chapter 4 Flashcards
chemical level
atoms -> molecules
cellular level
cells -> extracellular material and fluid
tissue level
tissue -> epithelial, connective, muscular, nervous
stem cells can….
replicate or turn into different types of cells
embryonic stem cell
blastocyst - very early embryo
tissue stem cell
fetus, baby, and throughout life
stages of embryogenesis
clevage -> 8 cell stage -> blastocyst -> blastocyst inner mass cells
epithelial tissue
1) Epitlelia
2) Glands (exocrine & endocrine)
(ET) 1) Epitlelia tissue
- avascular layer
- covers exposed surfaces
- often contain secretary or gland cells scattered
(ET) 2) Glands
- derived from epitlelia
- predominately secretary cells
- 2 types ( 1) exocrine, 2) endocrine)
Functions of epithelial tissue
1) provides physical protection
2) control permeability
3) provide sensation
4) produce specialized secretion
features of epithelial tissue
- surfaces (apical surface - faces exterior of body, base - attached to underlying tissue)
- polarity (refers to structural differences between exposed and attached)
Epithelial layers
Squamous, Cubical, Columnar
epithelial attachments
- between adjustment cells & adjacent tissue
- barrier
- able to replace cells
- lack of blood cells
avascular
lack of blood
Intercelluar Connections
1) Hemidesmosomes
2) Tight (occluding) junctions
3) Adhesion belts
4) Gap junctions
5) Desmosomes
(IC) 1) Hemidesmosomes
attach to basement membrane
(IC) 2) Tight (occluding) junctions
- interlocking membrane
- prevent water & solute passage
- found in intestinal tract
(IC) 3) Adhesion belts
- continuous band of membrane proteins
- strengthen apical region
(IC) 4) Gap junctions
-held together by interlocking transportation proteins
(IC) 5) Desmosomes
- side of cells (adjacent)
- opposing locked together by CAM’s
- very strong
connexons
interlocking transportation proteins
