Ch. 15 - Respiratory System Flashcards
Ventilation
process of moving air from the atmosphere into the alveoli of the lungs and back out again. Two phases: inhalation/inspiration and exhalation/expiration
External respiration
the exchange of O2 and CO2 between the air in the alveoli and the blood supplying the alveoli
Transport
The transport of O2 and CO2 in the blood
Internal respiration
the exchange of O2 and CO2 between the blood and metabolically active cells of the tissues
What are the two divisions of the respiratory system?
conducting and respiratory
Conducting division
structures provide the passageway for air to move from atmosphere into areas where gas exchange occurs and then back out again; warms, humidifies, and cleans the air along its route
Respiratory Division
gas exchange between the lungs and blood occurs in these structures
Sinuses
air filled spaces within bone that contribute to voice, and decrease weight of the bones
Pulmonary capillaries
where gas exchange takes place
Alveoli
mainly contain space for air, but this space can be filled with infectious agents and immune cells if pneumonia sets in which prevents normal gas exchange from taking place.
Nose
entrance to respiratory tract and the primary organ of smell
Which lung has less lobes?
the left one to leave room for the heart.
Divisions of the respiratory system
upper and lower tracts
upper respiratory tract
structures above the vocal cords
lower respiratory tract
structures located below the vocal cords
Structures of upper respiratory tract
mouth, nose, pharynx, and the top end of the larynx
Structures of the lower respiratory tract
lower portion of larynx, trachea, bronchi, bronchioles, and alveoli.
Role of nasal cavities
increase surface area and are lined by mucous membranes; warm and humidify, and trap particles. If extensively vascularized, then the nose bleed happens.
Bones within nasal cavity
conchae; increase surface area, cause air moving past them to become turbulent/mixed which results in more contact between the air and the membrane.
What are the types of sinuses?
4 pairs: frontal, ethmoid, sphenoid, and maxillary; air-filled spaces that warm and humidify incoming air, connect nasal cavities; vocal resonance
Nasopharynx
- part of the conducting division
- conduit for air only
- adenoids lie in posterior wall
- closed off from oropharynx by uvula and soft palate
Oropharynx
- part of conduction division
- conduit for digestion and respiration
- palatine tonsils found at border
Laryngopharynx
- shortest of the three parts of pharynx
- part of conduction division
- conduit for both air and food
- opens into larynx and esophagus
Larynx
- directs air into trachea and food into esophagus
- contains vocal cords
- superior portion lined with stratified squamous epithelium
- inferior portion lined with mucous membranes that move trapped debris into pharynx for swallowing
Glottis and laryngeal cartilage
- cartilage in larynx prevents it from collapsing
- large cartilage: epiglottis, thyroid, cricoid
- small cartilage: arytenoid, corniculate, cuneiform
- glottis: vocal apparatus of the larynx (true vocal cords + rima glottidis)
Trachea
- extends from the larynx to its division into the left and right bronchi
- contains hyaline cartilage between fibrous tissue ligaments
- contains CARINA (ridge of cartilage that senses solid or liquids and triggers violent coughing to expel them)
- ciliated cells on the interior form the mucociliary escalator
- is ridged so it doesn’t collapse
Mucociliary escalator
traps particles and microorganisms and sweeps them into the pharynx to be swallowed
Order of bronchi through terminal bronchioles
- primary bronchi -> secondary bronchi -> tertiary bronchi -> primary bronchioles -> terminal bronchioles
Bronchi
supported by cartilage; interior contain ciliated mucous cells; little smooth muscle; mucociliary escalator
Bronchioles
- lack cartilage but have smooth muscle instead - lack mucous but still have ciliated cells
- no mucociliary escalator.
- have stem cells, and the ability to exchange gas
- have layer of smooth muscle that allows their diameter to change under the direction of the ANS/etc.
