RESPIRATORY SYSTEM
FUNCTION


RESPIRATION
 Can be divided into 5 stages:
X
X
X
X
X
UPPER RESPIRATORY TRACT
Includes the nose, nasal cavity and the pharynx
 The Nose and Nasal Cavity
X
X
The Nose
Z
External nose -
Z
External nares (nostrils) -
Nasal Cavity Z
Nasal septum -
Z
Roof of the cavity -
Z
Floor of the cavity -
Z
Nasal conchae (superior, middle, and inferior) -
Z
Internal nares (choanae) -
Z
Respiratory mucosa -
 Paranasal Sinuses
1
X
Four pair –frontal, maxillary, ethmoid, and sphenoid
 Pharynx -
X
Divided into 3 regions:
Z
Z
Z
Nasopharynx –
C
Uvula –
C
Pharyngeal tonsils –
C
Eustachian tubes –
Oropharynx –
C
Fauces –
C
Palatine tonsils –
C
Lingual tonsils –
Laryngopharynx –
LOWER RESPIRATORY TRACT
Consists of the larynx, trachea, bronchi and lungs
 The Larynx
X
Location –
X
Functions –
2
X
Structure
Z
Laryngeal cartilages
C
Thyroid cartilage –
R
Z
Z
Laryngeal prominence –
C
Cricoid cartilage –
C
Arytenoid cartilages –
C
Corniculate cartilages –
C
Cuneiform cartilages –
C
Epiglottic cartilage –
Internal larynx
C
Auditus –
C
Vestibule –
C
Vestibular folds –
C
Ventricles –
C
Vocal folds –
C
Glottis –
Muscles of the larynx [TO BE LEARNED IN LAB]
3
Z
C
Cricothyroid muscle –
C
Posterior Cricoarytenoideus muscles –
C
Lateral cricoarytenoideus –
C
Thyroarytenoideus –
C
Aryepiglottic muscle –
C
Vocalis muscle –
Production of Sound
C
Pitch –
C
Volume –
 The Trachea
X
Location –
X
Structure
Z
Tracheal cartilages –
C
Z
Carina –
Trachealis muscle –
 The Bronchial Tree
X
Trachea  [R] and [L] primary bronchi  secondary or lobar bronchi (3 on right, 2 on left)  tertiary (segmental)
bronchi  smaller bronchi  bronchioles (less than 1 mm diameter)  terminal bronchioles  respiratory
bronchioles  alveolar duct  alveolar sac  alveolus
X
Primary bronchi –
4
X
Bronchioles –
X
Terminal bronchioles –
X
Respiratory bronchioles –
X
Alveoli –
Z
Alveolar sac –
Z
Septal cells –
C
Pulmonary surfactant –
Z
Dust cells –
Z
Respiratory membrane –
THE LUNGS
Fill the thoracic cavity lateral to both sides of the mediastinum (houses the heart)
ANATOMY
 Apex –
 Hilus –
 Base –
 Costal Surface –
 Pleura –
5
X
Pleural cavity –
 Right Lung
X
Consists of 3 lobes:
Z
Z
Z
X
Oblique fissure –
X
Horizontal fissure –
 Left Lung
X
Consists of 2 lobes:
Z
Z
X
Oblique fissure –
X
Cardiac notch –
X
Lingula –
 Bronchiopulmonary Segments
 Blood Supply of the Lungs
X
Bronchial circulation (To the lung itself)
Z
Bronchial arteries –
Z
Bronchial veins –
C
Azygos vein and hemiazygos vein –
6
X
Pulmonary circulation (To circulation)
Z
Pulmonary trunk (from right ventricle)  right and left pulmonary arteries (O2 poor blood)  branch within the
lungs and travel with the bronchi  feed into pulmonary capillary networks  surround alveoli  gas
exchange  pulmonary veins (high in O2)  left atrium of heart
VENTILATION AND GAS EXCHANGE
 Ventilation –
X
X
X
X
Pressure Relationships in the Thoracic Cavity
Z
Intrapulmonary pressure –
Z
Intrapleural pressure –
*Any condition that equalizes the intrapleural pressure with the intrapulmonary pressure causes the lungs to collapse (atelectasis).
