Anatomy and Physiology II Exam 2

What are the functions of each type of white blood cell and how do they kill antigens?

Neutrophils: first responders in infection; phagocytosis which engulf pathogens, then destroy them with enzymes and reactive oxygen species

Lymphocytes:

• B cells: humoral immunity; produce antibodies that binds antigens which neutralize them or mark them for destruction

• T cells:

  • Cytotoxic T cells: kill infected/abnormal cells by releasing perforin (creates pores) and granzymes (trigger apoptosis)

  • Helper T cells: do not kill directly; activate and coordinate other immune cells via cytokines

Monocytes: long-term defense phagocytosis (after transforming into fixed or wandering macrophages)

Eosinophils: defense against parasites; releases toxic granules and enzymes onto large pathogens

Basophils: mediate inflammation and allergic responses; release histamine and other mediators that enhance inflammation and recruit other immune cells

Lymphatic system

A system consisting lymphatic vessels through which a clear fluid called lymph plasma passes.

What are the 3 major functions of the lymphatic system?

1.) Draining interstitial fluid

2.) Transporting dietary lipids absorbed by the gastrointestinal tract to the blood

3.) Facilitating the immune responses

Primary and secondary lymphatic organs

Primary: thymus gland and red bone marrow

Secondary: spleen, lymph nodes, and more

What is lymph plasma and what you would expect its contents to include?

Is a clear to milky fluid in the extracellular fluid compartment. It is the unaltered interstitial fluid that enters lymphatic vessels. In the GI tract, lymphatic fluids also include absorbed dietary lipids. Contains water, electrolytes, plasma proteins, white blood cells, cellular debris/waste products, pathogens, and absorbed lipids.

How do lymphatic capillaries differ in structure and function from blood capillaries? How are they similar?

Similarities:

• Composed of a single layer of endothelial cells

• Exchange between blood/tissues and extracellular fluid

• Extensive networks

• Maintain homeostasis of fluid and solutes

• Everything flows back to the heart

Differences:

• Lymphatic

  • Slightly larger than blood capillaries

  • Highly permeable

  • Unique one-way structure

    • The ends of endothelial cells overlap and permit interstitial fluid to flow in, but not out

    • When interstitial fluid accumulates, anchoring filaments pull openings wider

  • Anchoring filaments prevent collapse when tissue pressure arises

  • Absorbs large molecules, collects excess interstitial fluid which becomes lymph, transports immune cells, and absorbs dietary fats

• Blood

  • Continuous loops/networks

  • Less permeable

  • Continuous basement membrane

  • Smaller than lymphatic capillaries

  • Site of exchange between blood and tissues; deliver oxygen, nutrients, hormones; remove CO2 and metabolic wastes

How are lymphatic vessels similar, in structure, to veins?

Lymphatic vessels are structurally similar to veins in that both are thin-walled, tube-like vessels containing one-way valves to prevent backflow and possess a three-layer structure (tunica intima, media, and adventitia). Both systems are low-pressure systems that move fluid toward the heart and use surrounding muscular contractions to assist with transport.

The flow of lymph

Lymph flows from the periphery toward the central vasculature. It starts as interstitial fluid and enters the lymphatic capillaries. It then travels in the lymphatic vessels to the regional lymph nodes. After passing through regional lymph nodes, lymph ascends or descends to the thorax. Lymph is returned to the bloodstream, at the junction of the jugular and subclavian veins.

Lymph flow how? AST ME now!

The route of lymph flow through a lymph node:

1.) Afferent lymphatic vessel

2.) Subscapular sinus

3.) Trabecular sinus

4.) Medullary sinus

5.) Efferent lymphatic vessel (exit)

Lymphatic organs

The lymphatic system is composed of a number of primary and secondary organs and tissues widely distributed throughout the body. Consists of the thymus, lymph nodes, spleen, and red bone marrow.

What is the role of the thymus?

The thymus is a primary lymphatic organ that contains T cells. The T cells develop immunocompetence here.

What is the role of the lymph nodes?

There are about 600 lymph nodes scattered along lymphatic vessels which contain white blood cells. As the lymph passes through lymph nodes, the resident white blood cells scan for antigens.

What is the role of the spleen?

The spleen is the largest mass of lymphatic tissue in the body. It contains:

• White pulp which is lymphatic tissue where lymphocytes and macrophages carry out immune function.