Features of Respiratory Bronchioles
- formed by division of terminal bronchioles
- inner lining of bronchioles lacks mucous glands, but does contain ciliated cells
- minimal smooth muscle in their walls
Features of alveolar ducts
- short conduits of mainly connective tissue; elastic
- smooth muscle cells scattered throughout
Features of Alveolar sacs
grape-like clusters of individual alveoli that opened from the alveolar ducts; elastic
Alveoli
- structures across which gas exchange occurs
- thin walled with large lumen
- provide intimate contact between inhaled air and blood in pulmonary capillaries that wrap the alveolar walls (ONLY ONE CELL THICKNESS)
- collectively, the alveoli have a surface area of 70 m^2 (size of singles tennis court)
- pores allow air to flow into neighboring alveoli to maintain the same pressure across the alveoli
Type 1 alveolar cell
- most common cell type
- connected to a thin, elastic basement membrane w/ a pulmonary endothelial cell on the other side (“respiratory membrane”)
- composes the respiratory membrane
Type 2 alveolar cells
- cuboidal cells
- make and secrete surfactant
Surfactant
- complex mixture of DPPC, other phospholipids, proteins, and cholesterol
- reduces surface tension between water molecules lining inner alveoli surfaces
- produced in last month of pregnancy
- w/o surfactant, water coating the alveoli surface would form droplets, causing the collapse of the alveoli and cessation of gas exchange.
- significantly increases the compliance of the lungs
Type 3 alveolar cells
- AKA alveolar macrophages
- resident alveolar immune cells
- phagocytic cells that scavenge microorganisms and other particles not captured prior
Features of the lungs
- occupy most of the thoracic cavity
- encased by pleural membrane (controls infection)
- costal surfaces of the lungs border the ribs and include anterior, lateral, and posterior sides.
- right lung has 3 lobes; left lung has 2
Lung lobes are further divided into:
broncho-pulmonary segments
Broncho-pulmonary segments are divided into:
pulmonary lobules
Lung Pleura
each lung is surrounded by a pleural membrane with 2 layers; fluid lubricates and provides a barrier to the movement of microorganisms between organs of thoracic cavity.
Layers of Lung Pleura:
- visceral pleura
- parietal pleura
Visceral Pleura
tightly covers each lung
Parietal Pleura
lines inner wall of thoracic cavity, mediastinum, and diaphragm
Pleural cavity
small space between the two layers containing pleural fluid (secreted by mesothelial cells)
Direction of deoxygenated blood flow:
- Pulmonary Trunk
- Pulmonary arteries
- Lobar arteries
- capillary beds surrounding alveoli
Direction of oxygenated blood flow:
- venules
- small veins
- pulmonary veins
Pharynx
muscular tube with walls containing 2 layers of skeletal muscle
How is sound produced by the glottis?
by vibrations induced by the movement of air
Cystic fibrosis
very thick mucus production that cannot be transported away by a normal mucociliary escalator; repeated infections and damaged structures.
Hilum
anatomical opening through which blood vessels, nerves, and bronchi enter an organ
The cells in the walls of the bronchioles and in the visceral pleura are fed by:
bronchial arteries arising from the thoracic aorta
V/Q
- used to express how arterial blood flow to the alveolus is tightly coupled with ventilation
- V = ventilation
- Q = arterial blood flow
- highly affected by gravity
Q in V/Q
- arterial blood flow
- dramatically affected by the difference between the air pressure inside the lung and B.P. inside the alveolar capillary (alveolar capillary blood pressure must exceed alveolar air pressure for blood flow to past the respiratory membrane)
Zone 1 of intravascular pressure disribution
- area near top of lungs
- capillary blood pressure is less than the air pressure in the alveoli
- collapses capillaries and prevents flow
- V/Q ratio approaches 0
- P(alveolar) > P (artery) > P (venous)
Zone 2 of intravascular pressure distribution
- middle of lungs
- intermittent blood flow
- when capillary pressures are near their peak = capillary pressure > alveolar pressure allowing flow through the capillary.
- when capillary pressures are near diastolic values = capillaries collapse
- V/Q ratio ranges from 0 to its normal 1.0
- P (artery) > P (alveolar) > P (venous)
Zone 3 of intravascular pressure distribution
- base of the lungs
- capillary pressure is always > alveolar pressure
- flow is continuous
- this distributions does not occur when lying down
- V/Q ration is normal 1.0
- gravity influenced
- P (arterial) > P (venous) > P (alveolar)
alveolar dead space
volume of air that occurs when blood flow to a region of the lungs is limited due to pulmonary embolus or hypertension.