C
Forces pushing the lungs (visceral pleura) towards the thorax wall (parietal pleura):
R
R
R
C
Forces pulling the lungs (visceral pleura) away the thorax wall (parietal pleura):
R
R
INSPIRATION AND EXPIRATION
Dependant upon the relationship between volume change and pressure change
 Boyle’s Law (Ideal Gas Law) –
7
 Inspiration
X
Initiated by the contraction of the diaphragm and the external intercostal muscles
X
Diaphragm contracts  flattens out (normally dome-shaped)  thoracic cavity volume increases  ribs are raised by
the contraction of the external intercostals  also increases thoracic cavity volume lungs stretch  intrapulmonary
volume also increases  intrapulmonary pressure drops  air rushes into the lungs (because the atmospheric air
pressure is higher than the air pressure within the lungs)
 Expiration
X
Passive process that depends on the elastic recoil of lungs
X
Diaphragm relaxes  assumes its normal dome-shape  relaxation of external intercostals  rib cage lowers 
thoracic cavity volume decreases  lungs recoil back to a smaller size  causes an increase in intrapulmonary
pressure  intrapulmonary volume decreases  air moves out of the lungs
X
Forced expiration –
FACTORS INFLUENCING PULMONARY VENTILATION
 Pulmonary Surfactant –
X
Septal cells (Type II alveolar cells) –
 Airway Resistance –
 Lung Compliance –
RESPIRATORY VOLUMES AND CAPACITIES
 Respirometer or Spirometer –
 Respiratory Volumes
X
Tidal volume (TV) –
X
Residual volume (RV) –
8
 Respiratory Capacities
X
Vital capacity (VC) –
X
Inspiratory reserve volume (IRV) –
X
Expiratory reserve volume (ERV) –
X
Residual volume (RV) –
X
Total lung capacity (TLC) –
 Dead Space
X
Anatomical dead space –
X
Physiological dead space –
 Minute Respiratory Volume (MRV) –
 Alveolar Ventilation Rate (AVR) –
GAS EXCHANGES IN THE BODY
BASIC PROPERTIES OF GASES
 Dalton’s Law –
X
Partial pressure –
 Henry’s Law –
9
X
Gas solubility –
GAS EXCHANGE
 External Respiration –
 Internal Respiration –
TRANSPORT OF RESPIRATORY GASES BY BLOOD
OXYGEN TRANSPORT
 Association and Dissociation of Oxygen and Hemoglobin
X
The affinity of hemoglobin to oxygen is:
Z
In the body tissues:
Z
In the lungs:
 Factors Affecting the Affinity of Hemoglobin to Oxygen
X
pH –
X
Temperature –
10
X
DPG (2,3-Diphosphoglyceric acid) –
X
Fetal hemoglobin –
CARBON DIOXIDE TRANSPORT
 Carried in the blood by 3 methods:
X
X
Z
Carbamino hemoglobin –
X
 CO2 transport in plasma
X
Carbonic anhydrase [an enzyme in the RBCs]  catalyzes the formation of carbonic acid [H2CO3] from CO2 and H2O
 carbonic acid dissociates into H+ ions and bicarbonate [HCO3-] ions  H+ ions bind to hemoglobin, HCO3- ions
diffuse out of RBCs into the plasma in exchange for Cl- ions (chloride shift)  bicarbonate ions combine with Na+
ions [NaHCO3] and travel to the lungs where HCO3- is released
Z
Blood pH is not drastically affected because hemoglobin acts as a buffer by picking up any excess free H+ ions
Z
If hemoglobin is saturated, excess H+ ions are picked up by HCO3- ions to form carbonic acid (dissociates into CO2
and H2O so it does not alter pH either)
Z
If blood concentrations of H+ ions gets too low, carbonic acid can release H+ ions to restore the pH balance
CONTROL OF RESPIRATION
LOCAL FACTORS
 Bronchial Smooth Muscle and Changes in CO2 Concentration
X
Increased CO2 
X
Decreased CO2
11
 Pulmonary Arterioles and Changes in O2 and H+
X
Decrease O2 levels in alveoli (or high H+ levels) 
X
Increase O2 levels in alveoli (or low H+ levels) 
BRAIN CONTROL OF RESPIRATION
 Medulla Rhythmicity Center
X
Inspiratory neurons –
Z
Z
Z
Z
X
Expiratory neurons –
Z
Z
 Pons Respiratory Centers
X
Pneumotaxic center –
X
Apneustic center –
FACTORS INFLUENCING VENTILATION
 Hering-Breur Reflex –
 Cortical Input –
 Chemical Influences –
12
X
Aortic bodies (in the aortic arch) and carotid bodies (at the bifurcation of the common carotid arteries) –
X
CO2 and H+ ions levels
Z
Z
In increased amounts in the blood  pH in CSF drops (i.e. H+ increases)  chemoreceptors act on medullary
respiratory centers  send impulses to respiratory muscles  increased ventilation  more CO2 eliminated from
the blood  H+ levels consequently drop (increase in blood pH)
Z
X
O2 levels
X
pH levels
X
Exercise
X
Altitude changes
RESPIRATORY DISORDERS
 Atelectasis –
 Pneumothorax –
 Infant Respiratory Distress Syndrome (IRDS) –
 Sudden Infant Death Syndrome (SIDS) –
X
Possible causes:
13
 Chronic Obstructive Pulmonary Disease –
 Lung Cancer –
 Pleurisy –
14