tissue organization histology - is the study of tissues
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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
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
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
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
Glandular Epithelial Tissue Types
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-
forming cells” Macrophage - “big
eaters” phagocytic white blood cells
Mast cell - sentry cells; detect foreign substances; produce inflammatory chemicals– heparin; histamine
Plasma cells - produce antibodies
WBC - neutrophils, basophils, eosinophils, lymphocytes, monocytes
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
Types of Cells– osteocytes
– osteoblasts
– osteoclastsTypes 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)
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 fibersIntercalated discsOnly a single nucleus per cellOnly found in the heart
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
Epithelial Membranes
Cutaneous membrane - skinSerous 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