Junctions And Tissues Flashcards
What are the 3 types of junctions between cell types?
Adhering
Impermeable
Communicating
What are features of adhering junctions?
Mechanically held together
Eg desmosomes containing plaque
Common
What do belt desmosomes do?
Form continuous band around the cell, common in epithelial cells where they are associated with actin filaments
What do spot desmosomes do?
Spot weld cells together, and are attached on inside of the cell to keratin filaments
What do hemi desmosome do?
Attach the base of the cell to basal lamina
What are the features of impermeable junctions?
Prevent the passage of molecules between cells
Eg tight junctions
No molecules between cells
In invertebrates, what junctions form the same function as tight junctions?
Septate junctions
What are the features of communicating junctions?
Allow passage of small molecules from one cell to another Eg gap Common Connexins form the gap 1.5nm gap
How is the permeability of gap junctions changed?
Decreased intercellular pH
Increased intracellular calcium
What happens to gap junction during cardiac disease?
They are reduced in numbers or changed in distribution
What are the 4 main categories of tissue?
Epithelial
Connective
Muscle
Nervous
What are the features of epithelial tissue?
Tightly packed cells
Fastened together via desmosome junction and tight junctions
Acts as barrier and protects against mechanical injury
Secretory functions
What are the features of connective tissue?
Extra cellular matrix
Dense or loose
Blood and adipose
What are examples of dense connective tissue?
Cartilage, bone, tendon, ligament tissue
What is dense connective tissue composed of?
Fibrous proteins
Glyosaminoglycans attaches good protein core
What is loose connective tissue?
Holds small glands and epithelia together and includes the basal lamina of cells
What is the basic structure of collagen?
Triple helix
What are the features of muscle tissue?
Support and movement
Actin (thin)
Myosin (thick)
What are the 3 types of muscle tissue?
Skeletal
Smooth
Cardiac
What are features of skeletal muscle?
Striated muscle
Voluntary movement
What are features of smooth muscle?
Involuntary body activity
What are features of cardiac muscle?
Contraction of the heart
What is the role of nervous tissue?
Sense sense stimuli and transmit signals through an animal
Communicating
What are nervous tissue composed of?
Neurons and glial cells/ glia
What’s the role of dendrites?
Conduct impulses towards the nerve body
What’s the role of axons?
Transmit impulses away from the nerve body
What’s the role of Schwann cells?
Wrap around axon to form a multi layered membrane stealth to prove electrical insulation