• Red pulp which is blood-filled venous sinuses where platelets are stored and old red blood cells are destroyed.

Innate Immunity

Defenses that are present at birth and does no involve specific recognition of a microbe and acts against all microbes in the same way.

• 1st line of defense

  • Skin

    • Epidermis: intraepidermal macrophages, stratified squamous et (keratinized, waterproofed, and sun blocked)

    • Dermis: thick

  • Mucous membrane: mucus contains IgA (antibody)

  • Other

    • Fluids: tears, saliva, sweat, urine, feces, and vomit

    • Chemicals: lysozyme - in many fluids - breaks down cells walls of microbes; sebum - prevents skin from drying out and cracking; acidic secretions of stomach and vagina - help kill microbes

    • Nose hairs (filters air and traps microbes, dust, and pollutants) and cilia (found in respiratory tract and traps dust, microbes, and pollutants)

• 2nd line of defense

  • Antimicrobial substances: agents that kill or inhibit the growth of microorganisms, including bacteria, viruses, fungi, and parasites (ex. interferon and complement)

  • Natural Killer cells: rapid-response lymphocytes that destroy virus-infected and tumor cells without prior sensitization that releases perforin and granzyme

  • Phagocytes: specialized cells that ingest microbes and/or cellular debris (phagocytosis) (ex. neutrophils and macrophages)

  • Fever: elevated body temperature intensifies the effects of interferons, inhibits the growth of some microbes, and speeds up body reactions that aid repair (ex. mast cells and bacterial toxins)

  • Inflammation (ex. mast cells and releases histamine)

Inflammation

An attempt to dispose of antigens or foreign material at a site of injury in order to prevent the spread of germs. It prepares a site of injury for tissue repair and eventual return to homeostasis.

Signs/symptoms:

1.) Redness

2.) Pain

3.) Heat

4.) Swelling

Characteristics of inflammation:

1.) Vasodilation and increased permeability of blood vessels near site of injury and infection

2.) Emigration of phagocytes to the site of infection/injury'

3.) Tissue repair (epidermal and deep wound healing)

Perforin

Creates channels in the target cell’s plasma membrane which causes cytolysis.

Granzyme

Kills the infected cell by apoptosis which releases the germ and then phagocytes can ingest the germ.

Adaptive Immunity

The defenses that involve specific recognition of a microbe once it has breached the innate immunity defenses. It is highly specific, creates memory, and uses coordinated actions of T and B cells to eliminate pathogens.

• Cell mediated: viruses/intracellular antigens

  • Cytotoxic (CD8) T cells

    • Active cytotoxic T cells that use granzyme and perforin/granulysin combination to kill infected body cells

    • Form memory cytotoxic T cells

  • Helper (CD4) T cells

    • Active helper T cells co-stimulate cytotoxic and B cells with cytokines such as IL-2

    • Form memory helper T cells

• Antibody mediated: bacteria/extracellular antigens

  • B cells

    • Active B cells called plasma cell secrete antibodies

    • Form memory B cells

Antibody (a.k.a. immunoglobulin)

A protein produced by plasmacytes in response to a specific antigen; the antibody combines with that antigen to neutralize, inhibit, or destroy it. Functions of antibodies are neutralizing antigens; immobilize bacteria; agglutinate and precipitate antigens; activate complement; and enhance phagocytosis.

Complement system

A defensive system comprised of >30 proteins which are made by the liver and found in plasma/tissues. C3 begins an inflammatory cascade that leads to destruction of microbes through phagocytosis, cytolysis, and inflammation.

What is an antigen?

A substance that has immunogenicity (the ability to provoke immune response by stimulating antibody generation and/or T cell production) and reactivity (ability of antigen to react specifically with the antibodies and/or cells it provoked). Our immune systems are able to recognize and bind to at least a billion different antigen epitopes (different proteins on the outside of the antigens).

What are the 3 types of antigen-presenting cells (APCs)? Why do we need APCs?

The 3 APCs are B cells, dendritic cells, and macrophages are essential for initiating the adaptive immune response by detecting, engulfing, and presenting foreign antigens to T cells. They are a special class of migratory cell that processes and presents antigens to T cells during an immune response. They are strategically located in places where antigens are likely to penetrate the innate defenses and enter the body.

Major histocompatibility complex (MHC) antigens

MHCs are transmembrane glycoproteins that help T cells determine if a cell belongs to your body.

