9/3b Cell Biology/Mechanotransduction

Question 1

how to treat a ptnt with tight heel cords(achilles tendonds)?

Answer 1

apply serial casting to lengthen the tissue and normalize gait

Question 2

Tendon

Answer 2

connective tissue
faint lines in the direction of pull
transmit force in the line of direction
two main components:
1. Cells (fibroblasts)
2. Extracellular Matrix (glycoproteins and collagen)

Question 3

What are the cells of the tendon like?

Answer 3

they are called fibroblasts and they are all lined up in parallel between the fibers.
They Produce, Manufacture, and Secrete all the components of the ECM

Question 4

Extracellular matrix of the tendon

Answer 4

the ground substance is proteins
it is HYDROPHILLIC (water attracting)
Glycoproteins link the ECM components to each other
Collagen is TYPE I - it is more rigid than flexible so you can relay force on to the muscle

Question 5

Cytoskeleton

Answer 5

microfilaments
microtubules
Both of the above provide a continuous chain of communication from the outside of the cell to the nucleus - critical for shape and structure of cell

Question 6

Connect cell to cell

Answer 6

junctions

Question 7

process through which cells sense and respond to mechanical stimuli by converting them to biochemical signals that elicit specific cellular responses

Answer 7

Mechanotransduction

Question 8

Mechanotransduction pathway

Answer 8

mechanical stimulus (cast)
Tissue forces (impacts tissues)
cellular forces (forces stimulate the cells)
molecular response (leads to a response)

Question 9

Forces that tendons respond to at the tissue level:

Answer 9

tensile
compressive
hydrostatic
fluid shear
shear
vibration

Question 10

process for sensing mechanical stimuli

Answer 10

1. integrins on cell membrane allow for direct cell communication between cells through mechanical stimuli
2. conformational change - shape change of the integrim
3. stretch activated ion channels
4. receptor shape change - ligand shape change

Question 11

how is the mechanical signal transduced?

Answer 11

DNA RNA -> Protein

1. transduction from membrane to nuc
   - activate genes coding for collagen
2. trascription
   - dna->rna
3. translation by ribosomes
   - rna->pre-procollagen
4. Processing by ER, Golgi
   - pre-procollagen -> procollagen
5. exocytosis
6. extracellular procesing and org

Question 12

biological tissue with responses to mechanical stress

Answer 12

connective tissue, integumentary system, cardiopulm, neuromuscular

Question 13

Physical stress theory

Answer 13

changes in the relative level of physical stress cause a predictable response in all biological tissue
Force/Area

Question 14

Thresholds of the physical stress theory

Answer 14

define the boundaries for an effective DOSE (Amount of force, duration, and Frequency)

• Injury
• increased tolerance (hypertrophy)
• maintenance
• decreased tolerance (atrophy)
• death

Question 15

Stress

Answer 15

composite level of magnitude, time, and direction

Question 16

shifting thresholds in the physical stress theory indicate:

Answer 16

change in tolerance of an issue
continued hypertrophy
inflammation