Anatomy and Physiology 2402 by N7vJp41

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									                                    Anatomy and Physiology 2402
                                            Chapter 22
                                        Respiratory System

      Major Function: Supply the body with oxygen and dispose of carbon dioxide         How is the
                                                                                        respiratory system
      Respiration: Four Processes                                                       closely coupled with
       1. Pulmonary Ventilation – movement of air into and out of the lungs             the cardiovascular
          (commonly called breathing.)                                                  system?
       2. External respiration – movement of oxygen from the lungs to the blood         How is the
          and carbon dioxide from the blood to the lungs                                respiratory system
       3. Transport of respiratory gases – transport of oxygen from lungs to the        closely coupled with
          tissue cells and of carbon dioxide from tissue cells to the lungs             the sense of smell
       4. Internal respiration – movement of oxygen from blood to the tissue            and speech?
          cells and of carbon dioxide from tissue cells to blood

      Functional Anatomy of the Respiratory System:

      Nose _________________________________________________________________
      Nasal cavity ___________________________________________________________
      Pharynx ______________________________________________________________
      Larynx _______________________________________________________________
      Trachea ______________________________________________________________
      Bronchi and smaller branches ___________________________________________
      Lungs ________________________________________________________________
      Alveoli _______________________________________________________________

      Respiratory Zone: Actual sites of gas exchange                What is meant by cleanse? Remove dust,
         Respiratory bronchioles                                    pollen even some bacteria or fungal spores.
         Alveolar ducts               all microscopic structures    What is the mucociliary escalator?
         Alveoli

      Conduction Zone: all other respiratory passageways
          Rigid conduits: cleanse, humidify and warm incoming air

             Main bronchi
Trachea      Secondary bronchi          Bronchioles       Terminal             Respiratory         Alveolar
             Teriary bronchi                              bronchioles          bronchioles         ducts

      Nose and Paranasal Sinuses
           Functions of the nose:                                                                  Alveolar sacs
           1. Provides an airway
           2. Moistens and warms entering air
           3. Filters and cleans inspired air
           4. Serves as a resonating chamber for speech                                             Alveoli
           5. Houses olfactory receptors
Parts of the Nose:

Nasal cavity: Open space within the nose
External nares: External openings of the nose
Nasal septum: Divides nostrils
Posterior nasal apertures (internal nares or conchae[funnels]): nasal portion of nasopharynx
Palate: separates the nasal cavity from the oral cavity
     Soft palate: not supported by bone – posterior portion
     Hard palate: supported by bone – anterior portion
Vestibule: Part of nasal cavity just superior to the nostrils
     Lined with skin containing sebaceous and sudoriferous glands and numerous hair follicles
Vibrissae: nose hairs – filter coarse particles

The rest of the nasal cavity is lined with two types of mucous membranes:
     Olfactory mucosae: lines superior region, contains olfactory (smell) receptors      The epithelium
     Respiratory receptors: scattered goblet cells                                       layer of the mucous
                                                                                         membrane here is
              Underlining lamina propria contains mucus glands and serous glands
                                                                                         pseudostratified
              That secrete mucus and serous fluid which contains enzymes                 ciliated columnar
                      (lysozyme) and defensins (both antibacterials)                     epithelium
              Secrete about a quart of mucus per day.

      Sensory nerve endings Abundant in nasal mucosa – contact with irritating particles stimulates
       the sneeze reflex to expel the irritant.

      Rich plexuses of capillaries and veins underlie nasal epithelium to warm incoming air
       Dilate when cold
       Being so close to the surface and thin walled and in abundance, explains nose bleeds

      Nasal conchae (superior, middle and inferior conchae)
       1. Increase the mucosal surface area exposed to the air and                  How do the conchae help
       2. Enhance air turbulence.                                                   “reclaim moisture from
           a. deflect heavier particles onto the mucus coated surfaces              exhaled air?
           b. surfaces heating, humidifying and filtering of the air breathed in.
           c. serve to reclaim moisture from exhaled air.

