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Respiratory System Chapter 15

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Respiratory System Chapter 15 * * * * * * * * * * * * * * * * * * * The main function of the respiratory system is to supply oxygen to, & eliminate carbon dioxide ... – PowerPoint PPT presentation

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Title: Respiratory System Chapter 15


1
Respiratory SystemChapter 15
2
The main function of the respiratory system is to
supply oxygen to, eliminate carbon dioxide from
the body In order to accomplish this task, the
respiratory system must work in conjunction with
the cardiovascular system
3
  • Respiration refers to the overall exchange of
    gases between the atmosphere, blood cells
  • Respiration involves 3 processes
  • Pulmonary ventilation
  • Gas exchange (gas diffusion)
  • External respiration
  • Internal respiration
  • Gas transport

4
Anatomy Overview
The respiratory tract includes Nose (nasal
cavity)? Pharynx (nasopharynx, oropharynx,
laryngopharynx)? Larynx? Trachea? Bronchi
(primary, secondary (lobar), tertiary
(segmental)? Bronchioles? Terminal bronchioles ?
Alveolar ducts? Alveoli
Nasal cavity
Pharynx
Larynx
Trachea
Bronchi
Bronchioles
Respiratory bronchioles
Right Lung
Left Lung
Alveolar duct
Alveoli
5
Histology
Respiratory Epithelium Pseudostratified
Ciliated Columnar (PSCC)
6
Nose (nasal cavity)
Air normally enters through external nares
through nasal vestibule into nasal
cavity. Functions of nasal cavity include
warming, moistening filtering air olfaction
7
Pharynx
Air passes from nasal cavity into nasopharynx,
past oropharynx through laryngopharynx to
larynx Nasopharynx lined with PSCC epithelium,
but oro laryngopharynx lined with stratified
squamous epithelium
8
Larynx
Air passageway made of 9 pieces of cartilage
(1) Thyroid cartilage, (1) Epiglottis, (1)
Cricoid cartilage, (2) Arytenoid, (2)
Corniculate, (2) Cuneiform A.K.A your voicebox
because it contains the vocal cords
9
  • Thyroid cartilage protects anterior lateral
    walls of airway
  • Epiglottis leaf-shaped cartilage that protects
    opening (glottis) of airway when swallowing
  • Cricoid cartilage complete ring of cartilage
    protects posterior wall of airway attaches to
    trachea

10
  • Arytenoid, corniculate cuneiform cartilages
    attach to upper (false) vocal folds lower
    (true) vocal cords

11
Trachea
  • Tough but flexible windpipe, anterior to
    esophagus
  • attached to cricoid cartilage (at about C6
    vertebral level) ends within mediastinum by
    branching into left right primary bronchi (at
    T5 vertebral level)
  • End of trachea known as Carina

Carina
12
Trachea
  • Lined with respiratory epithelium
  • C-shaped pieces of hyaline cartilage
    protecting airway while allowing for swallowing
  • Trachealis muscle (smooth muscle) runs across
    posterior wall of trachea connecting ends of
    tracheal cartilage

13
Bronchi
  • Trachea splits into a left right primary
    bronchus which enters into the hilus (hilum) of
    each lung
  • Within the lung, the primary bronchi branch into
    secondary (lobar) bronchi (3 in right lung/2 in
    left lung)
  • Secondary bronchi then branch into 10 tertiary
    (segmental) bronchi
  • Tertiary bronchi then continue to branch into
    smaller smaller bronchi then into very narrow
    bronchioles

Carina
This branching patterns creates the bronchial
tree
14
Changes In Airway
  • As you go further down into the bronchial tree of
    each lung, changes in the airway occur
  • increased number of airways (1 primary 2 or 3
    secondary 10 tertiary bronchi 6000 terminal
    bronchioles millions of alveolar ducts)
  • decreased diameter of each airway
  • decreased amount of cartilage in the airways (no
    cartilage at all by terminal bronchioles)
  • increased amount of smooth muscle (relative to
    diameter)
  • lining epithelium changes from PSCC ? simple
    squamous epithelium (in alveoli)

15
Lungs
Located within the thoracic cavity, surrounded by
the double-layered pleural membrane parietal
pleura lines cavity wall visceral pleura
covers the lungs
16
Lungs- Anatomical Features
Right lung
Left lung
17
Airways within Lungs
  • Each lung has a primary bronchus entering at the
    hilum
  • Each lobe of a lung has a secondary (a.k.a.
    lobar) bronchus
  • Lobes are functionally divided into
    bronchopulmonary segments each segment has a
    tertiary (segmental) bronchus
  • Segments are functionally divided by elastic CT
    partitions into many lobules each lobule
    receives a terminal bronchiole

18
Relationship of Airways Pulmonary Vessels
  • As airways branch within lungs, they are
    accompanied by branches of the pulmonary artery
    (carrying de-oxygenated blood into the lungs),
    branches of the pulmonary veins (carrying
    oxygenated blood out of the lungs)
  • As the alveolar ducts expand to form alveoli,
    pulmonary arterioles will branch to form a
    network of pulmonary capillaries, surrounding the
    alveoli

