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- Cells change to
- - Adapt to a new environment
- - Escape
- - Protect themselves
- Cell types adapt in very specific ways
- - Muscle vs epithelium
- - nerves
- - Connective tissue
it can be a pathological response and functional response
- Atrophy is a decrease in cell size
- - may even result in the complete loss of cells
- - it is a sign of pathophysiology rather than a successful adaptation
- Usually caused by disease or ischemia
- - reduced blood supply--> reduced oxygen and glucose to tissues --> cellular shrinkage and death
- May also result from:
- -diminished nerve stimulation
- -poor nutrition
- -other diseases (e.g. Alzheimers disease in brain)
- Increase in the mass of cell but not in number of cells
- Increase in the number of muscle proteins (not fluid) to allow muscle fibers to do more work
- Common tissues
- -Cardiac muscle
- -Skeletal muscle
___________ is an increase in size of the cell and consequently in the _____ of the affected organ.
True or False
Hypertrophy can be physiologic or pathologic
it is caused by specific hormone stimulation or by increased functional demand
What are the signals for hypertrophy?
Mechanical signals- for ex. strech
Trophic signals- such as growth factors, hormones, and vasoactive agents .
- Increase in the number of cells of a tissue or organ from an increased rate of cell division.
- The cells involved must have mitotic ability
- In any given organ, its possible for its possible for both hyperplasia and hypertrophy to occur
- -Uterine muscle enlargment during pregnancy (hypertrophy)
- -Hyperplasia of the uterine endometrium during pregnancy (and also during every menstrual cycle)
True or False
hypertrophy only occurs in nondividing cells.
an adaptive mechanism that enables certan organs to regenerate
Example: removal of part of the liver leads to hyperplasia of the remaining liver cells (hepatocytes) to compensate for the loss
Occurs chiefly in estrogen-dependent organs, such as the uterus and breast.
the abnormal proliferation of normal cells, usually in response to excessive hormonal stimulation or growth factors on target cells
- An adaptive substitution to a different, "hardier" cell line
- - usually changes to a hypertophied or hyperplastic tissue
- Example: Replacement of ciliated columnar epithelium with stratified squamous epithelium in the respiratory tract of a smoker
- These precursor cells mature along a new pathway because of signals generated by growth factors in the cell's environment.
- A change to an abnormal cell line
- - Dysplastic cells are not normal and not found anywhere in the body
- - This is a precancerous change
- Characterized by atypical changes in the size, shape, and appearance, and of the cells (atypical hyperplasia)
- Caused by persistent injury or irritation progressing towards neoplasia (new, abnormal proliferation of cells)
- Examples of the precancerous changes of dysplasia
- -cervical dysplasia from human papiloma virus (HPV)
- -bronchial dysplasia from smoking
- Lead acts like iron, calcium and zinc
- Interferes with neurotransmitters in the CNS
- - May cause wrist, finger and foot paralysis in the peripheral nervous system
- Interferes with hemoglobin synthesis
- Accounts for a significant number of childhood poisonings
- - sources include paint, dust and soil, contaminated tap water, dyes, pottery glaze, gasoline.
Cell injury by Toxic Chemical Agents
- can be caused by direct contact of the chemical, with molecular components of the cell, formation of free radicals, or lipid peroxidation.
- -for example, carbon monoxide (CO)has a very high affinity for Hgb
- -CO is colorless and odorless
- -CO causes nausea and vomiting, headache, weakness, & tinnitus (ringing in the ears)
In what ways do cells become injured?
- Membrane permeability changes
- Interruption of oxidative metabolism (ATP production)
- Diminished protein synthesis
- Leakage of digestive enzymes
True or false
If two people are exposed to the same stimulus, they will incur the same degree of cellular damage.
What is tissue hypoxia?
- When cells are deprived of oxygen (hypo= low, oxia= oxygen)
- probably the most common cause of a non-adaptive cellular injury
What can cause hypoxia?
- Low levels of oxygen in the air
- Poor or absent hemoglobin function (hypoxemia = low oxygen blood)
- Respiratory or cardiovascular diseases
- Ischemia- reduced supply of blood, which carries oxygen
True or false
The reduction of oxidative metabolism causes ATP to decline.
- -this decreases Na+/K+ pump activity
- -Na+ begins to accumulate in cells
- -Water follows Na+ and also accumulates in cells
- -Intracellular K+ decreases, approaching levels outside the cell
- most common form of hypoxia
- injury often caused by the gradual narrowing of arteries(arteriosclerosis) and complete blockage by blood clots (Thrombosis)
- total lack of oxygen
- caused by a sudden obstruction, as with an embolus (a blood clot or other plug in blood circulation)
- an atom or molecule that has an unpaired electron that makes the atom very unstable and active
- to gain stability, the radical gives up or steals and electron
- Super oxide ion (O2-)
- Hydroxyl (OH)
- Peroxinitrite (ONOO-)
True or False
Free Radicals are easy to control.
