10: Organisms have a variety of mechanisms to combat disease.

10a. Know the role of the skin in providing nonspecific defenses against infection.

Vocabulary Epidermis Keratin Melanin Dermis Hair follicle Immunity Inflammatory response Fever Interferon Immune response Antigen Humoral immunity Cell-mediated Antibody Vaccination Active immunity Passive immunity

36—3 The Integumentary System The skin, hair, nails, and a variety of glands make up the ____________________ system. The ___________ is the largest organ in the body.

The Integumentary System What are the functions of the integumentary system? The integumentary system: serves as a ________________ against infection and injury. helps to regulate body ______________. removes waste products from the body. provides protection against ultraviolet radiation from the sun.

The Skin The Skin The skin is made up of two main layers—the _________________________ & _______________. Beneath the dermis is a layer of fat (hypodermis) and loose connective tissue that insulates the body.

The Skin Nerves Blood vessels Hair Sweat pore Sebaceous gland Hair follicle Epidermis The skin has an outer layer called the epidermis and an inner layer called the dermis. Dermis Muscle Sweat gland Hypodermis Fat

The Skin Epidermis  The outer layer of the skin is the __________________. The epidermis has two layers. The outer layer is made up of dead cells. The inner layer is made up of living cells. Cells in the inner layer undergo rapid cell division, producing new cells that push older cells to the surface of the skin. Older cells flatten and their organelles disintegrate. Older cells also begin making ________________, a tough, fibrous protein. When these cells die, they form a waterproof covering on the skin’s surface.

The Skin The epidermis also contains melanocytes, which are cells that produce _________________, a dark brown pigment. Melanin protects the skin from sun damage. Differences in skin ______________ result from different amounts of melanin and where melanocytes are distributed.

The Skin Dermis The dermis contains two major types of glands: The inner layer of the skin is the ____________________. The dermis contains collagen fibers, blood vessels, nerve endings, glands, sensory receptors, smooth muscles, and hair follicles. The dermis contains two major types of glands: sweat glands sebaceous, or oil, glands

The Skin If your body gets too hot, sweat glands produce sweat. When sweat evaporates, it cools the body. Sweat also gets rid of wastes from the blood, along with water. _______________________ glands produce an oily secretion called sebum. Sebum spreads out along the surface of the skin and helps to keep the skin flexible and waterproof.

How a Scab Forms

How a Scab Forms

How a Scab Forms

40-2 The Immune System What is the function of the immune system? The immune system is the body's main defense against _______________________. The immune system recognizes, attacks, destroys, and “remembers” each type of pathogen that enters the body. The immune system fights infection by producing cells that inactivate foreign substances or cells. This process is called ____________________.

40-2 The Immune System The immune system includes two general categories of defense mechanisms against infection: ____________________ defenses __________________ defenses

Nonspecific Defenses Nonspecific Defenses Nonspecific defenses do not _____________________ between one threat and another.

What are the body's nonspecific defenses against invading pathogens? ______________ _____________ of Defense  The first line of defense keeps pathogens out of the body. This role is carried out by skin, mucus, sweat, and tears. Your body's most important nonspecific defense is the skin. Few pathogens can penetrate the layers of dead cells at the skin’s surface. However, when the skin is broken, pathogens can enter the body and multiply. As they grow, they cause the symptoms of an infection, such as swelling, redness, and pain. If pathogens enter the skin, mucus, saliva, and tears, contain lysozyme—an enzyme that breaks down the cell walls of many bacteria. In addition, oil and sweat glands in the skin produce

Nonspecific Defenses Other nonspecific defenses include: _____________________in the nose and throat helps to trap pathogens. Cilia in the nose and throat push pathogens away from the lungs. Stomach acid and digestive enzymes destroy pathogens. _________________ __________ of Defense   If pathogens enter the body, the inflammatory response is activated. The inflammatory response is a nonspecific defense reaction to tissue damage caused by injury or infection.

Nonspecific Defenses The Inflammatory Response Wound Skin Phagocytes move into the area and engulf the bacteria and cell debris The inflammatory response is a nonspecific defense reaction to tissue damage caused by injury or infection. When pathogens enter the body, phagocytes move into the area and engulf the pathogens. In addition, platelets and clotting factors leak from the capillaries. Bacteria enter the wound Capillary

Nonspecific Defenses When pathogens are detected, the immune system makes ______________ ________________ cells, which fight the infection. Blood vessels near the wound expand, and white blood cells move from the vessels to enter the infected tissues. Many are _________________, which engulf and destroy bacteria. The infected tissue may become swollen and painful.

Phagocytosis of Pathogens _________________: occurs when a cell engulfs a particle Phagocytes: are white blood cells that destroy pathogens by surrounding and engulfing them. _______________: are white blood cells that provide the first line of defense against pathogens that have managed to enter the tissues Pus: a collection of dead macrophages and body fluids that forms in infected tissues

Phagocytosis

White Blood Cells

Nonspecific Defenses The immune system releases chemicals that increase the core body temperature, causing a _________________. This high temperature slows or stops the growth of pathogens. It also increases heart rate so white blood cells get to the site of infection faster.

Nonspecific Defenses Interferon Sometimes, virus-infected cells produce proteins that help other cells resist viral infection. These proteins are named ____________________ because they “interfere” with the growth of the virus. Interferons inhibit synthesis of viral proteins in infected cells and help block viral replication. This process ________________ the progress of infection and gives the specific defenses of the immune system time to respond.

Summary The most important function of the skin is to physically block __________________ from entering the body. Glands in the skin also produce ______________ oil and sweat that kill many bacteria.