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The Respiratory System

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The Respiratory System Chapter 15 Page 285 - 302 – PowerPoint PPT presentation

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Title: The Respiratory System


1
The Respiratory System
  • Chapter 15
  • Page 285 - 302

2
Functions
  • Facilitate the exchange of oxygen and carbon
    dioxide between air and the blood
  • Inspiration (inhalation)
  • Breathing in
  • Expiration (exhalation)
  • Breathing out
  • Ventilation (includes in/expiration)
  • breathing

3
The Respiratory and Circulatory Systems
  • Work together to do these functions
  • External respiration the exchange of gases
    (oxygen and carbon dioxide) between air and the
    blood
  • Transport of gases to and from the lungs and the
    tissues
  • Internal respiration - the exchange of gases
    between the blood and tissue fluid

4
The Respiratory Tract
  • Consists of the
  • Nose
  • Pharynx
  • Larynx
  • Trachea
  • Bronchial tree
  • lungs

5
Nasal Cavities
  • Lined by mucous membrane
  • Moistens and warms air during inhalation
  • Traps water droplets during exhalation

6
Pharynx
  • Connects the nasal cavity and oral cavity to the
    larynx
  • Pharynx commonly called throat

7
Larynx voicebox
  • Passageway for air between pharynx and the
    trachea
  • Contains your vocal cords
  • Sounds is produced when cords vibrate
  • The epiglottis (a tissue) prevents food from
    going into the larynx

8
Trachea windpipe
  • Connects larynx to bronchi
  • Located above the esophagus (foodpipe)
  • Held open by C-shaped cartilaginous rings
  • Lined with cilia

trachea
trachea
9
Cilia
  • Hair-like structures within the trachea, bronchi,
    larynx, and nasal cavity
  • Sweep up mucus-coated debris
  • To be coughed up
  • Swallowed or expelled
  • Smoking destroys
  • cilia toxins collect
  • in lungs

10
The Bronchial Tree
  • The trachea divides into right and left primary
    bronchi (bronchus) which will lead into the
    right and left lungs
  • Bronchi will branch out and make bronchioles
  • Walls are thinner than trachea
  • No cartilage rings
  • Each bronchioles will lead into alveoli

11
Alveoli air-pockets
  • Site of gas exchange (O2/CO2)
  • External respiration
  • Shape
  • Grape-like clusters
  • Increased SA (100 m2) for
  • gas exchange
  • Capillary rich
  • Increased blood flow for gas exchange

12
Alveoli (contd)
  • Lipoproteins
  • Maintains alveolar shape (prevents collapse at
    low pressure)
  • Keeps airway dry but the membrane moist
  • Surfactants
  • Lowers surface tension for easier gas exchange

13
Surfactants
  • Without surfactant,
  • the wet surfaces of the alveoli would stick
    together (due to surface tension)
  • lungs would not expand, no breathing

14
The Lungs
  • Located in the thoraciccavity
  • Cone-shaped
  • R. lung has 3 lobes
  • L. lung has 2 lobes (leaves room for the heart)

15
The Lungs (contd)
  • Each lobe is divided into lobules
  • Each lobules has a bronchiole with many alveoli
  • Each lung is covered by a serous membrane called
    a pleura
  • Pleura also covered chest wall and diaphragm
  • Lubricating serous fluid helps pleurae slide
    freely against each other during breathing

16
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17
Pleural Membrane / Intrapleural fluid
  • The fluid acts to even out pressure on the lungs,
    so all parts are compressed evenly (hydrostatic
    pumping)
  • Also reduces friction (a lubricant during
    inhalation)

18
Mechanism of Breathing
  1. Air moves in a continuous column from the pharynx
    to the alveoli
  2. Lungs lie inside the rib cage and intercostal
    muscles
  3. The lungs are covered by two pleural membranes
    which adheres to the thoracic wall.

19
  • Ventilation
  • Inspiration
  • active phase contraction of diaphragm and
    external intercostal muscles
  • Diaphragm lowers
  • Ribcage moves upward and outward
  • Thoracic volume increases
  • Pressure in the lungsdecreases
  • Partial vacuuman enclosed space from which
    part of the air has been removed
  • Air moves in passively

20
  • Expiration
  • Usually passive phase
  • Elasticity of thoracic wall causes lungs to
    recoil
  • Surface tension of alveoli causes them to close
  • Abdominal organs press UP against diaphragm
  • Ribcage moves down and inward
  • Increased pressure inside lungs pushesair out.

