study guide for humoral, respiration intro

what type of cell is most likely to start the immune response: a B cell, phagocyte, T cell, or a plasma cell?

• phagocyte → T cells → B cells

regarding T cells, what is the importance of antigen presentation?

• in order to activate a T cell, another cell must “present“ the antigen to the t cells in a certain way namely bound to an MHC protein

• antigen presentation is the key step that links the innate immune response to the adaptive immune response, allowing T cells to recognize a threat and respond appropriately.

what is a MHC protein? What is their major function?

• a membrane glycoprotein synthesized by a set of genes called the major histocompatibility complex

• the major functions of these proteins are “self“ recognition and to “present“ antigens to T cells

• this has to happen in order to activate the t cell

• each MHC protein has a specific 3-D shape with a narrow central groove (a specific antigen will bind to the groove)

class I MHC protein

• displaying non-self antigens tell immune system that the cells is infected with a virus or abnormal in some way and should be destroyed

• present in the membranes of all our nucleated cells

• as class I MHC protein is transported from golgi to the cells membrane, it picks up small peptides and displays them on the cell’s surface

• usually these peptides are normal and t cells ignore them, but if cell is infected with a virus (or cancerous), abnormal peptides are picked up and displayed - this activates the appropriate t cells which destroy the cell

• why donated organs often rejected…t cells recognize that these organs have abnormal (non-self) surfaces

• “i need to be destroyed“

class II MHC proteins

• displaying antigen tell immune system to be on the lookout throughout the body for that particular antigen

• only present in the membranes of lymphocytes and antigen-presenting cels

• ex of antigen-presenting cells: monocytes, macrophages, b cells, microglia of CNS, dendritic cells in stratum spinosum

• often a phagocytic cell engulfs a bacterium and breaks down the bacterium with a lysosome

• bind to the antigenic fragments of the bacterium and then display them on the surface of the phagocytic cell

• “be on the lookout“

terms of class I MHC proteins

• what types of body cells they occur on? - all nucleated cells

• what they “warn” the immune system of? - infected, abnormal cells

• what specific type of lymphocytes they may activate? - Tc cells

terms of class II MHC proteins

• what types of body cells they occur on? - lymphocytes, APCs

• what they “warn” the immune system of? - presence of pathogen in general

• what specific type of lymphocytes they may activate? - Tn cells, B cells

explain why donated organs are often rejected..

• t cells recognize that these organs have abnormal (non-self) surfaces

give a few examples of antigen-presenting cells.

• monocytes

• macrophages

• b cells

• microglia of CNS

• dendritic cells in stratum spinosum

explain how bacterial antigens eventually become displayed on the surface of a phagocyte. Be sure to include what type of MHC protein is involved.

• often a phagocytic cell engulfs a bacterium and breaks down the bacterium with a lysosome

• bind to the antigenic fragments of the bacterium and then display them on the surface of the phagocytic cell

• class II MHC proteins

in order for antigen recognition to occur, a T cell must bind to what two things?

• the MHC protein

• the correct antigen

what are the three major classes of T cells? Briefly describe the function of each type. Which of these is the main cell of cellular immunity?

• cytotoxic t cells: attack foreign cells and body cells either infected with viruses or abnormal in some way ; highly mobile cells that roam oour tissues and destroy target cells mainly by direct contact ; cellular immunity

• helper t cells: stimulate both t cells and b cells

• suppressor t cells: inhibit both t cells and b cells ; produced in relatively small numbers and are slow to act, basically they help turn off the immune response

describe what’s meant by a “clone army” of cytotoxic T cells?

• makes many activated cytotoxic t cells (clones)

• immediately begins destroying the infected or abnormal cell

in order to activate a cytotoxic T cell, this cell has to encounter what (be specific)?

• A cytotoxic T cell is activated when it recognizes its specific antigen bound to MHC I on a cell surface, along with the proper additional signals.

an activated cytotoxic T cell differentiates into what two classes of cells?

• effector (cytotoxic) t cells

• memory t cells

describe three ways in which active cytotoxic T cells can destroy infected cells (or abnormal cells, e.g., cancerous cells)?

