The Tissue Level of Organization - Cabrillo Collegepdarcey/Bio 4/Fall 2011/Class Notes... · The Tissue Level of Organization Chapter 3 Tissue • Definition – an aggregation of

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The Tissue Level of Organization

Chapter 3

Tissue

•  Definition – an aggregation of cells in which each cooperates with all others in the performance of a given function

•  Examples of general functions – Movement – Protection – Support – Production of chemicals

Principal Tissue Types

•  Epithelial •  Connective •  Muscular •  Nervous

Human Anatomy, 3rd edition Prentice Hall, © 2001

Epithelial Tissue •  Functions

–  Coverings and linings –  Forms glands

•  Characteristics –  Closely packed cells –  Basement membrane –  Nerves –  Avascular –  Cell growth and

replacement by mitosis •  Classification

–  Simple or stratified –  Squamous, cuboidal,

columnar, or transitional

Epithelia of Coverings and Linings


Squamous Epithelium

•  Simple Squamous Epithelium – Highly adapted to

diffusion, osmosis, & filtration

•  Stratified Squamous Epithelium – Surface layer is flat – Function -

protection

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Cuboidal Epithelium •  Simple cuboidal

epithelium •  Lines glands and

their ducts •  Function –

secretion and absorption

•  Stratified Cuboidal epithelium – Surface layer

cube-shaped – Function –

protection

Transitional Epithelium

•  Can be stretched •  Lines hollow

structures that expand

•  Function – prevents rupture of organ

http://www.mhhe.com/biosci/ap/histology_mh/stratepi.html


Columnar Epithelia •  Simple columnar

epithelium –  Functions –

protection, absorption, secretion

•  Pseudostratified columnar epithelium –  Appear stratified but

all cells connect to the basal lamina

–  Functions – protection, secretion

Pseudostratified Columnar Epithelium

•  Appear stratified but all cells connect to the basal lamina

•  Functions – protection, secretion

Glandular Epithelium •  Gland – 1 or more cells

– Unicellular gland – goblet cell – Multicellular – secretory sheets or groups of cells

•  Serous •  Mucous •  Mixed •  Cytogenic

•  Function – secretion •  Types

– Exocrine – to surface or ducts – Endocrine – to blood


Mechanisms of Glandular Secretion •  Merocrine

–  Secretion is released by exocytosis

•  Apocrine –  Residual name –  Mainly merocrine –  Secretion is released

by pinching off of vesicles

•  Holocrine –  Secretion is released

by entire cell bursting

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Connective Tissue

•  Most abundant tissue •  Functions are varied •  Characteristics

– Specialized cells, widely scattered – Rich blood supply – Much matrix

•  Extracellular fibers • Ground substance


Classification of Connective Tissues •  Embryonic

– Mesenchymal cells •  Adult connective tissues


Embryonic Connective Tissues Cell Types Found in Connective Tissue

•  Fibroblasts – Secrete the molecules that form the matrix

•  Ground substance –  Water and glycoproteins

•  Fibers – Fixed cells

•  Fibrocytes •  Macrophages

–  “Big eaters” – May be fixed or wandering

Additional Connective Tissue Cells •  Adipocytes

–  Fixed fat cells •  Mesenchymal cells

–  Fixed cells that can divide (mitosis) to replace damaged connective tissue

•  Melanocytes –  Fixed cells that store melanin

•  Lymphocytes –  Wandering immune system cells

•  Mast cells –  Around blood vessels –  Wandering cells that produce histamine & heparin

Connective Tissue Fibers •  Collagen fibers

–  Most common type –  White –  Strong, ropelike –  Form ligaments, tendons

•  Reticular fibers –  Thin –  Woven into rough, flexible network

•  Elastic fibers –  Yellow –  Thin –  Stretch

•  Contain elastin

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Types of Connective Tissue


Loose (Areolar) Connective Tissue

•  Fibers not abundant •  Binds epithelia to deeper

tissue •  Contains all 3 types of fibers •  Examples of locations

–  Between skin and muscles –  Around digestive tract –  Around blood vessels


Adipose Tissue

•  Most of the volume is adipocytes

•  Provides padding, slows heat loss, food reserve

•  Locations –  Wherever there is loose

connective tissue


Reticular Tissue

•  Reticular fibers form a strong network

•  Provides strength and support –  Lymphatic organs

•  Forms the framework (stroma) of many organs

•  Binds together cells of smooth muscle

Dense Connective Tissue

•  Types – Dense Regular Connective Tissue – Dense Irregular Connective Tissue – Elastic Connective Tissue


