Respiratory Flashcards
respiration
Breathing in oxygen for aerobic ATP production and disposing of the CO2 as a by-products
Respiratory passageways are located in the
Head, neck, trunk and lungs
General functions of the respiratory system
- Air passageway
- site for oxygen and carbon dioxide exchange
- Odor detection
- Sound production
- Rate and depth of breathing influence
Structural organization of the respiratory system
The upper respiratory tract: Larynx and above
The lower respiratory tract: The trachea and below
Functional organization of the respiratory system
Conducting zone brings air from the nose to terminal bronchioles
The respiratory zone participates in gas exchange: Respiratory bronchioles to alveoli
Mucosa
Mucus membrane; the respiratory lining
General structure of the respiratory mucosa
mucus
epithelium
basement membrane
lamina propria
Pseudostratified ciliated columnar epithelium lines the
Nasal cavity, paranasal sinuses, nasopharynx, trachea, inferior larynx, main bronchi and lobar bronchi
Simple ciliated columnar epithelium lines the
segmental bronchi, smaller bronchi and larger bronchioles
Simple ciliated cuboidal epithelium
lines the terminal and respiratory bronchioles (a progressive loss of cilia is observed)
Simple squamous epithelium
forms the alveolar ducts and alveoli
Mucous secretions
Produced by the secretions of goblet cells, mucous and serous glands
contains mucin protein
Increases mucus viscosity and serves to trap dust, dirt, pollen, etc.
Nose
first conducting structure for inhaled air
◦ Formed by bone, hyaline cartilage, dense irregular connective tissue, and skin
◦ One pair of lateral cartilages and two pairs of alar cartilages
Nasal cavity
from nostrils to choanae
Choanae
located in nasal cavity
an oblong-shaped internal space that leads to the pharynx
Nasal septum
Divides left and right nostrils
Nasal conchae
three paired, bony projections on lateral walls of nasal cavity
Superior, middle, and inferior conchae
Function of nasal conchae
Produce turbulence in inhaled air
Increases surface area over which air travels
Nasal meatus
three hollow passageways separated by conchae
Superior, middle, and inferior meatus
Nasal cavity parts
Nasal vestibule
Olfactory region
Respiratory region
Nasolacrimal ducts
Hairs in the nose are called:
vibrissae
Nasal vestibule
Area located just within the nostril
Olfactory region
Superior region contains olfactory epithelium
Contains odor receptors
Respiratory region of the nostril
Highly vascularized
Nasolacrimal ducts
Drain tears into nasal cavity
Primary role of nasal cavity
Warms, cleans and humidifies air
Paranasal sinuses
spaces within skull bones
◦ Named for specific bone in which they are housed
◦ All connected by ducts to nasal cavity
– Pseudostratified ciliated columnar epithelium
o Sweeps mucus into pharynx were it is swallowed
Pharynx
Throat
◦ Funnel-shaped passageway posterior to nasal cavity, oral cavity, and larynx
◦ Lateral walls are skeletal muscles
3 parts of pharynx
Nasopharynx
Oropharynx
Laryngopharynx
Nasopharynx
most superior part of pharynx
◦ An air passage—not for food
◦ Soft palate elevates during swallowing
◦ Connects to middle ear via auditory tube
◦ Opening tubes allows equalization of pressure on each side of tympanic membrane
◦ Contains tonsils—infection-fighting lymphatic tissue
◦ Pharyngeal tonsil on posterior nasopharynx wall
Oropharynx
middle pharyngeal region
◦ Posterior to oral cavity
◦ Passageway for both food and air
◦ Contains tonsils
◦ Palatine tonsils on the lateral walls
◦ Lingual tonsils at base of tongue
Laryngopharynx
inferior, narrow
region of pharynx
◦ Passageway for both food and air
Larynx
(voice box)
◦ Cylindrical airway between laryngopharynx and trachea
Functions:
◦ 1. Air passageway (usually open)
◦ 2. Prevents ingested materials from entering respiratory tract (Epiglottis covers superior opening during swallowing)
◦ 3. Produces sound for speech
◦ 4. Participates in sneeze and cough reflexes
Laryngeal inlet
connects pharynx and larynx
◦ Larynx formed and supported by nine pieces of cartilage
◦ Cartilages held in place by ligaments and muscles
Thyroid cartilage
large, shield-shaped