Do all body cells (except red blood cells) have MHC I antigens or MHC II antigens?

All body cells except RBCs have MHC I antigens.

Do all white blood cells have MHC I antigens or MHC II antigens?

All white blood cells have MHC I antigens. MHC II antigens are only found on antigen presenting cells (APCs) such as B cells, dendritic cells, and macrophages.

Antigen processing

Occurs when antigens are broken down into peptide fragments and attached to an MHC molecule.

Rule 1: B cells can recognize and bind to antigens

Rule 2: T cells must be presented with antigens

Antigen presentation

Occurs when the antigen-MHC complex is inserted into the plasma membrane and “presented.”

Steps in endogenous antigen processing and presentation.

Endogenous: antigens infecting the body cell from within

1.) Digestion of antigen into peptide fragments

2.) Synthesis of MHC I molecules

3.) Antigen peptide fragments bind to MHC I molecules

4.) Packaging of antigen-MHC I molecules into a vesicle

5.) Vesicle undergoes exocytosis and antigen-MHC I complexes are inserted into plasma membrane

Steps in exogenous antigen processing and presentation.

Exogenous: antigens present in our body fluids but outside our cells (ex. pollen, dust, bacteria, parasitic worms, and more).

1.) Phagocytosis or endocytosis of antigen

2.) Digestion of antigen into peptide fragments

3.) Synthesis of MHC II molecules

4.) Packaging of MHC II molecules into a vesicle

5.) Vesicles containing antigen peptide fragments and MHC II molecules fuse

6.) Antigen peptide fragments bind to MHC II molecules

7.) Vesicle undergoes exocytosis and antigen-MHC II complexes are inserted into plasma membrane

Where are T cells “born” and where do they become immunocompetent?

T cells develop immunocompetence in the thymus.

Where are B cells “born” and where do they become immunocompetent?

What plasma protein is found on helper T cells? What plasma protein is found on cytotoxic T cells?

What is the difference between cell-mediated immunity and antibody-mediated immunity?

How can cytotoxic T cells get activated and kill infected target cells?

How can effector B cells get activated and turn into plasma cells?

How do antibodies interact with antigens?

What are the 3 major outcomes of the complement system?

How is the secondary response to an antigen different from the primary response?

Components of the conducting zone.

Components of the respiratory zone.

Describe the different regions of the pharynx. Which region(s) serve as a common passageway for food and air?

How are vocal sounds produced (what “cords” are involved, what cartilage moves, etc.)?

What is the significance of the cilia lining some of the structures of the conducting zone?

What is the epiglottis and its role?

What are the roles of the goblet cells and macrophages in the respiratory system?

The structures that comprise the respiratory membrane. How would excess interstitial fluid (as with pulmonary edema) affect the rate of diffusion across this membrane?

Describe how alveolar surface tension, compliance, and airway resistance affect pulmonary ventilation.

What impact does surfactant have on surface tension in the alveolus?

What is Boyle’s law? Why is it extremely important to the respiratory system?

What muscles contract during normal inhalation? What does this do to the volume of the thoracic cavity?

What muscles relax during normal exhalation? What does this do to the volume of the thoracic cavity?

What muscles are utilized during forced inhalation? What about during force exhalation?

Explain how pressure gradients and airway resistance influence the flow of air.

How would having asthma affect the flow of air from the atmosphere into the lungs? What part of the respiratory system does it affect most?

What is it necessary to have pleural fluid in the pleural cavity?

What is the difference between ventilation and respiration?

Differentiate between external and internal respiration.

According to Dalton’s law, what is the partial pressure of a gas?

Most to least abundant gases found in atmospheric air. What is the pO2 at sea level (this is a specific number)?

According to Henry’s law, if a gas has a high partial pressure, it is more or less likely to stay in solution? If a gas has a high solubility, is it more or less likely to stay in solution?

Describe the diffusion paths of oxygen and carbon dioxide during external and internal respiration. What is the driving force behind oxygen and carbon dioxide diffusion?

How is oxygen transported in the blood? Carbon dioxide?

If you had an oxygen saturation of 98%, what would that mean?

What effect does the partial pressure of oxygen have on hemoglobin saturation? What affect do CO2, temperature, and blood acidity have on hemoglobin saturation?

Explain how the nervous system controls ventilation.