BIO 240 1st Edition Lecture 3 Outline of Last Lecture i Cytoplasm and cytoskeleton ii Organelles B Cell Resting Potential electrochemical equilibrium Outline of Current Lecture I Epithelial Tissue A Types B Functions C Characteristics Current Lecture I Epithelial Tissue A Types a Arrangement i Simple One single layer thick ii Pseudostratified Appears to be stratified but in fact each cell reaches the basement membrane and is therefore only one layer thick Almost always seen as pseudostratified columnar iii Stratified Two or more layers thick iv Transitional Different cell shape that is thin at the bottom and rounded at the top like a pillow Has the ability to expand and stretch b Shape i Squamous Flattened disc shaped ii Cuboidal Cube shaped iii Columnar Taller than it is wide column shaped B Functions a All epithelial tissue covers the outside of structures of lines the inside of structures It can i Serve as protection ii Aid with diffusion and or filtration iii Absorption iv Expansion These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute b Some epithelial tissue can form the secreting parts of glands and therefore has a part in secretion c Epithelial tissue is name by arrangement and then shape i Simple squamous Diffusion and filtration ii Simple cuboidal Secretion iii Simple columnar Absorption iv Stratified squamous Protection v Stratified cuboidal columnar Secretion vi Pseudostratified columnar Secretion vii Transitional Expansion C Characteristics a Cells are very closely packed together There is very little extracellular space b Has specialized cell to cell contact gap junctions tight junctions and desmosomes c Polarity There are distal and proximal ends i All epithelial tissue is attached to connective tissue by a basement membrane 1 The basement membrane is the point of attachment for epithelial and connective tissue It is made up of a basal lamina and a reticular lamina a The basal lamina has glycoproteins for epithelial tissue and the reticular lamina has glycoproteins for connective tissue d Avascular There is no blood supply This is the reason the epithelial tissue must be so thin e High regeneration rate they are mitogenic This is how we recover from sunburns so quickly f Specializations present in some epithelial tissue i Cilia ii Microvilli used to increase surface area to aid in increased absorption
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