Respiratory system
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Transcript of Respiratory system
The Respiratory System
Human Respiratory System
Figure 10.1
Components of the Upper Respiratory Tract
Figure 10.2
Passageway for respiration Receptors for smell Filters incoming air to filter larger foreign
material Moistens and warms incoming air Resonating chambers for voice
Upper Respiratory Tract Functions
Components of the Lower Respiratory Tract
Figure 10.3
Functions: Larynx: maintains an open airway, routes food and air
appropriately, assists in sound production Trachea: transports air to and from lungs Bronchi: branch into lungs Lungs: transport air to alveoli for gas exchange
Lower Respiratory Tract
Organs of the Respiratory system
Slide 13.1Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
· Nose· Pharynx· Larynx· Trachea· Bronchi· Lungs –
alveoli
Figure 13.1
Chapter 22, Respiratory System 8
Respiratory System
• Consists of the respiratory and conducting zones
• Respiratory zone– Site of gas exchange – Consists of bronchioles, alveolar ducts, and alveoli
Chapter 22, Respiratory System 9
Respiratory System
• Conducting zone – Provides rigid conduits 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
Chapter 22, Respiratory System 10
Major Functions of the Respiratory System
• To supply the body with oxygen and dispose of carbon dioxide
• Respiration – four distinct processes must happen– Pulmonary ventilation – moving air into and out of
the lungs– External respiration – gas exchange between the
lungs and the blood
Chapter 22, Respiratory System 11
Major Functions of the Respiratory System
– Transport – transport of oxygen and carbon dioxide between the lungs and tissues
– Internal respiration – gas exchange between systemic blood vessels and tissues
Chapter 22, Respiratory System 12
Function of the Nose
• The 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
Chapter 22, Respiratory System 13
Structure of the Nose
• The nose is divided into two regions– The external nose, including the root, bridge,
dorsum nasi, and apex – The internal nasal cavity
• Philtrum – a shallow vertical groove inferior to the apex
• The external nares (nostrils) are bounded laterally by the alae
Chapter 22, Respiratory System 14
Structure of the Nose
Figure 22.2a
Chapter 22, Respiratory System 15
Structure of the Nose
Figure 22.2b
Chapter 22, Respiratory System 16
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• Connects with pharynx posteriorly through
choanae (posterior nasal apertures*)• The ethmoid and sphenoid bones form the roof• The floor is formed by the hard and soft palates
*
Chapter 22, Respiratory System 18
Linings of Nasal Cavity
• 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– (Cribriform plate – small patch of olfactory mucosa
near roof)
*
Olfactory mucosa
Chapter 22, Respiratory System 20
Linings of Nasal Cavity
• Respiratory mucosa – Lines the balance of the nasal cavity – Glands secrete mucus containing lysozyme and
defensins to help destroy bacteria
Chapter 22, Respiratory System 21
Nasal Cavity
• 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
Chapter 22, Respiratory System 22
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
Chapter 22, Respiratory System 23
Functions of the Nasal Mucosa and Conchae
• During inhalation the conchae and nasal mucosa:– Filter, heat, and moisten air
• During exhalation these structures:– Reclaim heat and moisture– Minimize heat and moisture loss
Chapter 22, Respiratory System 25
Paranasal Sinuses
• Sinuses in bones that surround the nasal cavity
• Sinuses lighten the skull and help to warm and moisten the air
Chapter 22, Respiratory System 26
Pharynx
• Funnel-shaped tube of skeletal muscle that connects to the:– Nasal cavity and mouth superiorly– Larynx and esophagus inferiorly
• Extends from the base of the skull to the level of the sixth cervical vertebra
Chapter 22, Respiratory System 27
Pharynx
• It is divided into three regions– Nasopharynx– Oropharynx– Laryngopharynx
Chapter 22, Respiratory System 28
Nasopharynx
• Lies 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
Chapter 22, Respiratory System 29
Oropharynx
• Extends inferiorly from the level of the soft palate to the epiglottis
• Opens to the oral cavity via an archway called the fauces
• Serves as a common passageway for food and air• The epithelial lining is protective stratified
squamous epithelium• Palatine tonsils lie in the lateral walls of the fauces• Lingual tonsil covers the base of the tongue
Chapter 22, Respiratory System 30
Laryngopharynx
• Serves as a common passageway for food and air
• Lies posterior to the upright epiglottis• Extends to the larynx, where the respiratory
and digestive pathways diverge
