PHYSIOLOGY OF RESPIRATION

                                      

 

 I   Overview

                A.  Anatomy review

                        1.  conducting vs respiratory structures

                        2.  pleural membranes and cavity

                        3.  alveolus

                                a.  surface area

                                b.  respiratory membrane

                                            1.  Fick's Law

                                c.  elastic fibers     

                                d.  Type II  alveolar cells:  surfactant

                                e.  macrophages:  trypsin

                                f.   pores of Kohn

                 B.   Processes

                         1.  pulmonary ventilation  (bulk flow)

                         2.  external respiration  (diffusion)

                         3.  internal respiration  (diffusion)

                         4.  cellular respiration

 

When you have finished this unit you should be able to:

    -  identify the structures of the respiratory system, passageways, pleural membranes, pleural cavity, and alveolar structure

    -  describe the structure of the respiratory membrane

    -  explain the advantages of respiratory membrane structure, according to Fick's law

    -  distinguish between pulmonary ventilation, external respiration, internal respiration, and cell respiration

 

 

II  Pulmonary Ventilation

            A.  Air Flow,  F =  rP/R    

            B.  Pressure gradients

                       1.  atmospheric 

                       2.  intra-alveolar

                       3.  Boyle’s Law:  pressure-volume relationship      

                                   a.  changing thoracic volume:  respiratory muscles

                                            1.  resting ventilation

                                            2.  active ventilation

                        4.  lung to thoracic wall

                                    a.  pleural membranes

                                    b.  transmural pressure (gradient between intra-alveolar and intra-pleural pressure)

                                    c.  pneumothorax ---> atelectasis

            C.   Resistance

                        1.  airway diameter

                        2.  compliance

                                    a.  elasticity

                                    b.  surface tension (inside alveolus)

                                                1.  surfactant (surface active agent)

 

When you have finished this unit you should be able to:

    -  interpret the formula for air flow,  F =  rP/R  

    -  explain what is meant by atmospheric pressure

    - state Boyle's Law             

    - explain how volume and pressure affect air flow into and out of the lungs

    - list specific muscles in resting inhalation and describe how they effect thoracic volume

    - list specific muscles in resting exhalation and describe how they effect thoracic volume

    - list specific muscles in active inhalation and describe how they effect thoracic volume

    - list specific muscles in active exhalation and describe how they effect thoracic volume

    - describe the relationship between intra-alveolar, intra-pleural, and transmural pressure

    - explain why changing the volume of thoracic cavity also changes the volume of the lungs

    - explain the pressure changes which cause atelectasis

    - list the general causes of resistance in pulmonary ventilation

    - define compliance and state its effects on inhalation

    - list factors which affect compliance

    - define surface tension and explain how surfactant affects surface tension

    - discuss the effects of surface tension on inhalation and exhalation

 

 

           D.   Terminology

                        1.  volume + volume = capacity   

                        2.  hypoventilation

                        3.  hyperventilation

                        4.  hyperpnea

                        5.  dyspnea, apnea, eupnea

            E.  Lung disease

                        1.  obstructive

                                    a.  narrowed passages:  smooth muscle contraction, mucus

                                    b.  asthma, chronic bronchitis, emphysema

                                    c.  decreased  FEV1

                        2.  restrictive                           

                                    a.  damaged lung tissue, decreased surface area: scar tissue

                                                1.  alpha anti-trypsin

                                    b.  pulmonary fibrosis, emphysema

                                    c.  decreased vital capacity

   

            F.  Regulation of Pulmonary Ventilation

                        1.  neural

                                    a.  medullary areas

                                                1.  DRG (dorsal respiratory group)

                                                2.  VRG  (ventral respiratory group)

                                                3.  pre-Botzinger area

                                        b.  pons centers - influence medullary centers; fine-tune breathing transitions

                                                1.  apneustic center

                                                2.  pneumotaxic center

                                    c.  cortex - conscious control

                                    D.  hypothalamus and limbic system - emotional regulation

                       2.   chemical

                                    a.  [H+]

                                    b.  [CO2]

                                    c.  [O2]

                                    d.  receptors

                                                1.  central chemoreceptors

                                                2.  aortic bodies, carotid bodies

                        3.  mechanical

    

                                                    

                                 lung volume practice for respiration laboratory

 

   

 

  When you have finished this unit you should be able to:

    - distinguish respiratory volumes from respiratory capacities

    - compare and contrast hypoventilation, hyperventilation, and hyperpnea

    - define apnea, dyspnea, eupnea

    - compare obstructive and restrictive lung disease:  causes, diagnostic tests

    - discuss emphysema causes and diagnostic tests

    - list the different regions of the brain involved in ventilation and explain the general type of regulation done by each area

    - list the respiratory centers in the medulla and compare their roles in respiration

    - list the centers in the pons and describe the effects of these centers on the medullary centers

    - describe the location and role of the central chemoreceptors (note location of other chemoreceptors)

    - describe the effect that blood levels of [H+], [CO2], and [O2] have on these centers 

    - explain why these centers are less sensitive to drops in blood [O2] levels

    - explain the connection between  [CO2] levels and pH levels in the blood (include the reaction of COwith H20)

    - describe the Hering-Breuer reflex and why it is a  protective reflex

 

 

III   External Respiration and Internal Respiration

           A.  Partial pressures

                       1.  Dalton's Law

                                    a.  altitude effects                                                      

           B.  Hemoglobin                                               

                        1.  loading reaction:           deoxyhemoglobin  +  O2   --------------->    oxyhemoglobin

                                                                                                         lungs

                      

                        2.  unloading reaction:       deoxyhemoglobin  +  O2 <------------    oxyhemoglobin

                                                                                                         tissues

 

                                    a.  oxyhemoglobin dissociation curve:  % of oxyhemoglobin and the partial pressure of oxygen

                                    b.  affinity of oxygen for hemoglobin is decreased in low pH conditions;  Bohr effect

                                    c.  affinity of oxygen for hemoglobin is decreased in higher temperatures

 

When you have finished this unit you should be able to:

    - explain what partial pressure means

    - state Dalton's Law

    - describe the effect of high altitude or below sea level on the partial pressure of oxygen

    - write a simple equation for hemoglobin laoding and unloading reactions

    - state the effect of lower partial pressure of oxygen on the amount of oxygen bound to hemoglobin

    - explain the factors which cause oxygen to let go of hemoglobin

    - explain the factors which cause

    - state the effect of pH on the affinity between oxygen and hemoglobin, relate this to conditions in the body

    - state the effect of temperature on the affinity between oxygen and hemoglobin, relate this to conditions in the body

    - describe three ways carbon dioxide is carried from the tissues back to the lungs

    - how is the buffering inside the RBC related to the buffering of the plasma

    - what is the chloride shift

 

 

       

  

 

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