Ultimate Pathophysiology Review Guide (unfinished)

chapter4

Pathogenesis

Focuses on origin and development of disease

• traces how a pathogen or insult affects the body

Pathophysiology

Studies the functional changes a disease produces and how it evolves

Diagnosis

An indication of a disease through the evaluation of signs and symptoms

Signs

objective findings for a disease

Examples of signs for a diagnosis

a 3rd or 4th heart sound, lumps, high/low blood pressure

Symptoms

subjective findings for a disease

Examples of symptoms for a diagnosis

headache, pain, chills

Etiology

The specific cause of origin of a disease

Risk factors

factors that increase the probability of a disease but don’t directly cause the disease

Examples of risk factors

Family history, gender/race, lifestyle choices such as obesity or poor diet

Congenital

Present at birth

Inherited/genetic diseases

Diseases that are passed down from one or both parents

Idiopathic

The cause of disease is unknown

Iatrogenic

Disease is caused by treatment or procedure error

Prevention

Broader actions that reduce the chances of developing a disease

Prophylaxis

Medical measures to preserve health

Examples of prophylaxis

Vaccines

Predisposing factors

Modifiable or non-modifiable factors that increase the chances of developing diseases

Examples of predisposing factors

Smoking, chronic drug/alcohol usage

Acute

disease/infection that is short lived

Chronic

recurring or persisting long-term diseases

Insidious

Gradual onset of symptoms with vague or mild symptoms

Subclinical

Disease that is present but no obvious manifestations; may be lab-detectable

Latent

The state of a pathogen being dormant, though it can reactivate later

Manifestations

Overall clinical evidence of disease, groups signs and symptoms together

Lesion

A specific and localized change of tissue

Examples of lesions

Ulcers, nodules, plaques

Syndrome

Constellation of signs and symptoms occurring together

Sequelae

Unwanted long-term outcomes that result from diseases or injuries

Prevalence

Total number of cases within a population and a time period

Example of prevalence

Population of people in the United States living with diabetes

Incidence

Number of new cases arising in a population within a given time period

Examples of incidence

New cases of digestive problems caused by the protozoa Cyclospora in July 2026

Sensitivity

Proportion of people with disease who test positive

Specificity

Proportion of people without disease who correctly test negative

Morbidity

Disease rates within a group that is independent from death

Examples of morbidity

Depression rates among the youth

Mortality

Relative number of deaths resulting from disease

Example of mortality

Number of deaths per 100,000 caused by cancer

Epidemic

A higher than expected number of cases of an infectious disease within an area that is usually not endemic

Examples of epidemics

• Measles outbreaks across the United States since 2025

• Zika outbreak of 2015-16

Endemic

Disease native to and constantly present within a particular place

Examples of an endemic

Malaria in Sub-Saharan Africa

Pandemic

An epidemic that has spread across multiple countries or continents, affecting a large number of people globally

Examples of pandemics

• COVID-19 pandemic

• AIDS pandemic

Homeostasis

Body’s ability to maintain a constant internal environment

Normal level of fasting plasma glucose

70-99mg/dL

Normal levels of serum calcium

8.5-10.5 mg/dL

Labile cells

Cells that continuously divide throughout life

Examples of labile cells

Skin cells, hair cells

Stable cells

Cells that don’t continuously divide but re-enter the cell cycle when damaged

Example of stable cells

Liver cells, endothelial cells

Permanent cells

Cells that can not regenerate when they die

Examples of permanent cells

Neurons, cardiac cells

Hypoxia

reduced oxygen delivery to tissue

Ischemia

insufficient blood flow to tissue

Infarct

Localized area of cell death from ischemia

Necrosis

Cell death from any cause, shows recognizable morphologic patterns

Apoptosis

Programmed cell death

What type of injury is the most common cause of hypoxia

Ischemia

What injury is the most common cause of cellular injury

Hypoxia

Causes of hypoxia include

• low hemoglobin

• decreased RBC count

• reduced oxygen concentration

• disease of cardiovascular or respiratory systems

• poison

Six Intracellular Injury Pathways

• ATP depletion

• Mitochondrial damage

• Membrane damage

• Reactive oxygen species

• Calcium Entry

• Misfolded proteins

Atrophy

Decrease of cell size through loss of intracellular substances

• Redirect nutrients to other parts of the body

In atrophy, less protein synthesis leads to

more protein degradation

Causes of atrophy

Age, decreased work, injury, diseases, lower nutrition, decreased blood flow

Hypertrophy

Increase in cell size without the increase in cell number

Examples of physiologic hypertrophy

• The myometrium during pregnancy

• The heart when there is exercise

Example of pathologic hypertrophy

Left ventricular hypertrophy with valvular disease or hypertension

Hyperplasia

Increase in organ or tissue size due to an increase in cell number

Hyperplasia is mainly restricted to cells that are capable of this cellular process

Mitosis

Examples of physiologic hyperplasia

• Breast and uterine tissue during pregnancy

• Liver regeneration

Examples of pathologic hyperplasia

• Benign prostatic hyperplasia (enlarged prostate)

• Endometrial hyperplasia

• Epithelial hyperplasia driven by HPV

Metaplasia

When one cell type is replaced by another cell type

• Reversible

Examples of metaplasia

• Tobacco smoking

• GERD

Dysplasia

Disordered and abnormal growth

• not a true adaptation but a response to persistent injury

Coagulative necrosis

The structural proteins and cell’s proteolytic enzymes become denatured

Liquefactive necrosis

Tissue is digested by hydrolytic enzymes, turning it into a liquid, viscous mass

Example of liquefactive necrosis

Ischemic injury to the CNS

Caseous necrosis

Combination of both liquefactive and coagulative necrosis in which the dead tissue is considered ‘cheese like’

Fat necrosis

Focal destruction of fat in tissues with high fat content

Acute pancreatitis is most commonly associated with this type of necrosis

Fat necrosis

Gangrenous necrosis

Tissue death caused by severe hypoxic injury that usually affects the extremities or bowels

Types of gangrenous necrosis

• Dry

• Wet

• Gas

Dry gangrenous necrosis

Reflects pattern of coagulative necrosis. Loss of blood supply → infarct → coagulative necrosis

Wet gangrenous necrosis

Superimposed bacterial infection that reflects liquefactive necrosis

Gas gangrenous necrosis

Form of necrosis caused by the bacterium Clostridium perfringens that destroys tissues

Fibrinoid Necrosis

Type of necrosis that occurs in blood vessel walls

Physiological causes of apoptosis

• Embryogenesis

• Breast involution after weening

• Immune cell turnover

Pathological causes of apoptosis

• Severe, irreparable cell injury

• Accumulation of misfolded proteins

• Viral infections

• Blockage of ducts

Necroptosis

Back up death pathway when capsase-8 is blocked

Pyroptosis

Central to sepsis and pyogenic infection

Ferroptosis

Implicated in ischemia-reperfusion injury and neurodegeneration

Intrinsic apoptotic pathways

Triggered by internal cellular stress such as misfolded proteins, DNA damage, etc

Extrinsic apoptotic pathways

Triggered by external signals such as death ligands

Inflammation

Protective, stereotyped response to an injury, infection, or irritant stimuli

Purpose of inflammation

• Deliver defense molecules and cells to the site of injury

• Eliminate causative agent

• Clear necrotic debris

• Tissue repair

Onset of acute inflammation

Minutes to hours

Onset of chronic inflammation

Days to years

Duration of acute inflammation

Short, usually a few days