Post on 17-Dec-2015
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
I. EPITHELIAL
• Covers and protects body surface• Lines body cavities• Secretes and absorbs substances
into and out of blood• Forms glands
II. CONNECTIVE
• Supports and connects body and its parts
• Transports substances throughout the body
• Protection from invading microbes• Cells spread out; lots of matrix
III. MUSCLE
• Produces movement by shortening complex contractile proteins
IV. 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
• Protection• Secretion• Absorption• Excretion• Sensory
CHARACTERISTICS• 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)
Human Anatomy and Physiology, 7eby Elaine Marieb & Katja Hoehn
Copyright © 2007 Pearson Education, Inc.,publishing as Benjamin Cummings.
Figure 4.1: Classification of epithelia, p. 120.
Stratified
Simple
Apical surface
Basal surface
Apical surface
Basal surface
Squamous
Cuboidal
Columnar(a) (b)
Simple squamous
Simple cuboidal
Simple columnar
Pseudostratified
Transitional
Nonkeratinized stratified squamous
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
2. ADIPOSE
• Mostly fat cells (adipocytes)
• Protection, insulation, energy storage
Adipose
3. RETICULAR
• 3-D web• Defense; reticular network filters
harmful substances from lymph and blood
• Reticular cells phagocytic
Reticular
4. DENSE REGULAR
• Mainly bundles of collagen arranged in parallel rows
• Few fibroblasts• Ligaments (bone to bone) and
tendons (muscle to bone)
Dense regular
5. DENSE IRREGULAR
• Dermis of the skin
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
A. HYALINE CARTILAGE
• Shiny• Most prevalent type• Support tubes of respiratory
system, ribs, ends of long bones that articulate at joints
Hyaline cartilage
B. ELASTIC
• Strong and flexible• External ear, epiglottis, larynx
Elastic cartilage
C. FIBROCARTILAGE
• Strongest• Shock absorbers• Found between vertebrae and
knee joints• Rigid matrix filled with strong
white fibers
Fibrocartilage
7. BONE
• Osteocytes in matrix of collagen and mineral salts (65%)
• Support, protection, muscle attachment; mineral storage; hemopoiesis
• Haversian system
Bone
8. BLOOD
• Liquid matrix• Fibers only present at clotting• Plasma = 55%• Erythrocytes, leukocytes and
platelets are the cells
Blood
III. MUSCLE
• 1. Skeletal– Multinucleate, cross striations
• 2. Cardiac– Heart wall; cross striations,
intercalated disks, involuntary Visceral
• 3. 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