Respiratory system
Respiratory System
Functionally
Consists of the respiratory and conducting zones
Respiratory zone
Site of gas exchange
Consists of bronchioles, alveolar ducts, and alveoli
Respiratory System
Functionally
Consists of the respiratory and conducting zones
Respiratory zone
Site of gas exchange
Consists of bronchioles, alveolar ducts, and alveoli
Respiratory System
Conducting zone
Provides rigid structures for air to reach the sites of gas exchange
Includes all other respiratory structures (e.g., nose, nasal cavity, pharynx, trachea)
Respiratory muscles – diaphragm and other muscles
that promote ventilation
Respiratory System● Consists of upper and lower
parts
● The upper respiratory
include nose, nasal cavity,
laryngopharynx and larynx
●The lower respiratory
include,the trachea, bronchi,
bronchial tree, and the lungs
The Nose• The nose consists of the external nose and the nasal
cavity, both of which are divided by a septum into right and left halves.
• External NoseThe external nose has two elliptical orifices called the
nostrils, The lateral margin, the ala nasi, is rounded and mobile.
• Nasal Cavity The nasal cavity extends from the
nostrils in front, to the posterior nasal apertures or choanae behind, where the nose opens into the nasopharynx.
Structure of the Nose
Structure of the Nose
• The nose is divided into two regions:
The external nose
The internal nasal cavity
The external nose, including the root, bridge, dorsum nasi, and apex
Philtrum – a shallow vertical groove inferior to the apex
The external nares (nostrils) are bounded laterally by the alae
Nasal Cavity
• Lies in and posterior to the external nose
• Is divided by a midline nasal septum
• Opens posteriorly into the nasal pharynx via internal nares
• The ethmoid and sphenoid bones form the roof
• The floor is formed by the hard and soft palates
Nose
External nasal openings
(nostrils or nares)
Internal nasal
(choanae).
Vestibule – nasal cavity superior to the nares
Vibrissae – hairs that filter coarse particles from
inspired air
Olfactory mucosa
Lines the superior nasal cavity
Contains smell receptors
Nasal Cavity
Nasal Cavity
Respiratory mucosa
Lines the balance of the nasal cavity
Glands secrete mucus containing lysozyme and
defensins to help destroy bacteria
Inspired air is:
Humidified by the high water content in the nasal cavity
Warmed by rich plexuses of capillaries
Ciliated mucosal cells remove contaminated mucus
Nasal Cavity
Superior, medial, and inferior conchae:
Protrude medially from the lateral walls
Increase mucosal area
Enhance air turbulence and help filter air
Sensitive mucosa triggers sneezing when stimulated by
irritating particles
Function of the NoseThe only externally visible part of the respiratory system
that functions by Providing an:
airway for respiration
Moistening (humidifying) and warming the entering air
Filtering inspired air and cleaning it of foreign matter
Serving as a resonating chamber for speech
Housing the olfactory receptors
Regions of the nasal cavity
Nasal vestibule
Olfactory area
Kiesselbach’s plexus or Little's area
• Kiesselbach’s plexus is an integral anastomosis of five branches converging in the anterior inferior quadrant of the nasal septum (over the septal cartilage). The area has been referred to as Little’s Area, Kiesselbach’s Triangle or Kiesselbach’s Area. Little’s area is a common site of epistaxis (nose bleeds) in both paediatric and adult cases.
Little's area
-Epistaxis
-Rhinorrhea
-Rhinitis
• Sinuses in bones that surround the nasal cavity
• Sinuses lighten the skull and help to warm and moisten the air
Paranasal Sinuses
Paranasal sinuses● Air cavities located in the bones of skull around the nose
and open in the lateral wall of the nasal cavity.
● They include frontal, ethmoidal, sphenoidal and maxillary air
sinuses.
Pharynx
It is divided into three regions
Nasopharynx
Oropharynx
Laryngopharynx
The Pharynx● 12-13 cm long muscular tube lies behind the oral, nasal
and laryngeal cavities.
● Extends from the base of skull to the lower border of
cricoids cartilage at the level of lower border of 6th cervical
vertebra where it continues with esophagus.
NasopharynxLies posterior to the nasal cavity, inferior to the
sphenoid, and superior to the level of the soft palate
Strictly an air passageway
Lined with pseudostratified columnar epithelium
Closes during swallowing to prevent food from
entering the nasal cavity
The pharyngeal tonsil lies high on the posterior wall
Pharyngotympanic (auditory) tubes open into the
lateral walls
Oropharynx
Extends inferiorly from the level of the soft palate to the epiglottis
Serves as a common passageway for food and air
The epithelial lining is protective stratified squamous epithelium
Palatine tonsils lie in the lateral walls
Lingual tonsil covers the base of the tongue
Oro-pharynx ● Lies behind the oral cavity
● Its junction with nasopharynx at the isthmus or called
oropharyngeal orifice
● It contains the palatine tonsils in its lateral walls
Laryngo-pharynx:● Lies behind the larynx and continupus anteriorly with the
inlet of larynx.
● On each side of inlet of larynx, the laryngopharynx has a
dead space called piriform recess which is the site for
stagnation of food stuff and foreign bodies.
