ch 21 - Immune system

Gastric acid in the stomach, acid mantle on skin, lysosomes in saliva, mucous membranes, are part of what immune system line of defense?

1st line

innate surface barriers

An individual gets a snake bite and goes to the hospital to receive antibodies against the venom. This is a form of:

artificially acquired passive immunity

most activated B-lymphocytes differentiate into

plasma cells

Which substance triggers direct apoptosis in infected body cells?

granzymes

This outcome of the complement system creates pores in a pathogen’s cell membrane, allowing an efflux and influx of substances, ultimately leading to cell death.

membrane attack complexes (MAC’s)

Often times a virus-infected cell will release _________ to prevent spread of the infection.

interferons

Instead of directly destroying pathogens, antibodies use what four defensive mechanisms?

• neutralization

• agglutination

• precipitation

• complement activation

Fever, inflammation, phagocytes, natural killer cells, and antimicrobial proteins are all part of what immune system line of defense?

2nd line

innate internal barriers

Which immune response takes longer to respond?

adaptive immunity

Lysozyme in saliva is a part of what line of defense of the body?

1st line of defense

innate surface barriers

Mucous-coated cilia in the respiratory tract is a part of what line of defense of the body?

1st line of defense

innate surface barriers

What are the two kinds of phagocytes?

• neutrophils

• macrophages

Most abundant type of white blood cell and first responder that phagocytizes pathogens?

neutrophils

Type of white blood cell that arrives later to defend, can provide longer defense, often eat bigger things?

macrophages

What are the two kinds of macrophages?

• free - can wander thru tissue spaces

• fixed - reside permanently in particular organs

How is phagocytosis initiated? (what must bind?)

phagocyte binds to pathogen using receptor

General steps of phagocytosis?

1. 1. phagocyte receptors bind to pathogen

2. 2. pathogen is engulfed and enclosed within a vesicle

3. 3. lysosome in phagocyte fuses with pathogen vesicle to break down

What organelle in macrophages are responsible for the chemical breakdown of pathogens during phagocytosis?

lysosomes

The process where pathogens are marked by antibodies or complement proteins for destruction

opsonization

What kind of cells kill cancer cells + virus-infected cells before adaptive immunity can be activated?

natural killer cells

What innate internal defense induced apoptosis?

Natural killer cells

What abnormalities of a cell would cause NK cells to activate?

lack of MHC’s (major histocompatibility complex) (self-identifying surface proteins)

What do NK cells release to kill an infected cell?

• 1. perforins (to make holes)

• 2. granzymes (to degrade cell enzymes)

What are the four cardinal signs of inflammation?

• swelling

• redness

• warmth

• pain

Which is untrue regarding the purposes of inflammation?

its a specific response

Caused by histamine, what physiological response is chemically invoked during inflammation?

vasodilation, increases blood flow to area

Kinins, prostaglandins, histamine, and complement proteins are chemical all involved in?

inflammation

If inflammation is activated by pathogens, what chemical system is activated?

complement

Inflammatory chemicals induce what two things that allow for phagocyte mobilization?

• vasodilation

• increased vascular permeability

After inflammation begins, phagocytes flood the area with what kind leading? and what following?

neutrophils lead

monocytes follow

In order what are the steps of phagocyte mobilization?

1. 1. leukocytosis

2. 2. margination

3. 3. diapedesis

4. 4. chemotaxis

What cells release histamine?

mast cells

What occurs during the first step of phagocyte mobilization?

neutrophils are released from bone marrow into blood stream

What occurs during the second step of phagocyte mobilization?

neutrophils + other phagocytes cling to walls of capillaries once they reach the spot of injury (areas will have cell adhesion molecules that indicating location)

What occurs during the third phase of phagocyte mobilization?

neutrophils flatten and squeeze out of blood stream thru endothelial cells into injured tissue

What occurs during the fourth phase of phagocyte mobilization?

the neutrophils + other leukocytes release chemotactic agents that call more WBC’s to area

What function of inflammation would cause heat and redness?

increased blood flow to area

What function of inflammation would cause swelling?

increased capillary permeability

• brings fluid to leak into damaged tissues

What role do macrophages play in inflammation?

Arrive after inital neutrophils + dispose of final cell debris

What anti-microbial protein is secreted by infected body cells to protect surrounding healthy cells?

interferons

How do interferons combat viruses?

• prevent further replication of virus

What are three pathways of activating the complement system

1. 1. classical - antibodies that have coated the target cell activate the pathway

2. 2. lectin - lectins produced to recognize invaders bind to invaders + then can bind to and activate complement

3. 3. alternative - spontaneously activated factors interact

What kind of immunity does the complement system contribute to?

innate and adaptive

The complement system initiates a cascade that results in what three things?

