Review Sheet B Test #2         Biology 2213             Dr. James Adams

Chapter 20 B Lymphatic System
        Two functions: Circulatory, Immune

  Circulatory function: Lymphatic Vessels
        3 liters of fluid lost from (fenestrated) capillaries daily, returned to circulatory system
                 via lymph vessels.
        Lymphatic capillaries: dead ended in tissues cell of epith. act like minivalves.
                allow in fluid, bacteria, etc.  (know lacteals)
        Lymphatic trunks (veins): like circulatory veins; the same factors that aid venous return
                aid lymph movement (pumpless system)
Know:  Lumbar, intestinal, bronchomediastinal, subclavian, jugular trunks; Cisterna 
        chyli, thoracic duct, right lymphatic duct (these dump lymph into circ. system at 
        juncture of internal jugular vein and subclavian vein), lacteals

Immune FunctionLymphoid Tissues -- framework of reticular CT
     Lymphoid Cells B Lymphocytes/macrophages/"dendritic" cells (See immune system, 
            below); reticular cells (secrete reticular fibers of stroma of lymphoid organs)
     Diffuse Lymphatic Tissue -- found throughout walls of most mucosal membranes
  Lymphoid Organs
      I.  Lymph nodes -- cortex (with lymphocytes [follicles, w/germinal centers]), medulla
                (with macrophages), capsule with trabeculae, stroma (reticular network)
         Found where many smaller (afferent) vessels come together; fewer efferent vessels 
               (exit at hilus) causes lymph to slowly; lymph percolates through sinuses of nodes, 
               which gives time for lymph to be cleaned
         Concentration where "appendages" attach to trunk (inguinal, axillary, cervical regions) 
    "Bubos":  Infected -- swollen and painful; Cancerous B swollen, with little pain initially

  Other lymphoid organs: all have supportive reticular networks, stored
        macrophages/lymphocytes, efferent (but no afferent) lymphatic vessels so cannot 
         filter lymph
   
II.  Spleen -- largest, left side beneath diaphragm
            Functions: like lymph nodes, site of immune surveillance (macs./lymphs.) Also blood 
            filter (includes removing old RBC=s/platelets), stores (complexed) iron (from old 
            hemoglobin), stores platelets
        Anatomy: red/white pulp
   
III.  Thymus -- functions early in life; activates T lymphocytes
            Cortex/medulla, with epithelial tissue (star-shaped thymocytes) framework -- these 
                thymocytes are the source of the lymphocyte activating hormones.
   
IV.  Tonsils -- pharyngeal (adenoids), palatine, lingual, tubal
            Obvious germinal centers for lymphocytes.
            Not fully encapsulated to allow entry of bacteria for activation of immune system;
                however, crypts may be easily infected
    V.  Peyer=s Patches -- lymphoid nodules, at end of ileum (small intestine)
    VI.  Appendix -- off of cecum (beginning of large intestine); many lymphoid follicles
           
Tonsils, Peyer=s Patches, and appendix, along with diffuse lymphatic tissue in the |
            mucosal linings, make up the MALT (Mucosal Associated Lymphatic Tissue) 

Chapter 21 B Immune System
    Functional System -- main components: lymphocytes (specific) and macrophages (non-
        specific) functions:  Direct cell attack, antibody production against foreign antigens.
    Very specific, but must be primed (by exposure).

    I.  Non-specific (Innate) defenses
        A. Surface membrane barriers: cutaneous/mucus membranes -- First Line of defense
            keratin of stratified squamous epithelium of skin, mucus (sticky) of mucus membs.    
            Chemical protection (of membs.): sebum, lysozyme (saliva, tears), HCl, etc.
        B. Cellular/Chemical defenses (if surfaces breached) -- Second Line of defense
            1.  Inflammatory response (initiated by chemicals [histamine, prostaglandins, kinins, 
                lymphokines, etc.] released by many different cells [basophils, etc.])
            2.  phagocytosis (macrophages, etc.)
            3.  natural killer cells (non-specific "lymphocytes") -- drop chemical "bombs" on
                tumor/viral-infected cells
            4.  antimicrobial substances (complement, interferons)
            5.  fever (pyrogens) --  How does fever help?

   
II. Specific Defenses -- The Immune response -- Third Line of defense
            (nice summary, Fig. 21.20, pg. 791)
        Characteristics: Specific, memory, systemic
     Immunity
                Humoral (antibodies [Ab=s], produced by B lymphoctyes)  
                Cell-mediated (T lymphocytes). 
            Macrophages
, although non-specific, activate helper T lymphocytes, which, in 
            turn, activate more lymphocytes (both B & T cells) and macrophages, which also 
            phagocytize Ab covered antigens (rough foreign particles). T cells become
            immunocompetent (able to recognize antigens) in thymus, B cells in red B-marrow.