19
Alveoli
  • Alveoli are expanded chambers of epithelial
    tissue that are the exchange surfaces of the
    lungs
  • There are about 150 million alveoli in each lung
  • Multiple alveoli usually share a common alveolar
    duct, creating alveolar sacs

20
Alveoli
  • There are three types of cells found within
    alveoli
  • Alveolar Squamous epithelial (aka type I)
    cells primary cells making up the wall of the
    alveoli
  • Septal (aka type II) cells sectrete
    surfactant to reduce surface tension which
    prevents alveoli from sticking together allows
    for easier gas exchange
  • Alveolar macrophages (aka dust cells)
    phagocytic cells that remove dust, debris
    pathogens

21
Gas exchange (external respiration) occurs
across the Respiratory membrane the fused
membranes of the alveolar epithelium the
pulmonary capillary endothelium
22
Physiology of Respiration
  • Respiration refers to the overall exchange of
    gases between the atmosphere, blood cells
  • Respiration involves 3 processes
  • Pulmonary ventilation
  • Gas exchange
  • External respiration
  • Internal respiration
  • Gas transport

23
Physiology of Respiration
Pulmonary Ventilation exchange (movement) of
gases between the atmosphere lungs movement of
gases occurs because of pressure differences
between the atmosphere (atmospheric pressure
(Po)) lungs (intrapulmonic pressure (Pi))
  • Two phases of ventilation
  • Inspiration
  • active process involving contraction of
    diaphragm external intercostal muscles
  • Expiration
  • normally passive due to relaxation of above
    muscles
  • can be made active (forced expiration) due to
    contraction of abdominals internal intercostal
    muscles

24
Pulmonary Ventilation
25
Lung Volumes Capacities
  • Respiratory frequency (f) number of
    ventilations (inspirationexpiration) per minute
  • Tidal volume (TV) - amount of air moved in or
    out of the lungs during a normal breath
  • Minute ventilation (VETV x f)- amount of air
    inhaled or exhaled in one minute

26
Lung Volumes Capacities (cont.)
  • Inspiratory reserve volume (IRV) amount of air
    that can be inhaled after a normal inspiration
    (above the resting TV)
  • Inspiratory capacity (IC TVIRV) amount of
    air inhaled after a normal expiration
  • Expiratory reserve volume (ERV) amount of air
    that can be exhaled after a normal expiration
  • Residual volume (RV) amount of air remaining
    in lungs even after maximal expiration

27
Lung Volumes Capacities (cont.)
  • Vital capacity (VCTVIRVERV) maximum amount
    of air you can exhale, following a maximal
    inhalation
  • Total lung capacity (TLCTVIRVERVRV)
    maximum amount of air in your lungs, following a
    maximal inhalation

28
Gas Exchange (gas diffusion)
  • External respiration - the diffusion of O2 CO2
    between the alveoli blood across the
    respiratory membrane
  • occurs because of pressure differences of each
    gas within alveolar air pulmonary
    (deoxygenated) blood
  • results in creation of oxygenated blood

29
Gas Exchange
  • Internal respiration the diffusion of O2 CO2
    between the blood interstitial fluid across the
    endothelium of systemic capillaries
  • occurs because of pressure differences of each
    gas between systemic (oxygenated) blood
    interstitial fluid
  • results in creation of deoxygenated blood

30
Gas Transport - O2
  • During external respiration O2 diffuses across
    respiratory membrane into blood plasma
  • The majority of O2 (98.5) then immediately
    diffuses into RBCs binds (loosely) to the iron
    (Fe3) in hemoglobin for transport
  • only 1.5 is transported freely dissolved within
    plasma

31
Gas Transport CO2
  • During internal respiration CO2 diffuses from
    interstitial fluid into plasma
  • Only 7 of CO2 remains in plasma for transport,
    the rest diffuses into RBCs
  • Within RBCs 23 binds to the globin proteins of
    hemoglobin (Hb) (carbaminohemoglobin)
  • Most (70) of CO2 gets converted within RBCs to
    bicarbonate ions (HCO3-) CO2 H2O H2CO3
    (carbonic acid) HCO3- H
  • HCO3- diffuses out to plasma (as Cl- diffuses
    in) the H attach to Hb to maintain normal
    plasma pH (so plasma does not become too acidic)

32
Control of Respiration
  • Unconscious control of breathing occurs through
    the activity of the respiratory centers of the
    brain
  • Medulla oblongata Rhythmicity center
    controls basic pattern of breathing inhale 2
    seconds, exhale 3 seconds
  • Pons has 2 centers (apneustic pneumotaxic
    centers) that can unconsciously modify the rate
    depth of respiration

Respiratory centers can be influenced by
mechanoreceptors (i.e. stretch receptors in
lungs) chemoreceptors (sensitive to CO2 levels,
arterial pH, O2 levels) in the body, as well as
by higher brain centers
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