Cell Injury and Adaptation Flashcards
What are the 5 minor types of adaptation?
- Atrophy
- Hypertrophy
- Hyperplasia
- Metaplasia
- Dysplasia
What is atrophy?
Decrease in size or number of cells
- cells are not dead
** organ/tissue reached normal growth but then decreased in size
What are causes of atrophy?
- Decreased workload
- Denervation
- Decreased blood supply or oxygen
- Malnutrition
- Aging
- Loss of endocrine stimulation
What are examples of physiological atrophy?
Non lactating mammary gland
post partum uterus
- they aren’t being used so it decreases size
What is hypoplasia?
incomplete development or underdevelopment
** congenital condition
What is aplasia?
lack of development, organ or tissue doesn’t develop at all
What is hypotrophy? What is another name for hypotrophy?
Progressive loss of vitality of certain tissues or organs
Also called abiotrophy
What is an example of physiological hypertrophy?
- Hypertrophic pregnant uterus
- Exercise/Increased workload
**normal, physiological increase in size of cells and organs
What are examples of physiologic hyperplasia?
Hormonal - mammary gland during pregnancy
Compensatory- hepatectomy
**liver cells replicate to form new liver tissue
What most commonly causes pathologic hyperplasia?
Excessive hormonal or growth factor stimulation
Ex: Epidermal thickening - repeated irritation
Ex: Respiratory mucosa - in viral infections
What are examples of metaplasia?
- Chronic irritation in lungs (smoking)
- Vit-A deficiency
- Estrogen toxicity
- Mammary tumors
** seen on histo not GE
What are causes of cell injury?
- BacT, Fungi, Viruses (infectious agents)
- Hypoxia or anoxia
- Immune mediated diseases
- Genetics
- Aging
- Toxicity
What are the consequences of aortic thromboembolism in cats?
Anoxic damage to muscles of the hind limbs
What are the mechanisms for cell injury?
- Depletion of ATP
- Mitochondrial damage
- Entry of Ca+
- Oxidative stress ( increase in ROS)
- Membrane damage
- DNA and protein damage
What happens when there is ATP depletion?
- Failure of Na/K pump - salt stays inside cell and H20 follows causing CELL SWELLING
- Switch from aerobic to anaerobic glycolysis - makes lactic acid which makes acidic pH
- Detachment of ribosomes - decreased protein synthesis
What are the major consequences of mitochondrial injury?
- Forms mitochondrial permeability transition pore (MPTP) - leads to decreased ATP
- Production of ROS - released from mitochondria bc of altered membrane potential due to MPTP
- Activation of apoptosis - proteins leak out and cause cell death
leads to cell necrosis + cell death
What happens when Ca homeostasis is lost?
- Opens MPTP
- Activates enzymes: phospholipases, proteases, endonucleases, ATPases
** both cause ATP depletion leading to cell injury
The accumulation of Ca+ can cause these 3 major forms of cell damage:
- Membrane damage
- Nuclear damage
- ATP depletion
What is a physiological example of when ROS are produced?
Normally produced during cellular respiration by mitochondria
** normally removed by scavenging mechanisms (Vit A and Vit E remove ROS)
How can cell injury result from ROS?
Increased production causes oxidative stress and decreased scavenging
What are normal ways the body removes/neutralizes ROS?
Antioxidants like Vitamin A + E and glutathione
What are pathological sources of ROS?
- Inflammation
- Transition metals
- Nitric Oxide (NO)
- Absorption of radiant energy
What is the result of ROS?
- Lipid peroxidation in membranes - membrane damage
- Oxidative modification of proteins
- DNA damage - Lesions in DNA
Why do cells adapt?
To preserve function and viability
