Exam 1:cell injury Flashcards
cell injury
what is etiology
-causative mechanisms
-the why of the disease/what caused it to happen?
-it can be be simple, complex, unknown/idiopathic (cryptogenic) or iatrogenic “occurred as a result of a medical/surgical intervention”
an example iatrogenic etiology
vaginitis caused by candida albicans as a result from a tx with abx
epidemiology
risk factors and distribution in populations
(i.e. age, ethnicity, socioeconomic status, geographic location and incidence and prevalence of the disease)
incidence
number of new cases occurring in a given population within a given time period
(Down syndrome in US is 1 in 690 births (1/690x 100=0.14%)
prevalence
number of cases existing in both old and new
(Down Syndrome in US is 400,000 for a population of about 314 million=0.13% (400,000/314,000,000x100=0.13%)
pathogenesis
disease mechanisms, sequence of events that occurs between the stimulus events and the manifestations of the disease
(i.e pharyngeal infection- it involves what occurred physiologically and pathologically between the time that the patient encountered the infecting organism an appearance of clinical manifestations)
clinical manifestations
signs, symptoms, and diagnostic criteria
-physical signs/findings are usually related to the outcome of a physical examination or assessment
-symptoms or subjective
outcomes
cure, remissions, chronicity or death
-primary: directed towards preventing the initial occurrence of a disorder
-secondary/tertiary: seek to arrest or retard the existing disease and its effects through early detection and appropriate tx/reduce the occurrence of relapse and establishment of chronic conditions
(i.e. rehab)
causes of cell adaptation
-may be physiologic (disappears when the stressors removed) or pathologic (remain when stressor is removed)
-cell may be neither injured or killed by stressors, rather they adapt to changes, they change size, number and characteristics
-Atrophy
-Physiologic
-Pathologic
what happens in the cell during atrophy
decrease or shrinkage in cell size, the whole organ can shrink if enough of the cell do
an example of cell atrophy d/t physiologic change
with early development, like the thymus gland atrophies during childhood
cell atrophy during pathologic change
-occurs as a result of decreased workload, use, pressure, blood supply, nutrition, hormonal/nervous stimulation: immobilized people with skeletal muscle disuse atrophy
what are the mechanisms of atrophy
decreased protein synthesis/increased protein degradation, or both
what happens to muscles if you dont use it
it atrophies: less ER mitochondria, myofilaments
what happens in nerve loss
decrease o2 and AA uptake
what is cell hypertrophy?
increase in size of cells that consequently increases size of affected organ
what causes physiologic change during cell hypertrophy and give an example
- Physiologic: caused by increased demand in stimulated by hormones and growth factors, in skeletal muscles response to heavy work
i.e. Pregnancy and hormone induced uterine enlargement
Example of pathologic change that causes cell hypertrophy
- chronic hemodynamic overload (HTN/heart valve dysfunction)
what causes the left ventricle of the heart to hypertrophy?
increase blood pressure
what does cardiac hypertrophy trigger?
-mechanical signals (like stretch) and trophic signals (like growth factors and vasoactive agents)
o Stretch: triggered from increased workload- can increase production of growth factors and vasoactive factors (eg. angiotensin)
o Membrane sensors activate pathways and trigger transcription factors to increase synthesis of muscle proteins
o Initial enlargement: dilation but is short lived -> increased muscle proteins for muscle fibers to do more work
o Nucleus increases DNA synthesis: cell size associated with cellular component increase not cell fluid
o Eventually, cardiac hypertrophy = increased growth of adult myocytes
what can prolonged hypertrophy cause to the heart
contractile dysfunction, decompensation and then heart failure
what is cell hyperplasia
-an increase in the number of cells in an organ or tissue that is still capable of mitotic division.
Response to severe and prolonged injury
Production of growth factors stimulate remaining cells to make new components and divide, also can be from increased output of new cells from tissue stem cells
physiologic cause of cell hyperplasia (2)
- compensatory hyperplasia and hormonal hyperplasia
o Compensatory: adaptive mechanism that enables certain organs to regenerate (liver renews self by duplicating differentiated cells, callus forming on skin, inflammatory response)
o Hormonal hyperplasia: mostly in estrogen dependent organs like uterus and breast (uterus enlarges during pregnancy
pathologic cause of cell hyperplasia
- abnormal proliferation of normal cells and can be in response to excessive hormone stimulation or growth factors on target cells
o Hyperplastic cells are identified by pronounced enlargement of the nucleus, clumping of chromatin, and the presence of one or more enlarged nucleoli (endometrium hyperplasia d/t imbalance of estrogen and progesterone and causes excessive menstrual bleeding, BPH)
what is metaplasia
- reversible replacement of one mature cell type by another less differentiated cell type
- Associated with tissue damage, repair, and regeneration
- Replacement cell might be more suitable for change in conditions
(i.e.GERD damages squamous epithelium and are replaced by glandular epithelium to better tolerate the acid or smoker trachea epithelial cells replaced by stratified squamous- do not secrete mucus or have cilia (worse))
what is dysplasia
- abnormal changes in size, shape, and organization of mature cells
o maladaptation; deranged cell growth and differentiation within a specific tissue; results in cells that vary in size shape, and appearance and is a precursor of cancer
o Not considered a true adaptive process
o Related to hyperplasia and often called atypical hyperplasia
o Mostly in epithelia
o Dysplasia: NOT cancer and doesn’t lead to cancer
o Can be reversible if does not involve entire epithelial thickness and stimulus is removed
how does cell injury occur?
if the cell is stressed or unable to maintain homeostasis, can recover or die
what does cell injury and cell death result from? (4)
- from toxic chemicals, infections, physical trauma, and hypoxia
Ex. of cell injury are (1) ischemic and hypoxic injury, (2) ischemia-reperfusion injury, (3) oxidative stress or accumulation of oxygen-derived free radicals–induced injury, and (4) chemical injury.
what is the basis for most disease today?
impaired ATP production
what happens to cells with impaired ATP production? give example
cell cannot produce adequate energy in the form of ATP to fuel normal activities of that particular cell type - Example: hypoxia- insufficient oxygen the aerobic phase cannot progress and ATP production declines and hypoglycemia- the anaerobic portion of ATP relies on the adequate glucose from glycolysis, if glucose is m issing ATP production stalls
list examples of direct cell membrane damage (5)
- free radicals (reactive oxygen species)
- activation of the complement system
- lysis by enzymes
-lysis by viruses - physical/ chemical stressors
what are free radicals
unstable compounds with an unpaired electron in its outer ring, this makes free radicals anxious to mate with other substances and they have a particular affinity for lipid substances (which is what cell membranes are made of)
what happens during activation of the complement system
during acute inflammation activated complement proteins can cause destruction of the normal cell membrane
what happens during lysis by enzymes?
allowing organisms to dissolve surrounding tissue and allows them to move deeper into the tissues, blood and lymphatics
what happens during lysis by virus
certain viruses once they have infected a cell will cause membrane rupture as newly produced viral particles leave the host
- example would be a HIV or Hep B)
