
–secrete synovial fluid