Defenses Overview & Barriers
Defenses & Barriers Objectives
-
Describe how the integumentary system, cardiovascular system, skeletal system, and lymphatic system play a role in defense.
-
List the two non-specific innate defenses and the two specific acquired defenses.
-
Provide examples of barriers that keep pathogens and parasites out of the body.
The body’s defenses against pathogens are often called the “immune system.” However, there is no single immune system like the other organ systems we have been covering in this course. The body has multiple defenses against pathogens, involving multiple organ systems.
This video provides an overview of the human defenses against pathogens and parasites.
Here are four organ systems involved in the response against pathogens.
Integumentary System
Skin and secretions like tears and urine are a barrier against pathogens. Mucus-membranes line the trachea to trap and move pathogens up and out of the respiratory system.
Skeletal System
The bone marrow produces white blood cells and each cell can destroy pathogens in different ways.
Cardiovascular System
Some white blood cells travel through the blood to distant locations like the thymus and lymph nodes, while others patrol the blood in search of pathogens.
Lymphatic System
Some white blood cells monitor pathogens that may have accumulate in the lymph (extracellular fluid). Lymphocytes wait in lymph nodes, prepared to pounce on pathogens.
These organ systems form four lines of defense
Two non-specific and two specific defenses.
This is a quick look at the four basic defenses, two that are non-specific (barriers and inflammation) and two that are specific involving T Lymphocytes (T cells) killing infected cells and B lymphocytes (B cells) producing antibodies.
Two lines of defense are non-specific, pre-programmed and similar responses to any potential pathogen.
Barriers
Structures and chemicals keep pathogens from entering the body.
Inflammation
Wounded cells release chemicals that dilate blood vessels and bring in blood to clean the wounded area. The next section describes inflammation in detail.
Barriers
The skin is a very effective barrier, but even shallow abrasions to the epidermis could lead to an infection.
Mucus is a critical barrier secretion in the respiratory system, but excessive mucus can result in a variety of disorders, including sinusitis.
The next section provides an overview of inflammation, another non-specific defense.
Check your knowledge. Can you:
-
describe how the integumentary system, cardiovascular system, skeletal system, and lymphatic system play a role in defense?
-
list the two non-specific innate defenses and the two specific acquired defenses?
-
provide examples of barriers that keep pathogens and parasites out of the body?
Go back to the Defense Systems Guide Overview
Go forward to the Inflammation Page
Defense Systems Guide Contents
Complete all four of these sections before taking the quiz and making your media piece.
Back to Module 9
This week’s overview
This Guide
9A: Defense Systems
Products Information
9A: Quiz & Media
