Transcript Functions of Respiratory System

Functions of Respiratory System
Ventilation - moves air to and from alveoli.
Large surface area for gas exchange.
Regulates pH of body fluids.
Permit vocal sounds (communication).
External nares
• Upper Respiratory Tract
– Nose
– Nasal cavity
– Pharynx (3 parts)
• Lower Respiratory Tract
- Larynx
- Trachea
- Bronchi
- Bronchioles
- Alveoli
Conditions inspired air:
Filter
Warm
Humidify
Functions to conduct air
to site of gas exchange.
Respiratory Tract (Passageway)
External nares > nose > nasal cavity >
pharynx (naso-, oro- laryngo-) >
larynx > trachea > 1o bronchi > 2o bronchi >
3o bronchi > bronchioles > terminal bronchioles >
respiratory bronchioles > alveolar duct >
alveolar sac > alveoli (end).
The Respiratory Tract is divided into:
– Conducting Zone
– Respiratory Zone
• Two types of mucosa in nasal cavity
– Olfactory mucosa – houses olfactory receptors
– Respiratory mucosa – lines nasal cavity
PARANASAL SINUSES
“Respiratory Epithelium”
• Lines conducting portions of tract.
• Pseudostratified ciliated columnar epithelium
(with goblet cells)
– Produces mucus to trap foreign particles
• Lamina propria is the connective tissue layer
(Epithelium and lamina propria = mucus membrane)
Respiratory Epithelium
• External nares
– Open into nasal cavity
– Vestibule guarded by hairs
• Nasal cavity
– Superior, middle and inferior meatuses
• Narrow grooves and conchal surfaces
• Hard palate
– Divides nasal and oral cavities
• Soft palate
– Superior nasopharynx and pharynx
• Internal nares
– Between nasal cavity and nasopharynx
The Pharynx
Portions shared by digestive and respiratory systems
Nasopharynx
Superior portion: from internal nares to uvula.
Oropharynx
Continuous with oral cavity
Laryngopharynx
Between hyoid and entrance to esophagus
Nasopharynx
• Superior to where food enters.
• Only an air passageway.
• Closed off during swallowing (uvula).
• Pharyngeal tonsil (adenoids)
– Located on posterior wall
– Destroys entering pathogens
• Contains the opening to the auditory tube
Oropharynx
• Extends from soft palate to the epiglottis.
• Stratified squamous epithelium.
• Two types of tonsils in the oropharynx
Palatine tonsils – in the lateral walls of fauces.
Lingual tonsils – on posterior surface of tongue.
Laryngopharynx
• Passageway for both food and air.
(shared respiratory and digestive)
• Stratified squamous epithelium
• Continuous with the esophagus and larynx
Lower Respiratory Tract: The Larynx
• Surrounds glottis - air passes through glottis to reach lungs
• Epiglottis - prevents solids from entering respiratory system
Laryngeal
cartilages
When swallowing, elevation of larynx folds epiglottis over glottis,
steering materials into the esophagus.
Trachea
• From C6 to T5
• About 4.5 inches in length.
• About 1 inch in diameter.
• Submucosa includes “C” rings of cartilage
Posterior wall (without cartilage) distorts, allowing
food passage through esophagus.
• Contains the muscle trachialis.
Trachea
1)
2)
3)
1) pseudostratified ciliated columnar epi
2) tracheal cartilage ring
3) trachealis muscle
Left and Right 1o Bronchi
• Right and left primary bronchi
– Trachea branches within mediastinum.
• Bronchial tree
– Enters lungs at hilus (“entry/exit”).
– Extensively branching passageways.
The Lungs
Lungs
• Separated by fissures
– Right lung has three lobes.
– Left lung has two lobes.
• Costal surface
– Anterior surface
– Follows inner contours of rib cage
• Mediastinal surface
– Contains hilus
• Left lung bears costal notch
• For clarity, the degree
of branching has been
reduced: an airway
branches approximately
23 times before
reaching the level of a
lobule.
Bronchopulmonary Segments
Bronchi and Bronchioles
Basic structure of a lobule,
cut to reveal the arrangement
between the alveolar ducts
and alveoli.
Alveoli consist of 3 types of cells
1) Alveolar Type I cells – simple squamous
epithelium, make the ‘walls’ of alveoli for gas
exchange.
2) Alveolar Type II cells – simple cuboidal cells,
release surfactant, help make lungs Compliant.
3) Alveolar Macrophages – phagocytic cells,
protects the alveolar surface.
Respiratory Muscles
Ventilation - movement of air into and out of lungs.
Eupnea - normal quite
breathing at rest.
Inspiration:
 volume of
thoracic cavity.
Muscle activity required:
Diaphragm
External Intercostals
Sternocleidomastoid
Scalenes
To increase depth and frequency of breaths:
Sternocleidomastiod
Scalenes
Expiration:  volume of thoracic cavity.
No Muscular activity required (in eupnea)
When Forcefully
exhaling (hypereupnea):
Muscles used:
Internal Intercostals
Rectus abdominis
Transverse abdominis,
Internal and External
obliques.
Positions and
relationships
between the major
respiratory centers.
Three pairs of nuclei in reticular formation
of pons and medulla oblongata
Respiratory rhythmicity center - Sets respiratory pace.
Located in the medulla oblongata.
Dorsal Respiratory Group (DPG) = inspiration.
Ventral Respiratory Group (VPG) = forced breathing.
Apneustic center - Strong, sustained inspiratory movements,
used for ‘overdrive’ when breathing deep. Pons
Pneumotaxic center - Inhibits apneustic and inspiratory
centers, limits over inflation of lungs. Pons
Sensory Receptors - regulate respiration.
Mechanoreceptors
detect changes in lung volume or arterial blood pressure
Chemoreceptors
Changes in PCO2, pH, PO2 of blood and CSF
Central chemoreceptors - in medulla
Peripheral chemoreceptors
Aortic bodies (in aorta)
Carotid bodies (in carotids)