biology 211 anatomy & physiology i histology the study of tissues
TRANSCRIPT
Biology 211Anatomy & Physiology I
Histology
The study of tissues
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.
All tissues: -
-
With only a few, rare exceptions, all organs of the human body are composed of four types of tissue:
lines internal and external surfaces, including hollow organs. Also forms glands.
provides support and fills spaces
produces movement
carries and integrates electrical information
Each of these can have one or more subtypes
Epithelium
- Covers body surfaces (e.g. skin, cornea)
- Lines body cavities (e.g. peritoneal cavity, pericardial cavity
- Lines insides of hollow organs (e.g. stomach, heart, lung. aorta, oviduct)
- Forms glands (e.g. sweat glands, pancreas, salivary glands)
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
Epithelium always supported by connective tissueand separated from it by a basement membrane.Depends on connective tissue for vessels, nerves, etc. Epithelium Basement membrane Connective tissue
Mucous Membrane orSerous Membrane
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 = Two or more layers =
Actually one layer but looks like more =
Flat = Cube-shaped = Taller than wide =
Change shape from squamous to cuboidal =
Epithelium
Number of layers Shape of surface cells
Squamous Simple CuboidalStratified ColumnarPseudostratified Transitional
Simple Squamous Epithelium
Simple Cuboidal Epithelium
Simple Columnar Epithelium
Pseudostratified Columnar Epithelium
Stratified Squamous Epithelium
Stratified Cuboidal Epithelium
(Stratified) Transitional Epithelium
Epithelium
No good examples of stratified columnar epithelium. Found only in parts of the male reproductive system
Epithelium also forms all glands in the body
Glands classified by
a) Whether or not they have ducts
b) Their method of secretion
Yes = Duct carries product to surfaceNo = Product secreted into surrounding extracellular matrix, picked up by blood vessels
Product released from undamaged cells Top part of cell lost during secretion Entire cell lost during secretion
Exocrine glands also classified by
c) Shape, and whether or not either the duct and/or the secretory part branches
Characteristics of Connective Tissue
- Lots of extracellular matrix; Relatively few cells
- Cells usually do not communicate with each other
- Highly vascular
- Different types of CT 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.
Connective Tissues
Common cells
Fibers
Connective Tissues
Ordinary connective tissues
Specialized connective tissues
Loose Areolar Connective Tissues
Adipose Connective Tissues
Dense Regular Connective Tissues
Dense Irregular Connective Tissues
Specialized Connective Tissues: Hyaline Cartilage
Specialized Connective Tissues: Elastic Cartilage
Specialized Connective Tissues: Fibrous Cartilage
Specialized Connective Tissues: Bone
Muscle Tissue:
Skeletal Muscle
Cardiac Muscle
Smooth Muscle
Very longUnbranched
ShorterBranched
ShortUnbranchedSpindle-shaped
Hundreds per cellPeripheral
One or two per cellCentral
One per cell
Central
Yes Yes No
Skeletal Cardiac Smooth Muscle Muscle Muscle
Myocytes
Nuclei
Striations
Skeletal
Cardiac
Smooth
More detail on muscle tissues and their cells when we discuss the muscular system
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