Cell Adaptation Flashcards
Types of adaptative morphological changes
- Hypertrophy (increase size)
- Atrophy (decrease size)
- Hyperplasia (increase number)
- Metaplasia (converting to different kind of cell -shape/function)
- Intracellular storage
- Apoptosis
What type of cells undergo hypertrophy?
Non-dividing cells (eg. myocytes, neurons)
Examples of physiological hypertrophy
- Skeletal Muscle - increased muscle activity on exercise
- Cardiac Muscle - sustained outflow in athletes
- Uterine Muscle - pregnancy
Hormonal:
- Testosterone and Oestrogen - sex organs during puberty
- Prolactin and Oestrogen - breast tissue for lactation
Examples of pathological hypertrophy
- Cardiac Muscle (left ventricle) - increased outflow pressure due to systemic hypertension, aortic valve disease
- Cardiac Muscle (right ventricle) - increased outflow pressure due to pulmonary hypertension, pulmonary valve disease
- Arterial smooth muscle - hypertension
Does the uterus undergo hyperplasia or hypertrophy during pregnancy
Both :)
What is the mechanism of hypertrophy in the heart
Mechanical - stretching
Trophic (Agonists) - angiotensin, a-adrenergic hormones
Growth factors - IGF-1
Is hyperplasia seen in non-dividing populations
No
Examples of physiological hyperplasia
Breast - puberty, pregnancy, lactation
Red cell precursors in bone marrow - high altitude
Skin - corns on feet due to persistent physical trauma
Thyroid - puberty, pregnancy (due to increased metabolic demand)
Examples of pathological hyperplasia
Prostate gland
Parathyroid gland - hypocalcemia
Endometrium - Oestrogen (precursor to endometrial carcinoma)
Thyroid gland - thyroid follicular cells undergo diffuse hyperplasia due to autoantibody effect on TSH in Graves Disease
HPV (skin, larynx, cervix)
How does hyperplasia occur
- Growth factor driven proliferation of mature cells
2. Increased output of new cells from tissue stem cells
Which organ can regenerate upon partial removal
Liver
Examples of physiological atrophy
Neonate - umbilical vessels and ductus arteriosus
Early Adulthood - thymus (thymic involution, peaks at childhood)
Old age - uterus, testes, brain, bone
Examples of pathological atrophy
Loss of function - muscle atrophy, osteoporosis
Loss of innervation - muscle atrophy and nerve transection
Loss of blood supply - skin atrophy or bedsores
Severe malnutrition
Loss of hormonal stimulation - hypopituitarism (adrenal cortex, thyroid, gonads)
Excess hormones - corticosteroids (skin)
Mechanisms of atrophy
- Decreased protein synthesis (because of reduced metabolic activity)
- Increased protein degradation (by ubiquitin-proteasome pathway cancer cachexia)
What is autophagy
Process in which starved cells eat its own components in an attempt to reduce nutrient demand to match the supply
What is the purpose of the ductus arteriosus
Normal fetal structure allowing blood to bypass circulation to the lungs by shunting flow from the pulmonary artery to the aorta
What happens if the ductus arteriosus does not close (Atrophy)
Patent Ductus Arteriosus
What causes pressure atrophy in the liver
Chronic right heart failure
How do tumours induce protein degradation in skeletal muscles (muscle wasting)
- Lipid-mobilising factor
- Proteolysis-inducing factor
What is brown atrophy
Lipofuschin graunules are residual bodies from the auttophagy process that impart a brown discolouration to the tissue (pigment accumulation)
What is the most common form of epithelial metaplasia
Columnar Epithelium changing to Stratified Squamous Epithelium (respiratory tract of smokers; stones in excretory duct of salivary gland, pancreas, bile duct)
What is Barrett’s Oesophagus
Squamous Epithelium changing to Columnar Epithelium
What is Myositis Ossificans
Mature lesion in the Connective Tissue that is completely ossified
3-6cm in dimension, well delineated, soft glistening centers, firm gritty periphery
Cause: trauma (more than 50%)
Treatment: simple excision
Types of Squamous Metaplasia
- Ciliated Pseudostratified Columnar Epithelium of Respiratory Tract (Smoking, chronic bronchitis)
- Simple Columnar Epithelium of Endocervix (Changes in pH, injury, inflammation)
- Transitional Cell Epithelium of bladder (Schistosomal infection, Bladder Calculi)
