8. Cell Junctions & Tissues Flashcards
(24 cards)
what are the three categories of cell junctions and an example of each
adhering junctions e.g. desmosomes
impermeable junctions e.g. tight cells
communicating junctions e.g. gap junctions
what is the most common tissue where desmosomes are found
skin and muscle
where tissues are subject to stress
describe the structure of a desmosome
consists of a desmosome plaque
inside, a core joins the plaque
the desmosome core is filled with glycoproteins called what?
cadherins
what are the three types of desmosomes, give a brief description of each
belt desmosomes - form a continuous band around the cell
spot desmosomes - connect cells, attached internally to keratin filaments
hemi-desmosome - attach the base of the cell to the basal lamina
what is the purpose of tight junctions
prevent molecules leaking between adjacent cells
allows them to have different compositions
what is the most common type of junction
gap junctions
gap junctions are tiny pores composed of proteins called what
connexins
how many connexins in a gap junction
12
what can change the permeability of a gap junction
pH or calcium
what are the 4 types of tissues
muscle
connective
nervous
epithelial
what does epithelial tissue line
organs and cavities
what does epithelial tissue protect against
mechanical injury and provide a barrier against microbes and fluid loss
what type of cell junctions fasten epithelial tissue
desmosomes & tight junctions
what is the purpose of connective tissue
provides mechanical strength
binds and supports other tissues
give 2 examples of dense connective tissue
cartilage and tendons
dense connective tissue is made of what
fibrous proteins and proteoglycans
what does loose connective tissue do
holds small glands and epithelial tissue together r
what is the function of muscle tissue
support and movement
what two proteins are frequently found in muscle tissue
actin and myosin
what are the three types of muscle tissue
skeletal
cardiac
smooth
what is the function of nervous tissue
senses stimuli and transmits signals throughout the animal
role in communication
list some components of a nerve cell
cell body denditres axon Schwann cells myelin sheath terminal buttons
what type of tissue is blood and adipose tissue considered as
connective tissue
