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    Respiration: 1. The Respiratory Tract A. The Upper Respiratory Tract

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    MsKizzy
    The respiratory system consists of the upper and lower respiratory tract. The upper tract filters and conditions air before it reaches the lungs. The lower tract contains the lungs where gas exchange occurs via the respiratory membrane in the alveoli. Oxygen diffuses into the blood and is transported primarily by hemoglobin in red blood cells. Carbon dioxide diffuses out of the blood and is transported in the bloodstream and exhaled. Breathing is controlled by neural centers that detect changes in blood gases via chemoreceptors and regulate respiratory muscles.

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    Respiration: 1. The Respiratory Tract A. The Upper Respiratory Tract

    Uploaded by

    MsKizzy
    103 views28 pages
    The respiratory system consists of the upper and lower respiratory tract. The upper tract filters and conditions air before it reaches the lungs. The lower tract contains the lungs where gas exchange occurs via the respiratory membrane in the alveoli. Oxygen diffuses into the blood and is transported primarily by hemoglobin in red blood cells. Carbon dioxide diffuses out of the blood and is transported in the bloodstream and exhaled. Breathing is controlled by neural centers that detect changes in blood gases via chemoreceptors and regulate respiratory muscles.

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    Animal Physiology Powerpoint

    Original Title

    Lecture 11 Respiratory System

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    The respiratory system consists of the upper and lower respiratory tract. The upper tract filters and conditions air before it reaches the lungs. The lower tract contains the lungs where gas exchange occurs via the respiratory membrane in the alveoli. Oxygen diffuses into the blood and is transported primarily by hemoglobin in red blood cells. Carbon dioxide diffuses out of the blood and is transported in the bloodstream and exhaled. Breathing is controlled by neural centers that detect changes in blood gases via chemoreceptors and regulate respiratory muscles.

    Copyright:

    Attribution Non-Commercial (BY-NC)
    Download as PPT, PDF, TXT or read online from Scribd
    Download as ppt, pdf, or txt
    103 views28 pages

    Respiration: 1. The Respiratory Tract A. The Upper Respiratory Tract

    Uploaded by

    MsKizzy
    The respiratory system consists of the upper and lower respiratory tract. The upper tract filters and conditions air before it reaches the lungs. The lower tract contains the lungs where gas exchange occurs via the respiratory membrane in the alveoli. Oxygen diffuses into the blood and is transported primarily by hemoglobin in red blood cells. Carbon dioxide diffuses out of the blood and is transported in the bloodstream and exhaled. Breathing is controlled by neural centers that detect changes in blood gases via chemoreceptors and regulate respiratory muscles.

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    Download as PPT, PDF, TXT or read online from Scribd
    Download as ppt, pdf, or txt
    of 28

    RESPIRATION

    1. The Respiratory Tract


    A. The upper respiratory tract
    • Nose
     lined by ciliated columnar
    epithelium
     mucus secreting cells
     dense vascular network in
    submucosa
     filtering air
     warming air
     humidifying air
     sneezing reflex
    • Pharynx
     Epiglottis
    • Larynx
     vocal cords
     glottis
    B. The lower respiratory tract
    • Trachea
    • Bronchi
    • Bronchioles
    • Respiratory bronchioles
    • Alveolar ducts and alveoli
    • Conducting zone
     to warm and humidify the air
     to distribute the gas
     to serve as part of body defense system
    • Respiratory zone
    • Respiratory tract defense system
     Mucocilliary transport system: mucus escalator
     Cough reflex
     Macrophages
    2. The Lung Mechanics
    A. Lung pressures and ventilation
    • The thorax and respiratory
    muscles
     thoracic cage: ribs (12),
    sternum, diaphragm
     pleural space

     respiratory muscles during


    inspiration:
    - diaphragm
    - external intercostal muscles
    - accessory muscles
     respiratory muscles during
    expiration:
    - Diaphragm
    - internal intercostal muscles
    -
    • Lung pressures
     Air flows because of pressure
    gradients
     pleural pressure (Ppl)
     alveolar pressure (PA)
     Pressure changes during
    respiratory cycle
     pneumothorax
    • Lung volumes and capacities
     Spirometry
     tidal volume (VT)
     inspiratory reserve volume (IRV)
     expiratory reserve volume (ERV)
     residual volume (RV)
     inspiratory capacity (IC)
     functional residual capacity (FRC)
     vital capacity (VC)
     total lung capacity (TLC)
     forced vital capacity (FVC)
     FEV1: timed forced expiratory
    volume in one second
     FEV1/FVC = 80%: more
    useful for detecting obstructive
    vs restrictive lung diseases
    • Minute respiratory volume (V, minute ventilation)
    V = VT * f (respiratory rate)
    • Dead space volume (VD)
    • Alveolar ventilation (VA): VA = (VT - VD) * f
    B. Mechanical Properties of the lung
    • Lung Distensibility
    • Pressure-volume curve
    • Compliance (CL= DV/DP)
    • Pulmonary surfactant
     surface tension