• inflammation

• opsonization → phagocytosis

• cytolysis

Leukocytes + macrophages release what chemical in response to exposure to foreign substances?

pyrogens

Pyrogens act on what part of the body to induce fever?

hypothalamus

What is known as an abnormal elevation in body temp?

pyrexia

Aside from suppressing bacterial growth, how does fever response fight infection?

spleen + liver hide sequester iron and zinc to make bacteria growth difficult

increases metabolic rate = speeds repair of tissues

What two mechanisms facilitate adaptive immunity?

• humoral immunity

• cellular immunity

Which type of immune response is characterized by fast response, restriction to site of initial infection + nonspecific?

innate

Which type of immune response is characterized by bodywide response, slow to mobilize, memory, and specific?

adaptive

Which cells are responsible in cellular immunity?

T cells:

• cytotoxic T cells

• helper T cells

Which cells are responsible in humoral immunity?

B cells (which make antibodies)

Which mechanism of adaptive immunity targets pathogens in bodily fluids like bacteria and toxins?

humoral

Which mechanism of adaptive immunity targets intracellular pathogens like cancer cells + foreign tissue?

cellular

How does humoral immunity act on pathogens?

- mark for destruction

- neutralize/inactivate pathogen with antibodies

What two ways does humoral immunity act on pathogens?

• directly - killing infected cells

• indirectly - releasing chemicals + enhancing inflammation

Known as any substance that triggers an immune response + can mobilize adaptive defenses?

antigen

Complete antigens possess what two important properties?

immunogenicity: ability to stimulate multiplication of certain lymphocytes

reactivity: ability to react with lymphocytes and antibodies

What is known as an incomplete antigen?

hapten

Non-self antigens are recognized as foreign by the immune system and generate what in response to first encounter?

antibodies

Cell surface proteins that identify cells as self-antigens

MHC proteins (major histocompatibility complex)

What cells of the adaptive immune system do not respond to specific antigens?

ACP’s

Where do B + T lymphocytes originate?

red bone marrow

Where do B lymphocytes mature?

red bone marrow

Where do T lymphocytes mature?

thymus

During maturation of lymphocytes what two abilities do they develop?

• ability to recognize its antigen = immunocompetence

• knowledge to not attack own cells = self tolerance

During their development, what causes lymphocytes to become activated?

encountering + properly binding to its antigen

If a lymphocyte is activated, what process are they selected for?

clonal selection

What is positive and negative selection used for in the process of lymphocyte development?

ensures cell can recognize self antigens

positive = properly able to + move onto next phase

negative = unable to + eliminated

T cells are only able to be activated upon encountering the antigen via?

APC’s presenting the antigen

Upon activation + proliferation (primary encounter with antigen), B cell clones differentiate into what two kinds of cells?

• plasma cells

• memory B cells

What proliferation from B cells creates antibodies?

plasma cells (to fight whatever is encountered)

Which immune response is slower + smaller?

primary

Which immune response is larger + faster?

secondary

type of humoral immunity in which the body is producing antibodies in response?

active

type of humoral immunity in which readymade antibodies are introduced into body?

passive

Acquiring a response to bacteria or viral infection through contact with pathogen would be considered what type of immunity?

active: naturally acquired

Acquiring immunity through a vaccine is considered what kind of immunity?

active - artificially acquired

Immunoglobulins are/also called?

antibodies

Antibodies are made by?

plasma cells (after b-cells)

Upon their release in response to an antigen, antibodies bind with?

that specific antigen

What is the structural makeup of an antibody?

4 polypeptide chains

• 2 short light chains

• 2 long heavy chains

Antibodies responding to different antigens have very different _____ regions.

variable

The variable + constant regions of a antibody structure combine to form what?

antigen binding site

How do antibodies interact with antigens?

inactivate + tag for destruction

To conduct their defensive mechanism, what must occur with antibodies?

antigen-antibody complex must form (antibodies attach to antigen)

What defense mechanism of antibodies is neutralization?

antibodies cover + block binding sites of pathogens

What defense mechanism of antibodies is agglutination?

clumps together antigens of pathogens, makes easier to phagocytize + restricts to one area

What defense mechanism of antibodies is precipitation?

antibodies form ball lattice structure with agglutinated pathogens

Upon being activated, antibodies can enact complement system, what occurs during this?

opsonization + membrane attack complexes (causes cell death)

Role of regulatory t-cells

moderate immune response

Role of helper t cells?

• stimulate b-cells to make antibodies

• stimulate/activate t-cells

Role of helper t-cells?

informs other cells + induced proliferation + signal activation upon contact with a pathogen

How do regulatory T-cells regulate immune response?

inhibitory cytokines