Communicable Diseases and Body Defenses

Flashcards covering communicable diseases, transmission methods, and the body's defenses against them.

What are communicable diseases also known as?

Infectious or transmissible diseases.

How are contagious diseases spread?

Via direct contact.

How are vector diseases spread?

Via an intermediate host.

What are the characteristics of bacteria?

Unicellular, microscopic organisms with a cell wall but no nucleus.

How do bacteria reproduce?

By simple fission.

What causes diseases from pathogenic bacteria?

Either an allergic reaction to the bacteria or the toxins they produce.

What are the characteristics of viruses?

Non-cellular, consist of RNA or DNA surrounded by a protein coat, and cannot reproduce unless inside a cell.

What are the characteristics of fungi?

Multicellular, many macroscopic, and mainly affect the skin.

What are the characteristics of parasites?

Multicellular, macroscopic, and live within a host organism.

How are diseases communicated by direct contact?

Touching an infected person.

How are diseases communicated by indirect contact?

Touching an object touched by an infected person.

How are diseases communicated by droplets?

Tiny pathogen-containing droplets are emitted during breathing, coughing, sneezing, etc., and are then inhaled or digested.

How are diseases communicated by ingestion?

Consuming food or drink contaminated with pathogens.

How are diseases communicated by airborne transmission?

When droplets dry out, bacteria dies but viruses remain alive and stay in the air.

How are diseases communicated by vectors?

Transferred by animals like ticks, mosquitoes, flies, and mites.

What is the role of skin in non-specific defenses?

A physical barrier that pathogens cannot pass through; sweat kills pathogens; local fauna attacks invading pathogens.

What is the role of eyes in non-specific defenses?

Eyelids, eyelashes, and eyebrows are physical barriers; tears contain lysozyme and salt that kills pathogens.

What is the role of the ear in non-specific defenses?

Cerumen (ear wax) is a physical barrier that traps pathogens and pushes them out of the ear; hairs are a physical barrier.

What is the role of the nasal cavity in non-specific defenses?

Nose hairs and mucus are physical barriers preventing pathogens from entering the respiratory system.

What is the role of the trachea and bronchi in non-specific defenses?

Mucous and cilia are physical barriers that trap pathogens and remove them from the respiratory system.

What is the role of the oral cavity in non-specific defenses?

Mucous membranes trap pathogens; saliva contains acid that kills pathogens.

What is the role of the stomach in non-specific defenses?

Acid kills pathogens and prevents infection of the digestive system.

What is the role of the urethra in non-specific defenses?

Urine kills pathogens and pushes them out of the urinary system.

What is the role of the vagina in non-specific defenses?

Acidic secretions kill pathogens and prevent infection of the reproductive system; labia is a physical barrier.

What is the role of the anus in non-specific defenses?

Mucus membranes trap pathogens preventing infection of the digestive system.

What is the role of phagocytes in internal defenses?

Cells engulf and digest pathogens using phagocytosis, including leucocytes and macrophages.

What is the role of the lymphatic system in internal defenses?

Consists of lymph vessels and lymph nodes, prevents infection by sending phagocytes to tissues to kill pathogens.

What is pathogenesis?

The step-by-step development of a disease from infection by a pathogen to termination of either the germ or the host.

What is virulence?

How well a pathogen causes disease.

What is epidemiology?

The study of the factors affecting the health of populations.

What is aetiology (etiology)?

The study of what causes a disease.

What is a vector?

The item that transfers the pathogen to its host.

What is transmission?

The passing of disease from an infected individual to unaffected individuals.

What is an endemic disease?

A common disease that occurs at a constant, but low, rate in a specific population.

What is an epidemic?

When an endemic disease occurs more frequently than expected, in each area over a given time.

What is a pandemic?

An epidemic of infectious disease that has spread over a larger area (continent, worldwide).

What is eradication?

The reduction of a pathogen and its subsequent disease to zero.

What is the cell-mediated response?

Cell-mediated immunity provides resistance to the intracellular phase of bacterial and viral infections.

what are the steps of the cell mediated response?

Foreign antigen presenting cell reaches the lymph glands, T-cell for that antigen is sensibilized and divides, clones specialize into killer T-cells, helper T-cells, supressor T-cells, and memory T-cells.

what is the role of killer T-cells?

migrate to site of infection and secrete substances that destroy them.

what is the role of Helper T-cells?

secrete substances that help to activate B-cells for antibody mediated response. They also attract macrophages to site so they can destroy antigen and intensify macrophage activity.

what is the role of Suppressor T-cells?

release substances to inhibit B and T cell activity when either the immune activity is excessive or once the infection has been dealt with.

what is the role of Memory T-cells?

remain in lymphoid tissue in case antigen returns at later date. If the same antigen invades the body again, the memory cells can initiate a faster response by producing the correct Killer t- cells for the correct antigen more quickly.