Title: Respiratory System Chapter 15
1Respiratory SystemChapter 15
2The 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
4Anatomy 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
5Histology
Respiratory Epithelium Pseudostratified
Ciliated Columnar (PSCC)
6Nose (nasal cavity)
Air normally enters through external nares
through nasal vestibule into nasal
cavity. Functions of nasal cavity include
warming, moistening filtering air olfaction
7Pharynx
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
8Larynx
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
11Trachea
- 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
12Trachea
- 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
13Bronchi
- 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
14Changes 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)
15Lungs
Located within the thoracic cavity, surrounded by
the double-layered pleural membrane parietal
pleura lines cavity wall visceral pleura
covers the lungs
16Lungs- Anatomical Features
Right lung
Left lung
17Airways 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
18Relationship 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
19Alveoli
- 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
20Alveoli
- 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
21Gas exchange (external respiration) occurs
across the Respiratory membrane the fused
membranes of the alveolar epithelium the
pulmonary capillary endothelium
22Physiology 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
23Physiology 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
24Pulmonary Ventilation
25Lung 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
26Lung 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
27Lung 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
28Gas 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
29Gas 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
30Gas 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
31Gas 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)
32Control 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