PATH 3610 - Midterm 2

According to the major principles of disease, what are the two ways healing occurs?

Healing occurs by regeneration or repair (granulation and fibrosis)

What is a scar composed of?

A scar is a lesion that is fibrous tissue

Define fibrosis

Fibrosis is the condition or state of laying or development of fibrous tissue in an organ, fibrous tissue is collagen and fibrocytes

What are the four basic steps to healing by repair?

Agent inactivated and removed

Debride nonviable materials

Provide building framework - Matrix and migration of cells

Repair

What is angiogenesis?

Formation of new blood capillaries

In the context of healing, what is granulation tissue

The fundamental repair system in tissue that cannot regenerate, leading to fibrosis. It results in replacing original tissue with fibrous tissue

What are the two main components of granulation tissue?

Blood capillaries (angiogenesis) and fibroblasts forming collagen fibrils

What does mature granulation tissue become?

Dense fibrous tissue, also known as mature fibrous tissue or a scar

Is granulation tissue the same as granulomatous inflammation?

No, granulation tissue is NOT granulomatous inflammation

What two components form granulation tissue?

Capillaries and fibroblasts

What is primary healing (first intention)?

Occurs when tissue is placed in its original orientation

How does the amount of granulation tissue required differ in primary healing compared to secondary healing?

Primary healing requires less granulation tissue than secondary healing

Describe the sequence of events in primary healing within the first 10 days

24 hours - neutrophils

3 days - macrophages

5 days - granulation tissue

10 days - mature collagen

How long does it take for a scar to form in primary healing?

1 month

What is secondary healing (second intention)?

Occurs when there is a large tissue defect

What are two potential outcomes related to granulation in secondary healing?

Proud flesh and keloid

How long does secondary healing typically take?

it takes months to heal

What characterizes healing by second intention?

Allowing a wound or injury to heal with granulation and replacement with fibrous tissue only - no intervention

Why does secondary healing take longer than primary healing?

Because the surface area is larger

List the layers of the skin from superficial to deep

Epidermis (epithelium), dermis (fibrous tissue), subcutis (fat)

What are the components found in the wound area during healing?

Blood clot, granulation tissue, myofibroblasts

What replaces granulation tissue in the wounded area?

Fibrous tissue = scar

What is the deciding factor in whether tissue regeneration or repair occurs?

The presence or absence of stem cells

Describe continuously dividing cells (labile)

Stem cells replicate and replace terminally differentiated (mature) cells

Describe quiescent cells (stable)

Most cells are terminally differentiated with some stem cells

Describe terminally differentiated (permanent) cells

Cells that do not regenerate

Give examples of growth factors involved in healing

Epidermal growth factor (EGF), platelet derived GF, vascular endothelial GF, fibroblast GF, transforming GF

Where is Epidermal growth factor (EGF) found?

Urine and salvia

What is another name for Vascular endothelial GF

angiogenin

What is the relationship between TGF-alpha and EGF

TGF-alpha = EGF, TGF-beta (-)

Name two interleukins involved in healing

IL1 and TNF

List systemic factors that modulate healing

Age +/-, malnutrition, vitamin C, zinc, amino acids, haematological abnormalities, diabetes mellitus, corticosteroids, cytotoxic chemotherapy

Give examples of Haematological abnormalities that modulate healing

Neutropenia, haemophilia

How do corticosterioids affect healing?

Inhibit phospholipase A, reduces leukocyte emigration - endothelium, reduces and alters collagen production

How does cytotoxic chemotherapy affect healing?

Targets mitotically active cells

List local factors that modulate healing

Blood supply, infection, foreign bodies, implants

What type of virus is Zikavirus classified as?

Arbovirus

Define Arbovirus

Stands for Arthropod Borne virus, meaning it is transmitted by arthropods such as mosquitos

What are the two key aspects of the bodys response to Zikavirus infection

Involves viremia and a systemic inflammatory response

What type of transmission is associated with Zikavirus

Transplacental (vertical) transmission

What condition in newborns is specifically linked to Zikavirus

Microencephaly - small brain

What are the different kingdoms used to classify infectious agents

Prion, viruses, eubacteria (bacteria chlamydiae, rickettsia, mycoplasma, ureaplasma), fungi, protista (protozoa), and animalia (helminths, arthropods)

What role does politics play in the context of infectious disease

Plays a major role in the definitions of infectious diseases

Define endemic in the context of infectious diseases

Native to a particular region

Define epidemic in the context of infectious disease

That an infection is affecting many people

Define pandemic

That an infection is affecting all of the people (globally widespread)

What are the two categories of risk mentioned in relation to individual variation in disease?

Real and perceived

What are the two types of 'real' risk?

Statistical value and Infection fatality rate/Case fatality rate

What is an extreme example of 'perceived' risk?