Paranasal sinuses:
    Frontal
    Sphenoid                  Lighten the skull
    Ethmoid                   Warm and moisten air
    Maxillary                 Mucus produced in them flows into nasal cavity

∆    Rhinitis – inflammation of the nasal mucosa
    Sinusitis: inflamed sinuses.
    Cause: cold viruses, streptococcal bacteria and various allergens.
       What causes the “sinus headache”?
  Pharynx: connects the nasal cavity and mouth superiorly to the larynx and esophagus inferiorly
      Commonly called the “throat”.
      Divided into three parts:

         1. Nasopharynx: Lies above where food enters - serves as air passageway only
                           During swallowing, the soft palate and uvula move superiorly closing off
When we laugh soft
                           nasopharynx – prevents food from going up into nasal cavity.
palate does not close      Pharyngeal tonsil (adenoids) destroys pathogens entering the nasopharynx
during swallowing and       in air
food may be sprayed out       ∆ Infected adenoids: if enlarged, may block passage forcing person to
the nose.                     breathe through the mouth. Air is not properly warmed and moistened or
                              filtered. Can affect sleep and speech.

        2. Oropharynx: Lies posterior to the oral cavity seen through the fauces (archway)
                         Both food and air pass through here
                                                                        Epithelium of mucous
                         Paired palatine tonsils: lateral walls
                                                                        membrane changes to
                         Lingual tonsil: Covers base of tongue          stratified squamous
        3. Laryngopharynx: Serves as passage for both food and air
                           Posterior to epiglottis extending to larynx where food and air passages
                           diverge. Food gets the “right of way”. When we swallow, air is
                           temporarily stopped.
                           Laryngopharynx continues with the esophagus
                           Larynx continues with the trachea.

       Larynx: Voice box
             Functions 1. Provide open airway
                       2. Switching mechanism to route air and food to proper channels
                       3. Houses vocal cords (sound conduction)

   Epiglottis: Made of elastic cartilage covered in taste buds
      Open when air is moving through passage
      Closes when swallowing
   Vocal Ligaments: form vocal folds or true vocal cords            Voice Production:
      Vibration produces sounds                                      How does it work?
      Glottis: opening between Vocal ligaments
   Vestibular folds: False vocal cords                       Entire length of pharynx, oral
      Superior to True Vocal Cords                           and nasal cavities serve as a
      Do not produce sound – help close epiglottis           resonating chamber to amplify
                                                             and enhance sound quality
      ∆Laryngitis: Inflammation of the vocal folds
              Vocal folds swell, interfering with vibration (causes hoarseness or inability to speak
              above a whisper (vocal folds do not have to vibrate to whisper)

       Valsalva’s maneuver: _____________________________________________________
                                            Trachea                Trachea is elastic enough to stretch
                                                                   and during inspiration and recoil
Trachea: Windpipe                                                  during expiration
      Divides into the bronchi (going to each lung)
      Three layers –
      1. Mucosa: contains goblet cells and pseudostratified ciliated epithelium
             with thick underlying lamina propria (alveolar tissue)
      2. Submucosa – connective tissue layer deep to mucosa
             Contains seromucous glands that helps produce “mucus sheets” of trachea
      3. Adventitia – Outermost layer. Connective tissue layer reinforced by 20 C-shaped
             rings of hyaline cartilage which prevent collapsing.

Posterior part of trachea – no cartilage here so esophagus can expand during swallowing.
Trachealis muscle: Muscle decreases diameter of trachea to expel air with force as during
coughing (up to 100 mph!)
Carina: spear of cartilage marks point where trachea branches into bronchi. Highly sensitive:
triggers coughing when any foreign object touches it.
Heimlich maneuver (abdominal thrusts) _________________________________________

                                The Bronchi and Subdivisions
                                    The Bronchial Tree

Bronchial tree: site where conduction zone gives way to respiratory zone
Conduction zone:
      1. Right and left primary (main) bronchi:
          Splits from the trachea and enters the hilus of each lung.
          The right is shorter, wider and more vertical so it is easier to inhale foreign objects.
          Air is already warmed, filtered and humidified before entering bronchi.
      2. Secondary (lobar) bronchi: Bronchi divide inside the lung
          (3 on the right and 2 on the left)
      3. Tertiary (segmental) bronchi: Bronchioles divide into smaller and smaller branches
          (fourth and fifth order bronchi… 23 order)
      4. Bronchioles: any that are smaller than 1mm in diameter
      5. Terminal bronchioles (bronchial or respiratory tree): the smallest bronchioles less
          than 0.5mm in diameter.

