Chapter 22: Respiratory System Flashcards
Larynx (voicebox)
- vocal folds macy act as a sphincter to prevent air passage
- example: Valsalva’s Maneuver
- glottis closes to prevent exhalation
- abdominal muscles contract
- intra-abdominal pressure rises
- helps to empty the rectum or stabilizes the trunk during heavy lifting
trachea
- windpipe: from the larynx to primary bronchioles
- wall composed of 3 layers:
1. mucosa
2. submucosa
3. adventitia: outermost layer
*tracheostomy
Conducting zone structures
Trachea-> right and left main (primary) bronchi
- main bronchus enters the hilum of one lung
- each main bronchus branches into lobar (secondary) bronchi (three right, 2 left)
- each lobar bronchus supplies one lobe
Conducting zone structures
Trachea-> right and left main (primary) bronchi
- main bronchus enters the hilum of one lung
- each main bronchus branches into lobar (secondary) bronchi (three right, 2 left)
- each lobar bronchus supplies one lobe
** Lobar (secondary) branchus-> segmental (tertiary) bronchus-> bronchioles-> terminal bronchioles are the smallest
respiratory zone
respiratory bronchioles, alveolar ducts, alveolar sacs (clusters of alveoli)
alveoli features
- surrounded by fine elastic fibers
- open alveolar pores-equalizes air pressure throughout the lung
- house alveolar macrophages-keep surfaces sterile
smoking
- tobacco
- nicotine: stimulates increased HR
- carbon monoxide: blocks oxygen transport in HB
- Tar: cancer causing
- > smoking paralyzes cilia
- > without cilia inhaled particles cling to wall or enter lung
- cilia helps move mucus
lungs
2 lungs
- left has 2 lobes
- right has 3 lobes
- > Apex-> superior tip just under clavicle
- > Base: concave inferior portion above diaphragm
- > hilum: vessels
Occasionally food or liquids will “go down the wrong pipe,” initiating a cough reflex. Which structural barrier has been breached if this happens?
epiglottis
The respiratory membrane is composed of ________.
the alveolar membrane, the capillary wall, and their fused basement membrane
Men tend to have deeper voices than women because their vocal cords …
are longer and thicker
Blood supply
- > pulmonary circulation (low pressure, high volume):
- pulmonary AA- blood from heart to be oxygenated
*pulmonary vv: freshly oxygenated blood
- > Bronchial circulation:
- oxygenated blood to lung tissue
Pleurae
- > thin, double-layered serosa
- parietal pleura: thoracic wall
- visceral pleura: on lung tissue
- pleural space: pleural fluid for lubrication
- > allows friction free movement during breathing
pressure relationships in the thoracic cavity
- Atmospheric pressure:
- pressure exerted by the air surrounding body
- 760 mm Hg at sea level
- > respiratory pressures:
- negative respiratory pressure is less than Patm :(
- positive respiratory pressure is greater than Patm
- zero respiratory pressure= Patm
intrapulmonary pressure
Intrapulmonary (intra-alveolar) pressure (Ppul)
- Pressure in the alveoli
- Always eventually equalizes with Patm
Intrapleural pressure (Pip):
- Pressure in the pleural cavity
- Always a negative pressure (
pressure relationships
- if Pip (intrapleural pressure)= Ppul (intrapulmonary pressure) the lung collapse
- > (Ppul-Pip)= transpulmonary pressure
- keeps the airways open
- the greater the transpulmonary pressure, the larger the lungs
pulmonary ventilation
- inspiration and expiration
- mechanical processes that depend on volume changes in the thoracic cavity
- volume changes -> pressure changes
*pressure changes -> gases flow to equalize pressure
Boyle’s law
- the relationship between the pressure and volume of a gas
- pressure (p) varies inversely with volume… P1V1=P2V2
Inspiration
an active process:
-inspiratory muscles contract
- thoracic volume increases
- lungs are stretched and intrapulmonary volume increases
- intrapulmonary pressure drops (to -1 mm Hg)
- air flows into the lungs, down its pressure gradient, until Ppul (intrapulmonary pressure)=Patm
sequence of events: Inspiration
- Inspiratory muscles
contract (diaphragm
descends; rib cage rises). - thoracic cavity volume increases
- lungs are stretched; intrapulmonary volume increases
- intrapulmonary pressure drops (to -1 mm Hg)
5. Air (gases) flows into lungs down its pressure gradient until intrapulmonary pressure is 0 (equal to atmospheric pressure).
expiration
Quiet expiration is normally a passive process:
- Inspiratory muscles relax
- Thoracic cavity volume decreases
- Elastic lungs recoil and intrapulmonary volume decreases
- Ppul rises (to +1 mm Hg)
- Air flows out of the lungs down its pressure gradient until Ppul = 0
Note: forced expiration is an active process: it uses abdominal and internal intercostal muscles
sequence of events: expiration
- Inspiratory muscles
relax (diaphragm rises; rib
cage descends due to
recoil of costal cartilages). - thoracic cavity volume decreases
- elastic lungs recoil passively; intrapulmonary volume decreases
- intrapulmonary pressure rises (to +1 mm Hg)
- Air (gases) flows out of
lungs down its pressure
gradient until intra-
pulmonary pressure is 0.