◦ Forms lateral and anterior walls of larynx
◦ Laryngeal prominence/ Adam’s apple on anterior side
Cricoid cartilage
ring-shaped
◦ Just inferior to thyroid cartilage
Epiglottis
spoon-shaped, elastic cartilage
◦ Closes over laryngeal inlet during swallowing
Laryngeal ligaments are
intrinsic or extrinsic
Extrinsic ligaments
◦ Attach external surface of larynx to other structures (e.g., hyoid bone)
Intrinsic ligaments
◦ Vocal ligaments & vestibular ligaments
Vocal ligaments
◦ Covered with mucosa to form the vocal folds (true vocal cords)
◦ Produce sound when air passes between them
◦ Rima glottis is opening between
Vestibular ligaments
◦ Covered with mucosa to form the vestibular folds (false vocal cords)
◦ No role in sound production
Extrinsic skeletal muscles
◦ Stabilize larynx and help it move during swallowing
Intrinsic skeletal muscles
◦ Located within larynx
◦ Contraction results in change in dimension of rima glottis
◦ Involved in voice production and swallowing
Sound production
vocal cord vibration
Range of voice determined by
length and thickness of vocal cords
Pitch
(frequency) determined by tension on vocal cords
Loudness
depends on force of air passing across vocal cords
Pharynx, nasal and oral cavities, and paranasal sinuses serve as
resonating chambers
◦ Lips, teeth, and tongue help form speech sounds
Lower respiratory tract includes:
◦ Conducting pathways from trachea
to terminal bronchioles
◦ Structures involved in gas exchange
◦ Respiratory bronchioles
◦ Alveolar ducts
◦ Alveoli
Trachea
(windpipe)
– Flexible, slightly rigid, tubular organ
– From larynx main bronchi
Tracheal cartilages
◦ C-shaped rings of hyaline cartilages
◦ Ensure trachea is always open
◦ Rings are connected by anular ligaments
Carina
internal ridge at inferior end of trachea (where it splits) containing many sensory receptors
– Initiates cough reflex
Trachealis muscle
and on trachea’s posterior surface
o Connects open ends of C- shaped cartilages
Histology of the tracheal wall
◦ Mucosa: pseudostratified ciliated columnar epithelium and lamina propria
◦ Submucosa: areolar connective tissue with
blood vessels, nerves, serous and mucous
glands, lymphatic tissue
◦ Tracheal cartilage
◦ Adventitia: elastic connective tissue
Bronchial tree
system of highly branched air passages
Gross anatomy of bronchial tree
– Trachea splits into right and left main bronchi
– Each main bronchus branches into lobar bronchi then to segmental
-Bronchioles (two types)
o Terminal bronchioles (last part of conducting zone)
o Respiratory bronchioles (first part of respiratory zone)
histology of the bronchial tree
◦ Main bronchi are supported by incomplete rings of cartilage
◦ Cartilage lessens as bronchi divide
◦ Bronchioles have no cartilage
◦ Have proportionally thicker layer of smooth muscle
◦ Muscles can cause bronchoconstriction or bronchodilation
Respiratory zone structures are
Microscopic
Respiratory bronchioles subdivide
to
alveolar ducts
Alveolar ducts lead to
alveolar sacs
alveolar sacs are clusters of
alveoli (single units)
Alveoli are made of
simple squamous epithelium which facilitates gas exchange
Alveoli can exchange with
neighbors via connections through
alveolar pores
Alveoli
◦ Each lung contains 300 to 400 million
◦ Surrounded by pulmonary capillaries
◦ Divided by interalveolar septum
◦ Contain elastic fibers
Cell types of alveolar wall
◦ Simple squamous alveolar type I cells
◦ Alveolar type II cells (septal cells)
◦ Alveolar macrophage (dust cells)
Simple squamous alveolar type I cells
95% of cells
Alveolar type II cells (septal cells)
Secrete oily pulmonary surfactant
Alveolar macrophage (dust cells)
◦ Leukocytes that engulf microorganisms
◦ Can be fixed or free
Alveolar wall
◦ Thin barrier between alveoli and pulmonary capillaries
◦ Oxygen diffuses from alveolus > capillaries
◦ Erythrocytes become oxygenated
◦ Carbon dioxide diffuses from blood > alveolus
◦ Expired to external environment
Gross Anatomy of the Lung
Lungs are in thorax on both sides of the mediastinum
◦ Each lung has a conical shape
◦ Wide concave base atop diaphragm
◦ Apex on superior side by clavicle
Lung surfaces
◦ Costal surface adjacent to ribs