Respiratory Zone: Defined by the presence of alveoli
             Begins as the terminal bronchioles feed into the respiratory bronchioles
   1. Respiratory bronchioles: Covered in scattered alveoli
   2. Alveolar ducts: lead into terminal clusters of alveoli
   3. Alveolar sacs: clusters of alveoli (like a bunch of grapes).
   4. Alveoli: Thin walled sacs at the terminal end of the respiratory zone.
             Sites for gas exchange (one alveolus is a single sac)
             About 300 million of them account for most of lung volume
             Greatly increase surface area.
 Terminal                  Respiratory
bronchioles                bronchioles with             Alveolar ducts                       Alveoli
                           alveolar sacs

                                           Respiratory Membrane

    Respiratory membrane: capillary walls and alveolar walls and their basal lamina fused
          This forms an air-blood barrier – gas flows on one side and blood flows on the other

              Type I cells: single layer of squamous epithelial cells with flimsy basal lamina thinner
              than tissue paper (form walls of alveoli) surrounded by thin cobweb of capillaries.

              Type II cells: scattered cuboidal cells secrete fluid containing surfactant.
                    Coats surface of alveoli: reduces surface tension of alveolar fluid
                             1. to keep alveoli from collapsing
                             2. allow for better diffusion of gases

              Alveoli:                                                    Huge numbers of pathogens are inhaled,
              1. Are surrounded in elastic fibers                         but alveolar surfaces are generally sterile
              2. Have alveolar pores: connect adjacent alveoli            because of macrophages crawling over
                     Equalizes pressure                                   their surfaces. However, ~ 2 million dead
                     Alternate routes if some alveoli are diseased        macrophages must be removed from
              3. Have alveolar macrophages: crawl over alveolar           dead ended alveoli per hour. Cilia
                      surfaces (remove pathogens inhaled)                 currents created from higher regions
                                                                          they are passively swept up and then
                                                                          swallowed.
                                            Lungs and Pleurae
                                        Gross Anatomy of the Lungs

    Root: vascular and bronchial attachments to the mediastinum
    Apex: Narrow superior tip of the lungs
    Base: concave inferior surface that rests on the diaphragm
    Costal surface: anterior and posterior lung surfaces that are in close contact with the ribs
    Hilus: an indentation through which pulmonary and systemic blood vessels and the primary
    bronchus enter and leave the lungs
    Cardiac Notch: Only in the smaller left lung; a concavity that allows for the heart
    Lobes: Left lung is divided into upper and lower lobes
           Right lung is divided into upper, middle and lower lobes
    Bronchopulmonary segments: Each is served by its own blood vessels and air passageways
    Lobules: smallest subdivision of lung visible to the unaided eye.
    Stroma: part of the lung that is not air spaces
           Mostly elastic connective tissue
                                                         Segments

           Each segment is served by its own separate blood vessels and air passageways
           1. Each lung has similar, but not identical patterns
           2. Segments are important because
              a. pulmonary disease is often confined to one or a few segments and
              b. because of connective tissue partitions, diseased
                segments can be surgically removed without damaging neighboring
                healthy segments.
                                     Blood Supply and Innervation of the Lungs

           Pulmonary Circulation:
             Pulmonary arteries: blood coming to lungs from heart (deoxygenated)
             Pulmonary capillary networks: surround alveoli where gas exchange occurs
             Pulmonary veins: blood leaving lungs to heart (oxygenated)
           Bronchial Circulation:
             Bronchial arteries: provide oxygenated systemic blood too lung tissue, arise from the aorta

