General History of Histology Flashcards
Definition of Tissue
Groups of cells with a common function
Major tissue types
Epithelial, connective, muscle, nervous
Tissues are classified by…
-Embryological origin
-Composition of extracellular matrix (ECM)
-Structure
-Function
Embryological Origin of Tissues
-Primary Germ layers
-Formed during gastrulation of blastocyst (aka histogenesis)
Primary germ layers
Endoderm (inner), mesoderm (middle), ectoderm (outer)
How are blastocysts formed?
Zygotes (baby eggs) continuously split in half till they form a ball
What’s gastrulation?
Happens when cells migrate inward to make an upside-down U shape & change to form the primary germ layers.
Ectoderm (outer layer)
-Epidermis cells
-Brain neuron
-Peripheral nervous system neuron
Mesoderm (middle layer)
-Notochord cells
-Skeletal muscle cells
-Kidney tubule cells
-Red blood cells
Endoderm (inner layer)
-Pancreatic acinar cells
-Thyroid follicular cells
-Lung alveolar cells
Definition of Extracellular Matrix (ECM)
Complex, nonliving material found btwn cells
The amount of _____ varies. Epithelium has very little _____ & lots of cells; some connective tissues are primarily composed of _____ with very few cells.
…ECM…
What is ECM made of?
Water, proteins, glycoproteins, and proteoglycans
ECM function?
To connect cells and/or aid in communication
_____ is usually made by cells, so it’s considered organic material
ECM