21
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22
Respiratory Control Center
  • Medulla Oblongata (controls heart rate)
  • Automatic control breathing rate and depth
  • Inspiration
  • Phrenic nerve sends impulses to the diaphragm
  • Intercostal nerve sends impulses to the
    intercostal muscles
  • Expiration
  • No nerve impulse

23
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24
Nervous Input
  • After forced inhalation,
  • Stretch receptors on alveolar walls initiate
    inhibitory nerve impulses
  • STOP INHALING!!!
  • Impulse travels via vagus nerve from inflated
    lungs to the medulla oblongata
  • Respiratory Center stops sending out nerve
    impulses

25
Chemical Input
  • Respiratory center is sensitive to CO2 and H
    levels in the blood
  • Increase breathing rate/depth increases
  • O2 level is detected by carotid bodies (in the
    carotid artery) and aortic bodies (in the aorta)
    and communicated to the respiratory center
  • Decrease breathing rate/depth increases

26
ASTHMA
27
Mechanics of Breathing
  • Air normally enters through the
  • nostrils, which are lined with hairs that filter
    out dust and other particles, and moistens it.
  • then passes the pharynx
  • the larynx - voice box, responsible for sound
    production
  • and the trachea (note cartilaginous rings)
  • down through the bronchus and the bronchioles,
  • and into the alveoli of the lungs

28
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29
Overview
  • Page 294
  • Excellent summary diagram

30
Gas Exchange - Diffusion
  • Concentration gradient pressure drives movement
    of gases into out of blood at both lungs body
    tissue

capillaries in lungs
capillaries in muscle
blood
lungs
blood
body
31
Partial Pressure of Gases in the Blood (mmHg) in
the Lungs
32
Hyperventilation (breathing quickly)- not enough
CO2
  • breathe too deeply or too rapidly ? exhale too
    much CO2
  • CO2 level decreases
  • feel anxious
  • hyperventilate more
  • The lowered level of CO2 causes the pH of the
    blood to rise
  • Fewer H ions
  • becomes more alkaline (basic)
  • leading to alkalosis and tetany (severe
    twitching, caused by muscle contraction)

33
Hemoglobin
  • Why use a carrier molecule?
  • O2 not soluble enough in H2O for human needs
  • Hb O2 ? Hb O2 (oxyhemoglobin)
  • Hb CO2 ? HbCO2 (carbaminohemoglobin)
  • Hb H ? HHb (reduced hemoglobin)

34
Gas Exchange in the Body
  • External Respiration
  • Exchange of gases between air and blood
  • Partial pressure pressure exerted by O2 gas and
    CO2 gas ? PO2 and PCO2
  • Blood in pulmonary capillary
  • PCO2 gt P(atm air)
  • So CO2 diffuse out of the plasma and into the
    lungs

capillaries in lungs
blood
lungs
35
External Respiration - Transporting CO2 in blood
  • CO2 is carried by bicarbonate ions (HCO3)
  • More HCO3 more CO2
  • HCO3 buffer

bicarbonate H HCO3? H2CO3 carbonic
acid H2CO3 ? CO2 H2O
carbonic anhydrase
36
pH /temperature levels
Normal pH and temperature for Hb
  • Hb a protein
  • Denature in the wrong pH or temperature
  • Increased temp and decreased pH
  • Hbs affinity for O2 decreases
  • O2 is released
  • But CO2 affinity increases

37
Internal Respiration - Transporting CO2 in blood
  • Dissolved in blood plasma as bicarbonate ion

carbonic acid CO2 H2O ? H2CO3 bicarbonate H
2CO3 ? H HCO3
carbonic anhydrase
38
HHb (reduced hemoglobin)
  • Produced when H ions are produced from internal
    respiration
  • Since the H ions are taken up, pH usually stays
    constant
  • Blood in the systemic capillaries is a
    darkmaroon colour bcRBCs have HHb

carbonic acid CO2 H2O ? H2CO3 bicarbonate H
2CO3 ? H HCO3
carbonic anhydrase
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