● Inferiorly, it is continuous with the esophagus
The Pharynx● long muscular tube
lies behind the oral, nasal
Parts of Pharynx
1. Naso-pharynx
2. Oro-pharynx
3. Laryngo-pharynx
Laryngopharynx
Lies posterior to the upright epiglottis
Extends to the larynx, where the respiratory and
digestive pathways diverge
Larynx● A phonation box and air passage, located in the middle
anterior part of the neck.
● It is made of a number of cartilages connected together by
membranes, ligaments, muscles
.
Larynx
Short passageway connecting laryngopharynx with trachea
Composed of 9 pieces of cartilage
Thyroid cartilage or Adam’s apple
Cricoid cartilage hallmark for tracheotomy
Cavity of Larynx● Extends from inlet of larynx to the beginning of trachea
● In the central, middle part of laryngeal cavity, it contains
two pairs of vocal folds or cords
Epiglottis closes off glottis during swallowing
elastic cartilage that covers the laryngeal inlet
during swallowing
Glottis – pair of folds of mucous membranes, vocal folds (true vocal cords, and rima glottidis (space)
Cilia in upper respiratory tract move mucous and trapped particles down toward pharynx
Cilia in lower respiratory tract move them up toward pharynx
Larynx (Voice Box)
Attaches to the hyoid bone and opens into the
laryngopharynx superiorly
Continuous with the trachea posteriorly
Framework of the Larynx
Attaches to the hyoid bone and opens into the
laryngopharynx superiorly
Continuous with the trachea posteriorly
Structures of Voice Production
Mucous membrane of larynx forms
Ventricular folds (false vocal cords) – superior pair
Function in holding breath against pressure in
thoracic cavity
Mucosal folds superior to the true vocal cords
Have no part in sound production
Vocal folds (true vocal cords) – inferior pair
Vibrate and produce sound with air
Sphincter Functions of the Larynx
The larynx is closed during coughing, sneezing, and Valsalva’s maneuver
Valsalva’s maneuver
Air is temporarily held in the lower respiratory tract by closing the glottis
Causes intra-abdominal pressure to rise when abdominal muscles contract
Helps to empty the rectum
Functions of larynx
The three functions of the larynx are:
To provide a patent airway
To act as a switching mechanism to route air and
food into the proper channels
To function in voice production
Trachea● Extends from larynx to
superior border of T5
Divides into right and left
primary bronchi
The trachea begins at the
laryngeal outlet
and terminates at the level of
the sternal angle, by dividing
into the right and left bronchi
(carina = bifurcation of
trachea)
● It is 10 cm long having a
fibromuscular wall supported by
a number of C-shaped hyaline
cartilages.
Trachialis
C-shaped hyaline cartilages
Bronchi and
Bronchial Tree● The right and left
principle bronchi begins
at the level of sternal
angle
● The right principle
•The left principle
bronchus
Tertiary bronchus
(Bronchopulmonary Segment)
BronchiRight and left primary bronchus goes to right and left lungs
Carina – internal ridge
Most sensitive area for triggering cough reflex
Divide to form bronchial tree
Secondary lobar bronchi (one for each lobe), tertiary (segmental) bronchi, bronchioles, terminal bronchioles
• upper lobe
• middle lobe
• lower lobe
•transverse
fissures.
•Oblique
fissures.
• upper lobe
• lower lobe
•Oblique
fissure.
• pleural sac
Lungs
Gross Anatomy of the LungsLungs occupy all of the thoracic cavity except the
mediastinum
Root – site of vascular and bronchial attachments
Costal surface – anterior, lateral, and posterior
surfaces in contact with the ribs
Apex – narrow superior tip
Base – inferior surface that rests on the diaphragm
Hilus – indentation that contains pulmonary and
systemic blood vessels
❖The costal surface of the lung is large,
smooth, and convex. It is related to the costal pleura,
which separates it from the ribs, costal cartilages,
and innermost intercostal muscles.
❖The mediastinal surface of the lung is
concave because it is related to the middle
mediastinum, which contains the pericardium and
heart. The mediastinal surface includes the hilum,
which receives the root of the lung.
❖ The diaphragmatic surface of the lung, which is
also concave, forms the base of the lung, which rests
on the dome of the diaphragm
The hilum of the lung
is a wedge-shaped area on
the mediastinal surface of
each lung through which the
structures forming the root of
the lung pass to enter or exit
the lung.
Pleura● Serous sac investing the lungs.
● Consists of outer parietal and inner visceral layers
separated by a small space called pleural cavity.
-Pleuritis
-Pneumothorax
-Haemothorax
Each lung enclosed by double-layered pleural membrane
Parietal pleura – lines wall of thoracic cavity
Visceral pleura – covers lungs themselves
Pleural cavity is space between layers
Pleural fluid reduces friction, produces surface tension (stick together)
Pleura
Diaphragm
❖ Is the musculotendenous it has two parts
• Muscular part fixed
• Central part movable• The fibers of the
muscular part radiated in the center forming central tendon and it has no bony attachments
Opening of the diaphragm
• Aortic hiatus at the level
of T12 for aorta
• Esophagus hiatus at the
level of T10 for esophagus
• Caval opening for IVC at
the level of T8
Caval opening
Aortic hiatus
Esophageal
opening
Intercostal muscles