Chapter 23 - Respiratory System Flashcards
What does the respiratory system consist of?
- nose
- pharynx (throat)
- larynx (voice box)
- trachea (wind pipe)
- bronchi and lungs
What are the two structural parts of the respiratory system? (structural classification)
- Upper respiratory system
2. Lower respiratory system
What does the upper respiratory system consist of?
Nose, nasal cavity, pharynx and associated structures
What does the lower respiratory system consist of?
Larynx, trachea, bronchi, and lungs
What are the two functional parts of the respiratory system? (functional classification)
- Conducting zone
2. Respiratory zone
What is the function of the conducting zone?
Filter, warm, and moisten air and conduct it into the lungs
- nose, nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, terminal bronchioles
What is the function of the respiratory zone?
Main site of gas exchange between air and blood
- respiratory bronchioles, alveolar ducts, alveolar sacs, alveoli
How is the nose divided?
Into an external portion and an internal portion (nasal cavity)
What are external nares?
nostrils
Two openings on the undersurface of the external nose
What are the three functions of the interior surface of the external nose?
- Warming, moistening, and filtering incoming air
- Detecting olfactory stimuli
- Modifying speech vibrations as they pass through the large, hollow resonating chambers
What is the nasal cavity?
Merges with the external nose, and communicates with the pharynx through two openings (internal nares)
What are the internal nares? (choanae)
Two openings
- inside the nasal cavity
- where nasal cavity communicates with the pharynx
What is the function of the nasal septum?
Divides the nasal cavity into right and left sides
What are the superior, middle and inferior meatuses?
Three nasal passages (openings that open to the outside)
- located beneath each of the corresponding nasal conchae
What are the three functions of the respiratory syste,?
- Gas exchange
- Regulate blood pH
- Olfactory, filters, vocal sounds, excretes water and heat
What is the function of the nasal meatus?
Increases surface area in the internal nose
- prevents dehydration by trapping water droplets during exhalation
Where is the olfactory epithelium located?
What kinds of cells does it contain?
Near the superior nasal conchae
- contains olfactory receptors, supporting cells and basal cells
What is the pharynx?
The throat
What are the functions of the pharynx?
- passageway for food and air
- houses tonsils
- resonating chamber for speech sounds
What are the three regions of the pharynx?
- Nasopharynx
- Oropharynx
- Laryngopharynx
What is the nasopharynx?
Superior region of pharynx
- helps to equalize pressure between the pharynx and middle ear
What is the pharyngeal tonsil? (adenoid)
Lymphatic tissue
- located in the superior portion of nasopharynx
What is the oropharynx?
Intermediate portion of pharynx
- respiratory and digestive functions
What is the fauces?
Only opening in the oropharynx
- opens to the mouth
What tonsils are located in the oropharynx?
Palatine and lingual tonsils
What is the laryngopharynx?
Inferior portion of pharynx
- opens into esophagus and larynx
- respiratory and digestive functions
What is the larynx?
Voice box
- connects laryngopharynx with the trachea
What is the thyroid cartilage (Adam’s apple)?
Two fused plates of hyaline cartilage
- forms anterior wall of larynx
- present in males (more pronounced) and females
What is the epiglottis?
Large, leaf-shaped piece of elastic cartilage
- it is depressed during swallowing to cover the opening of the windpipe
What does the glottis consist of?
True vocal cords and a pair of folds in mucous membrane
What is the cricoid cartilage?
Landmark for making an emergency airway (tracheotomy)
Ring of hyaline cartilage
- forms the inferior wall of larynx
- attached to the first ring of cartilage of the trachea
What are the arytenoid cartilages?
Forms part of the larynx
- to which the vocal folds (vocal cords) are attached
- these allow and aid in the vocal cords’ movement
What are the ventricular folds (false vocal cords)?
Superior pair of mucous membrane folds
- in the larynx
- do not function in voice production
What are the vocal cords (true vocal cords)?