     Laplace Law: P = 2T/r

     atelectasis
    • Work of breathing
    W = force X distance
    Factors that affect the amount of work:
     lung compliance
     surface tension
     airway resistance
    - R  L  /r4
    - diameter of the airways
    Bronchoconstriction: histamine
    Broncodilation: CO2, EP (2 receptors)
    3. Pulmonary Circulation
    A. Vascular pressure and blood flow
    • Pulmonary circulation is a low-pressure system
     pulmonary arterial systemic pressure: 25
    mmHg
     pulmonary arterial diastolic pressure: 10
    mmHg
     mean pulmonary arterial pressure: 15 mmHg
     effect of the special gravity of blood on
    distribution of blood flow in the lung:
    - poor perfusion in the upper lung (functional
    dead space volume)
    • Hypoxic vasoconstriction
    balances blood flow with
    ventilation
     regional
    hypoxia/hypoxemia
     hypoxic vasoconstriction -
    a mechanism that
    balances the perfusion of
    blood with the availability
    of regional ventilation
     effect of hypoxic
    vasoconstriction at the
    high altitude
    • Exercise recruits capillaries
    and decreases transit time
    4. Gas Uptake and Transport
    A. Gases diffuse through respiratory membrane

    • Dalton’s law: PB = PO2 + PCO2 + PN2 + PH2O +


    PHe…
     barometric pressure: PB at the sea level = 760
    mmHg
     partial pressures
     PO2 = PB X F O2 = 760 X 0.21 = 160 mmHg
     vapor pressure of water
     PO2 in alveolar gas and venous blood: 100/40
    mmHg
    Gas exchange:alveoli and cells
    • Factors that affect the rate of gas diffusion through the
    respiratory membrane
     thickness of respiratory membrane (alveolar-capillary
    membrane): normally 0.1 - 0.5 µm
     pulmonary edema
     fibrosis of the lung
     surface area of the respiratory membrane: 70 m2 in
    the normal adult
     emphysema (dissolution of alveolar walls)
     diffusion coefficient
     solubility in water
     molecular weight
     carbon dioxide diffuses 20 times as rapidly as
    oxygen
     pressure difference across the respiratory membrane
    Respiratory membrane
    • Pulmonary pathologies
    B. Transport of oxygen
    • Transport of oxygen in the dissolved state
     only 2% of oxygen transported in the dissolved
    state in the water of the plasma and cells
    • Transport of oxygen by hemoglobin
     98% oxygen is carried to the tissues by reversible
    combination with hemoglobin
     oxygen carrying capacity: 20 ml/100ml blood
     oxygen saturation: percent O2 saturation = O2
    content/O2 capacity x 100
     oxyhemoglobin dissociation curve
     factors that affect the oxyhemoglobin curve
    Oxygen-hemoglobin dissociation

    "2,3-DPG and oxygen/Hb binding"

    • Factors that
    affect the
    oxyhemoglobin
    curve
    • Factors contributing to the total oxygen content
    of arterial blood
    C. Transport of carbon dioxide
    • Dissolved in plasma: (7-10%)
    • Carbaminohemoglobin: (15-30%)
    • As bicarbonate: (60-70%)
     CO2 + H2O H2CO3 H+ + HCO3-
    catalyzed carbonic anhydrase
     H+ + Hb- HHb
     chloride shift
    D. Control of Breathing
    • Neural mechanisms
     Medullary respiratory centers
    inspiratory neurons: set the rhythm
    expiratory neurons
     receive synaptic inputs from the cortex and
    pons
     effects of pulmonary stretch receptors
    (proprioreceptors)
     failure of the respiratory center
    by physical damages (concussions, cerebral
    edema)
    by overdose of chemical substances
    (barbiturate, anesthetics)
    • Reflex control of ventilation
     Chemoreceptors monitor blood gases and pH
     Control centers in the brain stem regulate activity
    to respiratory muscles
    • Chemical mechanisms
     chemoreceptors
    central chemoreceptors (in the medulla): monitor
    only H+ in CSF
    peripheral chemoreceptors (aortic bodies and
    carotid bodies)
     control of the alveolar ventilation by the arterial CO2
     control of the alveolar ventilation by the arterial H+:
    exclusively by peripheral chemoreceptors
     control of the alveolar ventilation by the hypoxia:
    relatively insensitive to hypoxia
    Carotid body oxygen sensor Central chemoreceptor
    Chemoreceptor reflex

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