- abnormally high V/Q ratio
Pulmonary shunt
- impaired ventilation -> collapsed alveolus
- Low V/Q ratio
Strep Throat
- streptococcus pyogenes
- pharyngitis, laryngitis, and fever
- can lead to scarlet fever (red rash)
Laryngitis
inflammation of larynx, esp. vocal cords
- commonly caused by upper respiratory tract bacterial and viral infections
- speaking is difficult but not a serious health concern
Pneumonia
- wide range of lung infections
- caused by bacterial, viral, fungal, or protozoan infections.
- fluid accumulation in alveoli and poor lung inflation
Asthma
- affects > 20 million people in the US
- SOB, inflamed/constricts airways, coughing, wheezing, difficulty breathing, etc.
Emphysema
- over inflation of lung alveoli in response to breakdown of the alveolar wall and a decrease in respiratory function
- SOB and coughing
- emphysema + chronic bronchitis = COPD
Cystic Fibrosis
- most common genetically inherited disease among white americans
- caused by a mutation in a chloride channel (CTFR) resulting in a dramatic increase in the production of a thick mucus
- affects production of tears, sweat, saliva, and digestive juices
- respiratory failure
Lung cancer
- leading cause of cancer deaths in men and women
Sudden Infant Death Syndrome (SIDS)
- sudden death of an infant <1 year old
- unexplained
- die of apnea while sleeping
Pressure Differential
- the magnitude of the difference in pressure between any two spaces that are occupied by a gas
- independent of whether or not the gas can move from one space to another
- if gas can move = gradient
Pressure gradient btwn atmosphere and alveoli
atmosphere = 760 mmHg
alveoli = 758 mmHg
- pressure difference = 2 mmHg
- high (atmosphere) to low (alveoli)
Pressure differential btwn alveolar and pleural spaces
- normally, the pressure in the pleural cavity is always < pressure in alveoli
- alveolar pressure = 760 mmHg
- pleural pressure = 754 to 756 mmHg
- differential = 4-6 mmHg
- no pathway btwn alveolar and pleural spaces = no gradient
- only way a gradient could be created is with a pneumothorax
How is the pressure of a gas determined?
measured in mmHG, and is determined by the number of gas particles, temperature, and volume of space in which the gas molecules are contained
Boyle’s Law
- if the volume decreases, pressure increases
- if volume increases, pressure decreases
- constant temperature
if the number of gas particles and the volume containing them stay fixed, but the temperature increases, the pressure will _______________and vice versa
increase (like popcorn)
How does Boyle’s law aid in ventilation of the lungs?
indicates that for ventilation to occur, you must establish a pressure gradient between the lungs and the atmosphere
Compliance
relative ease with which the lungs (or any space) can expand to take in additional volume; stretch
- high compliance: system exhibits large volume increases with small pressure changes
Flow Rate
F = ▵P/R
- ▵P = pressure differential
- R = resistance to flow (diameter of the airways)
Alveolar Pressure
- intrapulmonary pressure P(alv)
- air pressure in alveoli
- pressure gradient between atmospheric and alveolar pressure causes air to move into or out of the lungs
- between breaths ~760mmHg
Intrapleural Pressure
- P(ip)
- measured in the thin space between the visceral and parietal pleura
- typically 754 to 756 mmHg
- two opposing forces
Transpulmonary Pressure
- P(tp)
- measured across the visceral pleura
- difference between alveolar pressure and intrapleural pressure
- in between breaths, = 6 mmHg
- commonly used as indicator of lung volume bc higher pressures = larger lung volumes and lower pressures = lower volumes
- represents force that tends to collapse lungs
Breathing
inhalation, exhalation, post-exhalation period
tidal volume
the volume of air that enters the lung during inspiration
During expiration, how does alveolar pressure compare to atmospheric pressure?
Alveolar pressure is higher
Cough reflex
response to activation of sensory neurons along the posterior wall of the trachea, pharynx, and carina of the trachea.
- sensory info carried by vagus nerve to medulla
Sneeze
- aka sternutation
- convulsive expiration of air directed through nose
- sensory info comes from nasal epithelium which is sent to CNS
Yawn
- aka oscitation
- results from deepest possible breath; not associated with exertion
- reflex that requires inhalation while stretching the eardrums, followed by expiration
Hiccup
- aka singultus
- involuntary contraction of the diaphragm followed 250 msecs later by closure of the vocal cords
Laughing/crying
short bursts of air during expiration
Valsalva maneuver
- performed when you try to exhale against a closed airway (pinched/closed mouth/nose)
- muscles pulling inward on the thoracic cavity decrease its volume and increase the pressure throughout the respiratory system structures.