Inferior pair of mucous membrane folds
- in the larynx
What is the function of the ventricular folds (false vocal cords)?
Function in holding the breath against pressure in the thoracic cavity
- when a person strains to life a heavy object
What are the principal structures of voice production?
Vocal cords (true vocal cords)
How do vocal cords produce sound?
Air passes through the elastic vocal folds and causes them to vibrate
How it pitch controlled?
By the tension of the vocal cords
- higher the tension, higher the pitch
What are the other structures necessary for converting sound into recognizable speech?
Pharynx, mouth, nasal cavity, paranasal sinuses
- all act as resonating chambers
- muscles of the face, tongue and lips help us enunciate words
What is the trachea?
Windpipe
- passageway for air
What are the cartilages shaped like the letter “C”?
16-20 incomplete, horizontal rings of cartilage of hyaline cartilage (look like letter “C”)
- can be felt through the skin inferior to the larynx
- open part of “C” faces posteriorly, towards the esophagus
What is the function of the “C” shaped cartilages?
- provides semirigid support, to prevent collapsing
What is the passageway that air takes to reach the lungs after the trachea?
Trachea –> Primary bronchi –> Secondary bronchi –> Tertiary bronchi –> Bronchioles –> Terminal bronchioles
What does the trachea divide into?
Right and left primary bronchus
What do the primary bronchi divide into?
Divide to form smaller bronchi
- Secondary bronchi
- one for each lobe of the lung
How many lobes does the right and left lungs have?
Right lung: has 3 lobes
Left lung: has 2 lobes
What do the secondary bronchi divide into?
Tertiary bronchi
- even smaller than secondary bronchi
What do tertiary bronchi divide into?
Bronchioles
What do bronchioles branch into?
Terminal bronchioles
What is the bronchial tree?
Extensive branching from the trachea through the terminal branchioles
- resembles an inverted tree
What are the lungs?
Paired cone-shaped organs in the thoracic cavity
- function in breathing
What is the pleural membrane?
Serous membrane that surrounds each lung
What are the two layers of the pleural membrane?
- Parietal pleura - lines the thoracic cavity
2. Visceral pleura - covers the lungs
What is the pleural cavity?
Space between the parietal and visceral pleura
- reduces friction between membranes
What is the base of the lungs?
Broad inferior portion
- fits over diaphragm
What is the apex of the lungs?
Narrow superior portion
What is the costal surface of the lungs?
Surface lying against the ribs
What do the mediastinal (medial) surface of the lungs contain?
A region (hilum) through which bronchi, pulmonary blood vessels, lymphatic vessels, and nerves enter and exit
What constitutes the root of the lung?
The hilum
- held together by the pleura and connective tissue
What is the cardiac notch?
A concavity where the apex of the heart sits
How do the oblique fissures extend?
Extends inferiorly and anteriorly
armpit to stomach
Which fissure does the right lung have that the left does not?
Horizontal fissure
- superior to the oblique fissure
What are the lobes of the right lung?
Superior lobe
Middle lobe
Inferior lobe
What are the lobes of the left lung?
Superior lobe
Inferior lobe
What is the bronchopulmonary segment?
Segment of lung tissue that each tertiary bronchus supplies
- there are 10 tertiary bronchi in each lung
What are lobules?
Small compartments of each bronchopulmonary segment
What are respiratory bronchioles?
Terminal bronchioles that have subdivided into microscopic branches
What do respiratory bronchioles subdivide into?
Into several (2-11) alveolar ducts
What is an alveolus?
Tiny air sacs in the lungs where the exchange of oxygen and carbon dioxide takes place
What is an alveolar sac?
Consists of two or more alveoli that share a common opening
What is the function of type I alveolar cells?
Main sites of gas exchange
- more numerous than type II
What is the function of type II alveolar cells?
Septal cells
- secrete alveolar fluid, keeps the surface between the cells and the air moist
- found between the cells of type I
What is surfactant?