• by secreting perforins into the target cell

• by activating gene’s in the pathogens nucleus that cause it to die

• by secreting a powerful toxin called a lymphotoxin

explain the function of memory cytotoxic T cells.

• they remain inactive until person is exposed to the same antigen in the future

• then they immediately differentiate into active cytotoxic t cells that quickly neutralize the pathogen the second time around

in order to activate a helper T cell, this cell has to encounter what (be specific)?

• when an inactive helper t cell encounters its target antigens bound to a class II MHC protein, it is activated and differentiates into two classes of cells:

• makes many activated helper t cells (clones) ; these cells release several interleukins (chemical messengers) that coordinate many aspects of the immune system

• makes many memory helper t cells (which remain inactive)

what do active helper T cells secrete? In general, what are the effects of this secretion?

• helper T cells secrete cytokines that amplify, direct, and coordinate the entire immune response.

which immune response creates a clone army of antibodies? Which a clone army of cells?

• the humoral immune response

unlike T cells, what do B cells display on the surface of their cell membranes? Similarly, when an inactive B cell encounters its target antigen in the interstitial fluid, what specific part of the B cell does the antigen bind to?

• b cells launch a chemical attack

• own specific antibody and class II MHC protein

• B cells display membrane-bound antibodies (BCRs)

• Antigens bind directly to the antigen-binding sites on those receptors

explain the process of sensitization of a B cell.

• when an inactive b cell encounters its target antigens in the interstitial fluid, the antigen gets bound to the b cell’s antibody

• this binding causes the b cell to preare for activation in a process called sensitzation

• b cell brings some of the antigens actually into the cell, where they get bound to class II MHC proteins

• then get inserted into the b cell’s membrane and display the antigen

in order to activate a sensitized B cell, the B cell has to join to what specifically?

• joining to a helper t cell that has already been activated by exposure to the same antigen

• an already activated helper t cell binds via its t cell receptor to the MHC complex of the sensitized b cell and begins secreting interleukins that activate the b cells

an activated B cell differentiates into what two classes of cells?

• many activated b cells

• makes many memory b cells

an active B cell differentiates into what type of cell that actually produces antibodies?

• plasma cell

which organelle is especially abundant in a plasma cell? Why is this?

• lots of RER

explain the function of memory B cells.

• these memory cells remain inactive

• when a person is exposed to same antigen in the future, they immediately differentiate into active b cells that quickly form plasma cells

• which secrete a tremendous amount of antibody to neutralize the pathogen the second time around

what is a synonym for antibody? describe the structure of an antibody.

• immunoglobulins

• two identical light chains and two identical heavy chains

• each chain has a constant region and a variable region

• the variable regions have different amino acid sequences

what specific part of the antibody forms the antigen binding site?

• together the variable regions of both the light and heavy chains form a highly specific 3D structure (this forms the antigen binding site)

it’s been estimated that each of us can produce about 100 ___ different types of antibodies, each specific for a different antigen.

million

list all the major classes of immunoglobulins. Which class is the most abundant?

• IgM, IgA, IgD, IgG, IgE

• IgG is the most abundant

give an example of how IgG helps destroy pathogens.

• it protects the body in many ways

• ex: when IgG covers a bacterium, receptors on macrophages recognize the IgG (heavy chains) and engulf the IgG-bacterium complex

• opsonization: buttering up the bacterium ; candy coating

what are some ways in which antibodies help thwart or attack pathogens.

• preventing viruses, bacteria from being able to bind to our cells

• activating the complement system

• attracting phagocytes

• causing agglutination (clumping) of pathogens

allergies are caused by hypersensitivity of which class of antibody?

• IgE hypersensitivity

What specific type of cell do these antibodies bind to? And what chemical is released by these cells that cause the symptoms of an allergy?

