Intro to the Respiratory System Flashcards
What is the primary function of the respiratory system?
Delivery of O2 to lungs for gas exchange, and removal of CO2 produced by tissues out of the lungs.
What is external respiration?
Exchange of gases between atmospheric air and blood.
List additional important functions of the respiratory system.
- Acid-base balance
- Immunity
- Thermoregulation
- Site of metabolism/activation
- Vocalisation/communication
What structures comprise the upper respiratory tract?
- Nasal cavity
- Pharynx
- Larynx
What structures comprise the lower respiratory tract?
- Trachea
- Bronchi
- Bronchioles
- Alveolar ducts
- Alveoli
How is air delivered to the upper respiratory tract?
Air enters via nose (sometimes mouth).
What divides the left and right nasal cavities?
Nasal septum.
What are conchae?
Mucosa lined bone scrolls in the nasal cavity.
What are meatuses?
Openings/canals in the nasal cavity.
What type of epithelium mostly lines the nasal cavity?
Respiratory epithelium.
What is the function of the epiglottis?
Protects airway during swallowing.
What are paranasal sinuses?
Diverticula of the nasal cavity within the skull.
List the functions of the paranasal sinuses.
- Thermal protection
- Mechanical protection
- Lighten head
What is the pharynx?
The common cavity through which air and ingesta pass.
What does the pharynx connect?
Oral cavity to oesophagus and nasal cavity to larynx.
What are the anatomical borders of the pharynx?
- Dorsally - base of skull and C1-C2
- Ventrally - larynx and mandible
- Laterally - pterygoid muscles and suspensory part of hyoid apparatus
- Rostrally - soft palate separates rostral pharynx into dorsal and ventral (nasopharynx and oropharynx)
What is the larynx?
Musculocartilaginous organ that connects pharynx to trachea.
What are the functions of the larynx?
- Protect trachea from aspiration
- Vocalisation
- Pressure build-up (glottis closure)
What type of epithelium lines the larynx?
Stratified squamous epithelium near pharynx, respiratory epithelium elsewhere.
What is the innervation of the larynx?
Innervated by branches of vagus nerve (cranial laryngeal n., caudal (recurrent) laryngeal n.).
What does the recurrent laryngeal nerve supply?
All intrinsic muscles except cricothyroideus.
What is the structure of the trachea?
Extends from larynx to bifurcation at base of heart, C-shaped hyaline cartilages connected by fibroelastic tissue.
What type of epithelium lines the trachea?
Respiratory epithelium (ciliated, pseudostratified columnar epithelium).
What is the difference between bronchi and bronchioles?
Bronchi are lined by ciliated, pseudostratified columnar epithelium and supported by cartilage; bronchioles are smaller, lack cartilage, and are lined by variably ciliated or non-ciliated columnar epithelium.
What are conducting airways?
All airways up until bronchioles, where there is no gas exchange.
What are respiratory airways?
Respiratory bronchioles to alveoli, where gas exchange occurs.
What is an acinus?
The functional unit consisting of terminal bronchiole and its distal structures.
What type of epithelium is found in respiratory bronchioles?
Cuboidal epithelium (club cells)
Club cells produce secretions and are a source of new cells.
What is the function of the flattened squamous epithelium (type 1 pneumocytes) in the alveoli?
Gas exchange
What are the main functions of type II pneumocytes in the alveoli?
Secrete fluid (surfactant) to prevent alveolar collapse (atelectasis)
Surfactant reduces surface tension in the alveoli.
What are the gaps in the septum of alveoli called?
Pores of Kohn
These connect alveoli for efficient movement of air.
List the components of the blood-gas interface.
- Surfactant
- Alveolar epithelial cell (pneumocyte)
- Epithelial basement membrane
- Connective tissue
- Capillary basement membrane
- Capillary endothelial cell
- Blood plasma
- Red blood cell
What two main components make up the lungs?
- Parenchyma (functional tissue)
- Interstitium (soft tissue, nerves, glands, blood and lymph vessels)
What is the role of the pleura in the lungs?
Encloses potential space and small amount of fluid
The pleura consists of parietal and visceral layers.
How many lobes does the left lung have?
2 lobes: Cranial and Caudal
The left lung is smaller to accommodate the heart.
What are the lobes of the right lung?
- Cranial
- Middle
- Caudal
- Accessory
What does the visceral pleura cover?
Surface of the lung including fissures
Contains abundant elastic fibers.
What are the three parts of the parietal pleura?
- Costal pleura
- Diaphragmatic pleura
- Mediastinal pleura
What is the diaphragm?
Musculotendinous sheet separating thoracic and abdominal cavity
It has openings for structures like the esophagus and aorta.
What is the function of the diaphragm in respiration?
Drives volume change of thorax and therefore negative pressure for breathing.
What is contained within the mediastinum?
- Heart in pericardiac sac
- Trachea
- Esophagus
- Thymus
- Mediastinal lymph nodes
- Great vessels
- Nerves including vagosympathetic trunk
True or False: The mediastinum contains the lungs.
False
The mediastinum does not contain the lungs, caudal vena cava, or right phrenic nerve.
What is the pathway of non-oxygenated blood in pulmonary circulation?
RV -> lungs -> LA
What type of blood exchange occurs in pulmonary circulation?
Gas exchange
Describe the pressure and volume characteristics of pulmonary circulation.
Large volume, low pressure
How do pulmonary arteries and veins differ in relation to bronchi?
Pulmonary arteries follow bronchi, veins do not always
What is the source of blood for bronchiole circulation?
From aorta
What is the pressure and volume characteristic of bronchiole circulation?
Low volume, high pressure
What is the pathway of oxygenated blood in bronchiole circulation?
LV -> lungs -> RA (via azygous v.)
What do anastomoses between bronchial and pulmonary circulations help preserve?
Lung tissue
What physiological response occurs in hypoxic vasoconstriction?
Reflex vascular smooth muscle contraction
What happens to areas that receive little alveolar oxygen in terms of blood flow?
Reduced flow from the pulmonary artery
How does hypoxic vasoconstriction affect ventilation and perfusion?
Maximizes oxygen exchange
What is angiogenesis in the context of bronchopulmonary circulation?
New bronchopulmonary arterial anastomoses
Fill in the blank: The common capillary network helps preserve lung tissue if the pulmonary supply becomes _______.
compromised
What effect does vasodilation of bronchial arteries have on blood flow?
Increases flow
What is the primary function of the common capillary network between bronchial and pulmonary circulations?
By-pass the obstructed pulmonary artery