Complex mixture of phospholipids and lipoproteins
- lowers surface tension of alveolar fluid
- reduces the tendency of alveoli to collapse
What are alveolar macrophages (dust cells)?
Phagocytes that remove fine dust particles and other debris from the alveolar spaces
What forms the respiratory membrane?
Alveolar and capillary walls
- where exchange of gases occurs
How do the lungs receive blood?
Via two sets of arteries:
- Pulmonary arteries
- Bronchial arteries
What is the only artery that carries de-oxygenated blood?
Pulmonary arteries
Describe the pathway of the microscopic airway.
Terminal bronchioles –> respiratory bronchioles –> alveolar ducts –> alveolar sacs –> alveoli
What are the three basic steps of respiration?
- Pulmonary ventilation
- External (pulmonary) respiration
- Internal (tissue) respiration
What is pulmonary ventilation?
Breathing
- inhalation (inflow) and exhalation (outflow) of air
What is external (pulmonary) respiration?
Exchange of gases between the alevoli and the blood in pulmonary capillaries
What is internal (tissue)respiration?
Exchange of gases between the blood in systemic capillaries and tissue cells
Why does air move into or out of the lungs?
Pressure changes
Air moves INTO lungs -when air pressure inside lungs is less than the air pressure in the atmosphere
Air moves OUT OF lungs - when air pressure inside lungs is greater than the air pressure in the atmosphere
What is inhalation (inspiration)?
Breathing in
- achieved by increasing the size of the lungs (lungs expand)
What is Boyle’s Law?
Inverse relationship between volume and pressure
- if volume goes up, pressure goes down
- if volume goes down, pressure goes up
What is the most important muscle of inhalation?
Other muscles?
Diaphram
- external intercostals
What happens to the diaphram during contraction?
inhalation
Contraction causes it to flatten
- increases the vertical diameter of the thoracic cavity
What happens to the external intercostals during contraction? (inhalation)
Contraction elevates the ribs
- increases the chest cavity
What is intrapleural (intrathoracic) pressure?
Pressure between the two pleural layers in the pleural cavity, during quiet inhalation
What is the alveolar (intrapulmonic) pressure?
Pressure inside the lungs
What are the alveolar and intrapleural pressures at rest?
Alveolar = 760 mmHg Intrapleural = 756 mmHg
What are the alveolar and intrapleural pressures during inhalation?
Alveolar = 758 mmHg Intrapleural = 754 mmHg
What are the alveolar and intrapleural pressures during exhalation?
Alveolar = 762 mmHg Intrapleural = 756 mmHg
What is exhalation (expiration)?
Breathing out
- a passive process
- no muscular contractions are involved
What is elastic recoil?
Natural tendency for the chest wall and lungs to spring back after they have been stretched
What two forces contribute to elastic recoil?
- Recoil of elastic fibers that were stretched during inhalation
- Inward pull of the surface tension due to the film of alveolar fluid
What muscles are active during forced exhalation?
Abdominals and internal intercostals
Which pressure is always lower than the other, alveolar or intrapleural pressure?
Intrapleural is always lower than alveolar
What are the three other factors that affect the rate of airflow and the ease of pulmonary ventilation?
- Surface tension of the alveolar fluid
- Compliance of the lungs
- Airway resistance
How does the surface tension of the alveolar fluid affect the rate of airflow in breathing?
Surface tension produces an INWARD force
- causes alveoli to assume the smallest diameter possible
- surface tension must be overcome during breathing in order to expand the lungs
How does compliance of the lungs affect the rate of airflow in breathing?
Compliance = amount of effort required to stretch the lungs and chest wall
- high compliance = lungs expand easily
- low compliance = resist expansion
How does airway resistance affect the rate of airflow in breathing?
Large-diameter airways have decreased resistance (inhalation, bronchioles enlarge)
Airway resistance increases during exhalation as the diameter of bronchioles decreases
- any condition that narrows of obstructs the airways increases resistance
What does eupnea mean?
