Tissue level of Organization Flashcards
Groups of cells with common embryonic origin and functions
Tissues
is the science that deals with the
study of tissues
Histology
4 basic types of tissue
Epithelial
Connective
Muscular
Nervous
Cells lie close together in continuous sheets with little extracellular material
Epithelial Tissue
- Cover surfaces and line cavities; always a free (apical) surface
- Forms glands
Epithelial Tissue
- Has no blood vessels (is avascular)
- Has a nerve supply
- Has a high capacity for cell division
Epithelial Tissue
Arrangement of cells in layers
Simple epithelium: 1 layer of cells
Stratified Epithelium: more than 1 layer of cells
more than 1 layer of cells
Stratified Epithelium
1 layer of cells
Simple epithelium
Cell Shapes
Squamous
Cuboidal
Columnar
Transitional (change shape)
- Important for filtration (kidneys) or diffusion (lungs, capillaries)
- Called endothelium when lining heart, blood and lymphatic vessels
- Called mesothelium when in serous membranes
Simple Epithelium
single layer of flat cells
Simple Squamous Epithelium
- Single layer of cube-shaped cells; round, centrally located nucleus.
- Covers surface of ovary; anterior surface of lens of the eye; forms pigmented epithelium at posterior surface of retina of the eye, lines kidney tubules and smaller ducts of many glands; secreting portion of some glands
- Function: Secretion and absorption.
Simple Cuboidal Epithelium
Cube-shaped cells, rounded nuclei
Simple Cuboidal Epithelium
Noncilated
Simple Columnar Epithelium
Cilated
Simple Columnar Epithelium
Appears stratified; nuclei at various levels
Pseudostratified Columnar
- Apical layer cells are flat
- Deep layers vary from cuboidal to columnar
- Cells in the basal layer divide and move upward toward apical surface
- Found in areas of surface wear and tear
Stratified Squamous Epithelium
develops tough layer of keratin in apical layer
Keratinized stratified squamous epithelium
does not contain large amounts of keratin, constantly moistened by mucus
Nonkeratinized stratified squamous epithelium
Keratinized (dead) surface cells
Stratified Squamous Epithelium
Rare
Stratified Cuboidal Epithelium
Variable in appearance; cells can stretch
Transitional Epithelium
Main function is secretion
Glandular Epithelium
may consist of a single cell or a group of cells that secrete substances into ducts (tubes), onto a surface, or into the blood.
Gland
Glands classification
Endocrine
Exocrine
hormones
Endocrine
secrete products into ducts that empty onto the surface
Exocrine
-Most abundant tissue type; typically found between other tissues
-Diverse functions that vary by specific tissue type
-Has good blood supply; exception: cartilage is avascular
Connective Tissue
Two basic elements of connective tissue
extracellular matrix and cells
present in several tissues
Fibroblasts
formed from monocytes
Macrophages
develop from B lymphocytes
Plasma cells
Secrete fibers
Fibroblasts
Engulf bacteria and cell debris by phagocytosis
Macrophages
Make antibodies
Plasma cells
- near blood cells
- Part of an inflammatory reaction: produce histamine that dilates blood vessels
Mast cells
- fat cells or adipose cells
- Store triglycerides (fat) for energy and provide protection
Adipocytes
in response to certain conditions they migrate from blood into connective tissues.
White blood cells
gather at sites of infection, phagocytosis
neutrophils