- can open closed auditory tubes/make sure eardrum is stretched for exam
- also be used for cardiovascular assessment bc increase in pressure in the thorax induces response in BP and heart rate.
Spirometry
measures a person’s breathing pattern, their maximum breath volumes, and the rate at which they move air (flow rate) through their conducting division
Tidal Volume (TV)
the volume inhaled, and exhaled in a normal resting breath.
- typical volume for an adult is 500 mL
Inspiratory reserve volume (IRV)
amount of additional air that can be inhaled in addition to the TV.
- associated with a very deep breath
- normally ranges from 2,100 to 3,200 mL in an adult
Expiratory reserve volume (ERV)
volume of air that can be forcefully expelled, after exhaling the tidal volume
- normal range is 1,000 to 1,200 mL in an adult
Residual Volume (RV)
amount of air left in the lungs after a completed ERV
- typically 1,200 mL in and adult and represents the lowest lung volume a person can achieve.
- helps keep the alveoli open no matter how hard we try to empty our lungs
Inspiratory Capacity (IC)
combination of TV and IRV (500 mL + 3000 mL)
Functional residual capacity (FRC)
amount of air left in lungs after we exhale our tidal volume. Combination of RV and ERV (1200 mL + (1000mL to 1200 mL) = 2200 to 2400 mL)
Vital Capacity (VC)
- combination of ERV, TV, and IRV
- represents the total amount of air that a person can move in or out of their lungs
- 3600-4900 mL depending on body size
Total lung capacity (TLC)
represents the combination of all lung volumes
- dependent on body size
- btwn 4500 and 6000 mL
External Respiration
respiration across the alveolar respiratory membrane
Internal Respiration
occurs between the systemic capillaries and tissues of the body.
In the lungs where do O2 and CO2 move?
- O2 moves from air to blood
- CO2 moves from blood to air
In the tissues where do O2 and CO2 move?
- O2 moves from blood to tissue
- CO2 moves from tissue to blood
What does gas diffusion result from?
a difference in concentration
Hemoglobin
- protein that is made-up of four subunits that functions to transport oxygen in the blood
- transports > 98% of the O2 in blood
Each RBC carries how many hemoglobin molecules?
250-300 million
Each individual RBC has the potential to carry up to how many O2 molecules?
1.2 Billion
Oxyhemoglobin Dissociation Curve
shows how the P (O2) of blood determines the degree of Hb saturation
- not linear bc as O2 molecules bind to hemoglobin, they make it easier for more O2 molecules to bind.
- certain conditions can cause shifts in the curve (ex. blood pH change and temp.)
- right shift = reduction in affinity
- left shift = increase in affinity
Carboxyhemoglobin
CO bound to Hb (cherry-red blood)
Carbaminohemoglobin
binding of CO2 to Hb
CO2 transportation in blood steps:
- CO2 diffuses into bloodstream
- 93% diffuses into RBCs and 7% dissolved in plasma
- 23% binds to Hb, forming carbaminohemoglobin, Hb+CO2 and 70% converted to H2CO3 by carbonic anhydrase
- H2CO3 dissociates into H+ and HCO3-
- H+ removed by buffers, especially Hb
- HCO3- moves out of RBC in exchange for Cl- (chloride shift)
Haldane Effect
CO2 more readily binds to unoxygenated Hb
Hypoventilation can lead to:
too little CO2 removal from the body; increases CO2 levels and “pushes” the reaction to the right leading to respiratory acidosis.
Hyperventilation can lead to:
excessive removal of CO2 from the body; leading to respiratory alkalosis
- can treat by breathing from a bag
Where is the respiratory center located?
in the medulla and pons of the brainstem
Sensors
chemoreceptors that detect chemicals in the blood (ex. PaCO2, PaO2)
- located in aortic arch, carotid bodies, and brainstem
Integrators
respiratory center in brainstem (neurons in medulla oblongata and pons)
Effectors
diaphragm and intercostal muscles that control breathing (rate and depth)
What nerves connect effectors to integrators?
Phrenic and intercostal nerves
What nerves connect sensors to integrators?
glossopharyngeal and vagus nerves