Normal pattern of quiet breathing
What is costal breathing?
Pattern of shallow (chest) breathing
- upward and downward movement of the chest due to contraction of external intercostal muscles
What is diaphragmatic breathing?
Pattern of deep (abdominal) breathing
- outward movement of the abdomen due to contraction of the diaphragm
What is tidal volume?
Volume of one breath (VT)
What is minute ventilation?
Total volume of air inhaled and exhaled each minute
MV = 12 breaths/min x 500mL/breath
= 6 litres/min
What is a spirometer?
Apparatus commonly used to measure the volume of air exchanged during breathing and the respiratory rate
What is the anatomic (respiratory) dead space?
The conducting airways with air that does not undergo respiratory exchange
- about 30% of each breath does not each the alveoli
- remains in the nose, pharynx, larynx, trachea, bronchi, bronchioles and terminal branches
What is the alveolar ventilation rate?
Volume of air per minute that actually reaches the respiratory zone
What is the inspiratory reserve volume?
Additional inhaled air during a deep breath
What is the expiratory reserve volume?
Additional exhaled air pushed out during a forced exhale
What is residual volume?
Air that remains in the lungs after an expiration
What is the inspiratory capacity?
Sum of tidal volume and inspiratory volume
What is the functional residual capacity?
Sum of residual volume and expiratory reserve volume
What is the vital capacity?
Sum of inspiratory reserve volume, tidal volume, and expiratory reserve volume
What is the total lung capacity?
Sum of vital capacity and residual volume
What is Dalton’s Law?
Each gas in a mixture of gases exerts its own pressure as if no other gases were present
What is partial pressure (Px)?
The pressure of a specific gas in a mixture
What affects the speed of the rate of diffusion of gases during breathing?
The partial pressure
- greater the difference in partial pressure, the faster the rate of diffusion
What does Henry’s Law state?
States that the quantity of a gas will dissolve in a liquid is proportional to the partial pressure of the gas and its solubility
When is a gas better able to stay in a solution?
It is greater when its partial pressure is higher and when it has a high solubility in water
What is external respiration or pulmonary gas exchange?
Diffusion of O2 from air in the alveoli of the lungs to blood in pulmonary capillaries
- diffusion of CO2 in the opposite direction
What is deoxygenated blood and what side of the heart does it come from?
Blood that contains more CO2 than O2
- comes from the right side of the heart
What is oxygenated blood and what side of the heart does it return to?
Saturated with O2
- returns to the left side of the left
What is internal respiration or systemic gas exchange?
Exchange of O2 and CO2 between systemic capillaries and tissue cells
- occurs throughout the body
What factors affect the RATE of pulmonary and systemic gas exchange?
- partial pressure difference of the gases
- surface area available for gas exchange
- diffusion distance
- molecular weight and solubility of gases
What two things bind together to form oxyhemoglobin?
Oxygen and hemoglobin
What percentage of O2 is bound to hemoglobin in the blood?
- 5% bound to hemoglobin
- 1.5% is dissolved in blood plasma
What is the most important factor that determines how much O2 binds to hemoglobin?
Partial pressure
- the higher the partial pressure, the more O2 combine with Hb
How many molecules of O2 can bind with one molecule of hemoglobin?
4
What happens to the partial pressure of 02 as it travels from pulmonary capillaries to tissue capillaries?
Partial pressure is high in pulmonary capillaries - 02 binds with hemoglobin
Partial pressure is low in tissue capillaries - 02 is release from hemoglobin, diffuses into the tissue cells
What are the other factors the affect the affinity of hemoglobin for oxygen?
- Acidity (pH)
- Partial pressure of CO2
- Temperature
- BPG (2,3-bis-phosphoglycerate)
What affect does pH (acidity) have on the affinity of hemoglobin for oxygen?
Increasing acidity (a LOW pH #), increases the unloading (dissociation) of oxygen from hemoglobin
What affect does the partial pressure of CO2 have on the affinity of hemoglobin for oxygen?
