Cell injury/death, inflammation/immune response Flashcards
Etiology
Cause
Pathogenesis
sequence of cellular or tissue events in response to the etiologic agent, from initial stimulus to the ultimate expression of the disease
morphologic changes
structural alterations in cells and organs of the body that characterize the disease or are diagnostic of the etiologic process
clinical significance
functional consequences of the morphologic changes
Cell Adaptations
hypertrophy: increase in size (Myocardial fibers)
atrophy: shrink or decrease in size
hyperplasia: increase in number of cells/increased rate of cellular division
Metaplasia: reversible change in which one adult cell type is replaced by another adult cell type (can result in neoplasia)
Cell Injury
cause and types
Causes: hypoxia, physical or chemical agents and drugs, infectious agents, immunological reactions, genetic defects, nutritional imbalance, aging
Types: metaplasia (reversible)
(irreversible): disturbance in cell membrane and cell wall, mitochondrial dysfunction
What happens to the cell when it is injured and dies?
-ATP depletion
-decreased ATP synthesis
anaerobic metabolism and acidosis
-number of Na/K pumps decrease
more Na in cell pulls more water
-dilation of ER causes decreased protein synthesis
-accumulation of free radicals with not enough
antioxidants
-Ca influxes which causes more damage and can
cause cell death/catabalize cell membrane
-Mitochondrial damage and loss of membrane integrity results in cell death
-apoptosis (cell eats self)
What are the two types of cell death?
Necrosis:
- abnormal and not regulated
- loss of membrane integrity
- stimulates inflammation (increase leukocytes triggers lysosomes to release enzymes for digestion of cell substances)
Apoptosis:
- normal and regulated (can become abnormal in disease)
- physiological (cell no longer needed) or pathological (cell is threat)
- contents of cell shrink, membrane remains intact and does not stimulate inflammation
What are free radicals?
chemicals that have a single unpaired electron in outer orbit (unstable!)
produced during mitochondrial respiration
cause cell damage by reacting with nucleic acids, and other cellular proteins and lipids
What are the two types of oxygen derived free radicals?
- Reactive Oxygen Intermediates (ROS)
types: O2 superoxide H2O2 hydrogen peroxide
OH hydroxyl radical
produced in phagocytic leukocytes and mainly macrophages and neutrophils - Nitric oxide Intermediates (NOS)
produced by leukocytes and other cells
types: physiological {endothelial (eNOS), neuronal (nNOS),}
non-physiological {inducible (iNOS)}
What free radical causes the most damage?
OH hydroxyl radical
What regulates free radicals?
Antioxidants (physiological substances that protect the body against damage from chemical reactions caused by free radicals)
Function: bind to and break down free radicals by enzymes
block formation
bind to ions to take free radicals away and out of cell
repair damage they cause in cell
Types of Antioxidants
catalase (enzyme from perioxisomes organelle) superoxide dismutase (SOD) gluthione peroxidase (GSH) CoQ10 Vitamin E, A, C, and Beta-Carotene Synthetic Ones (dopamine and other meds)
What is oxidative stress?
When the balance between free radicals and antioxidants is off and there is more free radicals than antioxidants.
Which NOS is the problem/causes damage?
iNOS is induced by inflammatory cytokines and responsible for production of NO in inflammatory reactions; also critical for wound healing
What is the role of the three NOS?
vascular smooth muscle relaxation, vasodilation
antagonizes platelet activation
decreases leukocyte recruitment
microbicidal agent
Where do all blood cells reside?
stem cell pool, bone marrow pool, and peripheral blood pool