Mass psychosis

What was the leading cause of death by infectious disease in 2023

Tuberculosis

Define case fatality rate

Deaths/deaths

Define crude mortality rate

Deaths/population

Define infection fatality rate

Deaths/infection

What are the two main categories of contact that can lead to the spread of infectious disease?

Direct contact and indirect contact (fomite)

What are vector-borne diseases?

Infections transmitted by the bite of infected arthropod species

What is the difference in particle size between droplet and aerosol/airborne transmission

Droplets are larger than 5 micrometers (um), while aerosols/airborne particles are less than 5 um

What is feco-oral transmission?

Route of infection involving the ingestion of fecal particles

What does nosocomial mean?

Infections acquired in a hospital or 'care' setting

What is vertical transmission of infectious disease?

Spread of infection from parent to offspring through genetics or pregnancy

What is horizontal transmissssion of infectious disease?

Spread of infection from person to person

What are zoonotic diseases

Animal diseases that spread to humans

What are the three main areas of human intervention in disease

Prevention of disease, control of disease, and treatment of diseae

What are the two levels at which disease prevention can be implemented

Individual and population levels

At what level is disease control primarily focused

Population level

At what level is disease treatment primarily focused

Individual level

What are the three main strategies for the prevention of disease?

1. Avoid contact 2. Induce immunity 3. Prophylaxis

What are some methods listed under the 'avoid contact' strategy for disease prevention

Inherent, distancing, isolation vs. quarantine, education, and eradicate

What are two examples of diseases that have been targeted for eradication through human intervention

Smallpox and rinderpest

What is the key difference between isolation and quaratinw

Isolation separates sick individuals from healthy individuals, while quarantine separates people potentially exposed to a disease

What are the two types of adaptive immunity that can be induced for disease prevention

Passive immunity and active immunity (vaccination)

Under what circumstances is inducing adaptive immunity considered the most effective method for disease prevention

If there is an effective vaccine

What is prophylaxis

Involves the use of therapeutic compounds - treatments and passive immunity for disease prevention

What is an example of passive immunity in context of prophylaxis

Tetanus antitoxin

What is the definition of vaccination

Defined as to inoculate with vaccinia (Cowpox virus)

List the different types of vaccines

Killed/inactivated (Sinovac), Toxoid, Live and Modified live, RNA vaccine (Pfizer, Moderna), Virus vector

Provide the meaning of 'toxic' and 'oid' as used in 'toxoid'

Toxic means causing death, and oid means like

What are the four general approaches to the treatment of any disease

Specific treatment (remove cause), relieve workload, symptomatic (clinical signs), and replace function

What is the broad term used for therapeutic compounds in the specific treatment of infectious diseases

The broad term used is 'Antimicrobial'

List the types of antimicrobial therapeutic compounds

Antibiotic (antibacterial), antiviral, and antiprotozoal

Besides therapeutic compounds, what is another specific treatment for infectious disease

Passive immunity

What is a subclinical infection

When an individual is infected but shows no clinical signs or symptoms

What is clinical disease also known as and what are its characteristics

Also known as clinical case and is characterized by being infected and having disease

Define latent infection

When an individual is infected but the agent is hidden, inactive or dormant

What is a shedder in the context of infectious disease

Someone who is shedding the virus

What is an amplifier in the spread of infectious disease

Similar to a superspreader

Define a superspreader

An individual with a high viral load who 'emits' large numbers of infectious particles and they usually infect others who also become superspreaders

What are the two main categories of infectious agents

Viruses and bacteria

List three characteristics of viruses

pass through ultra-fine filters, are mobile genetic elements, multiple only in cells

What is the protein coat of a virus called, and what is its function

Called a capsid and it allows the virus to move from cell to cell

What type of genetic material can be found in the genome of a virus

RNA or DNA

How does the passage describe a virus's attitude towards the nature of the organisms it infects

A virus is indifferent to the nature of the large creature it inhabits temporarily

List three ways in which viruses can cause pathogenicity

Inhibiting host cell DNA, RNA, or protein synthesis, damaging the plasma membrane (e.g. Herpesvirus), and causing direct cytolysis (e.g Ebola)

How can viral proteins in the cell membrane lead to pathogenicity

Can incite immune attack, potentially leading to autoimmunity (e.g. Hep B)

How does HIV cause pathogenicity

By damaging cells involved in antimicrobial defense

How can viruses damage cells that have other dependent cells

Poliovirus damaging nerve cells that control muscles

What cellular outcomes can be caused by viral infection, leading to pathogenicity

Can cause cell activation or neoplastic transformation (e.g. Hep B, papillomavirus)

What are the two main branches of the host response to viral infection

Innate response and the adaptive response

Name two components of the innate immune response to viral infection

Interferon (alpha and beta) and inflammation

Name two components of the adaptive immune response to viral infection

Antibody and cellular immunity

Is 'doing nothing' considered a therapy for viral infection

No, doing nothing is explicity stated as not a therapy