Respiratory System Flashcards
Functions of Respiratory System
*main: breathing - involves inhalation & exhalation
- Gas exchange
- Gas conduction (warmed, humidified, cleansed)
- Sound production
- Olfaction (olfactory epithelium)
- Defense (i.e. hairs w/in) nostrils - brisae)
Division of Respiratory System;
- Anatomically
- Functionally
Anatomically; Can be divided into tracts:
i) Upper respiratory tract (nose to pharynx)
ii) Lower respiratory tract (larynx down to and including the lungs)
Functionally; the system can be divided into functional zones
i) Conducting zones (passageways that transport air; nose to terminal bronchioles)
ii) Respiratory zone: small airways dedicating to gas exchange (respiratory bronchioles to alveoli)
Upper Respiratory Tract
Comprised of;
- nose and nasal cavities
- paranasal sinuses
- pharynx
*are all part of the conducting portion of respiratory system
Lower Respiratory Tract
Comprised of:
- Larynx
- Trachea
- Bronchi
- Lungs
Nose
- Is main conducting airway for inhaled air
- supported superiorly by paired nasal bones (form bridge of nose)
- Supported anteroinferiorly from the bridge by fleshy, cartilagenous dorsum nasi
Nasal Cavity & associated structures;-
-conchae, nasal meatus, vestibule
- begins as internal component of nose, ends as openings to nasopharynx (CHOANAE)
- nasal septum divides nasal cavity into right & left portions
- shell like bony scrolls form lateral walls (superior, middle & inferior nasal conchae)
- conchae = condition air in the spaces between (nasal meatus)
- anterior region of nasal cavity = vestibule
- lined w/ psuedostratified ciliated columnar epithelium
- most superior part = olfactory epithelium
Paranasal sinuses - function & name (4)
- Four bones of the skull contain paired air sacs = paranasal sinuses
- make bones lighter in weight
- Frontal
- Ethmoidal
- sphenoidal
- maxillary
Pharynx - features
-3 regions
*Shared by two organ systems - digestive & respiratory* aka throat -funnel shaped -lined by mucosa Divided into 3 regions;- -Nasopharynx -Oropharynx -Laryngopharynx
Nasopharynx
- most superior region
- conducts air
- lined w/ psuedostratified ciliated columnar epithelium
- Continous w/ nasal cavity & superior to soft palate
- opening of auditory tubes found in lateral walls
- posterior nasopharynx wall houses single pharyneal tonsil
Oropharynx
- begins at end of soft palate & ends at lvl of hyoid bone
- opening of oral cavity into oropharynx = fauces (throat)
- has 2 pairs of muscular arches on lateral walls
- conducts air & serves as passageway for food/air
- non-keratinized stratified squamous epithelium (strong enough to w/stand abrasion)
- lymphatic organs: First line of defense when foreign materials digested
Laryngopharynx
- Starts inferior to hyoid bone - continuous w/ larynx and esophagus
- Same function & structure as oropharynx
Lower Respiratory Tract (conducting portion)
Comprised of;-
- larynx
- trachea
- bronchi
- bronchioles - terminal
Larynx
-(aka voicebox)
-continuous w/ larynopharynx
-supported by framework of cartilages, ligaments & muscles
FUNCTIONS: passageway for air, prevents ingested matter from entering, sound for speech, assist. in increasing pressure in ab. cavity, participates in sneeze & cough reflex
3 major cartilages:
1. Thyroid Cartilage
2. Cricoid cartilage
3. Epiglottis
Major Cartilages of the larynx; Thyroid Cartilage
- largest cartilage
- has anterior & lateral wall only (shield shaped)
- V shaped anterior projection = laryngeal prominence (Adam’s Apple)
- usu. larger in males due to testoterone’s influence on cartilage growth
- composed of hyaline cartilage
Major Cartilages of the larynx: Cricoid Cartilage
- inferior to thyroid cartilage
- complete ring-shaped cartilage
- maintains openness of windpipe
- composed of hyaline cartilage
Major cartilages of the larynx: Epiglottis
- Spoon shaped cartilage that projects superiorly into pharynx
- swallowing causes epiglottis to close opening - prevents materials entering lower respiratory tract
- made of more elastic elastic cartilage
Sound Production
- vocal folds found in larynx comprised of vocal ligaments covered by mucous membrane
- opening b/w vocal folds = rima glottidis
- vocal folds + rima glottidis = glottis
- when air forced through rima glottidis, causes vibration of vocal folds = sound
Trachea
aka windpipe
- inferior to larynx, superior to primary bronchi, anterior to oseophagus
- 12-14cm in length
- supported by C-shaped tracheal cartilages (to help maintain & keep trachea open)
- mucosa lined w/ psuedo-stratified columnar epithelium & mucin-secreting goblet cells (helps humidify air & trap debris)
- bifurates into 2 smaller tubes = bronchi
- ridge where they separate = carina
Bronchial Tree
- highly branched system
- begin w/ primary bronchi & end w/ terminal bronchi
- belong to conducting portion
- reside w/in substance of lungs
- branches into left & right primary bronchi @ carina
- right wider & more vertical - divides into 3 secondary bronchi
- left divides into 2 secondary bronchi
- secondary bronchi divide into 8-10 tertiary bronchi (or segmental/lobar)
