Bio Exam 3 (Chapter 24)

Memory cells

long-lived cells found in the lymph nodes, ready to attack should a "known" antigen infect the body again.

Adaptive immunity

continually develops over your lifetime as it encounters and attacks specific pathogens. ensures you will have better protection from a specific pathogen each time you encounter it. strictly internal, deploying when innate immunity defenses fail to ward off a pathogen.

B cells

fully develop and become specialized in the bone marrow. Must be primed. defend primarily against pathogens circulating in body fluids.

interstitial fluid

Nutrients and wastes for all cells are exchanged in this. Most of this fluid reenters the blood and the circulatory system through capillaries, but some remains in the tissue. This excess fluid flows into small lymphatic vessels.

vertebrates

Only *blank* have adaptive immunity

The internal innate defenses depend on

white blood cells and defensive proteins.

​​Phagocytic cells

white blood cells that engulf foreign cells or molecules and debris from dead cells by phagocytosis, or "cellular eating."

immune system

your body's defense against infectious disease. a collection of organs, tissues, and cells that together perform the vital function of safeguarding the body from a constant barrage of pathogens

secondary immune response

If memory cells are exposed to a previously encountered antigen, they rapidly give rise to new effector cells and memory cells, a process known as the

Third line of defense

Internal adaptive defenses, lymphocytes, antibodies.

Second line of defense

Phagocytic cells, natural killer cells, defensive proteins, inflammatory response.

Internal innate defenses

They are ready with immune cells and defensive proteins should a pathogen make it past the external innate defenses

The chemical signals

attract phagocytic cells, which engulf bacteria and the remains of body cells killed by bacteria or physical injury.

Some barriers of external innate defenses block or filter out pathogens.

-Intact skin forms a tough outer layer that most bacteria and viruses cannot penetrate. -Normal bacterial skin flora -Nostril hairs filter particles from the incoming air. -Ear wax traps pathogens before they can travel too far down the ear canal. -Organ systems that are open to the external environment are lined with cells that secrete mucus, a sticky fluid that traps bacteria, dust, and other particles.

As interstitial fluid circulates

phagocytic cells inside lymphatic tissues and organs engulf the invaders.

chemical barriers in the form of antimicrobial secretions.

-Sweat, saliva, and tears contain enzymes that disrupt bacterial cell walls. -The skin contains oils and acids that make it inhospitable to many microorganisms. -The cells of the stomach produce acid that kills most of the bacteria we swallow.

Antigens

-are molecules that elicit a response from a lymphocyte, -are usually on the surfaces of viruses or foreign cells, and -also include toxins secreted from bacteria, molecules from mold spores, pollen, house dust, and molecules on cell surfaces of transplanted tissue.

clonal selection produces

-cells that will fight the first exposure to an antigen (effector cells) and -cells that will respond to future exposures (memory cells).

allergens

Antigens that cause allergies

clonal selection

At first, an antigen activates only a tiny number of lymphocytes with specific antigen receptors. These "selected" lymphocytes then multiply through cell division, forming a clone of lymphocytes (a population of genetically identical B cells or T cells) with a specific antigen receptor.

First line of defense

Skin, secretions, mucous membranes.

effector cells

Some of the newly produced B cells are short-lived cells that have an immediate effect against the antigen. secrete huge quantities of antibodies. The response peaks about two to three weeks after the first exposure and starts to decline.

thymus

a gland in the chest

The lymphatic system

a network of vessels, tissues, and organs where pathogens and cells involved in innate immunity and adaptive immunity interact with each other to carry out defensive actions.

protruding from the surface of B cells and T cells are

antigen receptors that bind to an antigen. One cell may recognize an antigen on the mumps virus, for instance, whereas another detects an antigen on a tetanus-causing bacterium.

histamine

causes nearby blood vessels to dilate (widen) and leak fluid into the wounded tissue, a process called swelling. The excess fluid heals damaged tissue by diluting toxins in it, bringing it extra oxygen, and delivering platelets and clotting proteins to it that promote scabbing.

cytotoxic T cells

destroy pathogens within body cells. the only T cells that actually kill infected cells.

pathogens

disease-causing agents like viruses and bacteria.

helper T cells

do not directly carry out attacks on pathogens but aid in stimulating both the B cells and the cytotoxic T cells in their responses. respond to infection by stimulating the activity of B cells and cytotoxic T cells

Innate immunity

doesn't change much from the time you are born, and its components attack pathogens indiscriminately. Includes both external and internal defenses.

External innate defenses

keep the pathogen from entering the body and do so in a variety of ways. forms the frontline of your immune system because they prevent infection, as opposed to your body's other defenses, which fight an infection after it occurs.

Lymph nodes

key sites where particular white blood cells called lymphocytes multiply during times of infection

antibodies

may serve as physical barriers that prevent pathogens from entering body cells. also aid in pathogen destruction. The binding of *blank* to antigens on pathogens can also result in clumps that are easily engulfed and destroyed by circulating phagocytic cells.

Immature T cells

migrate via the blood to the thymus, a gland in the chest, where they mature and become specialized. Must be primed.

inflammatory response

often makes infected areas red, swollen, painful, and warm to the touch. Injured cells of damaged tissues release chemicals that trigger various internal innate defenses.

antigen receptors on T cells

only recognize fragments of antigens, and the fragments must be displayed, or presented, on the surface of body cells by special proteins before T cells are activated.

Natural killer (NK) cells

recognize virus-infected and cancerous body cells

Damaged cells

release chemical signals that increase blood flow to the damaged area, causing the wound to turn red and warm.

Antigen receptors on B cells

specialize in recognizing intact antigens that are on the surface of pathogens or circulating freely in body fluids.

primary immune response

the first response to an antigen

The two main functions of the lymphatic system are

to return tissue fluid to the circulatory system and to fight infection.