NRS236 Chapter 2: Cell Injury, Adaptation, and Maladaptive Changes

Factors that cause cellular adaptive and maladaptive changes

Exercise, hormones, physical agents of injury, chemical injury, infectious agent, immunological reaction

genetic defects, nutritional imbalances

Physical agents of injury

physiologic response often include initiation of inflammatory response

Chemical injury

injure plasma membrane and gain access to the cell's interior to cause dysfunction of organelles

Infectious agent

variety of microorganisms that carry out injurious cell processes in a distinctive manner

Immunologic reaction

overreaction of immune system, causing attack on body's own cells, causing cell injury and creating disease

Genetic defects

can damage and mutate DNA, resulting in the initiation of events that can cause cell injury

Starvation

can cause inadequate supply of nutrients necessary for proper cell function

Overnutrition

causes excessive fat stores that can place stress on heart and pancreas

Function of epithelial cells

Line artery walls

Secrete angiogenesis growth factor

Secrete vasodilation and vasoconstriction substances

Secrete nitrous oxide

Secrete thrombogenic substances to cause clots

Angiogenesis growth factor

stimulate the synthesis of new blood vessel branches

physiologic reaction

adaptive/normal results of some injury

pathogenic reaction

leading to disease

Muscle atrophy

cells decrease in size, causing decrease in muscle tissue

Muscle atrophy causes

underuse of muscle, paralysis, loss of hormone stimulation, inadequate nutrition, decreased blood flow, aging

Muscle hypertrophy

individual cell size increases, enlarged tissue mass which causes greater metabolic demands and energy needs

physiological hypertrophy

the enlarged muscle is adequately perfused and supplied with blood flow, oxygen, and nutrients because of angiogenesis

Ex: exercise

Pathological hypertrophy

An increase in cellular size without an increase in the supportive structures necessary for the enlarged cells increase in metabolic demand. Seen in hypertension or heart failure.

Hyperplasia

increase in number of cells

Ex: growth of breast cells during pregnancy

hyperplasia causes

increased physiologic demands

increased growth factor/hormonal stimulation

persistent cell injury and irritation

Metaplasia

one cell type is replaced by another cell type

ex: GERD

Metaplasia cause

genetic reprogramming in response to change in environmental conditions

Dysplasia

Deranged cell growth within a specific tissue; cells vary in size and shape; rate of mitosis increases

ex: cervical dysplasia

Dysplasia causes

chronic irritation and inflammation or a precancerous condition

Neoplasia

the new and abnormal development of cells that may be benign or malignant

Benign

not harmful

Malignant

cancerous

Endothelial injury

causes inflammation reaction and initiates the process of atherosclerosis

Endothelial injury causes

hypertension: increased force of blood can wear down endothelial cells

free radicals: stealing electrons from healthy cells and causing cell injury and membrane damage

high glucose: sugar molecules are spikey and stick to walls, then puncture and tear off cells

hyperlipidemia: LDLs (low-density lipoproteins) line endothelial cells and damage them when they break off

Ischemia

Lack of blood supply

Infarction

death of tissue as a consequence of prolonged ischemia

Hypoxic cell injury (hypoxia)

oxygen deprivation - when blood cannot deliver enough oxygen to the cells

Free radical injury

-Free electron on an oxygen atom that is attracted to cell membranes attaches and damages them

-Penetrate cell plasma membranes, disrupt internal organelles, and damage the nucleus and its DNA

Free radical injury causes

UV rays, atmospheric pollution, stress, poor diet, smoking, and medication

Free radical injury interventions

-Vitamin A: fish oil and milk products

-Vitamin C: citrus

-Vitamin E: nuts, seeds, legume

-Beta carotene: orange foods (carrots, sweet potatoes, mangos, and squash)