Free Radicals are difficult to control and initiate chain reactions
Free Radical formation
- Formation of free radicals
- -normal metabolism, ionizing radiation, drug metabolism
- Mechanisms of injury:
- -Lipid peroxidation- destruction of unsaturated fatty acids by free radicals
- -Protein destruction- Fragmentation of polypeptide chains and denaturation
- -DNA alteration- breakage of DNA strands
how are free radicals inactivated ?
- -Block synthesis or inactive free radicals
- -vit E, Vit C,albumin, ceruloplasmin (carries copper), and transferrin (carries iron)
- -Superoxide dismutes (SOD)
- -Glutathione peroxidase (GPx)
- Forma of alcohol found in mood-altering beverages
- In the liver, ethanol is converted to acetaldehyde which is toxic in the liver (Free radical damage)
- This toxicity lead to deposition of fat, hepatomegaly, interruption of protein transport, decreased fatty acid oxidation, increased membrane rigidity, and liver cell necrosis
_______-_______ injuries are mechanical injuries resulting in tearing, _______, or crushing of tissues.
True or False
The most uncommon blunt injuries are caused by falls and auto accidents.
the most common blunt injuries are caused by falls and auto accidents.
What are the different forms of Trauma?
- incised wound
- Gunshot wound
Bleeding into the skin or underlying tissue
- A collection of blood in an enclosed space
- -subdural & epidural hematomas in the skull
- - compartment syndrome
Removal of the superficial layers of the skin caused by contact between the skin and the injuring object
a rip or tear when the elasticity of the skin or tissue will not hold up to the pressure applied by injuring object
A cut that is longer than it is deep
A cut that is deeper than it is long
How does a stab wound compare to a puncture wound?
There will be more tearing with a puncture wound, where a stab wound will have smoother edges
Gun shot Wound (GSW)
- Can be penetrating: bullet remains in the body
- or perforating: bullet exits the body
When do asphyxial injuries occur?
due to failure of airflow or oxygen to the lungs
What are the categories of Asphyxiation?
- Oxygen failing to reach the blood
- results from a lack of oxygen in the environment
- -entrapment in and enclosed space or filling of the environment with a suffocating gas
- - or a blockage of the external airway
- caused by compression and closure of the blood vessels and air passages resulting from external pressure on the neck
- This causes cerebral hypoxia or anoxia
- either prevent the delivery of oxygen to the tissues or block its utilization
- Carbon monoxide is the most common chemical asphyxiants
- an alteration of oxygen delivery to tissue resulting from the inhalation of fluid, usually water.
- The major mechanism of injury is hypoxemia (low blood oxygen levels)
- For adequate cellular function and integrity, adequate amounts of proteins, lipids & carbohydrates are required
- - Low levels of plasma proteins, like albumin, encourage movement of water into the tissues, causing edema
- - Hyperglycemia and hypoglycemia
- Vitamin deficiencies
- Extreme Temperatures
- Atomospheric pressure
- Water pressure
- ionizing radiation
- Hypothermia: vasoconstriction, ice crystal formation causing cellular swelling
- Hyperthermia: loss of fluids and plasma protiens
Blast injuries: compressed waves of air, Thorax collapses; organ hemorrhage and rupture
- Causes nitrogen to dissolve in blood
- When pressure removed, nitrogen is released and forms gas emboli.
- Electron removal from active cells
- DNA is mos vulnerable target
Acute loud noise or cumulative effect
- also known as infiltrations
- An important manifestation of cell injury is the intracellular accumulation of abnormal amounts of various substances and the resultant metabolic disturbances.
The two categories of substances produces by accumulation are:
- Normal cellular substance: excess water, proteins, lipids, and carbohydrates
- Abnormal substance: either endogenous (such as a product of abnormal metabolism or synthesis) or exogenous (infectious agents or a mineral)
The types of cellular accumulations are :
- Cellular swelling: the shift of extracellular water into the cells.
- The metabolic failure cased by hypoxia, reduced levels of ATP and ATPase permit sodium to accumulate in the cell while potassium drifts outward. The increased intracellular sodium concentration increases osmotic pressure, drawing more water into the cell.
- Cellular swelling is reversible and is considered sublethal. it is an early manifestation of almost all types of cellular injury, including severe or lethal cell injury.
Lipids and Carbohydrates
- These may accumulate throughout the body but are most commonly found in the spleen, liver, and CNS (can cause neurologic dysfunction & severe mental retardation)
- The most common site for intracellular lipid accumulation, for fatty change, is liver cells.
- As lipids fill the cells, vacuolation pushes the nucleus and other organelles aside. The livers outward appearance becomes yellow and greasy.
- Alcohol abuse is one of the most common causes of fatty liver.
- Intracellular accumulations of glycogen are seen in genetic disorders called glycogen storage diseases and in disorders of glucose and glycogen metabolism
- As with water and lipid accumulation, glycogen accumulation results in excessive vacuolation of the cytoplasm
- The most common cause is the disorder of glucose metabolism, diabetes mellitus