• tissues under mucous membranes are rich in b cells that produce IgE

• when an allergen enters the body, as usual a helpter t cell gets activated and secretes interleukins that activate these b cells thus leading to IgE producing plasma cells

• the resulting IgE antibodies attach to nearby mast cells

• when exposed to antigen for the second time, the antigen binds to the IgE on these mast cells

what are some of the especially dangerous symptoms of an allergic response?

• this very quicky causes the mast cells to release histamine which causes:

• itching, constriction of airways, capillary dilation, mucus secretion, pain

What is meant by the primary versus the secondary immune response to a pathogen?

primary:

• the initial response to antigen exposure

• 2 weeks to develop maximum antibody levels and activity

• IgG levels lag behind IgM levels

secondary:

• when the same antigen appears again, it triggers a more rapid and extensive response

• the more robust secondary response is largely due to the existence of memory cells

• antibody levels rise more rapidly and IgG does not lag behind IgM, they rise at the same rate

• IgG continues to rise to levels well beyond what was seen in the primary response and remains elevated for longer time

Do the primary and secondary responses occur just in antibody-mediated immunity or do they also occur in cell-mediated immunity?

• both cell-mediated and humoral immunity

for humoral immunity, describe three ways in which the secondary response differs from the primary?

• antibody levels rise more rapidly and IgG does not lag behind IgM, they rise at the same rate

• IgG continues to rise to levels well beyond what was seen in the primary response and remains elevated for longer time

What are the two routes that air may take to get to the larynx?

• mouth or oral cavity

What anatomical features create turbulence in the nasal cavity? How is turbulence beneficial?

• the air starts to flow in swirls and eddies (turbulence) as it hhits the superior, middle, and inferior nasal conchae

• also filtered, humidified, and warmed to some extent by the mucous membranes lining the nasal cavity

Where exactly are the olfactory receptors located? Describe the pathway by which olfactory information passes to the brain.

• located in olfactory epithelium

• air that flows superiorly in the nasal cavity hits the olfactory epitheloium and stimulates the olfactory receptors

• the olfactory nerves (CN I) pass through the cribriform plate of the ethmoid in order to join to the olfactory bulb of the brain

What are the two largest pieces of cartilage that make up the larynx?

• thyroid cartilage: the largest cartilage piece of the larynx, made of hyaline cartilage ; anterior medial laryngeal prominence is easy to palpate on your throat

• cricoid cartilage: the second largest cartilage piece of the larynx ; just inferior to the thyroid cartilage

What are two functions of the larynx?

• voice box

• a cartilaginous chamber that contains the vocal cords and helps to keep food/drink out of the trachea

Where is the laryngeal prominence located?

• visible bump on the front of your neck over the larynx (voice box).

• adam’s apple

what type of cartilage makes up the epiglottis? What is the function of the epiglottis? To which bone does it attach?

• a flaplike piece of elastic cartilage superior to the opening of the larynx

• covers up the larynx when we swallow ; thus routes food/liquids to the more posterior esophagus

• attached to the hyoid bone

• if any food or liquid accidentally enter larynx a cough reflex is triggered

What is the glottis?

• collectively made up of the vocal cords and the opening (to the trachea) between them

Describe the basic structure and location of the vocal cords.

• ligaments covered with a stratified squamous EPI that run from the thyroid cartilage to the posterior arytenoid cartilage

What is the function of the stratified squamous epithelium that covers the vocal cords?

• helps protect them from the air friction

What is the mechanism for producing high-pitched versus low-pitched sounds?

• high-pitched: when vocal cords are taut (stretched)

• low-pitched: when relaxed

What structures are involved in adducting and abducting the vocal cords?

• Abduction (open cords): posterior cricoarytenoid muscle

• Adduction (close cords): lateral cricoarytenoid + interarytenoid muscles

What determines the loudness of the vocalizations we produce?

• on the force of air passing between the vocal cords

What structures besides the larynx help refine the vocalizations we produce?

• the larynx produces only crude sounds

• more precise sounds result from the combined actions of the lips, tongue, and the throat

What influence do the cranial sinuses have on vocalizations?

• Cranial sinuses influence vocalizations by acting as air-filled resonance spaces that modify and enrich the sound of the voice.

