Disease definition

A deviation from the normal state of health or wellness

Aetiology

Study of the causes/origins of disease

Pathogenesis

Sequence of events leading to disease development

Pathophysiology

Study of functional/physiological changes caused by disease

Diagnosis

Identification of disease through signs and symptoms

Prognosis

Expected outcome or probability of recovery

Manifestations

Clinical evidence/effects of disease

Sign

Objective, observable finding

Symptom

Subjective, felt by patient

Syndrome

Collection of signs and symptoms that occur together

Latent stage

No manifestations yet

Subclinical stage

Pathology present, no obvious signs

Prodromal period

Vague, nonspecific symptoms

Clinical stage

Clear manifestations

Remission

Manifestations subside

Exacerbation

Signs and symptoms increase

Insidious onset

Gradual, vague signs

Acute disease

Sudden onset, short duration

Chronic disease

Gradual onset, long duration

Risk factors

Tendencies promoting disease development

Modifiable risk factor example

Occupation

Non-modifiable risk factor example

Age, sex, heredity

Precipitating factor

Triggers an acute episode

Sequelae

Unwanted outcomes directly from primary condition

Complications

New secondary problems after disease emerges

Atrophy

Decrease in cell size

Hypertrophy

Increase in cell size

Hyperplasia

Increase in cell number

Metaplasia

Replacement of one mature cell type with another

Dysplasia

Abnormal cell size/shape/organization

Cellular adaptation definition

Development of a new altered steady state

Mechanisms of cell injury

ATP depletion, oxidative stress, membrane damage, mitochondrial loss

Reversible cell injury

Cell swelling, membrane blebbing, ribosome detachment, chromatin clumping

Irreversible cell injury

Membrane disruption, mitochondrial densities, nuclear changes

Pyknosis

Nuclear shrinkage

Karyorrhexis

Nuclear fragmentation

Karyolysis

Nuclear dissolution

Liquefactive necrosis

Occurs in CNS; tissue becomes liquid mass

Apoptosis

Programmed cell death without inflammation

Apoptosis features

Cell shrinkage, membrane changes, no inflammation

Acute inflammation

Short duration

Chronic inflammation

Long duration, fibrosis, mononuclear cells

Cardinal signs of inflammation

Pain, heat, redness, swelling, loss of function

Mast cells

Initiate inflammation via degranulation

Basophils

Function like mast cells in blood

Neutrophils

First responders; early phagocytes

Chemokines

Mediate leukocyte chemotaxis

Histamine

Dilates arterioles

Fever mechanism

Pyrogens act on hypothalamus

Phagocytosis steps

Recognition → Engulfment → Fusion → Destruction

Serous inflammation

Blisters

Purulent inflammation

Pus, neutrophils

Fibrinous inflammation

Fibrin deposition

Granulomatous inflammation

Macrophages, epithelioid cells, giant cells

Abscess

Pus-filled area of apoptotic neutrophils + liquefactive necrosis

Active immunity

Involves host immune response

Hypersensitivity example

Organ transplant rejection

Autosomal dominant example

Huntington disease

X-linked recessive examples

Hemophilia, G6PD deficiency, Duchenne muscular dystrophy

Down syndrome features

Upward slanting eyes, single palmar crease, leukemia risk, reduced IQ

Down syndrome diagnosis

Amniocentesis, CVS, sonogram

Duchenne muscular dystrophy

X-linked; dystrophin mutation; early death

Cystic fibrosis

Diagnosed by sweat test; CFTR defect; thick mucus

Sickle cell disease

HbS; spleen damage; painful crises

Prader-Willi syndrome

Paternal chromosome 15 deletion

Usher syndrome

Retinitis pigmentosa

Sanfilippo A

Lack of sulfamidase enzyme

Cayman ataxia

Speech difficulty; not fatal early

Genetic mutation

Can cause disease without family history

Benign tumor

Slow growing, movable, compresses tissue

Malignant tumor

Invades, metastasizes

Carcinoma in situ

Has not invaded neighboring tissue

Tumor diagnosis

Determined by oncology

Grade I tumor

Well differentiated

Stage I tumor

Localized

TNM system

Tumor size, node involvement, metastasis

Neoplasia

New growth

Exogenous factor example

Carcinogens

Endogenous factor example

Genetics

Disease definition (homeostasis)

Disruption of homeostasis

Adaptive changes

Atrophy, hypertrophy, hyperplasia, metaplasia

Non-adaptive change

Dysplasia