Transcript Functional+Anatomy+of+the+Respiratory+System

Respiratory System
Objectives:
Functional Anatomy of the Respiratory System
• Name the organs forming the respiratory passageway from the
nasal cavity to the alveoli of the lungs (or identify them on a
diagram or model) and describe the function of each.
• Describe several protective mechanisms of the respiratory
system.
• Describe the structure and function of the lungs and the pleural
coverings.
Upper and Lower Respiratory Tracts
Upper Respiratory Tract
Lower Respiratory Tract
Organs of the Respiratory System
1. Nose
2. Pharynx
3. Larynx
______________
4. Trachea
5. Bronchi
6. Lungs—alveoli
Figure 13.1
Functions of the Respiratory System
1. Passageways to the lungs (nose, pharynx, larynx, trachea, bronchi)
purify, humidify, and warm the incoming air.
• The conducting zone of the respiratory system is made up of the
nose, pharynx, larynx, trachea, bronchi, bronchioles, and terminal
bronchioles
2. Gas exchanges between the blood and external environment only
occurs in the alveoli of the lungs
• The respiratory zone of the respiratory system is made up of the
respiratory bronchioles, alveolar ducts, and the alveoli.
1. The Nose
• Only externally visible part of the respiratory system
• Air enters the nose through the external nostrils (nares)
• Interior of the nose consists of a nasal cavity divided by a
nasal septum
nasal septum
Upper Respiratory Tract
Figure 13.2
Anatomy of the Nasal Cavity
Olfactory
receptors are
located in the
mucosa on the
superior surface
• The rest of the cavity is lined with respiratory mucosa
resting on thin-walled veins that
• Warm the incoming air
• Mucus produced by mucous glands moisten air & traps incoming
foreign particles
• Ciliated cells of the mucosa move the sheet of contaminated mucus
away from the lungs and toward the throat for swallowing
(The oral mucosa does not of these functions)
Anatomy of the Nasal Cavity
• Lateral walls have projections
called conchae
• Increase surface area
• Increase air turbulence within the
nasal cavity
• The nasal cavity is separated
from the oral cavity by the
palate
• Anterior hard palate (bone)
• Posterior soft palate (muscle)
Paranasal Sinuses
• Cavities within bones surrounding the nasal cavity are
called sinuses
• Sinuses are located in the following bones
• Frontal bone
• Sphenoid bone
• Ethmoid bone
• Maxillary bone
Function of the sinuses
• Lighten the skull
• Act as resonance chambers for
speech
• Produce mucus that drains into the
nasal cavity
Upper Respiratory Tract—Paranasal Sinuses
Figure 13.2
2. Pharynx (Throat)
• Muscular passage from
nasal cavity to larynx
• Three regions of the pharynx
• Nasopharynx—superior region
behind nasal cavity
• Oropharynx—middle region
behind mouth
• Laryngopharynx—inferior region
attached to larynx
• The oropharynx and
laryngopharynx are common
passageways for air and
food
Structures of the Pharynx
• Tonsils of the pharynx
1. Pharyngeal tonsil (adenoids) are located in the nasopharynx
2. Palatine tonsils are located in the oropharynx
3. Lingual tonsils are found at the base of the tongue
Structures of the Pharynx
• Pharyngotympanic tubes open into the nasopharynx
If either the middle ear or the sinuses are
infected, the exudate will drain into the nasal
passages and possibly lead to congestion,
or “postnasal drip.”
Conversely, a nasopharyngeal infection can
easily spread to the middle ear cavity or the
sinuses because of the continuity of their
mucosae, thus causing otitis media or
sinusitis, respectively.
3. Larynx (Voice Box)
• Routes air and food into proper channels
• Plays a role in speech
• Made of eight rigid hyaline cartilages and a spoon-shaped
flap of elastic cartilage (epiglottis)
Structures of the Larynx
• Cricoid cartilage
•the only complete ring of cartilage
around the trachea
http://www.youtube.com/watch?v=QvGYvK6qScE&feature=related
http://www.getbodysmart.com/ap/respir
atorysystem/larynx/thyroid_cricoid/tuto
rial.html
• Thyroid cartilage
• Largest of the hyaline cartilages
• Protrudes anteriorly (Adam’s apple)
• Epiglottis
• Protects the superior opening of the larynx
• Routes food to the esophagus and air
toward the trachea
• When swallowing, the epiglottis rises and
forms a lid over the opening of the larynx
Normal larynx as seen during larynx examination or laryngoscopy
1=vocal cords, 2=vestibular fold(false vocal cords), 3=epiglottis,
Structures of the Larynx
• Vocal folds (true vocal cords)
• Vibrate with expelled air to create sound (speech)
• Glottis—opening between vocal cords
http://www.youtube.com/watch?v=
qpt0kigakWY&feature=related
4. Trachea (Windpipe)
• Four-inch-long tube that connects larynx with bronchi
• Lined with ciliated mucosa
• Beat continuously in the opposite direction of incoming air
• Expel mucus loaded with dust and other debris away from
lungs
Mucus serves to trap dust,
bacteria, and other foreign
debris that manage to enter the
respiratory passageways.
