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HISTOLOGY
THE STUDY OF TISSUES
TISSUES
• Organization of similar cells
embedded in a matrix (nonliving,
intercellular material
• Matrix can be rigid, gel, fluid or
nonexistent
• Specialize in performing at least one
unique function essential for life
1. EPITHELIAL
• Covers and protects body surface
• Lines body cavities
• Secretes and absorbs substances into
and out of blood
• Forms glands
2. CONNECTIVE
• Supports and connects body and its
parts
• Transports substances throughout
the body
• Protection from invading microbes
• Cells spread out; lots of matrix
3. MUSCLE
• Produces movement by shortening
complex contractile proteins
4. NERVOUS
• Communication between body parts
and integration of their activities
1. EPITHELIAL
• 2 types:
1. Membranous – covers and lines body
2. Glandular – exocrine and endocrine
FUNCTIONS
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•
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Protection
Secretion
Absorption
Excretion
Sensory
CHARACTERISTICS
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Limited amount of matrix
Basement membrane
Avascular
Held together by fused cell
membranes
• Reproduce by mitosis
• Nutrients by diffusion
• Polarity
CLASSIFICATION OF
MEMBRANOUS EPITHELIUM
• Based upon cell shape
– Squamous (flat), cuboidal, or columnar
• Based upon # of cell layers
– Simple (single) or stratified (layered)
Figure 4.1: Classification of epithelia, p. 120.
Squamous
Apical surface
Cuboidal
Basal surface
Simple
Apical surface
Basal surface
(a)
Human Anatomy and Physiology, 7e
by Elaine Marieb & Katja Hoehn
Stratified
Columnar
(b)
Copyright © 2007 Pearson Education, Inc.,
publishing as Benjamin Cummings.
Simple squamous
Simple cuboidal
Simple columnar
Pseudostratified
Transitional
Nonkeratinized
stratified squamous
CLASSIFICATION OF
GLANDULAR EPITHELIUM
• Exocrine – discharge products into
ducts
• 1. Apocrine
• 2. Holocrine
• 3. Merocrine
• Endocrine – ductless glands
II. CONNECTIVE
• Most abundant and diverse
• Connects, supports, transports and
defends
• Few cells, mostly matrix (nonliving
extracellular material); various
numbers and kinds of fibers
1. AREOLAR
•
•
•
•
Most common and widely distributed
Matrix is soft gel – hyaluronic acid
Matrix = collagen and elastin fibers
Fibroblasts (secrete matrix) are the
predominant cells
• Macrophages (phagocytosis)
• Mast cells – secrete histamine
Areolar
B. ADIPOSE
• Mostly fat cells (adipocytes)
• Protection, insulation, energy storage
Adipose
C. RETICULAR
• 3-D web
• Defense; reticular network filters
harmful substances from lymph and
blood
• Reticular cells phagocytic
Reticular
D. DENSE REGULAR
• Mainly bundles of collagen arranged in
parallel rows
• Few fibroblasts
• Ligaments (bone to bone) and tendons
(muscle to bone)
Dense regular
E. DENSE IRREGULAR
• Dermis of the skin
• Joint capsules
Dense irregular
6. CARTILAGE
• One cell type: chondrocyte
• Chondrocytes produce fibers and
tough gristlike material (chondroitin
sulfate)
• Avascular – nutrients diffuse through
perichondrium which surrounds
cartilage mass
F. HYALINE CARTILAGE
• Shiny
• Most prevalent type
• Support tubes of respiratory system,
ribs, tip of nose, ends of long bones
that articulate at joints
Hyaline cartilage
G. ELASTIC
• Strong and flexible
• External ear, epiglottis
Elastic cartilage
H. FIBROCARTILAGE
• Strongest
• Shock absorbers
• Found between vertebrae and knee
joints
• Rigid matrix filled with strong white
fibers
Fibrocartilage
I. BONE
• Osteocytes in matrix of collagen and
mineral salts (65%)
• Support, protection, muscle
attachment; mineral storage;
hemopoiesis
• Haversian system
Bone
J. BLOOD
•
•
•
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Liquid matrix
Fibers only present at clotting
Plasma = 55%
Erythrocytes, leukocytes and
platelets are the cells
Blood
III. MUSCLE
• A. Skeletal
– Multinucleate, cross striations
• B. Cardiac
– Heart wall; cross striations, intercalated
disks, involuntary Visceral
• C. Smooth
– involuntary, one nucleus per cell, non
striated
Skeletal muscle
Cardiac muscle
Smooth muscle
IV. NERVOUS
• Nerve cells
– Neurons
• Cell body (soma), axons (away) dendrites
(toward cell body)
• Neuroglia
– Connecting and supporting cells
IV. Nerve