◦ Mediastinal surface adjacent to mediastinum
◦ Diaphragmatic surface adjacent to diaphragm
Hilum
◦ Indented region on lung’s mediastinal side
◦ Bronchi, pulmonary vessels, autonomic
nerves, lymph vessels pass through here –
“root of lung”
The right lung Is
larger
(3 lobes)
◦ Horizontal fissure separates superior (upper) lobe from middle lobe
◦ Oblique fissure separates middle lobe from inferior (lower) lobe
Left lung
smaller (2 lobes)
◦ Oblique fissure separates superior and inferior lobes
-Lingula
◦ Three surface indentations accommodate heart and aorta
-Cardiac impression
-Cardiac notch
-Groove-like impression for aorta on medial
surface
Each lung has multiple
bronchopulmonary segments
bronchopulmonary segments
◦ 10 in right / 8-10 in left
◦ Each supplied with its own bronchus, pulmonary artery, vein, and lymph vessels
◦ Each segment organized into lobules (smallest units)
Innervation of the respiratory system is
autonomic
◦ Innervates smooth muscles and glands of respiratory structures
Bronchiole constriction is
parasympathetic
Bronchiole dilation is
sympathetics
2 types of blood supply to lungs
pulmonary circulation and bronchial circulation
Pulmonary circulation
replenishes O2, eliminates CO2
– Pulmonary arteries carry deoxygenated blood to pulmonary capillaries
– Blood is reoxygenated
– Blood enters pulmonary venules and veins, returns to left atrium
Bronchial circulation
transports oxygenated blood to tissues of lungs (systemic circulation)
◦ Bronchial arteries branch off descending aorta
◦ Bronchial veins collect venous blood
Lymph vessels in the lungs are located:
◦ Within lung’s connective tissue
◦ Around bronchi
◦ In pleura
Pleura
serous membrane
◦ Outer lining of lung surfaces and adjacent thoracic wall
◦ Each lung enclosed in a separate visceral pleural membrane
◦ Helps limit spread of infections
Lymph system is important in the lungs because
it prevents excess fluids
and collects particles not picked up by cilia
Visceral pleura
inside
adheres to lung surface
Parietal pleura
outside
lines internal thoracic walls
Pleural cavity
◦ Located between visceral and parietal serous membranes
Serous fluid produced by
serous membranes
◦ Lubricates, allowing pleural surfaces to slide by easily
How the Lungs Remain Inflated
two parts:
Intrapleural pressure
Intrapulmonary pressure
Intrapleural pressure
(within the pleural cavity) is low but important
◦ Lungs cling to chest wall, chest wall expands
◦ Elastic tissue in lungs pulls back in response – creates a vacuum
Intrapulmonary pressure
(in alveoli) is greater than intrapleural pressure, lungs remain inflated
4 processes of respiration
◦ Pulmonary ventilation
◦ Alveolar gas exchange
◦ Gas transport
◦ Systemic gas exchange
Pulmonary ventilation
atmosphere and alveoli
2 phases
◦ Air moves down its pressure gradient
◦ Air enters lung during inspiration; exits during expiration
Alveolar gas exchange
(external respiration) alveoli and blood
Gas transport
lungs and systemic cells
Systemic gas exchange
(internal respiration) blood and the systemic cells
2 phases of pulmonary ventilation
Inspiration brings air into the lungs (inhalation)
Expiration forces air out of the lungs (exhalation)
2 types of pulmonary ventilation
◦ Quiet - rhythmic breathing occurs at rest
◦ Forced - vigorous breathing accompanies exercise
volume changes in the
thoracic cavity
◦ Thoracic volume changes vertically,
laterally, and anterior-posteriorly
◦ Based on what muscles are involved
Boyle’s gas law
Relationship of volume and pressure
◦ At constant temperature, pressure (P) of a gas decreases if volume (V) of the container increases, and vice versa
◦ Inverse relationship between gas pressure and volume
Air pressure gradient
air flows from high to low pressure until pressure is equal
Volumes and pressures associated with
breathing
Atmospheric pressure (pressure of air in
environment)
Alveolar volume (collective volume of
alveoli)
Intrapulmonary pressure (pressure in
alveoli)
Intrapleural pressure (pressure in pleural
cavity)
Changes in pressure result in
changes in air flow
At rest, the atmospheric pressure and
intrapulmonary pressure are
equal
the intrapleural pressure is lower.