Increased partial pressure of CO2, hemoglobin releases more O2 readily
How is the partial pressure of CO2 related to blood acidity?
Low blood pH (acidity) results from a high partial pressure of CO2
What affect does temperature have on the affinity of hemoglobin for oxygen?
As temperature increases, so does the amount of O2 released from hemoglobin
What are the three methods of carbon dioxide transport in the blood?
- Dissolved cardbon dioxide
- Carbamino compounds
- Bicarbonate ions
What is carbaminohemoglobin?
Hb — CO2
A carbamino compound
- a way for CO2 to bind to hemoglobin
What is a bicarbonate ion?
HCO3-
The dissociation of carbonic acid (H2CO3)
What is the function of the respiratory centre in the brain?
Controls the rate and depth of respiratory movements of the diaphragm and other respiratory muscles
Where is the respiratory centre located in the brain?
In the brain stem
- medulla oblongata and pons
What are the three areas of the respiratory center?
- Medullary rhythmicity area (in the medulla)
- Pneumotaxic area (in the pons)
- Apneustic area (in the pons)
What is the function of the medullary rhythmicity area?
Control the basic rhythm of respiration
- there are inspiratory and expiratory areas
What is the function of the inspiratory area?
Nerve impulses generated in the inspiratory area establish the basic rhythm of breathing
- 2 seconds per inhalation
- 3 seconds per exhalation
How does quiet breathing operate?
- inspiratory area is active = generates nerve impulses for 2 seconds
- breathing muscles contract
- inspiratory area becomes inactive = nerve impulses stop
- muscles relax for about 3 seconds, allows for passive elastic recoil of muscles
What neurons are active during quiet breathing, inspirtory or expiratory?
Inspiratory
- expiratory areas remains inactive during quiet breathing
What happens when the neurons in the expiratory area are active?
Forceful exhalation
- cause contraction of internal intercostal and abdominal muscles
What is the function of the pneumotaxic area?
Helps coordinate the transition between inhalation and exhalation
- turns off inspiratory area before the lungs become too full
What is the function of the apenustic area?
Helps coordinate the transition between inhalation and exhalation
- send stimulatory impulses to the inspiratory area
- results in DEEP, LONG inhalation
What happens if the pneumotaxic area is more active?
Breathing rate is more rapid
- overrides signals from the apneustic area
How does the cerebral cortex affect respiration?
Gives us the ability to voluntarily control our breathing
- ability to hold our breath on command
What happens if we hold our breath for too long?
CO2 and H+ build-up in the body
- inspiratory area becomes strongly stimulated to overcome voluntarily holding our breath
How do chemoreceptors function in respiration?
Very responsive to changes in levels of CO2, O2 and H+
- provide input to the respiratory centre
Where are the central chemoreceptors located?
for respiration
Located in or near the medulla oblongata in the CENTRAL nervous system
What do central chemoreceptors respond to?
Changes in H+ and CO2 in cerebrospinal fluid
Where are peripheral chemoreceptors located?
for respiration
Located in the aortic bodies and carotid bodies
- part of the PERIPHERAL nervous system
What do peripheral chemoreceptors respond to?
Changes in O2
What is hypercapnia? (hypercarbia)
Slight increase in the partial pressure of CO2
- central chemoreceptors are stimulated
- respond vigorously to the resulting H+ increase
What is hyperventilation?
Results from increased CO2, decreased pH (increased H+) or decreased O2
- input from central and peripheral chemoreceptors causes inspiratory area to become highly active
Does oxygen levels or carbon dioxide level more strongly stimulate the inspiratory area?
More strongly stimulated by increased CO2 rather than low O2
What is hypoxia?
Deficiency of O2 at the tissue level
What are the four types of hypoxia?
- Hypoxic hypoxia - low O2 in arterial blood
- Anemic hypoxia - too little functioning hemoglobin
- Ischemic hypoxia - blood flow to tissue is reduced
- Histotoxic hypoxia - tissues are unable to use delivered O2
What effect does proprioceptor stimulation have on respiration?
