unit 2 Flashcards
Histology
the study of tissues, especially with a microscope
Tissues definition
- Aggregation of similar cells, their products, and materials
surrounding - Have specific structure & function
Tissue components
- cell
- Extracellular Matrix (ECM)
ECM Components (varies by tissue type
- Extracellular fluid- mostly water
- Proteins
-Glycoproteins attached to plasma membranes
-Fibrous proteins- long, thin proteins like collagen
-Proteoglycans- enormous carbohydrates with
multiple protein-carbohydrate attachments
ECM Functions
- Protection of cells
- Holds cells together
- Facilitates cellular communication
Other names for ECM
- Interstitial fluid
- Tissue fluid
types of tissues
Epithelial
Connective
Nervous
Muscular
types of Epithelial tissues
Simple
- Simple Squamous
- Simple Cuboidal
- Simple Columnar
- Pseudostratified Columnar
Stratified
- Stratified Squamous
- Stratified Columnar
- Stratified Cuboidal
- Transitional
types of Connective tissue
- Fibrous Connective
Tissue - cartilage
- bone
- blood
types of Fibrous Connective
Tissue
Loose Fibrous
Connective Tissue (Areolar, Reticular, Adipose)
Dense Fibrous
Connective Tissue (Dense Regular, Dense Irregular, Elastic)
types of Cartilage
Hyaline, Elastic, and Fibrocartilage
types of bone
Spongey and Compact
types of Muscular tissues
Skeletal, Smooth, and Cardiac
how are cells in tissues joined?
Cells in tissues, especially epithelial tissues,
often are joined together by junctions
Junction Functions
- Bind cells together
- Allow near-instant cell-cell communication
Typical Junction Locations
- Lateral surface- side of cells
- Basal surface- bottom of cell
Types of Cellular Junctions
- Tight Junctions
- Desmosomes
- Hemidesmosomes
- Gap Junctions
Tight Junctions
- Tightly joins epithelial cells near apical surface
- Seals space between cells
- Prevents fluids squeezing between cells
- Prevents bacterial invasion
- Weak- can be broken easily
Desmosomes
- Holds cells together
- Strong- Resists mechanical stress
- Loose, not continuous like tight junctions
Hemidesmosomes
- Half-desmosomes
- Bind basal cells of epithelial tissue to underlying
fibers (basement membrane) - Prevents cells from peeling away
Gap Junctions
- AKA Communicating Junction
- 6 proteins forming a large channel
- Solutes and water pass through cell-to-cell
- Allows near-instant communication
- Common in smooth muscle & cardiac muscle
how do tissues grow
Tissues grow by increasing in cell number or size
Hyperplasia
growth due to increase in cell number
Hypertrophy
growth due to increase in cell size
Stem cells
Differentiate to give rise to cell/ tissue types
Embryonic stem cells
Embryonic stem cells- give rise to ALL cell
types
Totipotent
can become all adult cell types
and placenta cells
Pluripotent
can become all adult cell types
Adult stem cells
give rise to 1 or a small number of cell types
types of adult stem cells
- Multipotent- a few types
- Unipotent- 1 type
Atrophy
loss of cell size
- Caused by disuse and/or aging
Apoptosis
planned loss of cell number
- Programmed cell death
- Non-inflammatory
Apoptosis
- Organ development- removing excess cells
- Normal maintenance- cycling out older/damaged cells
Necrosis
death of cells
- Due to lack of blood supply or damage
- Inflammatory
- Not always reversable
Regeneration
- Replacing dead cells with cells of same type
- Restores organ function
Fibrosis
- Replacing dead cells with scar tissue-
Mostly fibrous proteins like collagen - Does not fully restore organ function
- Faster, requires fewer resources
Epithelial tissue (Epithelium)
- Closely adhering cells, one or more layers thick
- Almost no extracellular matrix
Epithelial tissue functions
- Line organs, form glands
- Protection, Secretion, Absorption, Filtration
and/or Sensation
- Cell polarity- cells are not perfectly symmetrical
- Apical surface- upper
- Basal surface- lower
- Lateral surface- side
