Altered Cells And Tissues Flashcards
Cellular Adaptation
-Cells adapt to changes (stressors) in their environment
-They increase glucose absorption when their glucose stores are low
-They initiate repair mechanisms when they are damaged
-When cells are damaged they can either adapt or die
Cell Injury Common Causes
-inadequate oxygen
-chemical, thermal, or physical agents
-ionizing radiation
-toxins
-microbes
-inflammation and immune reactions
-nutritional imbalance
-genetic and metabolic defects
-aging
Cell Injury - Inadequate Oxygen
-Usually result of ischemia
-Inadequate blood flow doesn’t just effect oxygen delivery but also transport of glucose for fuelling cells and removal of metabolic waste products like CO2
Cell Injury: Physical, Thermal, Chemical
-These can be anything from a high speed MVA to frostbite to industrial accidents
Cell Injury: Ionizing Radiation
-X ray or gamma rays may damage DNA or cause proteins to midfield in the cell
Cell Injury: Toxins
-Depending on the toxin, they can damage enzyme pathways in your cells or destroy the membranes of your cells
Cell Injury: Microbes
Could be bacteria, yeasts, moulds, and viruses
Cell Injury: Inflammation and immune reactions
-If you have an autoimmune disease that causes your own antibodies to cross react and attack your own cells
Cell Injury: Nutritional Imbalances
-This can be considered anything from scurvy due to lack of vitamin C to chronic excess sugar in your diet leading to type 2 diabetes
Cell Injury: Genetic and Metabolic Defects
-Some genetic diseases cause the accumulation of abnormal products, which can damage cells
Cell Injury: Age
-aging causes progressive, mild injury that ultimately leads to cell death directly or renders cells less able to withstand other forms of injury
Cell Injury
-Injury may occur anywhere within the body’s structural hierarchy
-Genes influence how we react to injury
-Impaired health may result from the inflammation and repair process that follows injury
-Cells will react differently based on different injuries
If cytoskeleton is damaged ..
Then cell with make an enzyme or increase it’s concentration to repair it
If DNA is damaged..
Then the cell will run another program to make a different enzyme to detect the change and correct it
If damage is too extensive ..
-or not enough raw materials are around like glucose, oxygen, amino acids, etc
-then cell isn’t going to be able to fix itself
-May result in inflammation or even cell death
Examples Acute Mild Injury
Hydronic change
Steatosis
Examples Chronic Mild Injury
Intracellular accumulations
Altered growth and differentiation
Not all injured cells ___
Die
-some are able to survive but may exhibit physiological changes
-these changes may be reversible or permanent depending on type and extent of injury
Whether or not cell injury is reversible depends on
-the duration and severity of injury or stress
-mild injuries produce visible, reversible changes in cells which reverts to normal when the cause of injury disappears
-long term mild injury or stress leads to changes that persist until the cause of the injury disappears
Acute Mild Injury Causes
-Brief, visible cell change
Most Common Cause of Acute Mild Injury
-Most common cause is brief hypoxia or anoxia though toxins may exert a similar effect
-Two most common types of injury or stress are 1) hydropic change 2) steatosis
Hydropic Change
-Eg Congestive heart failure
-Occurs because of change in intracellular sodium concentration
-Normally extracellular sodium is higher than intracellular sodium
-This concentration difference is maintained by the sodium pump mechanism of cell membrane which constantly pumps sodium out of the cell as fast as it seeps in
-Lack of oxygen deprives pump of its energy (ATP) damaging this mechanism and allowing sodium to seep across the membrane and into the cytoplasm
-Because solutes attract water, a rise in intracellular solute (sodium) attracts water into the cytoplasm
Hydropic change is ___
Reversible if the injurious situation is corrected
Steatosis
-Eg Fatty Liver (accumulation of fat in the cell)
-Most common in liver cells because of the livers premier role in fat metabolism
-often in people who abuse alcohol
-now more common in young adults and children due to obesity
Steatosis is ___
Reversible
-However chronic steatosis of the liver can progress to cirrhosis and liver failure
Common types of Chronic Mild Injury
-Two most common types of cell response to common mild injury or stress are intracellular accumulations and altered patterns of cell growth and differentiation
Types of Intracellular Accumulations
-Cholesterol
-Protein
-Pigment
-Environmental Particles
Intracellular Accumulations
-Water and fat accumulate within reversibly injured cells as a result of mild short term injury
-More prolonged injury is associated with other accumulations, including cholesterol, protein, pigment, and various environmental particles
Intracellular Accumulations: Cholesterol
-Eg. Atherosclerotic artery
-Low density lipoproteins or very low density lipoproteins carry cholesterol from your liver to your fat cells
-if too much LDL or VLDL in your blood stream then can bind and buildup in areas they shouldn’t and begin narrowing arteries causing atherosclerosis
-still don’t know why this happens
Intracellular Accumulations: Proteins
-Normal body proteins are long chains of amino acids that must be folded into appropriate shape for their function
-When they are damaged and fold inappropriately they may clump together and accumulate
Protein Accumulation Example
-Tau protein accumulation in Alzheimer’s disease
-Tau normally stabilizes microtubules which form the cytoskeleton in cells
-During cell stress or damage tau can be released, misfolded and bind to other tau molecules clumping together
-Too much clumps inside the cell and the cell can’t transmit neurotransmitters for instance and died, usually via apoptosis
-Theory for developing Alzheimer’s disease
Other Protein Accumulation Examples
-Include most of the other Neuro degenerative disease
-Include: Huntington’s, Parkinsons, and ALS as well as many other diseases such as the buildup of alpha 1 antitrypsin in the liver of patients with genetic alpha 1 antitrypsin deficiency mutation which can result in in COPD and liver cirrhosis
Pigment Intracellular Accumulations
-Most widely occurring pigment accumulation is lipofuscin
-Golden brown substance most notable in long lived cells such as brain neurons, cardiac myositis, and liver hepatocytes
-It’s presence indicates wear and tear
-End result of fatty acid oxidation in lysosomes associated with many diseases from Parkinson’s to COPD
-It May be symptomatic of membrane damage, or damage to mitochondria and lysosomes
Other Pigment Accumulation Examples
-Bilirubin in jaundice (often due to liver diseases, gallstones, pancreatic tumours, etc)
-Melanin (used by skin keratinocytes to protect against UV damage; tanning)
Cellular Accumulation Environmental
-Inhaled particles from cigarette smoke or air pollution accumulate in respiratory cells and bronchial lymph nodes and contribute to a variety of resp diseases
Types of Altered Cell Growth and Differentiation
-Atrophy
-Hypertrophy
-Hyperplasia
-Metaplasia
-Dysplasia