Pulmonary: Structure and Function of Pulmonary System Flashcards
What structures does the upper respiratory tract contain?
Nasal Cavity
Pharynx
What connects the upper respiratory tract and the lower resp. tract?
The larynx
What does the larynx contain?
Epiglottis, thyroid, cricoid cartilages
How many generations does the tracheal tree have?
Up to 23
Name the point at which the trachea first divides (creating a left and right side)
Carina
How many lobar bronchi are on each side of the lungs?
Right - 3
Left - 2
Name the region where the tracheal tree ends, what is contained in that region, and what it’s function is.
Acinus.
It includes respiratory bronchioles, alveolar ducts, and alveolar sacs
It is the region in which gas exchange takes place
What is the primary function of the pulmonary system?
Respiration via ventilation
gas exchange!
Name the non-respiratory functions of the pulmonary system.
- Phonation
- Acid-base balance
- Defense mechanisms: air conditioning and olfaction
- Metabolic functions: removing/inactivating vasoactive substances
- Filtration and removal of particles/microorganisms
How does the pulmonary system act to balance the acid-base concentrations in the body?
They regulate it by removing CO2 from the bloodstream
What structure(s) air condition ambient air?
Ventilation and mucosa of nasal and oral cavities
Explain what ACE is and what it does in the lungs
ACE (angiotensin converting enzyme) converts Angiotensin I into Angiotensin II. Both are vasoconstrictors and Angiotensin II has many other functions including stimulating ADH secretion
How are particles removed in the lower respiratory tract?
“Mucociliary Escalator”
- Respiratory tract is lined by mucous. This mucous is propelled by cilia and moves up to the pharynx
- Coughing forcefully propels mucous to pharynx
- *See videos/diagrams!
What do irritant receptors do?
produce and sneeze or cough
A sneeze is produced by:
receptors in the nasopharynx
A cough is produced by:
receptors in the trachea
Name the two functional divisions of the pulmonary system
Conduction Zone
Respiratory Zone
Anatomy of conducting zone: How many generations?
16
Anatomy of conducting zone: What are the boundaries?
Upper respiratory tract to terminal bronchioles
Anatomy of conducting zone: Are alveoli present?
NO!
What is the primary function of conducting zone?
Provide passage for air into and out of gas-exchange are of lung
NO GAS EXCHANGE
Explain the speed of air flow in the conducting zone.
Initially, air flow is fast through trachea but it slows down progressively as it travels down divisions of tracheal tree.
Why is this?
- Because of the increasing cross sectional area
What is the volume of air that is brought into the lungs but does not reach the respiratory zone called?
Anatomical Dead Space
How does the pulmonary system defend itself against inhaled particles > 10 micromillimeters?
They are filtered and trapped by nasal hairs and irritant receptors lining nasal passage initiate sneeze reflex
How does the pulmonary system defend itself against inhaled particles 2-10 micromillimeters in diameter?
Mucociliary transport system and then irritant receptors in airway initiate cough
How does the pulmonary system defend itself against inhaled particles < 2 micromillimeters?
These may reach the alveoli so phagocytic macrophages engulf them.
- Non-degradable particles lead to pulmonary fibrosis
The respiratory zone: what are the two sections and what generations do these occur on?
Transitional section: Where alveoli start to be seen: 17-19th divisions
Respiratory Section: alveoli completely line 20th-22nd divisions
What division is the alveolar sac?
23rd
The first site of gas exchange occurs at:
the respiratory bronchioles
Pores of Kohn
Allow adjacent alveoli to exchange air between each other
Name the two layers of alveolar septa
Epithelial layer
Basement Membrane
Name the 3 cell types in the epithelial layer of alveolar septa
Type I alveolar cells
Type II alveolar cells
Type III alveolar cells
Type I Alveolar cells:
provide the physical structure of the alveoli
Type II Alveolar cells:
produce surfactant (a lipoprotein that coats surface of alveoli)
Type III Alveolar cells
macrophages
What is the function of the basement membrane of the alveolar septa?
