Histology

Overview of Tissue ScienceChapter 4

Histology

• Histology - The study of tissues. • Tissues are collections of cells and

extracellular material that perform a specific but limited range of functions. The four tissue types, in varying combinations, form all of the structures of the human body.

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•Four basic tissue types

• Epithelial• Connective• Muscular• Neural

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Epithelial TissueA.Epithelia are layers that cover internal and external

surfaces.1. Important characteristics

a) Cells are bound closely together b) A free (apical) surface exposed to the environment

or some internal chamber.c) Attachment to underlying connective tissue by a

basement membrane.d) The absence of blood vessels (avascular)e) Epithelial cells that are damaged or lost are

continually replaced.

Epithelial Tissue

2. Functions of Epitheliaa) Physical protectionb) Permeability controlc) Sensation triggerd) Specialized secretions

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Epithelial TissueB.Classifying Epithelia

a) Number of layers• Simple (one cell thick)• Stratified (multiple cells thick)

b) Cell shape• Squamous (flat)• Cuboidal (cubic)• Columnar (tall columns)

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Epithelial Tissue

Table 4-1

Epithelial Tissue

Figure 4-5(a)

Epithelial Tissue

Figure 4-5(b)

Connective Tissue

Connective Tissue

Connective Tissue is the most diverse tissue of the body. Highly vascular;

distributed throughout the body, but are never exposed to the outside

environment.

Connective Tissue• Three basic components

• Specialized cells• Protein fibers• Ground substance-a fluid; the extracellular fibers and ground

substance form the matrix

Connective Tissue• Functions include

• Support and protection (Supportive)• Transportation of materials (Blood and Lymph)• Storage of energy reserves (Fat)• Defense of the body (Lymph)

Adipose Tissue

Figure 4.12c

Reticular Connective Tissue

Figure 4.12d

Dense Irregular Connective Tissue

Figure 4.12e

Dense Regular Connective Tissue

Figure 4.12f

Elastic Connective Tissue

Hyaline Cartilage

Figure 4.12g

Elastic Cartilage

Figure 4.12h

Fibrocartilage

Figure 4.12i

Bone Tissue

Figure 4.12j

Blood Tissue

Figure 4.12k

Muscle Tissue

Functions of Muscles• Produce movement• Maintain posture• Support soft tissues• Guard entrances and exits• Control body temperature

Three Types of Muscles• Skeletal Muscle - voluntary• Cardiac Muscle - involuntary• Smooth Muscle - involuntary

Muscle Tissue

Figure 4-13(a)

Muscle Tissue

• Cardiac Muscle Tissue• Only in heart• Short, branched fibers• Single nucleus• Striated• Involuntary contraction

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Muscle Tissue

Figure 4-13(b)

Muscle Tissue

• Smooth Muscle Tissue• Short, tapering cells• No striations• Involuntary contraction

• Blood vessels• Urinary bladder• Digestive organs• Uterus

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Muscle Tissue

Figure 4-13(c)

Neural Tissue

Neural Tissue

• Properties of Neural Tissue• Conduct electrical impulses• Transfer, process, and store information• Comprises neurons and neuroglia

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Neural Tissue Structure

• Neurons• Dendrites

• Information entry

• Cell body• Information integration

• Axon (nerve fibers)• Information transmission

• Synaptic terminals• Information transfer

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Neural Tissue

• Neuroglia• Several types of neuroglia• Provide physical support• Maintain extracellular chemistry• Supply nutrients• Defend against infection

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Neural Tissue

Figure 4-14