Unit 10: Immune System

Holy Names Academy Study Guide - Freshman Biology - Unit 10

What is the first line of defense?

Physical or chemical external barriers EX: skin, hair, tears.

What is the second line of defense?

An internal non-specific reaction, when pathogens enter the body. (Inflammatory response)

What is the 2nd line of defense commonly known for?

The inflammatory response

What is a pathogen?

A disease-causing agent EX: bacteria, fungi, viruses

What are some common ways viruses/pathogens can be transmitted?

• Airborne

• Food or water-borne

• Through body fluids

How does your body protect you from illnesses?

Three lines of defense:

First two are non-specific (will attack anything)

Third is specific (has a target)

What is the first thing that happens in the inflammatory response?

A pathogen makes it past the 1st LOD - and specialized mast cells release a chemical signal called histamine into the blood.

What are mast cells?

Specialized cells whose job it is to recognize pathogens and release the histamine (they recognize name tags, antigens)

What is histamine:

Effectively an alarm for the rest of the body.

What does histamine cause?

• Blood vessels to expand and become leaky, which causes inflammation.

• Causes specialized wbc’s called macrophages to be released in response to the alarm

How to macrophages destroy pathogens?

By engulfing themselves around the pathogen and damaged cells. Once they engulf they display the antigens

What does MHC stand for?

Major Histocompatibility complex.

What is the job of the MHC?

MHC’s are proteins on all cells your body makes, that helps you recognize “self” from “non-self”

What happens when your body finds a cell without your unique MHC?

It starts the attack.

What is the first step of the ‘attack’?

Find cells that are specifically designed to fight the specific invader and attack.

How do we identify the pathogens?

The macrophage (displaying the antigen) goes to the helper T cell. The helper T cell has a protein used to identify the antigen. It binds to the macrophage and releases interleukins, that call T & B cells for assistance.

How does the Killer T work? - Cell mediated response

When the immune system finds the correct killer T cell, it is cloned. Then the Kiler T cells (CD8) finds the infected body cells and injects the toxin into them, causing them to rupture.

How do the B cells work? - Humoral response

Once it is found, if is cloned and turned into plasma cells, or memory B cells. They make antibodies.

What are antibodies?

Special proteins that attach to antigens. They identify the invaders for the cleanup crew and prevents the virus from infecting other cells by paralyzing the virus.

What is the last step of the specific immune system response?

Once the invader is eliminated, memory B and T cells remain. If the body sees the same antigen again, it immediately makes antibodies and releases interleukins faster than previously.

What happens to the killer T cells when the virus is no longer active?

Some of them shrivel