Cellular Adaptations Flashcards
What mechanisms do growth factors affect?
Cell proliferation and inhibition Locomotion Contractility Differentiation Viability Angiogenesis
How does increased growth occur?
Shortening of the cell cycle
Conversion of quiescent cells into proliferating cells
Where are the 3 important cell cycle check points?
Restriction point check
Check before DNA replication
Check after DNA replication
What is the restriction point?
Cell cycle check point towards the end of G1
Most critical checkpoint
Most altered checkpoint in cancer cells
What 2 substances exert the most control over the cell cycle?
Cyclins
CDKs (cyclic dependent kinases)
What is asymmetric replication of stem cells?
One daughter cell remains a stem cells whilst the other differentiates into a mature cell
Name the 5 important types of cellular adaptation
Regeneration Hyperplasia Hypertrophy Atrophy Metaplasia
Define regeneration
The replacement of cell losses by identical cells to maintain tissue or organ size
Do tendons have a good capacity to regenerate?
No
They heal slowly as they have a poor blood supply.
What is a traumatic neuroma?
Nerve cells in the PNS have been damaged and the axons regenerate but lose their way causing pain.
What is the Hayflick number?
The number of times a cell can regenerate - proportional to the maximum life capacity of the species
(61.3 in humans)
Which genes regulate normal cell proliferation?
Proto-oncogenes
Define reconstitution
Replacement of a lost part of the body
Define hyperplasia
Increase in tissue or organ size due to increased cell numbers
Name 2 physiological examples of hyperplasia
Endometrium under the influence of oestrogen
Bone marrow in response to hypoxia (RBC production)
Name 2 pathological examples of hyperplasia
Eczema
Thyroid goitre
Define hypertrophy
Increase in tissue or organ size due to increased cell size
What is hypertrophy usually caused by?
Increased functional demand or hormonal stimulation.
Give 2 examples of physiological hypertrophy
Skeletal muscle (body building) Smooth muscle in pregnant uterus
Give 2 examples of pathological hypertrophy
Right/left ventricular hypertrophy
Enlarged prostate gland in older men
Define atrophy
Shrinkage of a tissue or organ due to an acquired decreased in size and/or number of cells
Give a physiological example of atrophy
Ovarian atrophy in post-menopausal women
Give 2 examples of pathological atrophy
Muscle atrophy of disuse
Denervation atrophy
Define metaplasia
Reversible change of one differentiated cell type to another
What metaplasia occurs in smoking?
Bronchi:
Pseudostratified ciliated epithelium changes to stratified squamous
What metaplasia occurs in Barrett’s oesophagus?
Stratified squamous changes to glandular columnar epithelium
Define hypoplasia
Underdevelopment or incomplete development of a tissue or organ at the embryonic stage
Define aplasia
Complete failure of a specific tissue or organ to develop at the embryonic stage
OR
An organ whose cells have ceased to proliferative
Define involution
Normal, programmed shrinkage to an organ (overlaps with atrophy)
Give 2 examples of involution
Uterus after childbirth
Thymus in early life
Define atresia
The lack of orifice where there should be one
Define dysplasia
Abnormal maturation of cells within a tissue
Define hyperkeratosis
Increase in the thickness of the stratum corneum
Define parakeratosis
Retention of nuclei in the stratum corneum
What is myositis ossificans?
Inflammation and ossification of the muscle
Which cells does PDGF encourage to undergo division?
Fibroblasts
Smooth muscle cells
Glial cells
Which cells are granulocytes?
Neutrophils
Basophils
Eosinophils
Define spongiosis
Intercellular oedema in the epidermis