It is a thin elastic layer that allows gas exchange
Explain alveoli’s defense system
Alveolar phagocytes/macrophages ingest and remove foreign particles/bacteria through lymphatics located in terminal bronchioles
When does the cartilage disappear in the tracheal tree?
The bronchioles
Name the wall layers of the tracheal tree
Inner layer: epithelial lining
Middle layer: smooth muscle layer
Outer layer: connective tissue
*Cartilage surrounds outer layer
The entire respiratory tract/tracheal tree is lined by mucus producing cells and ciliated cells EXCEPT:
- Respiratory bronchioles
- Anterior 1/3 of the nose
- Portions of the pharynx
Cell types in the epithelial lining of tracheal tree:
- Ciliated cells
2. Mucus producing/secreting cells
What are the two cell types of mucus producing cells and where are they located?
Goblet cells are located proximal to the bronchioles
Clara cells are located in the terminal bronchioles
Pathology of Chronic Bronchitis
caused by hypertrophy of mucus producing cells which produce too much mucus and obstruct the airway
Pathology of Cystic fibrosis:
Genetic disease causing excessive mucous which accumulates in lungs and promotes infection
Define pulmonary circulation:
Un-oxygenated blood flow from R. ventricle that travels to pulmonary capillaries for gas exchange
Define bronchial circulation:
Oxygenated blood flow from left ventricle that supplies structures of pulmonary system
What is the function of pulmonary circulation?
- Facilitates gas exchange
- Acts as a reservoir for left ventricle
- Acts as a filter system to remove particles/emboli (clots or air)
What is the pressure (mmHg) in pulmonary system and why is it that way?
LOW pressure system (10-20 mmHg)
Only 1/3 pulmonary blood vessels are filled at any given moment to accommodate increased stroke volume without increasing pressures
Define pulmonary capillaries
the capillary beds that surround each alveolar sac. They are very dense to allow a lot of blood to be exposed to gas
What is the alveolocapillary membrane?
Where alveolar and capillary walls “merge together” to form a gas exchange membrane
What does the alveolocapillary membrane composed of?
- Alveolar epithelium and basement membrane
- Interstitial space
- Capillary basement membrane and epithelium
What occurs when there is damage to the alveolocapillry membrane?
- Plasma/blood can leak into alveolar space
2. Impair gas exchange
Hypoxic Vasoconstriction
Unique to lungs
If damage or partial pressure of O2 drops, alveoli’s send out a signal for the arterioles to vasoconstrict (get smaller) and therefore direct blood flow away from that area
Bronchial Circulation
Does NOT participate in gas exchange - part of systemic circulation
Supply the structures of the lungs
What is the function of bronchial circulation?
Supply nutrients to the structures of the lung
Describe how bronchial veins create functional “right to left” shunt of blood flow
Bronchial capillaries (deoxygenated) drain into pulmonary veins (oxygenated) –> this is called a left to right shunt
Lymphatic capillaries drain all structures of the lungs except:
the acinus ( respiratory bronchioles, alveoli ducts, alveoli )
How do lymphatic capillaries drain and protect the alveoli?
Accumulating fluid in the alveoli and the alveolar macrophages migrate up to the terminal bronchioles and then drain into lymphatic system.
What does the chest wall consist of?
Ribs
Intercostal musculature
What are the two layers of pleura
- Visceral pleura - lines the lungs
2. Parietal pleura - lines the chest wall
Pleura Cavity: what is it?
the potential space created between visceral and parietal pleura layers
Pleural Cavity: what is the function of pleural fluid?
It is secreted by the pleura itself and provides lubricant so that there is frictionless movement between visceral and parietal pleura
Pleura Cavity: What is the pressure?
“negative” or sub-atmospheric) -4 to -10 mmHg
Pneumothorax
when air enters into the pleural cavity, increasing the pressure, and collapsing the lung
