Module 1 Flashcards
Define atrophy and how it applies to pathophysiological processes
Atrophy: Decrease in the size of a tissue, organ, or the entire body. In atrophy of an organ or body part, there may be a reduction in the number or in the size of the component cells, or in both. Certain cells and organs normally undergo atrophy at certain ages or under certain physiologic circumstances. Atrophy in general is related to changes in nutrition and metabolic activity of cells and tissues.
A widespread or generalized atrophy of body tissues occurs when?
Under conditions of starvation, whether because food is unavailable or because it cannot be taken and absorbed due to the presence of disease. The unavailability of certain essential protein components and vitamins disturbs the metabolic processes and leads to atrophy of cells and tissues. Associated with the widespread atrophy due to lack of protein is the atrophy of certain tissues that is due to deficiencies of specific vitamins.
Define hypertrophy
Increase in size of cells (organs). Increase in cell size, the heart and kidneys are particularly prone to enlargement. It is associated with an increase accumulation of protein in the cellular components & not with an increase in cellar fluid. It is caused by hormone stimulation or increased functional demand.
What is hyperplasia?
An adaptive increase in the number of cells that can cause enlargement of tissues or organs
6 ways cells can change?
Atrophy, Hypertrophy, Hyperplasia, Metaplasia, Dysplasia, Anaplasia
Hypertrophy vs. hyperplasia
Hypotrophy-individual cells enlarge
Hyperplasia- adaptive increase in the number of cells that causes tissue enlargement
Which of the 6 ways in which cells change is considered precancerous?
Dysplasia
Metaplasia
An adaptive change of one cell type for another to suit the environment. Reversible replacement of one mature cell type by another (Epithelium changes in smokers)
What is an example of Metaplasia?
Squamous metaplasia of the bronchial epithelium due to smoking
or
Gastric or glandular metaplasia of the GE junction in Barrett’s Esophagus
Is metaplasia reversible?
yes, but it can also progress to a more detrimental growth (ie dysplasia)
Dysplasia
Disordered growth of tissues resulting from chronic irritation or infection. Abnormal changes in size, shape and organization of mature cells (can lead to cervical cancer)
How can cells get injured?
- Hypoxia
- Mechanical forces
- Extremes of temperature
- Electrical injuries
- Chemical agents and drugs
- Biological agents
- Ionizing radiation
- Nutritional imbalances
What is hypoxia?
A type of cell death. This is caused by a lack of oxygen to the cells. It causes ATP powered pumps to malfunction. ATP is depleted because little to no oxygen is given to the cell.
What happens during a hypoxic injury
Blood flow falls below a certain critical level that is required to maintain cell viability. The interrupted supply of oxygenated blood to cells results in anaerobic metabolism and loss of adenosine triphosphate (ATP), and cellular membrane disruption
Problems hypoxic injury creates
Disrupts the ability of mitochondria to produce ATP, which in turn prevents normal functioning of the Na/K pumps, which leads to leads to swelling & lysis. It is reversible if oxygen is restored quickly.
Mechanisms of cell injury:
1) Depletion of ATP: No energy
2) Impaired calcium homeostasis
3) Free radical injury
1) Depletion of ATP: No energy
2) Impaired calcium homeostasis: Activates pathways that lead to cell death
3) Free radical injury
- Generation of ROS
- Low chemical specificity, highly reactive
- Disrupts pathways
- Damages mitchocondrial DNA > apoptosis
What is ionizing radiation?
Ionizing radiation is radiation with enough energy so that during an interaction with an atom, it can remove tightly bound electrons from the orbit of an atom, causing the atom to become charged or ionized
how does ionizing radiation cause cell injury?
It affects cells by causing ionization of molecules and atoms in the cell, by directly hitting the target molecules in the cell, or by producing free radicals that interact with critical cell components. it can immediately kill cells, interrupt cell replication, or cause a variety of genetic mutations, which may or may not be lethal. Most radiation injury is caused by localized irradiation that is used in the treatment of cancer.
how does non-ionizing radiation cause cell injury?
unlike ionizing radiation which can directly break chemical bonds, nonionizing radiation exerts its effects by causing vibration and rotation of atoms and molecules. all of this vibrational and rotational energy is eventually converted to thermal energy.
Decreased oxygen concentration in the tissues
hypoxia
Decreased oxygen in the blood
hypoxemia
how does hypoxia cause cell damage?
It deprives the cell of oxygen and interrupts oxidative metabolism and the generation of ATP. Damage occurs due to hypoxia, even if it starts out as hypoxemia.
-diminishes ATP production
hypoxia causes ATP depletion or power failure in the cell, what widespread effects on the cell’s structural and functional components will this have?
As oxygen tension in the cell falls, oxidative metabolism ceases, and the cell reverts to anaerobic metabolism, using its limited glycogen stores in an attempt to maintain vital cell functions. cellular pH falls as lactic acid accumulates in the cell. this reduction in pH can have adverse effects on intracellular structures and biochemical reactions.
- Na/K+ ATPase cannot run fast enough so the cell swells up with water
- anaerobic metabolism used = lactic acid produced and the acid damages cell membranes, intracellular structures, and DNA
free radicals
free radicals are molecules with an unpaired electron in the outer electron shell
- extremely unstable and reactive
- can react with normal cell components
- damaging them
- turning them into more free radicals
- normally removed from body by antioxidants