Lesson 1: Innate Immunity Flashcards
(12 cards)
The Immune System
The immune system is made up of a variety of white blood cells (leukocytes) and proteins that attack foreign substances such as bacteria and viruses as well as physical barriers.
This system also destroys damaged cells and irregular growths such as tumours.
The immune system must be able to distinguish harmful from harmless substances and deal with both efficiently.
Harmful substances that cause disease are known as pathogens.
Two Defences Categories
The defences of the immune system can be divided into two categories;
1. Innate Immunity
Uses non-specific defenses that are activated immediately.
- Adaptive Immunity
Also called acquired immunity. Activated only after exposure to specific pathogens.
Innate Immunity
The innate immune response is the first to activate and the response is always the same, it is not pathogen specific.
Innate immunity is found in all animals and consists of two types of defenses;
External Barriers
Internal Defenses
External Barriers
Skin - a physical barrier that cannot normally be penetrated by bacteria and viruses. Secretions (sebum) from oil and sweat glands give the skin a pH ranging from 3-5 which is acidic enough to prevent the growth of most microorganisms
Mucous Membranes - are physical barriers that line the organ systems of the body These membranes secrete
mucous and other fluids that trap, wash away and/or destroy potential invaders
Cilia – cells of some mucous
membranes contain cilia that can sweep mucous out of the body. Found extensively in the respiratory system.
Blood Clotting – cuts and damage to the skin are sealed through the formation of blood clots.
Review notes on the blood clotting process.
Internal Defenses
The internal defenses become activated if there is a foreign substances that has entered the body.
The internal defenses consist of white blood cells that found in both the blood and interstitial fluid.
The most abundant cells of innate immunity are phagocytic cells (neutrophils and macrophages)
Other cells include natural killer cells that attack cancer cells and viruses.
Interferons are proteins that can help impede the spread of viruses.
The Inflammatory
Response
The inflammatory response is a major component of innate
immunity.
During the inflammatory response the affected area becomes red, warm and swollen.
There are several cellular components involved in the
inflammatory response.
Mast Cells
Mast cells are NOT blood cells. They do not circulate in the bloodstream.
Mast cells are found in the skin, joints, connective tissue, muscle and blood vessels.
These cells trigger the inflammatory response when the physical barriers have been damaged, infected or
encounters a toxin.
Basophils
These white blood cells circulate in the blood.
During an injury blood vessels
dilate to carry more blood to
the injured area.
Basophils detect foreign
material and release histamine and other chemical signals which begin the inflammatory response.
Neutrophils
These cells make up 60-70% of all white blood cells.
Neutrophils are attracted to the chemical signals produced by Basophils.
Neutrophils enter infected tissue and self destruct, destroying foreign invaders.
Monocytes
Monocytes make up 5% of all white blood cells.
When these cells detect foreign material they develop and enlarge into Macrophages
As Macrophages they attach to and ingest foreign material and destroy them with digestive enzymes.
Eosinophils
These white blood cells attack
larger parasites and worms
using enzymes.
The Lymphatic System
Involved in both innate and adaptive immunity.
The function of the lymphatic system is to return tissue fluid to the circulatory system and to fight infection.
The lymphatic system consists of a branching network of vessels, lymph
nodes, the bone marrow and other organs.