         Antigens activate certain pre-existing populations of B cells (free-floating antigens
        immunogenic) and T cells (through antigen-presenting macrophages) to divide, 
        producing plasma cells, for current usage (lots of rER in B cells for making Ab=
        [2000 per second]) and memory cells (for secondary response). Antigens may have 
        more than one antigenic determinant. Haptens (pg. 774) and allergies (pg. 794)

      Humoral Response -- B-Cell Activation (free-floating antigens); B-cells release
   
         Antibodies: structure -- two heavy (400 A.A.) and two light (200 A.A.) chains,
            each with constant (between all Ab types) and variable (for attachment to Ag=s) 
            regions. Some classes with multiple Ab units.
         Ab diversity: involves genetic recombination -- Know basic idea
         Active and Passive Humoral immunity
         Functions: Complement fixation, neutralization, agglutination, promote phagocytosis
                by opsonization

      Cell-Mediated Response -- T-Cell Activation
            Most T cells require antigen-presentation -- recognition of combined self-antigens
                (Major Histocompatibility Complex [MHC] proteins) and pieces of antigens
            MHC Classes I & II -- Know where found
            T cell types: cytotoxic, helper (understand the functions), other classes
         Both B and T cells require costimulation from antigens and chemicals -- helper T cells 
            are major releasers of some of these costimulatory chemicals and are therefore 
            responsible for helping activate both arms of the immune system. Explains why HIV 
            (which targets helper T cells) and AIDS are so devastating.
        Transplants and rejection.
    See summary Table 21.6, Table 21.7, and Figure 21.20.

Chapter 22 -- Respiratory System
    Respiration -- exchange of O2 and CO2; system open to air
        Steps: pulmonary ventilation, external respiration, transport (blood), internal respiration
            (external and internal respiration [exchange] completely passive diffusion)
        (Fifth step:  Cellular Respiration [chapter 24])
Anatomy

  I. Conducting Zone
   
A. Nose: humidifies & warms air, filters (air, mucus), olfaction
            bridge/septum (hyaline cart, bones), nostrils (nares), nasal cavities (surrounded by 
            bones [maxillae/palatine on floor]) with conchae/meati (for turbulence)
        Epithelium: P.C.C.E. with goblet cells (why?)
        Sneezing
        Paranasal Sinuses
    B. Pharynx: naso- (with openings for auditory tubes), oro-, laryngopharynx 
            oro- and laryngopharynx shared with digestive system
        uvula/epiglottis (elastic cartilage, with taste buds) close off nasopharynx/larynx 
            respectively, when swallowing
   
     know appropriate epithelial linings; tonsils here (which in which part?)
    C. Larynx (Voice box, Adam=s apple): framework of hyaline cartilage (know thyroid,
            cricoid, arytenoid cartilages), cricothyroid ligament, laryngeal muscles; support
            and stretch vocal cords (elastic conn. tissue)
        Vocal cords avascular; vibrate to produce sound. Higher frequency vibration (pulled 
            tight) = higher pitch; forceful expiration = louder. Sound involves pharynx, tongue, 
            nasal cavities, sinuses, etc.
        Glottis = opening between vocal cords; Stratified Squamous above (including epiglottis),
             P.C.C.E. below glottis
        Valsalva maneuver, involves epiglottis
   
D. Trachea: C-rings of hyaline cart., trachealis muscles (involved in coughing)
        Submucosa, with seromucous glands, P.C.C.E.: cilia move mucus up
    E. Major Bronchi, lobar bronchi, smaller bronchi, bronchioles (including terminal)
        Trends as tubes get smaller:
            1. cartilage rings replaced by irregular plates, and, in smallest, no cartilage
            2. epith. thins to simple cuboidal (non-ciliated) in terminal bronchioles
            3. relative amount of smooth muscle in wall increases (important in bronchioles for
                controlling air flow)

  II.  Respiratory Zone -- Gas exchange occurs here (diffusion) across moist membrane
    F.  Respiratory bronchioles and Alveoli -- @140m2 of surface area
        Respiratory membrane = simple squamous layer (type I cells) of alveolus + simple
            squamous endothelium of capillaries + sparse basement membrane between
        Respiratory Surface.: Type II (H2O + surfactant) secreting cells, keeps membrane 
            moist; macrophages scour surfaces for pathogens

    Gross Anatomy of Lung- Stroma (elastic conn. tissue), apex, base (on diaphragm), 
        hilus, cardiac notch (left), bronchial arteries/veins
    Pleurae (visceral/parietal)

Physiology
        Breathing (inspiration [inhalation], active; expiration [exhalation], passive
   
Intrapleural pressure (due to adhesiveness of serous fluid [water] between pleurae) must  
        always be less than intrapulmonary pressure; holds pleurae together (i.e., holds lungs to
        chest wall/diaphragm) during inspiration and allows for stretching of stroma