Patterns observed in structure as Bronchial tree divides
- incomplete rings of cartilage becomes smaller and less numerous
- all bronchi lined w/ pesudostratified columnar epithelium to trap debris
- bronchi branch into bronchioles - these lack rings and lined with simple columnar or simple squamous epithelium
Bronchioles
- less than 1 mm in diameter
- walls composed of relatively thick layer of smooth muscle
- contraction of muscles = narrowing of brionchioles = bronchoconstriction (aka asthma)
- relaxation of muscles = bronchodilation
- branch into terminal bronchioles - are last part of of conducting portion
Respiratory Portion of respiratory system
- respiratory bronchioles
- aveolar ducts & sacs
- pulmonary alveoli
Structures between terminal bronchioles -> alveolus
- Terminal bronchioles branch into respiratory bronchioles
- respiratory bronchioles branch into alveolar ducts
- alveolar ducts end w/ small saccular outpocketings called alveoli
- thin walls of alveolus is where respiratory gases diffuse
Alveolus - 2 types of cells
-alveolar macrophages
Walls formed by 2 types of cells;-
- Alveolar type 1 cells: simple squamous (majority - is where gas exchange occurs)
- Alveolar type 2 cells: almost cuboidal (produce pulmonary surfactant - decreases surface tension w/in alveolus and prevents collpase of alveoli
-alveolar macrophages: engulf any microorganism or particulate matter that makes it way into alveolus
Respiratory Membrane - function
-3 components
-Is the diffusion barrier across which respiratory gases exchanged between blood and air in alveoli
Consists of:
-plasma membrane of type 1 alveolar cells
-plasma membrane of capillary cell
-fused basement membrane of both cells
Pleura - what it is
- cell type
- visceral vs parietal
- pleural cavity
-Pleura = serious membrane that lines outer lung surface & adjacent thoracic wall
-formed from simple squamous epithelium (called mesothelium)
VISCERAL PLEURA: outer surface of lung
PARIETAL PLEURA: interior thoracic wall, lateral mediostinum and superior surface of diaphragm
-secrete serious fluid - for lubrication & tension b/w pleural membranes
Pleural cavity: space b/w visceral and parietal cavities
Lungs
- shape
- hilum
-conical in shape - base inferiorly rests on diaphragm, apex = superior most portion
-apex projects slightly superior and posterior to clavicle
-costal surface comes in contact w/ ribs
mediastinal surface housed concaver region = hilum (is where bronchi, pulmonary vessels, lymphatic vessels & nerves pass into and out of lungs
-hilum and its structures = root of lung
Left lung vs right lung
Left Lung:
-slightly smaller (due to heart projecting)
-heart makes indentation on medial surface = cardiac impression/cardiac notch
-oblique fissure - divides lungs into 2 LOBES (superior & inferior)
Right Lung:
-2 fissures (oblique & horizontal)
-divided into 3 LOBES (superior, middle & inferior)
Blood supply to & from lungs
-Pulmonary and bronchial circulation
- pulmonary circulation conducts blood to and from gas exchange surfaces of the lungs
- Bronchial circulation is a component of systemic circulation that delivers blood directly to and from bronchi and bronchioles
- is what actually oxygenates lungs
Pulmonary Ventilation - what is it
- what happens during inhalation & exhalation in terms of;
- volume, pressure and air flow
(AKA breathing) -Is the movement of air into and out of respiratory system -movement of gases follows Boyle's law (pressure) Inhalation: -volume of thoracic cavity increases -intrapulmonary pressure decreases -air flows into lungs Exhalation: opposite of inhalation
Thoracic wall dimension changes during respiration
-during inhalation & exhalation, thoracic cavity changes in 3 dimensions;
- Vertically: movement of diaphragm
- Lateral: rib cage is elevated and thoracic cavity widens (or rib cage depresses)
- Anterior/posterior: inferior position of sternum moves anteriorly and then posteriorly
Muscles of Respiration
- External intercostals: elevates ribs during inhalation
- Internal intercostals: depresses ribs during forced exhalation
- Diaphragm: major muscle of respiration
Diaphragm
- Internal dome-shaped muscle that physically separates thoracic and abdominopelvic cavities
- possesses central tendon - all of its fibres converge (has holes that allows diff. structures to pass through)
- Contraction of diaphragm causes a depression of muscle, thus increasing the vertical dimensions of thoracic cavity
4 continuous and simultaneous process of gas exchange
- Pulmonary ventilation: movement of respiratory gases b/w atmosphere and alveoli of lungs
- Alveolar gas exchange: exchange of resp. gases b/w alveoli and blood
- Gas transport: transport of resp. gases w/in blood b/w lungs and systemic cells of body
- Systemic gas exchange: exchange of gases b/w blood and systemic cells of body
Mechanisms of breathing
Several integrated aspects;
- specific actions of skeletal muscles
- volume changes w/in thoracic cavity
- pressure changes from volume changes
- pressure gradients
- volumes and pressures involved in breathing