Chapter 22, Respiratory System 32
Larynx (Voice Box)
• Attaches to the hyoid bone and opens into the laryngopharynx superiorly
• Continuous with the trachea posteriorly• 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
Chapter 22, Respiratory System 33
Framework of the Larynx
• Cartilages (hyaline) of the larynx (9)– Shield-shaped anterosuperior thyroid cartilage with a midline
laryngeal prominence (Adam’s apple)– Signet ring–shaped anteroinferior cricoid cartilage– Cricoid cartilage inferior to thyroid cartilage: the only
complete ring of cartilage: signet shaped and wide posteriorly– Three pairs of small arytenoid (anchor the vocal cords),
cuneiform, and corniculate cartilages• Epiglottis – elastic cartilage that covers the laryngeal
inlet during swallowing (9th cartilage)– Attaches to back of tongue
Chapter 22, Respiratory System 34
Framework of the Larynx
Figure 22.4a, b
Chapter 22, Respiratory System 35
Vocal Ligaments
• Attach the arytenoid cartilages to the thyroid cartilage
• Composed of elastic fibers that form mucosal folds called true vocal cords– The medial opening between them is the glottis– They vibrate to produce sound as air rushes up
from the lungs
Chapter 22, Respiratory System 36
Vocal Ligaments
• False vocal cords– Mucosal folds superior to the true vocal cords– Have no part in sound production
Chapter 22, Respiratory System 37
Vocal Production
• Speech – intermittent release of expired air while opening and closing the glottis
• Pitch – determined by the length and tension of the vocal cords
• Loudness – depends upon the force at which the air rushes across the vocal cords
• The pharynx resonates, amplifies, and enhances sound quality
• Sound is “shaped” into language by action of the pharynx, tongue, soft palate, and lips
Chapter 22, Respiratory System 38
Movements of Vocal Cords
Figure 22.5
Glottis - the space between the vocal cords
Chapter 22, Respiratory System 39
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– Acts as a splint to stabilize the trunk when lifting
heavy loads
Conducting zone of lower respiratory tract
Trachea • At the level of the sternal angle, the
trachea bifurcates into two smaller tubes, called the right and left primary bronchi.
• Each primary bronchus projects laterally toward each lung.
• The most inferior tracheal cartilage separates the primary bronchi at their origin and forms an internal ridge called the carina.
Bronchial tree
• A highly branched system of air-conducting passages that originate from the left and right primary bronchi.
• Progressively branch into narrower tubes as they diverge throughout the lungs before terminating in terminal bronchioles.
• Incomplete rings of hyaline cartilage support the walls of the primary bronchi to ensure that they remain open.
• Right primary bronchus is shorter, wider, and more vertically oriented than the left primary bronchus.
• Foreign particles are more likely to lodge in the right primary bronchus.
Bronchial tree• The primary bronchi enter the hilus of each lung
together with the pulmonary vessels, lymphatic vessels, and nerves.
• Each primary bronchus branches into several secondary bronchi (or lobar bronchi).
• The left lung has two secondary bronchi.The right lung has three secondary bronchi.
• They further divide into tertiary bronchi. • Each tertiary bronchus is called a segmental
bronchus because it supplies a part of the lung called a bronchopulmonary segment.
Bronchial Tree• Secondary bronchi tertiary bronchi bronchioles
terminal bronchioles • with successive branching amount of cartilage decreases and
amount of smooth muscle increases, this allows for variation in airway diameter
• during exertion and when sympathetic division active bronchodilation
• mediators of allergic reactions like histamine bronchoconstriction
• epithelium gradually changes from ciliated pseudostratified columnar epithelium to simple cuboidal epithelium in terminal bronchioles
45
46
Carina*• Ridge on
internal aspect of last tracheal cartilage
• Point where trachea branches (when alive and standing is at T7)
• Mucosa highly sensitive to irritants: cough reflex
*
Chapter 22, Respiratory System 47
Trachea
• Composed of three layers– Mucosa – made up of goblet cells and ciliated
epithelium – Submucosa – connective tissue deep to the
mucosa– Adventitia – outermost layer made of C-shaped
rings of hyaline cartilage
Chapter 22, Respiratory System 48
Trachea
Figure 22.6a
Chapter 22, Respiratory System 49
Conducting Zone: Bronchi
• The carina of the last tracheal cartilage marks the end of the trachea and the beginning of the right and left bronchi
• Air reaching the bronchi is:– Warm and cleansed of impurities– Saturated with water vapor
