Bio. 417 - Physiology

Lecture Review Notes

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      Lecture Review Topic - RESPIRATORY PHYSIOLOGY I & II

      1. Anatomy and Cytology
        1. Upper Track - Nasal and Nasopharynx
        2. Lower Track - Larynx, Trachea, Bronchial tubes, Bronchioles, Respiratory Bronchioles, Alveolar ducts, Alveolar sacs, Alveolar Sacs as Diffusion Membranes
        3. Functional Cells in the Lungs
          1. ... pneumocyte Type I, simple squamous epithelium(diffusion)
          2. ... pneumocyte Type II secretory cells (dipalmityl lecithin)
          3. ... Dust cells, macrophages

      2. Physiology Summary
        1. Upper Tract function - to protect moist membrane of lungs
        2. Warm Air, Filter Air, Moisturize Air
        3. Lower Track function - to provide for gas exchange between blood and air

      3. Ventilation
        1. Dead Space Ventilation (150 ml of Air), Air movement in structures where no GAS Exchange occurs
        2. Physics = Gas Laws
          1. Charles Law = At a constant Pressure, The volume of a gas is proportional to Absolute Temperature
          2. Gay-Lussac's Law = At a constant volume, The pressure exerted by a gas varies directly with Absolute temperature
          3. Daltons Law = Each gas in a mixture exerts a partial pressure Proportional to its concentration.
          4. Henry`s Law = A gas, exposed to a liquid, will dissolve in that Liquid Amount dissolved is proportional to the partial pressure.
          5. Boyle's Law (Ideal Gas Law) = PV = nRT, The pressure exerted by a gas varies w/volume
            1. P = Pressure, n = # of gas molecules, V = Volume,
            2. R = gas constant, T = Abs. Temp
            3. Good at Room Temp & Atmospheric pressure at Constant temperature, constant pressure.
        3. Lung Gas Volumes See Text

      4. Muscle Physiology of Ventilation, (aeration of tract)
        1. Inspiration (Active Process)
          1. Intercostal Muscles and Diaphragm => contraction
          2. Compliance = Ability to expand (1 cm increase for 130 ml air)
          3. Energy for Muscle contraction to Overcome Resistance to air flow
          4. Non elastic tissue Resistance.
        2. Expiration (Passive Process)
          1. Elastic Recoil
            1. Intrapleural (Negative) Pressure
            2. Elastic fibers throughout Lung tissue
            3. Surfactant (dipalmityl lecithin) Reduces surface tension & Prevents collapse of Alveoli
            4. Forced expiration = abdominal muscles (active)
          2. Work of Breathing (Effort to Expand and Contract the Lungs)
            1. Degree of Compliance
            2. Resistance of Airway
            3. Degree of Active Expiration (Abdominal muscles)
            4. Increased Work = Increased Metabolic Rate = Increased O2 needed
        3. Exchange (gas exchange) = Diffusion between blood & alveolar air
          1. Rate based on partial pressure differences
        4. Respiratory Control
          1. Vagal Control of Bronchial Smooth Muscle
          2. Contraction >Relaxation
            Nervous Parasympathetic
            Cholinergic)
            Sympathetic
            Adrenergic)
            Neurohormonal Acetylcholine Norepinephrine
            Chemical Histamine
            SRS-A
            Prostaglandin F-2a
            Prostaglandin E
            Physical Smoke Dust Sulfur dioxide SO2 Nebulized drugs
        5. Brain
          1. Medulla - Dorsal Respiratory Group, Ventral Respiratory Group - Generates Pulmonary Rhythm
          2. Pons Control Rate & Depth of Respiration - pneumotaxic center, apneustic center - modifies rhythm
          3. Inspiratory & Expiratory Centers (Stim. & Inhib. muscles)
        6. Phrenic & Intercostal nerves
        7. Receptors
          1. Stretch receptors in the Lungs (smooth muscles of Bronchi & Bronchioles)
          2. J-receptors (juxtapulmonary capillary receptors) pulmonary capillary pressure
          3. Irritant receptors - airway epithelium, sensitive to particulate matter, gasses, noxious substance
          4. CNS Chemoreceptors, Cortex, Thalamus, Ant. medulla (H+,CO2)
          5. Peripheral chemoreceptors - Aortic & Carotid bodies Increased CO2 & decreased O2
          6. Baroreceptors - Arterial & Venous vessels
          7. Major Feedback Mechanism = CO2 level, Normal, sufficient to maintain PCO2 = 40mmHg (Alveolar ventilation -Profound effect on CO2 out, Little effect on O2 in)

      5. Surface Tension
        1. Maintains stability of alveolus, preventing collapse
        2. Surfactant (Type II pneumocytes) = dipalmityl lecithin
        3. *Type II pneumocyte appears at 24 weeks of gestation;
          1. Surfactant production, 28-32 weeks;
          2. Surfactant in amniotic fluid, 35 weeks.
          3. Laplace equation for thin walled spheres P = 2T
            1. P = alveolar internal pressure r
            2. T = tension in the walls r = radius of alveolus
        4. During normal tidal respiration
          1. Some alveoli do collapse (Tidal pressure can't open)
          2. Higher than normal pressure needed (Coughing)
          3. Deep breaths & sighs promote re-expansion
          4. After surgery/Other conditions, Coughing, deep breathing, sustained maximal respiration