Quiet breathing: Inspiration
1) Intrapulmonary pressure and atmospheric pressure are initially equal (760 mg Hg)
– Intrapleural pressure is 4 mm Hg lower
2) Diaphragm and external intercostals contract increasing thoracic volume
– Intrapleural volume increases, so intrapleural pressure decreases
– Lungs pulled by pleurae, so lung volume increases and intrapulmonary pressure
decreases
– Because intrapulmonary pressure is less than atmospheric pressure, air flows in until
these pressures are equal
Quiet breathing: Expiration
3) Initially, intrapulmonary pressure equals atmospheric pressure
– Intrapleural pressure is about 6 mm Hg lower
4) Diaphragm and external intercostals relax decreasing thoracic volume
– Pleural cavity volume decreases, so intrapleural pressure increases
– Elastic recoil pulls lungs inward, so alveolar volume decreases and intrapulmonary
pressure increases
– Since intrapulmonary pressure is greater than atmospheric pressure, air flows out until
these pressures are equal
Forced breathing
– Involves steps similar to quiet breathing but recruits additional muscles
– Greater changes in thoracic cavity volume and intrapulmonary pressure
– More air moving in and out / chest volume changes are apparent
Nervous control of breathing
Autonomic nuclei within the brain coordinate breathing
◦ Respiratory center of the brainstem
◦ Sympathetic activation increases breathing rate
◦ Parasympathetic activation decreases breathing rate
Chemoreceptors monitor changes in
concentrations of H+, PCO2 and PO2
◦ Breathing rate changes based on these concentrations
◦ Too much oxygen decreases breathing rate
◦ Too much CO2 increases breathing rate
Central chemoreceptors
in medulla monitor pH of CSF
Peripheral chemoreceptors
are in aortic and carotid bodies
Airflow
amount of air moving in and out of lungs with each breath
– Depends on
1) The pressure gradient established between atmospheric pressure and intrapulmonary pressure
2) The resistance that occurs due to conditions within the airways, lungs, and chest wall
Pressure gradient can be changed by
altering volume of thoracic cavity
◦ If accessory muscles of inspiration are used, volume increases more
– Airflow increases due to larger pressure gradient
Resistance
greater difficulty moving air - may be altered by
1) Change in elasticity of chest wall and lungs
2) Change in bronchiole diameter (size of air passageway)
3) Collapse of alveoli
Compliance
◦ Ease with which lungs and chest wall expand
◦ Determined by surface tension and elasticity of chest and lung
◦ The easier the lung expands, the greater the compliance
Tidal volume
amount of air per breath
Respiration rate
breaths per minute
Pulmonary ventilation
Total amount of air moved in and out of
the lungs in one minute
Tidal volume × Respiration rate =
pulmonary ventilation
Anatomic dead space
conducting zone space
◦ Extra space in the lung where gas exchange does not occur
◦ About 150 mL
Alveolar ventilation
◦ Amount of air reaching alveoli per minute
◦ (Tidal volume – anatomic dead space) × Respiration rate = Alveolar ventilation
(500 mL – 150 mL) × 12 = 4.2 L/min
Physiologic dead space
◦ Normal anatomic dead space + any loss of alveoli
◦ Some disorders decrease number of active alveoli
Spirometer
- measures respiratory volume
- Assesses respiratory health
-Four volumes measured by spirometry: Tidal volume, Inspiratory reserve volume (IRV), Expiratory reserve volume (ERV), Residual volume
Tidal volume
- amount of air inhaled or exhaled per breath during quiet breathing
- type of volume measured by Spirometer (measures respiratory volume)
Inspiratory reserve volume (IRV)
- amount of air that can be forcibly inhaled beyond the tidal volume
- type of volume measured by Spirometer (measures respiratory volume)
Expiratory reserve volume (ERV)
- amount that can be forcibly exhaled beyond tidal volume
- type of volume measured by Spirometer (measures respiratory volume)
Residual volume
- amount of air left in the lungs after the most forceful expiration
