Lectures 9 & 10 - Basis of Disease I & II Flashcards
What is pathology?
Study of the structural and functional changes in cells, tissues, and organs of the body that cause or are caused by disease
What is pathophysiology?
Not only cellular and organ changes that occur with disease, but also the effects that these changes have on total body function
What 2 factors impact the cell’s response to stress?
- Duration of stress
2. Intensity of stress
Are cellular adaptations to stress reversible?
YUP
What are 5 cellular adaptations to stress?
- Atrophy
- Hypertrophy
- Hyperplasia
- Metaplasia
- Dysplasia
Describe atrophy.
Decrease in the size of a tissue resulting from a decrease in cell size or in the number of cells
6 causes of atrophy?
- Disuse
- Loss of trophic stimuli
- Insufficient nutrients
- Decreased blood flow
- Persistent cell injury
- Aging
Describe hypertrophy.
Increase in cell size, and thus an increase in the amount of functioning tissue mass
Involves an increase in the functional components of the cell that allow it to achieve equilibrium between demand and functional capacity
Cause of hypertrophy?
Results from an increased workload imposed on an organ or body part
Describe hyperplasia.
Increase in the number of cells in an organ or tissue and can only occur in tissues that are capable of mitotic division
Controlled process that occurs in response to an appropriate stimulus and ceases after the stimulus has been removed
Physiologic hypertrophy examples?
- Exercise
2. Pregnancy: breasts, uterus
Pathophysiogic hypertrophy example?
Kidney transplant: compensatory hypertrophy
Describe metaplasia.
One adult cell type is replaced by another adult cell type
Thought to involve the reprogramming of undifferentiated stem cells that are present in tissue
Cause of metaplasia?
Usually occurs in response to chronic irritation and inflammation which allows for substitution of cells that are better able to survive
Describe dysplasia.
Characterized by deranged cell growth of a specific tissue that results in cells that vary in size, shape, and appearance
Involves sequential mutations in proliferating cell populations
Strongly implicated as a precursor of cancer
Where is dysplasia most frequently encountered?
Metaplastic squamous epithelium of the respiratory tract and uterine cervix
2 examples of pathophysiologic metaplasia?
- Trachea and bronchial tree ciliated columnar cells to stratified squamous cells in response to smoking
- Chronic GERD: epithelial cells of esophagus turn into gastric epithelial cells
Why is dysplasia often thought of as irreversible (even though it is not)?
Because the stressors causing dysplasia are often very hard to remove (e.g. HPV)
What does cell stress lead to?
- Adaptation
OR - Cell injury
Can cell injury be reversible?
YUP, but not always
7 causes of cell injury?
- Mechanical forces
- Electrical injuries
- Nutritional imbalances
- Biological agents
- Poisons and chemical agents
- Hypoxia
- Extremes of temperature
How does heat affect cells?
- Accelerates cell metabolism
- Inactivates temperature sensitive enzymes
- Disrupts the cell membrane
- Coagulation of blood vessels
- Coagulation of tissue proteins
How does cold affect cells?
- Increases blood viscosity
- Induces vasoconstriction (SNS)
- Ice crystal formation
- Capillary stasis
- Arteriolar and capillary thrombosis
Is there a safe level of lead in the body?
NOPE
4 effects of high levels of lead in the body?
- Mental retardation
- Coma
- Convulsions
- Death
4 effects of low levels of lead in the body?
- Reduced IQ and attention span
- Impaired growth
- Reading and learning disabilities
- Hearing loss
Can lead cross the blood-brain barrier? Why/why not? What to note?
YUP because cannot tell the difference between lead and calcium
It also damages it
What other parts of the body does lead affect other than the CNS?
- Causes an increase in ROS, and a decrease in antioxidant systems
- Glomerular fibrosis and proximal tubule mitochondrial damage
How do agents causes cell injury?
- Some agents (like heat) produce direct cell injury
- Some agents (like genetic derangement) produce their effects indirectly through metabolic disturbances and altered immune responses
3 common causes of cell injury?
- Depletion of ATP
- Free radical formation
- Disruption of intracellular calcium homeostasis
How does the depletion of ATP injure the cell?
- Na+/K+ ATP-ase failure so the RMP is disturbed => membrane depolarization => increase in intracellular Ca++ and Na+ => cellular swelling => lysis
- Switch to anaerobic metabolism => increase in lactic acid => decrease in cellular pH => lysing of lysosomes => lysosymes released => lysis
Is cellular swelling reversible?
YUP
What is the ischemic reperfusion cell injury?
Reperfusion of an ischemic tissue is more damaging than the ischemia itself
Ischemia => inflammation due to chemokines and ROS released by endothelial cells => reperfusion causing massive inflammatory response
On what organ are experiments studying ischemic reperfusion injuries done? Why?
Kidneys because the kidney only has one arterial blood supply to it’s easy to cause ischemia