Dense Regular Connective Tissue

•  Lots of collagen fibers in bundles

•  Cells – fibroblasts in rows between bundles

•  Examples –  Tendons, ligaments

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Dense Irregular Connective Tissue •  Random

arrangement of fibers –  Resists stress

•  Occurs in sheets •  Locations

–  Periosteum –  Perichondrium –  Fibrous capsules of

some organs –  Dermis


Elastic Tissue •  Lots of elastic fibers •  Fibroblasts in spaces between fibers •  Provides stretch and strength

Cartilage

•  Dense network of collagenous fibers & elastic fibers in a gel-like substance

•  Avascular •  Cells – chondrocytes in lacunae

– Chondroblasts •  Perichondrium – surrounds surface of

cartilage •  Growth

–  Interstitial growth – Appositional growth

Growth of Cartilage

Types of Cartilage

•  Hyaline cartilage •  Fibrocartilage •  Elastic cartilage


Hyaline Cartilage

•  Most common •  Provides flexibility

and support •  Locations

–  Ends of bones –  Trachea –  Larynx –  Embryonic skeleton

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Fibrocartilage •  Visible collagenous fibers

with scattered chondrocytes

•  Provides strength and rigidity

•  Locations –  Intervertebral discs –  Symphysis pubis


Elastic Cartilage

•  Threadlike network of elastic fibers with chondrocytes

•  Provides strength and maintains shape

•  Locations –  Pinna –  Eustacian tube


Bone •  Solid matrix •  Cells

–  Osteocytes in lacunae

•  Central canal (Haversian canal)

•  Lamellae •  Osteon (Haversian

system) •  Canaliculi •  Periosteum


Blood •  Functions

–  Transport medium –  Regulation –  Protection

•  Composition –  Plasma – fluid –  Formed elements –

cells & cell fragments •  Erythrocyte •  Leukocyte •  Thrombocyte


A Red Blood Cell


SEM of RBCs

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Membranes •  Epithelial layer +

underlying connective tissue = epithelial membrane

•  Types –  Mucous membrane –  Serous membrane –  Cutaneous

membrane –  Synovial

membrane –  Endothelium

Fascia

•  Fascia – collective term for sheets of connective tissue

•  Functions – Provide strength and stability – Maintain positions of internal organs – Provide a route for the distribution of blood

vessels, lymphatics, and nerves •  3 types


Types of Fascia •  Superficial Fascia

–  Adipose tissue and loose connective tissue

–  Immediately deep to the skin

•  Deep Fascia –  Dense connective

tissue –  Strong internal

framework •  Subserous Fascia

–  Loose connective tissue

–  Between deep fascia and serous membranes

Muscular Tissue

•  Specialized cells •  Function - contraction •  3 types

– Skeletal muscle – Cardiac muscle – Smooth muscle


Skeletal Muscle

•  Connected to bones •  Striated •  Multinucleated •  Voluntary


Cardiac Muscle

•  Found in the heart •  Striations •  Branched cells •  Intercalated discs •  Involuntary

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Smooth Muscle

•  Found in walls of internal organs

•  Nonstriated •  Involuntary


Nervous Tissue

•  Specialized cells •  Function – conduction of

electrical impulses •  Cells

–  Neurons •  Neurosoma •  Axon •  Dendrites

–  Neuroglia

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The Tissue Level of Organization - Cabrillo Collegepdarcey/Bio 4/Fall 2011/Class Notes... · The Tissue Level of Organization Chapter 3 Tissue • Definition – an aggregation of