Cellular Adaptation / Cell Injury&Death / Cell Disorders(W1)

NURS 500

Cellular Adaptation

where cells change due to physio and pathologic stress in their environment

Stressors in a cell environment

size

number\form

normality / abnormality

Atrophy

a decrease in cell size (shrinking)

caused by disuse, denervation (loss of nerve simulation), loss of endocrine sim, loss of nutrition or decreased blood flow (ischemia)

ischemia

loss of blood flow

example of atrophy

loss of muscle mass - such as through limb casting

hormonal change /nutritional change can cause cell shrinkage

hypertrophy

increase in cell size

caused by increased workload or homonal change

where can hypertrophy occur

skeletal or cardiac cells (they cannot divide)

normal (physiologic) clinical manifestations of hypertrophy

inc. in heart or muscle size

ex uterus grows during pregnancy

abnormal (pathologic) clinical manifestations of hypertrophy

compensatory - occurs to help something perform better when it is not supposed to (IE myocardial hypertrophy)

adaptive - enlargement of an organ after a piece of it was removed or inactive (ie kidney tissue grows to replace loss of functional 2nd kidney)

physiologic

beneficial / NORMAL

pathological

ABNORMAL

hyperplasia

inc. of cell number that occurs in response to a stimulus and will stop when it is removed

can be physiologic or non-physiologic

abnormal hyperplasia is caused by

excessive hormonal or GFs on tissues

metaplasia

reversible replacement of one mature differentiated cell type by a diff. cell type due to irritation & inflammation

who is at risk of metaplasia

smokers - ciliated cells replaced by squamous cells (less functional) in airways such as trachea

chronic GERD /gastritis - cell change in esophagus or stomach

“Barret’s esophagus”

dysplasia

cell growth of a certain tissue that varies in size and shape - ATYPICAL growth that is considered pre-cancerous

caused by inflammation and irritation

seen in cervical / respiratory tracts

cell injury occurs…

when adaptive responses are compromised by things such as stress, mutations or environmental factors

cell stress can cause 2 things-

increased functional demand (inc. performance) or reversible cell injury

cells can either adapt to the stress and eventually relieve the stress or lead to irreversible cell injury (necrosis)

physical causes of cell injury

mechanical forces or temperature extremes

mechanical forces causing cell injury

injury or trauma caused due to body impact with another object

extreme temperature causing cell injury

high temp - causing vascular injury or cell membrane disruption (blood coagulation of blood vessels)

low temp- can cause inc. blood viscosity and causes vasoconstriction (ice crystals in blood. thrombosis or edema)

electrical injuries causing cell injury

electrical currents affecting cell bodies

clinical manifestations of cell injury

burns - breaks - muscle/deep tissue wounds - entry/exit wounds

radiation

leads to cell injury due to energy such as ionization , UV, or nonionizing waves that can damage cells through burns and exposure

chemical injury

drug (script ot street) that can lead to toxicity in cells

lead toxicity can occur

ex. kidney failure, cancer drugs. fetal alc syndrome

hypoxia

lack of oxygen (ischemia) within cells

can be caused by chest pain / cold skin / low urine output / shortness of breath

leads to anerobic (non-oxygen resp) metabolism - no ATP produced

free radical / Reactive oxygen species (ROS)

hypoxia occurs and leads to the mitochondrial complex to make ROS - which can damage cells

examples- inflammatory bowel disease, cancers, and infection

occurs in degenerative diseases and aging

ROS

Reactive Oxygen Species

produced by Mitochondrial Complex

is a component in inflammation

calcium- why is it important to maintain its homeostasis

crucial second messanger in mediation

it helps with smooth muscle contraction & glycogen breakdown in the body

too much can lead to cell death & injury

reversible cell injury

affects cell function but can recover if agent is removed (ie swelling & fatty change)

apoptosis

programmed cell death

'cell suicide”

within the cell (intrinsic) or occurring from factors outside of the cell (extrinsic)

key in embryonic development in growing and changing organs such as the uterus after childbirth

necrosis

cell death that is still apart of a living organism

unregulated and pathological occurrence

loss of cell part integrity and interferes with cell regeneration

destructive (ie gangreen)

single gene disorders

caused by a gene mutation at a single point

could be dominant or recessive or sex-linked

ie sickle cell anemia

single gene disorder types

autosomal dominant or autosomal recessive

autosomal dominant

single mutation from an affected bio parent is transmitted to offspring

autosomal recessive

genes from both parents sent to offspring where the parent could carry or be unaffacted by it

occurrence of autosomal dominant

50% chance of parent transferring to offspring

occurrence of autosomal recessive

25% for affected child born

50% for carrier child born

25% for normal (no gene) child born

sex linked disorder types

x-linked recessive and x-linked dominant

X is linked to mother (XX)

X linked recessive

transmitted by unaffected carrier mother

mother has one affected X and one unaffected X

chances for X linked recessive trait to be transferred

50% chance of daughter who is a carrier (female is XX)

50% chance for a son who will be affacted (male is XY)

X linked dominant

rare

affects males and females and is lethal to males in utero

examples of X linked dominant

Fragile X

Rett Syndrome

multifactorial disorders

could be congenital or environmental

examples of congenital disorders

cleft lip / palate

clubfoot

congenital heart disease

environmental disorders

coronary heart disease

diabetes

high blood pressure

chromosomal disorders

most common occurrence is abnormal number of chromosomes

ie Trisomy 21 (Down Syndrome) & Trisomy 18 (Edward’s)

could also occur due to structural changes in chromosomes such as deletion and translocation of a chromosome

Teratogenic Agents (Environmental Influences)

defects that are caused by direct exposure to pregnant person and fetus or soon-to-be pregnant person to something with a slow clearance rate

could also occur due to mutagenic effects that occur before pregnancy

ex radiation, drugs, chemicals, infectious agents