Cellular adaptation and tissue regeneration

Question 1

how do cells respond to inc demand or external stimulation

Answer 1

by hyperplasia or hypertrophy

Question 2

atrophy is a result of what

Answer 2

reduced supply of nutrients and growth factors

Question 3

metaplasia is what

Answer 3

cells change from one type to another

Question 4

what is hyperplasia

Answer 4

inc in the no OF CELLS in an organ or tissue resulting in inc volume of tissue/organ

• can be physiological/pathological
• process is CONTROLLED
• may lead to cancerous proliferation

Question 5

describe the mechanism of hyperplasia

Answer 5

• INC local production of GFs
• INC expression of GFR on responding cells
• intracellular signalling pathways ACTIVATED
• TFs produced, genes activated
• CELL PROLIFERATION

Question 6

what is hypertrophy

Answer 6

• in in SIZE OF CELLS due to synthesis of more structural components causing inc in SIZE OF ORGAN
• physiological/pathological
• caused by in FUNCTIONAL DEMAND/ specific HORMONAL STIMULATION

Question 7

what is the mechanism of hypertrophy

what are the 2 main pathways

Answer 7

• result of INC PRODUCTION OF CELLULAR PROTEINS
• induced by co-ordinated MECHANICAL SENSORS, GFs and VASO-ACTIVE agents
  Pathways: Akt (physiological) and GPCR–>Gq–> MAPK (pathological)

Question 8

can hypertrophy and hyperplasia coexist

Answer 8

yes

Question 9

what is atrophy

what are the types

Answer 9

shrinkage (reduced size) of organ/tissue
- from DEC IN CELL SIZE/NUMBER
- is an ADAPTIVE response
- physiological atrophy common in FOETAL DEVELOPMENT
- pathological depends on cause, can be local/generalised
- may cause CELL DEATH
-

Question 10

what are the causes of atrophy

give examples

Answer 10

• DEC WORKLOAD (atrophy of disuse)
  eg bed rest causes skeletal muscle atrophy
• LOSS OF INNERVATION (denervation atrophy)
  eg nerve damage
• DIMINISHED BLOOD SUPPLY
  eg arterial occlusive disease
• LACK OF NUTRITION
• LOSS OF ENDOCRINE STIMULATION
• PRESSURE ATROPHY (tissue compressed)

Question 11

repair usually consists of what

Answer 11

regeneration

scar formation and fibrosis

Question 12

the relative contribution of regeneration and scarring in tissue repair depends on what

Answer 12

• the ABILITY OF THE TISSUE to regenerate

- the extent of injury

Question 13

in adult tissues the size of cell population is determined by what

Answer 13

• rate of cell proliferation and differentiation

- rate of death by apoptosis

Question 14

what is a terminally differentiated cell

Answer 14

differentiated cells that are INCAPABLE OF REPLICATION

Question 15

what are stem cellsable to do

Answer 15

• self renewal
• can generate differentiated cell lineages
• pluripotent when they are EMBRYONIC SC: can generate all tissues of the body
• pluripotent cells–> multipotent/unipotent

Question 16

what are embryonic stem cells

where

Answer 16

• inner cell mass of BLASTOCYSTS in early embryonic development
• pluripotent

Question 17

what are adult (somatic) stem cells

where

Answer 17

• present in adult tissues tht continuously divide (bone marrow, skin, GI tract lining)

Question 18

what are induced pluripotent stem cells

where

Answer 18

• differentiated cells of adult tissues can be reprogrammed to become PLURIPOTENT

Question 19

what is the purpose of stem cell research on biology and medicine

Answer 19

• study specific signals and DIFFERENTIATIONN STEPS req for development of tissues
• prod knockout mice to study genes and develop models of human disease
• regenerate damaged organs