Cell Injury & Adaptation Flashcards
Describe homeostasis.
-stabilize normal state
-ability to maintain internal equilibrium by adjusting its physiological process
Describe cell adaptation.
-when homeostasis is distorted by stress or pathological stimuli
-cells preserve viability & function
-reversible
-can by physiological (normal) or pathological (abnormal)
-5 types: atrophy, hypertrophy, hyperplasia, metaplasia, dysplasia
Describe atrophy.
-decrease in size & # of cells & metabolic activity after normal growth is reached
-cells aren’t dead
-decreased protein syn & increased protein degradation
Describe the causes of atrophy.
- Decreased workload
- Denervation
- Decreased blood supply or oxygen
- Inadequate nutrition
- Loss of endocrine stim
- Aging (senescence)
Describe atrophy examples.
- Muscle disuse
- Sedentary atrophy
- Atrophy of adrenal cortex by reduction of ACTH
- Atrophy in tissues adjacent to tumor bc pressure & compromised blood supply
- Physiologic atrophy (ex; non lactating mammary gland, post partum uterus)
- Serous atrophy of fat (heart, bone)
- Compression atrophy (hydrocephalus)
Describe hypoplasia VS atrophy.
- Hypoplasia = incomplete development or underdevelopment of organ/tissue
-less severe than aplasia
-congenital
-never achieved full size - Atrophy = diminution in size of a cell, tissue, organ or part that was properly developed
-decrease size bc decrease cell #
Describe aplasia VS abiotrophy (hypotrophy).
- Aplasia = lack of development of an organ or tissue
- Abiotrophy = progressive loss of vitality of tissue/organ leading to disorder or loss of function
-degen hereditary disease of late onset
Describe hypertrophy.
-increased size of cells -> increased tissue/organ size
>syn of more organelles & structural proteins = bigger cells
-more common in cells with little replication
>stable cells (bone, cartilage, smooth muscle)
>permanent cells (neurons, cardiac & skeletal muscle myocytes)
>LESS COMMON IN: labile cells (epidermis, intestinal epi, bone marrow) because they proliferate alot
Describe examples of physiologic hypertrophy.
-hypertrophic uterus = pregnant
-weightlifting
Describe hypertrophy mechanism.
Describe cardiac hypertrophy.
-adaptation to stress can progress to cell injury if stress is not relieved
-limit beyond which enlargement of muscle mass is no longer able to cope w increased burden -> regressive changes in myocardial fibers (lysis, loss of myofibrillar contractile elements) or even myocyte death in extreme cases
-pathological hypertrophy: hypertension, aortic valve disease
Describe physiological VS pathological causes of hypertrophy.
- Physiological
-increased workload
-hormone stim - Pathological
-increased resistance
-physical obstruction
Describe hyperplasia.
-increase in number of cells of an organ -> increased size of tissue/organ
-common in cells capable of replication
>labile cells (best)
>permanent cells (little capacity)
>stable cells (intermediate)
Describe physiologic hyperplasia examples.
-hormonal (mammary gland during pregnancy)
-compensatory (hepatectomy)
Describe pathological hyperplasia.
-caused by excessive hormonal or growth factor stim
-EX
>epi thickening due to repeated infection
>respiratory mucosa in viral infections
>gingival hyperplasia
>whippets
Describe whippets.
-mutation of myostatin gene (2 base pair deletion) = truncated, inactive, myostatin protein
>myostatin = protein made by myocytes that inhibit myocyte growth
-congenital muscular hyperplasia ‘double muscling’ = genetic disease causing a skeletal muscle defect (increased number of myofibers)
Describe metaplasia.
-change in phenotype of a differentiated cell
-resp to chronic irritation -> cell withstand stress
-results in: less function or high propensity for malignant transformation (neoplasia)
-reversible if cause is removed
-in epi cells
Describe metaplasia examples.
-chronic irritation in lungs (columnar -> squamous) squamous is more resistant
-vit A deficiency = keratization
-estrogen toxicity
-mammary tumors
Describe dysplasia.
-abnormal development (mostly epi)
-term used in neoplastic process
>synonym = ‘carcinoma in situ’
-alters shape, size, organization