           The oxygen within the alveoli are enough for those cells that compose the alveoli… … but what
           about the cells in layers farther away? How do they get oxygen? Via Systemic Circulation:
           oxygenated systemic blood must go to lung tissue Aorta  Bronchial arteries  tissues of lungs

                                                   Bringing it Together
    Explain the difference in function of the pulmonary arteries and the bronchial arteries.
    The pulmonary arteries carry deoxygenated blood from the right ventricle to the lungs to pick up oxygen
    The bronchial arteries go from the left ventricle bringing oxygenated blood to nourish the tissues of the lungs.
    Why is this necessary? The cell layers composing lung tissue is too far away from the air that enters the lungs

              Pulmonary Plexus: Nerve fibers enter the lungs through here
                 Sympathetic nerves dilate air tubes
                 Parasympathetic nerves constrict air tubes       Function: Compartmentalizes organs so
                 Visceral sensory nerves allows for sensation     their functions don’t interfere with each
Review                                                                  other, which also helps to inhibit the
           Pleurae: (2401) Thin double layered serosae                 spread of infection. Reduces friction and
                 Parietal pleura: covers the thoracic wall             helps to prevent lung collapse.
                 Visceral pleura: covers the lung outer surface
                 Pleural fluid: fills the pleural cavity (lubrication – reduces friction)
                 Pleural cavity: thin space between the layers of the pleura

           ∆ Pleurisy: Inflammation of the pleura – dry kind and wet kind.
              Pleural effusion: fluid accumulation in pleural cavity (blood, watery fluid…)
                  Usual cause: left sided heart failure

                                                  Mechanics of Breathing

                                      Breathing (pulmonary ventilation):
                                            Inspiration: air flows into lungs
                                            Expiration: air flows out of lungs
                                      Pressure Relationships in the Thoracic Cavity

          Respiratory pressures are described relative to atmospheric pressure (Patm)
                 Positive respiratory pressure – area of lung is above atmospheric pressure
                 Negative respiratory pressure – area of lung that is below atmospheric pressure
                 Zero respiratory pressure - area of lung that is equal to atmospheric pressure
          Intrapulmonary pressure (Ppul) – pressure in the alveoli
                 Rises and falls with breathing but always eventually equalizes with atmospheric pressure
          Intrapleural pressure (Pip) pressure in pleural cavity
                 Fluctuates with breathing, but is always ~ 4mmHg less than Ppul
                 So Pip is negative relative to both Patm and Ppul. Why?

    Alveolar Surface Tension – Water is                   Surfactant: Interferes with water
    polar: each water molecule is attracted to            molecules’ attraction to each other. This
    the others. This tends to pull alveoli closed.        allows alveoli to expand to greatest size.

              Summary:
                  a. Two forces act to pull lungs away from the thorax wall causing lungs to collapse
                      1. Lungs’ natural tendency to recoil
                      2. Surface tension of alveolar fluid
                  b. Forces which enlarge lungs and prevent collapse:
                     1. Natural elasticity of the chest wall tends to pull thorax outward & enlarge lungs
                     2. The fluid between the pleurae make them difficult to separate.
                     3. Surfactant prevents alveoli from collapsing
                         Which of these forces win? Neither, if healthy.
                         Why? The fluid between the pleurae make them difficult to separate.

Pleural fluid must be kept at a minimum to maintain negative intrapleural pressure, so it is constantly being pumped out
into the lymphatics. If not, pressure builds and becomes positive relative to intrapulmonary pressure and lungs collapse.

          In summary, it is the Transpulmonary Pressure – (Ppul - Pip ) difference between
          intrapulmonary pressure and intrapleural pressure keeps lungs from collapsing.