Nerve impulses from proprioceptors stimulate inspiratory area in medulla
- rate and depth of breathing increase before gas level changes in blood
How are baroreceptors stimulated?
Stretch receptors
Stimulated due to overinflation of the lungs
- inspiratory area become inhibited; exhalation begins
- located in the walls of bronchi and bronchioles
What is the inflation (Hering-Breuer) reflex?
Reflex triggered to prevent overinflation of the lung
- once baroreceptors are no longer stimulated (stretch receptors), normal breathing resumes
What are the other six influences that affect respiration?
What are their effects?
- Limbic system stimulation - emotional anxiety may stimulate inspiratory area
- Temperature - increase in temp, increases rate of breathing. Sudden cold causes apnea
- Pain - severe pain causes apnea, moderate pain causes increase in breathing
- Stretching the anal sphincter muscle - increases respiratory rate
- Irritation of airways - immediate cessation of breathing, followed by coughing or sneezing
- Blood pressure - sudden rise in blood pressure, decrease in rate of respiration
What is apnea?
An absence of breathing
What is pulmonary perfusion?
As cardiac output rises, the blood flow to the lungs increases as well
What happens during exercise to respiration?
- rate of O2 diffusion into blood increases
- O2 consumption and pulmonary ventilation increase
What are the three NEURAL changes that send excitatory impulses to the inspiratory area during exercise?
- Anticipatory (limbic system)
- Sensory impulses from proprioceptors
- Motor impulses from cerebral cortex
What is asthma?
Disorder characterized by chronic airway inflammation, airway hypersensitivity and airway obstruction
- difficulty in breathing, coughing, wheezing, chest tightness, fatiuge, anxiety
What is chronic obstructive pulmonary disease?
COPD
- chronic and recurrent obstuction of airflow, which increases airway resistance
- emphysema and chronic bronchitis
What is emphysema?
Destruction of the walls of the alveoli
- produces abnormally large air spaces that remain filled with air during exhalation
- less surface area for gas exchange
What is chronic bronchitis?
Excessive secretion of bronchial mucus accompanied by a productive cough
- narrows the airway and impairs ciliary function
What is lung cancer?
Cancer of the lung …
What is pneumonia?
Acute infection or inflammation of the alveoli
- certain microbes enter the lungs, release damaging toxins, stimulating inflammation and immune responses
- inflammation and edema cause the alveoli to fill with fluid
What is tuberculosis?
Caused by mycobacterium tuberculosis
- once the bacteria are inside the lungs, they multiply
- healthy immune system will keep bacteria dormant for life
- compromised immune system (HIV, AIDS) bacteria may be able to spread throughout the body
What is a pulmonary edema?
Abnormal accumulation of fluid in the interstitial spaces and alveoli of the lungs
What is the common cold? (coryza)
Group of viruses called rhinoviruses
- sneezing, excessive nasal secretion, dry cough, congestion
What is seasonal influenza (flu)?
Caused by a virus
- chills, fever, headache, muscular aches
- respiratory illness, not gastric
What is cystic fibrosis?
A hereditary disorder affecting the exocrine glands.
- causes the production of abnormally thick mucus
- resulting in respiratory infection
What is sudden infant death syndrome (SIDS)?
Sudden, unexpected death of an apparently healthy infant during sleep
- exact cause is unknown
What is asphyxia?
Oxygen starvation due to low atmospheric oxygen
- interference with ventilation, external or internal respiration
What is aspiration?
Inhalation of a foreign substance such as water, food, or a foreign body into the bronchial tree
- drawing of a substance in or out by suction
What is dyspnea?
Painful or labored breathing
What is hypoventilation?
Slow and shallow breathing
What is rhinitis?
Chronic or acute inflammation of the mucous membrane of the nose due to viruses, bacteria or irritants
- excessive mucous causes runny nose, nasal congestion and postnasal drip
