Module #1: Structure and Function of Pulmonary System Flashcards
Name 2 components of respiratory tract
Upper Respiratory Tract and Lower Respiratory Tract
What are the components of the upper respiratory tract?
Nasal Cavity - warms/humidifies air; air at rest moves exclusively through nasal cavity
Pharynx - oropharynx/nasalpharynx/laryngopharynx
not as efficient to warm/humidify
What does the larynx do?
connects upper and lower respiratory tracts
What structures are found in the larynx?
epiglottis
thyroid
cricoid cartilages
smaller cartilage structures
What are the components of the Lower Respiratory Tract?
Pulmonary tree
Describe the velocity of air as it passes through the pulmonary tree
First passes through trachea –> high velocity (trachea has a small cross sectional area)
Velocity slows as the air passes through the bronchiole segments –> large cross sectional area
Describe how the pulmonary tree is segmented
Trachea bifurcates (splits) @ the sternal angle = carina into R and L primary bronchi and enters lungs @ Hilum
Primary bronchi split into lobar bronchi (3 R; 2 L)
Lobar bronchi break down into segmental bronchi (10) = surgical lobes; these are just specific areas on the lung that can be surgically removed if need be
Eventually divide and end @ terminal then respiratory bronchioles
What is the acinus and what happens here?
where the pulmonary tree ends
site of respiration (gas exchange)
What are the 3 structures that make up the acinus?
respiratory bronchiole
alveolar ducts
alveoli
What are the functions of the Pulmonary System?
Respiration (gas exchange) = PRIMARY FUNCTION
Phonation
Acid-Base balance
Pulmonary Defense Mechanisms
Olfaction
Metabolism
Filtration/removal of particles/microorganisms
What is phonation?
production of sounds by movement of air through vocal chords (larynx)
How does the lungs function in acid-base balance?
remove CO2 from blood stream
What is the pulmonary defense mechanisms?
Air Condition - insures optimal air temp/humidity for body
How does the Pulmonary System warm/humidify colder ambient air?
nasal/oral mucosa cavities are rich in blood supply –> warm/humidify the air
What is olfaction?
smelling
happens in nasal cavity, and is able to detect dangerous gases/material w/o bringing air into the lungs
What are the metabolic functions of the pulmonary system?
removal of some prostaglandins
removal leukotrines
removal of seratonin
removal of norepinephrine
inactivate bradykinin
production of ACE (angiotensin converting enzyme) that converts Angiotensin I to Angiotensin II
removal of ATP and AMP
Why is it important to filter/removal particles and microorganisms?
keep from reaching distal end of pulmonary tree so they don’t interfere w/ gas exchange
How are particles filtered/removed?
trapped in mucus sheath lining tubules
removed by ciliary action and reflex mechanisms
Describe Mucociliary Escaltor
Lining of respiratory tract produce mucous
particles become trapped in mucous
Mucous propelled away from alveoli via cilia
coughing forcefully propels mucous up towards pharynx
mucous is removed via swallowing or blowing or spitting
What do the irritant receptors do?
they produce sneeze or cough
where are sneeze receptors located?
nasopharynx - protect “front end” of conducting zone
where are cough receptors located?
trachea - protect deep structures of respiratory zone
How is the airways functional divided?
2 Zones:
Conducting Zone
Respiratory Zone
Describe the Conducting Zone? Anatomy and Function
Upper Respiratory Tract –> Terminal Bronchioles
First 16 generations of tracheal tree (NO ALVEOLI)
brings air into and out of gas-exchange areas of lungs
NO GAS EXCHANGE
Describe air flow through the conducting zone
fast through trachea (small cross sectional area) and then slows as travels down tracheal tree (large cross sectional area)
What is the Anatomical Dead Space?
conducting zone
volume of air that is brought into lungs but DOES NOT REACH respiratory (gas exchange) zone
What are the Defense Mechanisms in the conducting zone?
Mucociliary escalator (particles get trapped in mucous blanked” swept but towards pharynx by cilia where it is blown out or swallowed or spit
What are the components of the Respiratory Zone?
Transitional section
Respiratory Section
What segments do you start seeing alveoli?
Transtitional section –> divisions 17 - 19
How is the respiratory section of the respiratory zone divided?
Alveoli completely line 20-22 divisions
Alveolar Sac = 23 generation
What is the first site of gas exchange?
Respiratory bronchioles of acinus
Describe the Alveolar ducts
portion of acinus that is surrounded by grape-like cluster of the alveoli
What do the Pores of Kohn do?
connect adjacent alveoli and allow air exchange between them
What are alveolar sacs?
grape like cluster of individual alveoli
contain Pores of Kohn that connect alveoli to eachother
Where is the primary sites of gas exchange in the lung?
Alveoli
How many layers make up the alveolar septa and what are their names?