                                                      Summary

   In terms of pressure, what keeps the lungs from collapsing? ___________________________
   Which should be at a negative respiratory pressure?__________________________________
   Which has a respiratory pressure which fluctuates with breathing but always equalizes to zero
   respiratory pressure? __________________________________________________________

  When the diaphragm contracts (flattens) and pulls lungs open, does that create positive pressure or
  negative pressure? __________________________…and this causes what? _____________________
  When the diaphragm relaxes and allows the lungs to recoil, does that create positive pressure or negative
  pressure? ____________________________ …and this causes what? ___________________________
                                    Homeostatic Imbalance
Atelectasis – Lung collapse
       Usually caused by air entering the pleural cavity through a chest wound, but may be from
       a rupture of visceral pleura or as a sequel to pneumonia
Pneumothorax – presence of air in the intrapleural space
       Treated by withdrawing the air with a chest tube and closing the hole.

                     Pulmonary Ventilation: Inspiration and Expiration

Volume changes lead to pressure changes which lead to flow of gases to equalize pressure
Inspiration: 1. Action of diaphragm (most important for quiet inspiration)
             2. Action of intercostal muscles
                                                                      Lungs are stretched during
                                                                      inspiration and recoil passively
Diaphragm contracts – flattens inferiorly increases thoracic space    during expiration
Intercostals contract – lifts rib cage and pulls sternum up
       This causes them to swing outward expanding diameter of rib cage (front to back and
       side to side) only a few millimeters, but enough for 500mL air
Lungs are stretched and Ppul drops below Patm and air rushes in until pressure equalizes.

Deep (forced) inspiration: accessory muscles become involved
       Scalenes and sternocleidomastoid of neck and pectoralis of chest lifts rib cage more
       Erector spinae muscles straighten thoracic curvature
Expiration: A passive process
       Muscles simply relax and elasticity of lungs causes them to recoil.
       Pressure within lungs increase and air is pushed out until pressure is equalized.

Forced expiration: Abdominal muscles contract (oblique and transvesus mostly)
      1. Increases intra-abdominal pressure
         Forces abdominal organs superiorly against diaphragm
      2. Depresses rib cage (internal intercostals may help some)

                    Physical Factors Influencing Pulmonary Ventilation

                                     1. Airway Resistance

Homeostatic Imbalance:
a. Constriction of air passages increases resistance
           Causes: 1. inhaled chemicals or inflammatory chemicals such as histamine.
                    2. Asthma attack: respiratory passages can close almost completely
b. Injuries: punctured lung, broken ribs…
c. Pleural effusion or pneumotorax
d. Blockages: mucus, infectious material or tumors can block airways
e. Alveolar surface tension
                                       2. Alveolar Surface Tension

     Surface Tension: at the gas-liquid boundary liquid molecules are more strongly attracted to each
     other than to the gas molecules
             1. Draws liquid molecules together reducing contact with gas molecules
             2. Resists any force that tends to increase the surface area of the liquid

     Alveolar film (fluid coating alveoli) being mostly water, and water being highly polar tends to
     reduce alveoli to smallest size. If it were pure water, alveoli would collapse between breaths.
     Surfactant: in alveolar film prevents this

     Homeostatic Imbalance:

     Infant Respiratory Syndrome: Too little surfactant is produced. Alveoli collapse
       between breaths and must be forcibly re-inflated with each breath. Very energy consuming
       and stressful. Most often with premature babies.

     Bronchopulmonary dyspplasia: suffered by many survivors of IRDS. A chronic lung disease
      form childhood into adulthood results from inflammatory injury by the respirators used to treat
      IRDS.
                                 3. Lung Compliance

Lung compliance – refers to great distensibility of lungs (unbelievably stretchy)!
The more or easier a lung expands for a given rise in transpulmonary pressure is lung compliance.
     Determined by:
     1. Distensibility of lung tissue and thoracic cage
     2. Alveolar surface tension
Compliance can be diminished by
     1. Reduced natural resilience of lungs
         a. Fibrosis from diseases like tuberculosis          The lower the lung compliance, the
     2. Blockage of smaller air passages                      more energy is needed just to breathe.
     3. Reduced surfactant
     4. Decreased flexibility of thoracic cage

Summary: Factors that influence Ventillation
      1. Airway Resistance
              a. Constrictions
              b. Asthma
              c. blockages
      2. Alveolar Surface Tension
          a. Reduced amounts of surfactant
      3. Lung compliance
              a. Distensibility of lungs
              b. Distensibility of rib cage
              c. Alveolar surface tension
 Homeostatic Imbalance
 Deformities of thorax, ossification of costal cartilages (as is common in old age) and paralysis of
 intercostals muscles all reduce lung compliance.

