Mechanisms Of Intercellular Communication - Lecture 8

Question 1

Direct Communication

Answer 1

• Gap Junctions
• Membrane Nanotubes
• Mechanosignals

Question 2

Gap Junctions - Connexons

Answer 2

• channel
• Pore size is small
• Passage of sugars, amino acids, ions
• in all cells except for skeletal muscle

Question 3

Gap Junctions - Intercalated Disks

Answer 3

• cardiac muscle
• rapid and coordinated for rhythmic contractions
• small
• phosphorylation/dephosphorylation

Question 4

Nanotubes

Answer 4

• formed from the plasma membrane
• longer and have a large pore diameter
• transfer nucleic acids and organelles
• transfer cell components from stressed to healthy cells

Question 5

Mechanosignal Transduction

Answer 5

Conversion of mechanical stimuli into a cellular response

Question 6

Mechanosignal Transduction - Pulsatile and shearing stresses

Answer 6

• formation of new blood vessels
• vascular inflammation and progression of atherosclerosis

Question 7

Mechanosignal Transduction - Weightlifting

Answer 7

Mechanical stress to muscle fibres for weightlifting resulting in increased protein synthesis

Question 8

Mechanosignal Transduction - Bones and Cartilage

Answer 8

Remodelling of bone and cartilage through physical stresses

Question 9

Mechanosignal Transduction - Neural Electrical Impulse

Answer 9

Conversion of pressure into a neural (electrical) impulse that triggers a cell response

Question 10

Mechanosignal Transduction - Hearing

Answer 10

Conversion of a sound wave into an electrical signal

Question 11

Indirect Intercellular communication

Answer 11

Chemical Messengers: Paracrine, neurotransmitters, hormones and neuroendocrine

Question 12

Paracrine

Answer 12

• Clotting factors, growth factor
• Attaches to receptors on target neighbouring cells

Question 13

Neurotransmitters

Answer 13

• Synapse is a short distance but axons can be very long
• signal must be tightly controlled and needs an auto shutoff
• not too many molecules released

Question 14

Hormones

Answer 14

• Water or lipid soluble
• Must cross boundaries to reach target receptors

Question 15

Receptors Specificity

Answer 15

1. Cells express many different types of receptors
2. 100s or 1000s of receptors on a cell surface
3. Amount of receptors is controllable

Question 16

Hydrophilic Messenger (6 factors)

Answer 16

• Water-loving
• stored in secretory cell
• dissolves in plasma so no need for carrier
• crossing lipid membrane presents a barrier
• exocytosis
• travels through blood stream

Question 17

Hydrophobic Messenger

Answer 17

• Water-hating and lipid loving0
• Storage is more limited
• can’t dissolve in plasma and needs a carrier (binds)
• crossing a lipid membrane shouldn’t present a barrier
• secreted by diffusion