Chapter 23 - Respiratory System Flashcards
Functions of Respiratory System
- gas Exchange (O2, CO2, between air, blood)
- communication/vocalization
- olfaction
- helps control pH (acid-base balance)
- aids in regulating blood pressure by assisting in angiotensin II production
- help create pressure gradients for flow of lymph and venous blood
- expulsion of abdominal contents (defecation)
Principal Organs of the Respiratory System
- nose
- pharynx
- larynx
- trachea
- lungs
- bronchi
- pleurae
- respiratory muscles
Conducting Division of Respiratory Tract
- passages for airflow only (without gas exchange)
- nostrils through bronchioles
Respiratory Division of Respiratory Tract
- gas exchange areas
- alveoli and other distal gas-exchange regions
Upper Respiratory Tract
nose through the larynx (respiratory organs of the head and neck)
Lower Respiratory Tract
trachea through the lungs (respiratory organs of the thorax)
Pathway of Air (nose through pharynx)
- nostril
- nasal cavity
- posterior nasal aperture
- nasopharynx
- oropharynx
- laryngopharynx
- pharynx
Nose
- warms, humidifies, and cleanses air
- detects odors
- resonates voice
- externally shaped by nasal bones and cartilages
- from nares to posterior nasal apertures:
- nasal septum - septal cartilage, vomer, perpendicular plate of ethmoid bone
- superior, middle, inferior nasal conchae
- olfactory and respiratory epithelia
Pharynx
Three divisions:
- nasopharynx
- posterior to choanae and soft palate
- houses pharyngeal tonsil
- ciliated pseudostratified epithelium
- oropharynx
- posterior to root of tongue, extends from inferior tip of the soft palate to superior tip of the epiglottis
- entry from mouth
- nonkeratinized stratified squamous epithelium
- laryngopharynx
- from tip of epiglottis to esophagus
- nonkeratinized stratified squamous epithelium
Larynx
- “voice box”
- keeps food out of airway with epiglottis
- 9 prominent cartilages (incl. thyroid cartilage on anterior aspect)
- houses vocal cords and vestibular folds
Pathway of Air (trachea to pulmonary alveoli)
- trachea
- primary (main) bronchi
- secondary (lobar) bronchi
- tertiary (segmental) bronchi
- bronchioles
- terminal bronchioles
- respiratory bronchioles
- alveolar ducts
- alveolar sacs
Trachea
- tube anterior to esophagus
- c-shaped rings of hyaline cartilage
- carina: internal median ridge on lowest tracheal cartilage
- inner lining: ciliated pseudostratified columnar epithelium w/ goblet cells (mucociliary escalator)
- adventitia: outermost connective tissue connecting trachea to neighboring organs
Lungs
- superior apex, inferior base
- costals surface
- mediastinal surface
- hilum - slit
- root - bronchi, vessels, nerves
- left lung has cardiac impression w/ notch
- lobes separated by fissures
- left lung = 2 lobes
- right lung = 3 lobes
Bronchial Tree
- Main bronchi (right is wider, more vertical)
- Lobar bronchi (five total, one for each lobe)
- Segmental bronchi
- all bronchi lined with ciliated pseudostratified columnar epithelium and surrounded by smooth muscle
- bronchioles <1mm in diameter
- ventilates a pulmonary lobule
- each splits into 50+ terminal bronchioles
- surrounded by smooth muscle
Bronchioles
Terminal Bronchioles - final branches of conducting zone - lined with smooth muscle Respiratory Bronchioles - have alveoli (alveolar ducts, alveolar sacs)
Alveoli
Squamous (pneumocyte type I) Alveolar Cells
- 95% of surface area
- respiratory membrane is site of gas exchange
Great (pneumocyte type II) Alveolar Cells
- 5% of surface area
- produce surfactant
Alveolar Macrophages
- immune function
Pleurae
Visceral Pleurae (on lung surface) Parietal Pleurae (on inner surface of rib cage) Pleural Cavity - space between visceral and parietal pleurae - contains pleural fluid Functions: - reduction of friction - creation of pressure gradient - compartmentalization
Respiratory Muscles
Diaphragm
- prime mover of pulmonary ventilation
- contraction pulls it down and enlarges the thoracic cavity for inspiration
- relaxes for expiration
Internal and External Intercostals
Other muscle of chest, neck, and abdomen
Respiratory Neruoanatomy
- respiratory centers of medulla and pons
- respiratory input sources:
- central chemoreceptors (brainstem neurons that respond to pH of CSF)
- peripheral chemoreceptors (neurons in wall of aorta and carotid arteries that respond to pH, O2, and CO2 content of blood)
- stretch receptors in respiratory system
- irritant receptors
- higher brain centers (limbic system, hypothalamus, cerebral cortex)