                        Respiratory Volumes and Pulmonary Function Tests

                                        1. Respiratory Volumes

 Tidal Volume (TV) Air that moves in and out with each breath (usually about 500mL)
 Inspiratory Reserve Volume (IRV) What can be forced into the lungs past tidal volume
                    (2100-3200 mL)
 Expiratory Reserve Volume (ERV) What can be forced out of the lungs after tidal expiration
                            (1000-1200 mL)
 Residual Volume (RV) What is left in the lungs after even the most strenuous
             exhalation (about 2100 mL)
             Helps to keep alveoli the lungs from collapsing            All but TV tend to be smaller
                                                                        in women because of _____
                                      2. Respiratory Capacities         _______________________

 Inspiratory Capacity (IC) total amount of air that can be inspired after a tidal expiration
 Functional Residual Capacity (FRC) represents the amount of air remaining in the lungs after
                                      a tidal expiration.
 Vital Capacity (VC) the total amount of exchangeable air
 Total Lung Capacity (TLC)the sum of all lung volumes and is normally around 6000mL in males

                                                3. Dead Space

 Anatomical Dead Space: Air that fills the conducting zone conduits and never contributes to gas
 exchange in the alveoli. (about 150mL – in healthy young adults is 1mL for each pound body weight) *

 Alveolar dead space: if some alveoli fail to act in gas exchange for whatever reason.

 Total Dead Space: Alveolar dead space + anatomical dead space = total dead space

 If TV is 500mL only 350mL is involved in alveolar ventilation.
      Why? _____________________________________________________________________
 Slow deep breaths are more effective in oxygenating the blood

                                         Pulmonary Function Tests
 Spirometer –
            a. Forced vital capacity (maximum amount of gas expelled after a deep breath)
            b. Forced expiratory capacity (amount of air expelled in one second)

                                     Non-respiratory Air Movement
What other than breathing, moves air in and out of the lungsLHiccupping, coughing, sneezing, crying
laughing…
                                        Gas Exchange in the Body

Dalton’s Law of Partial Pressures: the total pressure exerted by a mixture of gasses is the sum of the
pressures exerted independently by each gas in the mixture.
       The Partial Pressure of each gas is directly proportional to the percentage of that gas in the mixture.

Henry’s Law: When a mixture of gases is in contact with a liquid, each gas will dissolve in proportion to its
partial pressure. This depends on
            1. solubility of gas in the liquid,
            2. concentration (partial pressure) of the gas,
            3. temperature of the liquid.

       This law is demonstrated in soft drinks

                                 Dalton’s and Henry’s Laws: Working together

       CO2 is most soluble in plasma*                   Bonus:
       O2 is only a twentieth as soluble as CO2         Faster breathing – more O2 goes into the blood,
       N2 is nearly insoluble                           but more CO2 does not go out because diffusion
                                                        of CO2 out of blood remains slow (regardless of
      Bonus: List 3 reasons why the partial             change in breathing). Explain this.
     pressures in the alveoli differs from
     that of the atmosphere


       State True or False and answer the question that follows
           1. The greater the pressure, the more gas will dissolve into the blood.
              What are the medical implications of this? __________________________________
              ____________________________________________________________________
           2. The lower the temperature, the more gas will dissolve in aqueous solution.
              What are some practical implications of this? _______________________________
              ____________________________________________________________________
           3. The amount of a gas that will dissolve in aqueous solution depends on solubility, partial
              pressure and temperature. Explain the implications of this to the human body under normal
              conditions. ___________________________________________________________
              ____________________________________________________________________


       Hyperbaric chambers: Can push greater PO2 than 1 atm.
                              This forces more O2 into the blood
       These chambers are used for: CO poisoning, circulatory shock, asphyxiation, gas gangrene, tetanus

       Oxygen Toxicity: When PO2 is greater than 2.5-3 atmospheres, it generates huge amounts of free
       radicals. This has profound CNS disturbances (coma  death)
                                Ventilation Perfusion Coupling
Ventilation - amount of gas reaching the alveoli
Perfusion - blood flow in pulmonary arterioles         These 2 things must match!

