Altered Cellular Biology and Function Flashcards
What is the importance of cellular function?
- movement
- Conductivity
- Metabolic absorption
- Secretion
- Excretion
- Respiration
- Reproduction
- Communication
What is needed to cellular survival and reproduction?
- energy for cellular metabolism
- material for amino acids, proteins, lipids, water, ions, and other essentials
- signals: cell to cell adhesion, cellular communication and signals
Atrophy
decrease in cell size
Hypertrophy
increase in cell size
Hyperplasia
increase in number of cells
Metaplasia
reversible replacement; replacement of one cell with another cell
Dysplasia
change in size, shape and organization
How can cell damage or injury occur?
- may be lethal or sub lethal
- due to chemicals, hypoxia, free radicals, immune, inflammation
- injury may be intentional (therapeutic) or unintentioal
- impact of modifying of modifying factors
What is hypoxia?
lack of sufficient oxygen in environment»_space; inability to get O2 to cells»_space; dysfunction of cytochromes
What are cytochromes?
redox-active proteins containing a heme, with a central Fe atom at its core, as a cofactor. They are involved in electron transport chain and redox catalysis
What happens when a cell has hypoxia?
Insufficient O2 in environment»_space; inability to get O2 to cells»_space; dysfunction of cytochromes
What happens to the mitochondria when there is hypoxia?
-change in membrane permeatility, loss of membrane potential, and decrease in ATP
**What happens during hypoxia with calcium influx injury?
-calcium ions are critical mediators of cell injury; usually maintained at low concentrations in the cell’s cytoplasm; thus ischemia and certain toxins can initially cause and increase in the release of calcium from intracellular store and later increase the movement across the plasma membrane
What is ischemia or reperfusion?
Anoxia-no oxygen
What happens during ischemia?
- cell membrane is damage
- Mitochondrial calcium overload
- high ATP consumption
- generation of highly reactive oxygen intermediates (oxidative stress)
What is a free radical?
- and uncharged molecule having an unpaired valence electron
- unstable molecule
What is oxidative stress?
- an imbalance between production and accumulation of oxygen reactive species (ROS) in cells and tissues and the ability of a biological system to detoxify these reactive products.
- ROS overwhelms the antioxidant system
- causes more damage to mitochondria and cell membrane
Example free radicals (aka reactive oxygen species aka ROS)
A singlet oxygen, hydrogen peroxide, superoxides, nitric oxide, and hydroxly anions
What is an antioxidant?
substances that may protect your cells against free radicals
What happens to a cell during a a chemical injury?
- damage to cell membrane
- cellular edema»_space; calcium enters cell»_space; mitochondria swells»_space; ATP decreases»_space;intracellular pH decreases and electrolytes become altered»_space; lysosomes break down»_space; organelles are destroyed
Examples of chemical injury?
- drugs
- metals: lead and mercury
- ethanol
- carbone monoxide
What are examples of physical agents that can cause cell injury?
- temperature:
- radiation (changes DNA)
- mechanical (compression, tension, torsion, shear)-(changes how cells are arranged, signaled, and synthesize proteins)
What does cell injury do to the cell?
abnormal metabolism, protein transport defects, lack of enzymes, presence of materials cannot be digested
What is necrosis?
- Cellular destruction, dissolution
- pathophysiologic
What is apoptosis?
- programmed cell death
- active process of self destruction
- physiologic
What is autophagy?
survival strategy or may be destructive
What happens during autophagy?
- the production of nutrients (amino acids, lipids, and nucleic acids) to combat starvation; and the elimination of invading pathogens, damaged organelles (altered mitochondria) and protein aggregates
- can promote survival or cell death
How does lead ingestion to lead to cellular injury?
lead mimics iron, calcium, zinc in many enzymes and alter catalyzing function
How does necrosis differ from apoptosis?
apoptosis is when the cell kills itself; natural death
How do antioxidant protect the cell from injury?
- they freely give free radicals electrons without turning into electron scavengers themselves
- neutralize free radicals by giving up some of their own electrons. In making this sacrifice, they act as a natural “off” switch for the free radicals. This helps break a chain reaction that can affect other molecules in the cell and other cells in the body
How does mercury alter cellular metabolism and cause cell injury?
damages the cell membrane, DNA, and macromolecular structure
How does ethanol alter celllar metabolism and cause cell injury?
metabolized by alcohol dehydroenase to acetaldehyde which is a cell toxin
How does carbon monoxide alter cellular metabolism and cause cell inury?
binds to heme in preference to O2 and results in hypoxia
How does carbon monoxide alter cellular metabolism and cause cell inury?
binds to heme in preference to O2 and results in hypoxia
How does temperature contribute to cell injury?
- hypothermia: may be lead to a collapse in ionic regulation, leading to an uncontrollable and lethal calcium influx
- hyperthermia: significant effects on proteins including unfolding, exposing hydrophobic groups, and aggregation with proteins