    I. Pulmonary Ventilation: Boyle=s Law P1V1 = P2V2
   
      Inspiration: diaphragm and external intercostal muscles; generates negative pressure,
            increases volume 0.5 liters (during normal, at rest breath)
        Expiration: largely passive relaxation and elastic recoil of lungs; forced expiration 
            involves more muscles (and is therefore active, requiring energy)
        Energy used in inspiration needed to overcome: resistance (see pgs. 821-822), lung
            compliance/elasticity, alveolar surface tension (reason for surfactants)
        Respiratory Volumes/Capacities and dead space: tidal, inspiratory/expiratory reserve, 
            residual (volume); vital, total lung (capacity)
        Dead Space -- basically air in conducting zone (not involved in exchange)
        Measurements: Minute respiratory volume, alveolar ventilation rate (AVR which is 
            more precise measure of actual ventilation)
    II. Gas Exchanges in the Body
        Need to Know: Dalton=s Law of Partial Pressures, Henry=s Law
        Partial Pressures (Po2 and Pco2 directly proportional to concentrations
        Gases (O2 and CO2) diffuse based on partial pressure gradients, and solubilities in 
            water (respiratory membrane/plasma) or attachment to Hb
        Gas flow in bronchioles coupled to blood flow in capillaries (perfusion)
            (nervous/chemical control of smooth muscles in both tubes)
        Blood usually completely oxygenated in .25s (blood in caps. for .75s at rest)
        External and internal respiration: partial pressure gradients opposite, but exchange
            mechanisms the same
    III. Gas Transport in the Blood -- Handout and page 833.
        A.  O2 -- 1.5% in plasma, 98.5% to heme; know oxy-(HbO2) and deoxy- (or reduced; 
                HHb) hemoglobin (Hb)
            Hb can hold four O2 molecules; when one molecule attaches, easier for others to 
                attach, due to a conformational change. Same is true for O2 release.


            Factors influencing Hb - O2 affinity:
                1. Po2: saturation curves; venous blood usually only about 30% deoxygenated
                2. Temperature: As TB 8, Hb - O2 affinity 9 (why important?)
   
             3. pH: As pH 9, Hb - O2 affinity 9 (why important?) ; called the Bohr effect.
                    typically, HHb can carry less O2 than Hb.
                4.  NO -- also carried attached to Hb, unloaded when O2 unloaded 
        B.  CO2 -- > 20% bound to globin of Hb (carbaminohemoglobin), 7-10% dissolved
                directly in plasma, < 70% dissolved as HCO3- in plasma (catalyzed by carbonic
                anhydrase inside RBC=s) (remember, H2O + CO2 ø H2CO3 ø H+ + HCO3-). 
                HCO3- diffuses out of RBC=s once made; Cl- moves in to offset negative ion loss --
                called the chloride shift. CO2 doesn=t directly interfere with Hb - O2 affinity, but 
                pH goes down, which does interfere with O2 carrying capacity.
            Haldane effect -- tied to Bohr effect; reflects increased ability of reduced Hb to carry
                more CO2, which means that CO2 increases the ability of blood to carry CO2.
            Everything that happens at the tissues happens in reverse at the lungs -- we blow off 
                CO2 which drags the above chemical equation to the left, which reduces the acidity, 
                which allows more O2 to load into the RBC's; in other words, everything happens 
                precisely in the manner we want it to!  (Chloride shift reverses as well).

Control of Respiration -- relatively complex
    Neural mechanisms
        Medullary respiratory centers
            Ventral respiratory group (VRG) -- the apparent pace-setter (eupnea).
                involves phrenic and intercostal nerves, both of which contain neurons that fire during
                inspiration and others during expiration, with mutual inhibition working between them,
                with feedback from stretch receptors in the lungs as well (see DRG)
            Dorsal respiratory group (DRG) -- not well understood; appears to be involved in
                integrating stretch and chemoreceptor inputs and communicating this info to VRG
        Pontine respiratory center -- also not well understood; appear to smooth out the transition
                from inspiration to expiration and back; also appears to modify the normal VRG
                generated rate during activities such as talking, exercise, etc.
        Generation of normal ventilation -- requires interconnections (as describe above) between
                neuronal networks, with two basic sets to generate the rhythm (see under VRG) -->
                one for inspiration and one for expiration that inhibit each other

    Factors influencing rate & depth of breathing:
        1.  Chemical influences: most important in immediate air intake adjustments.
                connected to nervous system controls -- work through chemoreceptors in carotid
                    arteries
            CO2 levels most important (why?); O2 and arterial pH influence air intake, too.
        2.  Stretch receptors

 

   Influence of Higher brain centers
        Hypothalamus (involuntary alterations in ventilation)
            emotional/pain responses; body temperature responses
        Cortical controls (voluntary)

    Reflexes altering/controlling ventilation         
            a.  pulmonary irritant reflexes
            b.  Hering-Breur (over inflation) reflex

Respiratory Adjustments during Exercise and at High Altitude
(pg. 831, 838-839)
    Understand basic changes that happen at beginning and during exercise
    Understand basic changes that happen over the course of a few weeks at high altitude