- type of volume measured by Spirometer (measures respiratory volume)
Inspiratory capacity (IC)
Tidal volume + inspiratory reserve volume
Functional residual capacity (FRC)
◦ Expiratory reserve volume + residual volume
◦ Volume left in the lungs after a quiet expiration
Vital capacity
◦ Tidal volume + inspiratory and expiratory reserve volumes
◦ Total amount of air a person can exchange through forced breathing
Total lung capacity (TLC)
◦ Sum of all volumes
◦ Maximum volume of air that the lungs can hold
Forced expiratory volume (FEV)
◦ Percent of vital capacity that can be expelled in a set period of time
Maximum voluntary ventilation (MVV)
◦ Greatest amount of air that can be taken in and then expelled from the lungs in 1 minute
Dalton’s Law
The total pressure in a mixture of gases is equal to the sum of the individual partial
pressures
Partial pressure
pressure exerted by each gas within a mixture of gases
* Measured in mmHg, Written with P followed by gas symbol (i.e., PO2 )
Atmospheric pressure:
Total pressure all gases collectively exert in the environment
– 760 mm Hg at sea level
– Includes N2, O2, CO2, H2O, and other minor gases
Gas always moving from
high partial pressure > low partial pressure
Henry’s law
at a given temperature, the solubility of a gas in liquid is dependent upon the
◦ Partial pressure of the gas in the air (driving force)
◦ Solubility coefficient of the gas in the liquid
Solubility coefficient
volume of gas that dissolves in a specified volume of liquid at a
given temperature and pressure
◦ A value that is specific for every single gas
◦ Gasses with lower solubility require a higher pressure to push them into the liquid
Oxygen
◦ PO2 in alveoli is 104 mm Hg –
blood capillary is 40 mmHg
◦ Oxygen diffuses from alveoli
> capillary
◦ Continues until blood PO2 is
equal to that of alveoli
Carbon dioxide in alvioli
◦ PCO2 in alveoli 40 mm Hg –
blood capillary is 45 mm Hg
◦ Carbon dioxide diffuses from
blood > alveoli
◦ Continues until blood levels
equal alveoli levels
Anatomical features of membrane contributing to efficiency (in lungs)
– Large surface area (70 square meters)
– Minimal thickness (0.5 micrometers)
Physiologic adjustments
ventilation-perfusion coupling
– Ability of bronchioles to regulate airflow and arterioles to regulate blood flow
◦ Ventilation changes by bronchodilation or bronchoconstriction
◦ Perfusion changes by pulmonary arteriole dilation or constriction
Oxygen diffuses out of systemic capillaries to
enter systemic cells
Partial pressure of oxygen in systemic cells
is lower than in capillaries
◦ Continues until blood PO2 is 40 mm Hg
◦ Systemic cell PO2 stays fairly constant
◦ Oxygen delivered at same rate it is used
unless engaging in strenuous activity
Carbon dioxide
◦ Diffuses from systemic cells to blood
◦ Partial pressure gradient driving process
◦ PCO2 in systemic cells 45mm Hg
◦ PCO2 in systemic capillaries 40 mm Hg
◦ Diffusion continuing until blood PCO2 is 45 mm Hg
Alveolar gas exchange decreases
blood PCO2, whereas systemic gas exchange increases blood PCO2
Alveolar gas exchange increases
blood PO2, whereas systemic gas exchange decreases blood PO2
Blood’s ability to transport oxygen depends on
– Solubility coefficient of oxygen
◦ This is very low, and so very little oxygen dissolves in plasma
– Presence of hemoglobin
◦ The iron of hemoglobin attaches oxygen
◦ About 98% of O2 in blood is bound to hemoglobin
Carbon dioxide can be
◦ 1. Dissolved in plasma (7%)
◦ 2. Attached to the globin portion of hemoglobin (23%)
◦ 3. As bicarbonate dissolved in plasma (70%)
◦ CO2 diffuses into erythrocytes and combines with water to form bicarbonate and hydrogen ion (HCO3- and H+)
Binding oxygen causes hemoglobin
to change shape
Cooperative binding effect
each O2 that binds or unbinds causes a change in hemoglobin shape
◦ This means it is relatively easy to remove 1 oxygen when 4 are bound, but extremely hard to remove 1 oxygen when only 2 are bound
◦ Graphed in the oxygen-hemoglobin saturation curve