2 layers:
Epithelial Layer
Basement Membrane
What are the cell types that make up the epithelial layer of the alveolar septa and what do they do?
Type I alveolar Cells = physical structure of alveoli
Type II alveolar cells = surfactant production
What is the function of the basement membrane?
thin elastic layer that ALLOWS GAS EXCHANGE
Describe the wall and lining of the Trachea
Anterior/lateral = C shaped cartilage
Posterior = smooth muscle
Describe the wall and lining of the large - smaller bronchi
cartilage continues to surround them but the progressive dimities in distal airways
describe the wall and lining of the bronchioles
no more cartilage
What are the 3 wall layers of the tracheal tree
Outer layer = connective tissue (cartilage)
Middle layer = smooth muscle
Inner layer = epithelial lining
What Regions would you NOT find mucous producing cells/ciliated cells?
Respiratory bronchioles (region of gas exchange)
Anterior 1/3 of nose
Portions of Pharynx
What is the defense mechanism of the alveoli?
Phagocytes
Macrophages
Is there a cough reflex in the alveoli?
NO
Macrophages/Phagocytes ingest particles/bacteria and migrate up to terminal bronchiole and move into lymphatic system
What cells make up the epithelial lying of the Respiratory Tract?
Ciliated cells
Mucous producing cells
Mucous glands
What is the function of ciliated cells?
“beat” to produce “waves” that provide physical movement of mucociliary elevator
What are the 2 types of mucous producing/excritory cells and where are they found?
Goblet cells = proximal to bronchioles
Clara cells = terminal bronchioles
Where are mucus glands found and what do they do
produce/secrete mucous
found throughout respiratory tract
What happens pathologically to mucuos producing cells in pt w/ Chronic Bronchitis?
hypertrophy of mucus produces cells –> to much mucuos produced
What happens to mucous production in an intubated pt?
mucous is still produced but removal mechanism are impaired
What is the pathology of Cystic Fibrosis?
excessive production of mucous, sweat and digestive juices
mucous accumulation in lungs promotes infection
Descibe pulmonary circulation
deoxygenated blood flows from right ventricle to pulmonary capillaries for gas exchange
Describe bronchial circulation
oxygenated blood flows from left ventricle
supplies structures of pulmonary system
What is the function of pulmonary circulation?
gas exchange!
act as reservoir for left ventricle
act as filter –> remove particles/emboli (clots or air)
Describe the Pressure and flow dynamics of pulmonary circulation
LOW PRESSURE SYSTEM (only 10-20 mmHg)
only 1/3 pulmonary blood vessels are perfused (filled) @ any given moment; allows for increased stroke volume w/o increasing pressure
How are the pulmonary capillaries arranged? What is the consequence of this arrangement?
capillary beds surround alveolar sacs
allows a lot of blood to be exposed to gases in alveoli
Describe the alveolocapillary membrane composition
Alveolar and capillary walls merge to form gas exchange membrane
- alveolar epithelium and basement membrane
- interstitial space
- capillary basement membrane and epithelium
what is the function of the alveolocapillary membrane
site of gas exchange
have a small amount of blood (100 ml) spread across a large area (70-100 m2)
What are the consequences of damage to the alveolocapillary membrane?
leakage of plasma/blood into alveolar space
impairment of gas exchange
What is Hypoxic Vasoconstriction
arterioles can direct blood away from site of damage or low partial pressure of O2
unique to lungs
Describe Bronchial circulation. What supplies it and what’s its function?
part of systemic circulation (oxygenated blood from left ventricle)
supplies nutrients to structures of the lung
DOES NOT PARTICIPATE IN GAS EXCHANGE
Describe the shunting of blood flow of some bronchiole veins
some bronchial capillaries (capillaries that feed oxygenated blood to structures of the lung) drain into pulmonary veins that are returning to left atria
right to left shunt - deoxygenated blood is passing into oxygenated circulation
What structures are NOT drained by lymphatic capillaries?
acinus
accumlating fluid and macrophages have to migrate up to terminal bronchioles to drain
What are the components of the chest wall?
ribs
intercostal musculature
What is the pleura?
double folded serous membrane
Visceral pleura lines the lungs
Parietal pleura lines the chest wall
What is the pleural space (aka pleural cavity)?
space between visceral pleura and parietal pleura
contains pleural fluid
Pleural Fluid:
Where does it come from?
What does it do?
Secreted by pleura itself
provides lubricant (allows frictionless movement between visceral and parietal pleura)
What is the pressure of the pleural space?
low (negative/sub-atmospheric) -4 - 10 mmHG
allows the lungs to expand and take in outside air
What is a Pneumothorax?
condition in which air enters into pleural cavity
increases pressure in pleural cavity –> compresses or collapses lung