        Higher PO2 dilates arterioles
        Lower PO2 constricts arterioles
        Higher PCO2 dilates bronchioles
        Lower PCO2 constricts bronchioles

So, poor ventilation means ↓ PO2 and ↑ PCO2 Pulmonary arterioles constrict and bronchioles dilate
What would have the opposite effect?


                                      Homeostatic Imbalances
∆ Pneumonia: exchange membrane thickens dramatically and diffusion is impaired
∆Emphysema: Walls of alveoli break through into others creating larger chambers and much
surface area is lost. (Read more about these disease on your own.)

Arterial blood is O2 higher than tissue cells – so it diffuses into tissue cells

Tissue cells are higher in CO2 than blood – so it diffuses into blood

CO2 is 20X more soluble in plasma and alveolar fluid than O2           Must remember the principle
Internal Respiration occurs by simple diffusion – How?                          of diffusion:
                                                                        Particles move from higher
                                         O2 transport                     concentration to lower
                                                                               concentration.
O2 – is carried by hemoglobin (little is dissolved in plasma)

        Oxyhemoglobin – (HbO2) – hemoglobin with O2 bonded
        Deoxyhemoglobin – (reduced hemoglobin) (HHb) has unloaded its O2

Fully saturated - each Hb molecules can bond to 4 O2 molecules
Partially saturated – Each Hb molecules has less than 4 O2 molecules bonded to it.

        Resting – Arterial blood is 98% saturated
                     Capillary blood is 75% saturated
                     Venous blood is 15% saturated                       Can both O2 and CO2 bind to
                                                                         hemoglobin at the same time?
                              Bohr Effect and Haldane Effect             Explain

Bohr effect: Acidosis (H+) weakens the HbO2 bond = Bohr effect
So,as more CO2 enters the blood, it causes more O2 to dissociate from Hb (So O2 is
released where it is most needed.)
The release of O2 from Hb allows more CO2 to combine with globin part of Hb and more
HCO3 to form = Haldane effect (This increases pH: alkaline)
                                                Nitric Oxide

          NO – is secreted by the lung and vascular endothelial cells
                 Function: Vasodilator and BP regulation

                                         ∆Homeostatic Imbalance

          Hypoxia
            1. Anemic hypoxia                           Read
            2. Ischemic hypoxia                         more
            3. Histotoxi hypoxia
            4. Hypoxemic hypoxia
          .
                                           Control of Respiration

1. Medulla: inspiratory center (quiet breathing)
2. Hypothalamus: modifies normal breathing
         a. Gasping: when surprised by pain, or the touch of something cold
         b Holding breath: when angry

           Increases respiration rate                   Decreases breathing rate
             1. When excited                              1. When calm
             2. When body temperature rises               2. When body temperature falls

          Breathing may even stop if you fall in cold enough water, (or gasping first and then apnea)

                                              Control of Respiration

          Cortex: Conscious control
          You can choose to breathe deeply or hold your breath, but involuntary centers will over-
          ride if the situation becomes critical.
                                                                                                        Read
                                         Homeostatic Imbalances                                  more
          ∆Hypercapnea: increased PCO2
          ∆Hyperventilation: normally self limiting response to either ↑ PCO2 or ↑ PO2 or both
          ∆Hypoxic drive:
                a. Acute mountain sickness
                b. Chronic obstructive pulmonary disease (COPD)
                1. Asthma                                                   What are “pink puffers”
                2. Tuberculosis                                             What are “blue bloaters”
                3. Lung cancer
          ∆Squamous cell carcinoma
          ∆Adenocarcinoma
          ∆Small cell (oat cell) carcinoma
          ∆Cystic Fibrosis

								
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