• Bronchi subdivide into secondary bronchi, each supplying a lobe of the lungs
• Air passages undergo 23 orders of branching in the lungs
Chapter 22, Respiratory System 50
Conducting Zone: Bronchial Tree
• Tissue walls of bronchi mimic that of the trachea
• As conducting tubes become smaller, structural changes occur– Cartilage support structures change– Epithelium types change– Amount of smooth muscle increases
Chapter 22, Respiratory System 51
Conducting Zone: Bronchial Tree
• Bronchioles – Consist of cuboidal epithelium– Have a complete layer of circular smooth muscle – Lack cartilage support and mucus-producing cells
Chapter 22, Respiratory System 53
Respiratory Zone
• Defined by the presence of alveoli; begins as terminal bronchioles feed into respiratory bronchioles
• Respiratory bronchioles lead to alveolar ducts, then to terminal clusters of alveolar sacs composed of alveoli
• Approximately 300 million alveoli:– Account for most of the lungs’ volume – Provide tremendous surface area for gas exchange
Alveoli
Slide 13.17
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
· Structure of alveoli· Alveolar duct· Alveolar sac· Alveolus· Gas exchange
Chapter 22, Respiratory System 55
Alveoli• Surrounded by fine elastic fibers• Contain open pores that:
– Connect adjacent alveoli– Allow air pressure throughout the lung to be
equalized• House macrophages that keep alveolar surfaces
sterile
Chapter 22, Respiratory System 56
Respiratory Membrane
• This air-blood barrier is composed of: – Alveolar and capillary walls– Their fused basal laminas
• Alveolar walls:– Are a single layer of type I epithelial cells– Permit gas exchange by simple diffusion– Secrete angiotensin converting enzyme (ACE)
• Type II cells secrete surfactant
Chapter 22, Respiratory System 57
Respiratory Membrane
Figure 22.9b
58
Surfactant
• Type II cuboidal epithelial cells are scattered in alveolar walls
• Surfactant is a detergent-like substance which is secreted in fluid coating alveolar surfaces – it decreases tension
• Without it the walls would stick together during exhalation
• Premature babies – problem breathing is largely because lack surfactant
59
Microscopic detail of alveoli• Alveoli surrounded by fine elastic fibers• Alveoli interconnect via alveolar pores• Alveolar macrophages – free floating “dust cells”• Note type I and type II cells and joint membrane
Chapter 22, Respiratory System 60
Gross Anatomy of the Lungs
• Lungs 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
Chapter 22, Respiratory System 61
Lungs
• Cardiac notch (impression) – cavity that accommodates the heart
• Left lung – separated into upper and lower lobes by the oblique fissure– smaller than the right lung
• Right lung – separated into three lobes by the oblique and horizontal fissures
• There are 10 bronchopulmonary segments in each lung
Chapter 22, Respiratory System 62
Gross Anatomy of Lungs• Base, apex (cupula), costal surface, cardiac notch• Oblique & horizontal fissure in right lung results in 3 lobes• Oblique fissure only in left lung produces 2 lobes
Chapter 22, Respiratory System 63
Mediastinal Surface of Lungs
• Blood vessels & airways enter lungs at hilus• Forms root of lungs• Covered with pleura (parietal becomes visceral)
Chapter 22, Respiratory System 64
Blood Supply to Lungs
• Lungs are perfused by two circulations: pulmonary and bronchial
• Pulmonary arteries – supply systemic venous blood to be oxygenated– Branch profusely, along with bronchi– Ultimately feed into the pulmonary capillary
network surrounding the alveoli• Pulmonary veins – carry oxygenated blood from
respiratory zones to the heart
Chapter 22, Respiratory System 65
Blood Supply to Lungs
• Bronchial arteries – provide systemic blood to the lung tissue– Arise from aorta and enter the lungs at the hilus– Supply all lung tissue except the alveoli
• Bronchial veins anastomose with pulmonary veins
• Pulmonary veins carry most venous blood back to the heart
Pleura and Pleural Cavities• The outer surface of each lung and the
adjacent internal thoracic wall are lined by a serous membrane called pleura.
• The outer surface of each lung is tightly covered by the visceral pleura.
• while the internal thoracic walls, the lateral surfaces of the mediastinum, and the superior surface of the diaphragm are lined by the parietal pleura.
• The parietal and visceral pleural layers are continuous at the hilus of each lung.
Pleural Cavities The potential space between the serous
membrane layers is a pleural cavity. • The pleural membranes produce a thin,
serous pleural fluid that circulates in the pleural cavity and acts as a lubricant, ensuring minimal friction during breathing.
• Pleural effusion – pleuritis with too much fluid