1. Biology 322 Human Anatomy
Basic Histology

2. Recall:
SYSTEMS are composed of one or more organs, all serving a common function
ORGANS are composed of one or more types of tissues, all serving a common function
TISSUES are composed of one or more types of cells and their products, all serving a common function
The study of structure at the level of tissues is called histology.

3. All tissues:
- Cells
- Extracellular Matrix
Ground Substance
Fibers

4. With only a few, rare exceptions, all organs of the human body are composed of four types of tissue:
Epithelium lines internal and external surfaces,
including hollow organs. Forms glands.
Connective Tissue provides support
and fills spaces
Muscle Tissue produces force and movement
Nervous Tissue carries and integrates
electrical information
Each of these can have one or more subtypes

5. Let’s start with Epithelium
- Covers body surfaces
(e.g. skin, cornea)
- Lines body cavities
(e.g. peritoneal & pericardial cavities
- Lines insides of hollow organs
(e.g. stomach, heart, lung. aorta, oviduct)
- Forms glands
(e.g. sweat glands, pancreas,
salivary glands)

6. Characteristics of Epithelium
- Highly cellular, with very little
extracellular matrix
- Cells form close contacts with
each other
- Avascular
- High capacity for regeneration
Functional characteristics of epithelia depend on the cells, rather than the extracellular matrix which is unspecialized

7. Epithelium always supported by connective tissue
and separated from it by a basement membrane.
Depends on connective tissue for vessels, nerves, etc.
Epithelium
Basement membrane
Connective tissue
Mucous membrane or
Serous membrane

8. Flat = "squamous" Epithelium Different types for different functions.
Classified according to:
a) Number of layers of cells
b) Shape of cells in the top layer
Single layer = "simple"
Two or more layers = "stratified"
Actually one layer but looks like more = "pseudostratified"
Flat = "squamous"
Cube-shaped = "cuboidal"
Taller than wide = "columnar"
Change shape from squamous to cuboidal = "transitional"

10. Epithelium Number of layers Shape of surface cells Squamous Simple
Cuboidal
Stratified
Columnar
Pseudostratified
Transitional

11. Simple Cuboidal Epithelium
Simple Squamous Epithelium
Pseudostratified
Columnar Epithelium
Simple Columnar Epithelium

12. Stratified Squamous Epithelium
Stratified Cuboidal Epithelium
Stratified Columnar Epithelium
(Stratified) Transitional Epithelium

13. Epithelium also forms all glands in the body
Glands classified by
a) Whether or not they have ducts
b) Their method of secretion
Yes = Exocrine; Duct carries product to surface
No = Endocrine; Product secreted into surrounding
extracellular matrix, picked up by blood vessels
Merocrine: Product released from undamaged cells
Apocrine: Top part of cell lost during secretion
Holocrine: Entire cell lost during secretion

14. Exocrine glands also classified by
Shape, and whether or not either the duct
and/or the secretory part branches

15. Connective Tissues
- Lots of extracellular matrix; Relatively few cells
- Cells usually do not communicate with each other
- Highly vascular
Different types of connective tissue all arise from
embryonic mesenchyme
Functional characteristics of connective tissues depend primarily on the extracellular matrix, which is often highly specialized, and not on the cells.

16. Connective Tissues Ordinary connective tissues
Specialized connective tissues
Loose (areolar) connective tissue
Adipose connective tissue
Reticular connective tissue
Elastic connective tissue
Dense regular connective tissue
Dense irregular connective tissue
Blood
Bone
Cartilage

17. Ordinary Connective Tissues
Common cells
Fibroblasts / Fibrocytes
Form the extracellular matrix of ordinary connective tissue

18. Connective Tissues Common cells Common Fibers Fibroblasts / Fibrocytes
Adipocytes
Mast cells
Plasma cells
Macrophages
Lymphocytes
(many others)
Collagen
Elastic
Reticular
How those cells and fibers are
arranged determines the specific type of connective tissue

19. Loose / Areolar Connective Tissue
Adipose Connective Tissue
Reticular Connective Tissue

20. Dense Regular Connective Tissue
Dense Irregular Connective Tissue

21. Specialized Connective Tissues: Cartilage
Hyaline Cartilage
Elastic Cartilage
More detail on cartilages and their cells when we discuss the skeletal system
Fibrous Cartilage

22. Specialized Connective Tissues:
Bone
Blood
More detail on these tissues and their cells when we discuss the skeletal and circulatory systems

23. Muscle Tissue: Skeletal Muscle Cardiac Muscle Smooth Muscle Voluntary
Striated
Involuntary
Nonstriated

24. Muscle Muscle Muscle Myocytes Nuclei Striations
Skeletal Cardiac Smooth
Muscle Muscle Muscle
Very long
Unbranched
Shorter
Branched
Short
Spindle-shaped
Hundreds per cell
Peripheral
One or two per cell
Central
One per cell
Yes No
Myocytes
Nuclei
Striations
More detail on muscle tissues and their cells when we discuss the muscular, circulatory, and other systems

25. Nervous Tissue: (no subtypes) 1) Neurons (Excitable cells)
Carry electrical signals
from one place to another
2) Supporting Cells
Nonexcitable
Support & nourish neurons
Glia in CNS
Satellite cells
Schwann cells
More detail on nervous tissue and its cells when we discuss the nervous system