Trachea (Windpipe)
Prevents airway from collapsing during breathing
Allows esophagus to bulge
Pulls trachea tighter when coughing
Trachealis muscle
Psudeostratified epithelium
Layers
Of the wall
Mucousa
Submucousa
Lamina Propria
Cilia
Figure 13.3a
Trachea (Windpipe)
Walls are reinforced with C-shaped
hyaline cartilage
The cartilaginous
reinforcements keep the trachea
open during the pressure
changes that occur during
breathing.
The incomplete rings of the
posterior tracheal surface make
it flexible, allowing a food bolus
Figure 13.3b
traveling through the posterior
esophagus to bulge anteriorly.
5. Main (Primary) Bronchi
• Formed by division of the trachea
• Enters the lung at the hilum (medial depression)
• Right bronchus is wider, shorter, and straighter than left
(most likely site for an inhaled object to become lodged)
• Bronchi subdivide into smaller and smaller branches (23
times)
Main Bronchi
Figure 13.1
Main Bronchi
Figure 13.4b
6. Lungs
• Occupy most of the thoracic cavity
• Heart occupies central portion called mediastinum
• Apex is near the clavicle (superior portion)
• Base rests on the diaphragm (inferior portion)
• Each lung is divided into lobes by fissures
• Left lung—two lobes
• Right lung—three lobes
The lungs also contain elastic
tissues that allow them to inflate
and deflate without losing shape
Lungs
Figure 13.4a
Lungs
Figure 13.4b
Coverings of the Lungs
• Serosa covers the outer surface of the lungs
• Pulmonary (visceral) pleura covers the lung surface
• Parietal pleura lines the walls of the thoracic cavity
• Pleural fluid fills the area between layers of pleura to allow
gliding
• These two pleural layers resist being pulled apart
Lungs
Figure 13.4a
Bronchial (Respiratory) Tree Divisions
• All but the smallest of
these passageways
have reinforcing
cartilage in their walls
• Primary bronchi
• Secondary bronchi
• Tertiary bronchi
• Bronchioles
• Terminal bronchioles
Bronchial (Respiratory) Tree Divisions
Figure 13.5a
Respiratory Zone
• Structures
1. Respiratory bronchioles
2. Alveolar ducts
3. Alveolar sacs
4. Alveoli (air sacs)
• Site of gas exchange = alveoli only
Bronchial (Respiratory) Tree Divisions
Figure 13.5a
Bronchial (Respiratory) Tree Divisions
Figure 13.5b
Respiratory Membrane (Air-Blood Barrier)
• Thin squamous epithelial layer lines alveolar walls
• Alveolar pores connect neighboring air sacs
• Pulmonary capillaries cover external surfaces of alveoli
ALVEOLI walls are extremely thin
(one layer of squamous epithelium
plus a basement membrane) for
easy gas exchange, and combined,
they present an extremely large
surface area.
Respiratory Membrane (Air-Blood Barrier)
Figure 13.6 (1 of 2)
Respiratory Membrane (Air-Blood Barrier)
On one side of the membrane
is air and on the other side is
blood flowing past
Figure 13.6 (2 of 2)
Gas Exchange
• Gas crosses the respiratory
membrane by diffusion
• Oxygen enters the blood
• Carbon dioxide enters the alveoli
Alveolar Macrophages
Alveolar macrophages
(“dust cells”) add
protection by picking up
bacteria, carbon
particles, and other
debris
Surfacant
• In order to function properly, the alveoli must always
stay moist. Special cells in the alveoli secrete a
substance called a surfactant which reduces the
surface tension of water, thereby enabling it to better
coat the cells of the alveoli to keep them moist and
keep them from sticking to each other when the
person exhales.
• The ability to secrete this chemical doesn’t develop
until around the eighth or ninth month of pregnancy,
so there frequently is a problem in premature babies
with the lack of surfactant causing the alveoli to stick
together when the baby exhales. Then, when the
baby inhales again, the stuck alveolar cells tear
away from their neighbors. Scar tissue forms at
these sites, thus the damage is permanent, and the
person’s lungs lose some of their elasticity and
ability to expand fully.
• A current “hot” area of research is searching for a
suitable replacement surfactant that could be placed
into the lungs of premature babies to prevent this
damage.
Surfactant (a lipid molecule)
coats gas-exposed alveolar
surfaces