Lecture 2 Basic Tissue Flashcards
HISTOLOGY:
• Study of the
microscopic structure and function of tissues.
TISSUES:
Structure formed by the grouping of cells with similar characteristics of form and function.
4 BASIC TYPES OF TISSUES
- Epithelial Tissue:
• forms protective coverings
• function in secretion and sensory - Connective Tissue:
• provides support for softer body parts
• binds structures together - Muscular Tissue:
• responsible for producing body movements.
Muscular Tissue:
• responsible for producing body movements. - Nerve Tissue:
• specialized to conduct impulses that help control and coordinate body activities.
Epithelial Tissue:
Simple: squamous, cuboidal, columnar, pseudostrat ified
Stratified: squamous (keratinized, nonkeratinized), cuboidal, columnar, transitional
Connective Tissue:
Solid soft: connective tissue proper, specialized (adipose, fibrous, elastic, reticular)
Solid firm: cartilage
Solid rigid: bone
Fluid: blood, lymph
Muscle
Involuntary: smooth, cardiac
Voluntary: skeletal
Nerve
Afferent: sensory
Efferent: motor
Basic tissues
Embryological Cell Layers
The basic tissue types of the body form from three embryological cell layers:
• Ectoderm
Mesoderm
• Endoderm
These embryological cell layers develop from embryonic cells during prenatal development (more on this later).
- EPITHELIAL TISSUE
• Covers and lines both the external and internal body surfaces, including vessels and small cavities.
• Serves as a protective covering or lining but is also involved in tissue:
- absorption
- secretion
- sensory
- other specialized functions.
• Protects complex inner structures from:
- physical, chemical and pathogenic attacks
- dehydration
- heat loss (acts as a barrier).
• Depending on classification, epithelial tissue can be derived from any of the three embryonic cell layers:
•Ectoderm:
- skin and oral mucosa
• Endoderm:
- respiratory and digestive tract
• Mesoderm:
- urinary tract
EPITHELIUM
• Cells packed closely together:
- surrounded by very little or no intercellular substance or tissue fluid.
• Epithelium is highly regenerative (its deeper cells reproduce by mitosis)
• Epithelial cells are:
- tightly joined together by desmosomes.
- joined to basement membrane by
hemidesmosomes.
EPITHELIAL CELLS:
EPITHELIUM
• Epithelium is avascular, having no blood supply of its own.
• Cellular nutrition (oxygen and metabolites) is obtained by DIFFUSION from the connective tissue:
• connective tissue is highly vascularized, providing its own source of nutrition
EPITHELIUM CLASSIFICATION
Cell Arrangement: Simple -1 layer, single layer of cells
Stratified - 2 or more layers (many layers)
Pseudostratified -1 layer but looks like 2
—Cell Shape:Squamous - flat
Cuboidal - cube
Columnar - rectangular
Transitional - changes shape
—Cell Function:Keratin - dead layer, no nucleus
(protection)
Cilia - hair-like projections
(propel other substances along.
Ex: fallopian tubes and egg)
EPITHELIUM: DIVISION
Simple:
• Squamous
• Cuboidal
• Columnar:
- ciliated
- non-ciliated
• Pseudostratified
Stratified:
• Squamous
- keratinized
- non-keratinized
• Cuboidal
• Columnar
• Transitional
Pseudostratified:
• Ciliated
• Non-ciliated
SIMPLE SQUAMOUS EPITHELIUM
SIMPLE SQUAMOUS EPITHE
• Very thin, flat cells, may vary in shape.
• Covers connective tissue with little intercellular matrix, attached by the basement membrane.
• Performs a filtering function on moist surfaces.
Endothelium: simple squamous epithelium lining of vessels and serou cavities (surround organs).
Location:
pulmonary alveoli (lungs)
-
inner and middle ear -
blood and lymphatic vessels -
heart -
serous cavities
SIMPLE SQUAMOUS EPITHELIUM
SIMPLE CUBOIDAL EPITHELIUM
SIMPLE CUBOIDAL EPITHE
• Cube-like cells, top view:
hexagon.
• Nucleus is in the center of the cell.
• Protection / covering for an organ.
• Contributes to secretion.
Location:
• Line the ducts of various glands, such as ducts of the salivary glands.
SIMPLE CUBOIDAL EPITHELIUM
SIMPLE COLUMNAR EPITHELIUI
• Rectangular: height greater than width, top view:
hexagon.
• Nucleus near the base of the cell.
• Function: protection, secretion/absorption due to goblet cells (secrete mucin: a carbohydrate-protein complex found in most secretions).
• May or may not be ciliated (having cilia) on surface
- carries mucous and debris towards exterior.
Location:
• Non-ciliated:
- stomach
- large/small intestine
- lining of cervical canal
• Ciliated:
- uterus
- fallopian tubes
- ductus deferens (male reproductive system)
- small intra-pulmonary bronchi (lungs)
SIMPLE COLUMNAR EPITHELIUM
PSEUDOSTRATIFIED COLUMNAR
EPITHELIUM
EPITHELIUM
• Crowded columnar cells (rectangular form is destroyed).
• Nuclei are at different levels.
• Serves to moisten, warm and clean lining membranes.
• May be ciliated or non-ciliated.
Location:
• Upper respiratory tract including nasal cavity and para nasal sinuses
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PSEUDOSTRATIFIED COLUMNAR
EPITHELIUM
STRATIFIED SQUAMOUS
NON-KERATINIZED EPITHELIUM
• Many layers of cells on an irregular basal laver.
• No layer of keratin.
• Kept moist from bodily secretions (ex: saliva), not the membrane itself:
- bodily secretions prevent it from drying out.
• Range from cuboidal to squamous cells, can have polyhedral shaped cells.
Cells are continually being replaced.
STRATIFIED SQUAMOUS
NON-KERATINIZED EPITHELIUM
Location:
• Buccal and alveolar mucosa
• Ventral part of tongue (underneath)
• Soft palate
• Floor of the mouth
• Sulcular epithelium
• Esophagus
• Cornea
STRATIFIED SQUAMOUS
NON-KERATINIZED EPITHELIUM
STRATIFIED SQUAMOUS KERATINIZED EPITHELIUM
• Located on dry surfaces.
• Has a keratin layer for protection.
• Great cell differentiation among its 5 layers:
1. Stratum basale
2. Stratum spinosum
3. Stratum granulosum
4. Stratum lucidum (palms & soles, not in oral cavity)
5. Stratum corneum (dead, non-nucleated)
KERATIN:
• Tough, fibrous, opaque, waterproof protein.
• Resists friction.
• Impervious to bacteria and other invaders.
• 1st line of defense.
• Nuclei are condensed and inactive.
STRATIFIED SQUAMOUS
KERATINIZED EPITHELIUM
STRATIFIED SQUAMOUS
KERATINIZED EPITHELIUM
Location:
• Skin
• Free gingiva (outside only)
• Attached gingiva
• Hard palate
• Dorsal of tongue
• Lips
TRANSITIONAL EPITHELIUM
• Ranges between stratified squamous non-keratinized and stratified columnar epithelium.
• Ranges from polyhedral to dome shaped, flat cells.
• Cells are soft, pliable, and loosely arranged.
TRANSITIONAL EPITHELIUM