      6. BLOOD GAS TRANSPORT
        1. External Respiration
          1. Exchange of gases between air in alveolus & blood
          2. Partial pressures of gases determine rate & amount
        2. Internal Respiration
          1. Exchange of gases between blood and tissues
          2. Partial pressures of gases determine rate & amount
        3. Oxygen Transport
          1. Hemoglobin (RBC) 4 Hemes w/ 4 globins
            1. Heme = red chromophore bind O2 at Fe
            2. Globin protein
              1. 2 alpha chains 141 amino acids; 2 beta chains 146 amino acids
              2. Fe Bonds (6) = 4 to heme, 1 to globin, 1 weak, reversible O2
          2. RBC and oxygen carrying capacity of the blood
            1. Oxygen transported in solution about 3% of total
            2. Oxygen bonded to Hemoglobin, Dependent on Hb concentration
              1. Hb = 12 - 16 g% (grams per 100ml of blood)
              2. Hb types = alpha, beta, fetal
              3. Hemoglobin saturation depends on:
                1. pH (Bohr effect) promotes O2 up take in lungs, O2 release in tissues
                2. Partial pressure of oxygen
                3. 23DPG (2,3 diphosphoglycerate)
                4. Shift to right = decreased affinity of O2 for Hb
                5. Shift to left = increased affinity of O2 for Hb
        4. Carbondioxide Transport
          1. Carbon dioxide is transported in solution 7%
          2. Bonded to Hb 25% (carbaminohemoglobin)
          3. Bicarbonate in the plasma 68%
            1. Carbonic anhydrase (enzyme) in the RBC

              CO2 + H2O <==CA==> H2CO3 <==> H+ = HCO3

            2. Chloride Shift = Bicarbonate into the plasma (Cl- into RBC)

      7. RESPIRATORY DISORDERS
        1. Hyperventilation
          1. Treatments :Rebreath air, hold breath (Increase CO2)
            Give oxygen for Hypoxemia
        2. Hypoventilation
          1. Acute Obstructive Disorders
            1. Heimlich maneuver
            2. Bypass, tracheostomy w/catheter to suck up secretion
          2. Asthma = Reversible Bronchioconstruction 4%-5% of population
            1. Extrinsic / Atopic = Allergic, inherited (familia), chromosome 11

              IgE, Chemical Mediators of inflammation

            2. Intrinsic = Negative for Allergy, Normal IgE, Negative Allergic Tests
              Nucleotide Imbalance cAMP/cGMP: cAMP = Inhibits mediator release, cGMP = Facilitates mediator release
            3. Intolerance to Asprin (Triad Asthma)
            4. Nasal Polyps & Asthma
            5. Treat cause, Symptoms in Acute Asthma
              1. Bronchial dilators
              2. steroids edema from Inflamation
              3. Bronchiohygene to prevent Secondary Infection, (Remove Excess Mucus)
              4. Education
          3. Bronchitis = Irreversible Bronchioconstriction
            1. Causes - Infection, Air polution, cigarette smoke
            2. Primary Defect = Enlargement & Over Activity of Mucous Glands, Secretions very viscous
            3. Hypertrophy & hyperplasia, Narrows & Blocks bronchi, Lumen of airway, significantly narrow
            4. Impaired Clearance by mucocillary elevator
            5. Microorganism retension in lower airways
              Prone to Infectious Bronchitis, Pneumonia
            6. Permanent Inflamatory Changes IN epithelium, Narrows walls, Symptoms, Excessive sputum, coughing
            7. CAN CAUSE EMPHYSEMA

          4. Emphysema
            1. Permanent enlargement of airways with distension of alveolar walls
              1. Thickened Bronchial Submucosa, Edema & Cellular Infiltration (loss of elasticity*)
              2. Dilation of Air spaces, due to distruction of alveolar walls (Air trapped by obstruction)
            2. Lower Respiratory tree distruction
              1. Respiratory Bronchioles, Alveolar ducts, & Alveolar sacs
            3. Types:
              1. Centrilobular (Centriacinar) = Respiratory Bronchioles
                1. Rarely seen in non Smokers, More in Men than Women, Found in Smokers with Bronchitis
              2. Panlobular (Panacinar) = all above
                1. Hereditary, Single autosomal recessive gene
                2. Deficient in 1-globulin (1-antitrypsin), Protects respiratory tract from neutrophil elastase (Enzyme that distroys lung connective tissue)
                3. Aged persons, Results from Bronchi or Bronchiolar constriction

            NOTE: Smoking = Leading cause of Bronchitis, Emphysema

          5. Cystic Fibrosis
            1. Thick mucus coagulates in ducts, produces obstruction,
              Too thick for cilia to move
            2. Major Systems Affected: Respiratory System, G. I. Tract,
              Reproductive Tract
            3. Inherited, autosomal recessive gene, most common fatal genetic disorder
              1. Major characteristic, Altered electrolyte composition (Saliva & sweat Na+, K+, Cl-)
              2. Family history of Cystic Fibrosis
            4. Respiratory Infections & G.I.Tract malabsorption
              1. Predisposes lung to Secondary infection (Staphylococcus, Pseudomonas)
              2. Damages Respiratory Bronchioles and Alveolar ducts, Produces Fibrosis of Lungs, Large cystic dilations)

      8. SURFACTANT DEFICIENCY
        1. (RDS) Respiratory distress of Newborn
          1. hyaline membrane disease of the new born
          2. decrease in surfactant, Weak, Abnormal complience of chest wall
          3. Small alveoli, difficult to inflate, Alveoli tent to collapse, many of varied sizes
          4. decrease in O2 diffusion area, lung difficult to expand, in compliance


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