• sinuses: frontal, ethmoid, sphenoid, maxillary

Where are the vestibular folds? What is their function?

• more superior folds that close the glottis during swallowing

• play an even more important role than the epiglottis in keeping food.drink out of the windpipe

What type of tissue lines the trachea?

• lined with pseudostratified columnar epithelium (lots of goblet cells and cilia)

What is meant by the “mucus escalator”? What is its function?

• traps debris and pathogens in the mucus

• then the cilia move the mucus upward to the throat to be swallowed - helps keep the lungs clean

What are the two functions of the C-shaped tracheal rings?

• c-shaped partial rings of hyaline cartilage

• tracheal rings prevent the trachea from collapsing during inhaltion

• open point of ‘C‘ points to the back and allows the esophagus to bulge forward as swallowed food passes through

How many primary and secondary bronchi are there?

• primary: at joint between manubrium and bod of sternum, the trachea forks into two primary bronchi

• 2 primary (right and left - one to each lung)

What type of tissue makes up much of the lungs?

• made up largely of elastic connective tissue which enables the lungs to “recoil“ during exhalation

How many lobes make up the left lung? the right lung?

• right: 3 lobes (superior, middle, and inferior)

• left: 2 lobes (superior and inferior)

What is the membrane called that directly covers the lungs? That lines the pleural cavity?

• visceral pleura, which continues as the parietal pleura

• which lines the thoracic cavity and the top of diaphragm

Where is the pleural cavity located? Is it a real open space? What is the function of pleural fluid?

• lubricated by pleutral fluid

• this fluid causes the plurae to stick to each other ; thus holding the lungs to the thoracic wall

• and reduces friction as they slide against each other

What do the secondary bronchi branch into?

• each primary bronchus divides into the secondary bronchi as it enter the lungs

• tertiary bronchi

How is a bronchiole different from a bronchus?

• bronchi are larger, cartilage-supported airways, while bronchioles are smaller, smooth-muscle–controlled branches that regulate airflow to the lungs’ gas-exchange areas.

• bronchioles: eventually the branches become the bronchioles, which are very fine branches that lack cartilage and are 1 mm or less in diameter

In general, what happens to the relative amounts of cartilage and smooth muscle as the airways of the lungs get smaller and smaller?

• the various respiratory passages get smaller and smaller, the relative amount of cartilage decreases and the amount of smooth muscle in the walls increases

What branch of the nervous system controls the constriction of the smooth muscle in the airways?

• this smooth muscle can contract and thus constrict the airways as in asthma

• the smallest branches are called the terminal bronchioles

Describe the remaining branches that occur between the bronchioles and the alveoli?

• the terminal bronchioles in turn branch into the thin-walled respiratory bronchioles

• the respiratory bronchioles branch into the alveolar ducts

• the alveolar ducts end at the alveolar sacs which are clusters of alveoli

In what structures of the lungs are gases actually exchanged? What is the approximate surface area of these structures?

• alveoli

• sites of gas exchange between the air and blood togehter add up to 70 square meters of surface area

Describe the relationship between the alveoli and the surrounding capillaries.

• alveoli: thin walled, balloonlike structures surrounded by a network of capillaries

• made up of a simple squamous EPI joined in many spots to the endothelium of the pulmonary capillaries ; essentially they share the same thin basement membrane ; allows gases to diffuse very rapidly

What two cell types are found in the alveoli? What are the functions of each type?

great alveolar cells: cuboidal cells with two major functions

• help repair damage to the squamous cells

• secrete pulmonary surfactant (a mixture of protein and phospholipids that coats the alveoli and smallest bronchioles and prevents them from collapsing during exhalation)

alveolar macrophages (dust cells)

• the most numerous cell in the lungs

• ingest dust particles, bacteria, RBCs that have escaped from ruptured capillaries

• basically keep the lungs clear and clean

What is the chemical composition and function of surfactant?

• Surfactant is a phospholipid-rich mixture that keeps alveoli from collapsing and makes breathing easier by lowering surface tension in the lungs.