physical factors influencing pulmonary ventiliation
-inspiratory muscles work to overcome 3 factors that hinder air passage and pulmonary ventilation
- airway resistance
- alveolar surface tension
- lung compliance
- airway resistance
- Friction = resistance to gas flow
- The relationship between flow (F), pressure (P), and resistance (R) is:F = (P2-P1)/ R
- > delta P is the pressure gradient between the atmosphere and the alveoli (2 mm Hg or less during normal quiet breathing)
- > Gas flow changes inversely with resistance (straw)
Airway resistance
Resistance is usually insignificant because of:
-Large airway diameters in the first part of the conducting zone
- Progressive branching of airways as they get smaller, increasing the total cross-sectional area
- Resistance disappears at the terminal bronchioles where diffusion drives gas movement
Airway resistance
-As airway resistance rises breathing become more strenuous
- Severely constricting or obstruction of bronchioles
- Can occur during acute asthma attacks and stop ventilation
-Epinephrine (SNS) dilates bronchioles and reduces air resistance
- alveoli surface area
- film over alveoli contains surfactant which reduces cohesiveness of water and prevents collapse of alveoli
- respiratory distress syndrome (RSD)
- lung compliance
-change in lung volume that occurs with a given change in transpulmonary pressure
- normally high due to:
- distensibility of the lung tissue
- alveolar surface tension
lung compliance
diminished by:
- nonelastic scar tissue (fibrosis)
- reduced production of surfactant
- decreased flexibility of the thoracic cage balloon
Why is the trachea reinforced with cartilage & why are these cartilaginous rings incomplete posteriorly?
cartilage prevents collapse during pressure changes w/ breathing. incomplete rings allows food bolus down the esophagus
Under what conditions does air tend to flow into the lungs? (thoracic volume & pressure)
increase thoracic volume and decrease in pressure
The pressure in the alveoli is known as __________.
intrapulmonary pressure
If transpulmonary pressure were to suddenly decrease to 0, predict the response by the lungs
The lungs would immediately collapse.
Surfactant helps to prevent the alveoli from collapsing by …
Interfering with the cohesiveness of water molecules, thereby reducing the surface tension of alveolar fluid
Air moves into the lungs during inspiration due to the force of
atmospheric pressure
What effect does increased airway resistance have on air flow?
reduces air flow
What would happen if an opening were made into the chest cavity, as with a puncture wound?
destroys the partial vacuum in the pleural space and the lung would collapse
respiratory volumes
Used to assess a person’s respiratory status:
- > Tidal volume(TV): air exchange between normal breathing
- > Inspiratory reserve volume (IRV): amount of air that can be forcefully inhaled
- > expiratory reserve volume (ERV): amount of air that can be forcefully exhaled
- > residual volume (RV): amount of air remaining in the lungs after a forceful exhale
Respiratory Capacities
- inspiratory capacity (IC): tidal volume and inspiratory reserve
- functional residual capacity (FRC): expiratory reserve and residual volume
- vital capacity (VC): volume of exchangeable air
- everything but residual volume
-total lung capacity (TLC)
Dead Space
- some inspired air never contributes to gas exchange
- anatomical dead space: conducting zones
- alveolar dead space: alveoli that are collapsed or obstructed
pulmonary function tests
can determine obstructive lung disease from restrictive lung disease
Non-respiratory air movements
- most result from reflex action
- examples: cough, sneeze, crying, laughing, hiccups, and yawns
Gas exchanges between blood, lungs, and tissues
- external respiration
- internal respiration
- to understand the above processes, first consider
- physical properties of gases
- composition of alveolar gas
external respiration
-exchange of O2 and CO2 across the respiratory membrane
- influenced by:
1. partial pressure gradients and gas solubilities
- ventilation-perfusion coupling
- structural characteristics of the respiratory membrane
partial pressures
- pressure exerted by a gas
- directly proportional to the percentage of that gas in the mixture
- at higher altitudes, partial pressures decline in direct proportion to decrease in atm pressure
- partial pressure gradients and gas solubilities
- Partial pressure gradient for O2 in the lungs is steep
- venous blood PO2= 40 mmHg
- alveolar PO2= 104 mmHg
- O2 partial pressures reach equilibrium of 104 mm Hg in .25 sec, about 1/3 the time a red blood cell is in a pulmonary capillary
partial pressure gradients and gas solubilities
- partial pressure gradient for CO2 in the lungs is less steep:
- venous blood PCO2= 45 mmHg
- alveolar PCO2= 40 mm Hg
- ventilation-perfusion coupling
- Ventilation: amount of gas reaching the alveoli
- perfusion: blood flow reaching the alveoli
- ventilation and perfusion must be matched (coupled) for efficient gas exchange
ventilation-perfusion coupling
- > Changes in Po2 in the alveoli cause changes in the diameters of the arterioles.
- Where alveolar O2 is high, arterioles dilate
- Where alveolar O2 is low, arterioles constrict (moves blood to other areas)
- > CHANGES IN PCO2 IN THE ALVEOLI CAUSE CHANGES IN THE DIAMETERS OF THE BRONCHIOLES
- WHERE ALVEOLAR CO2 IS HIGH, BRONCHIOLES DILATE
*WHERE ALVEOLAR CO2 IS LOW, BRONCHIOLES CONSTRICT
- thickness and surface area of the respiratory membrane
- > respiratory membranes: large surface area
- > edema/fluid causes increased thickening of membrane (CHF)
- > reduction in surface area with emphysema (destruction of alveoli)
internal respiration
- > Capillary gas exchange in body tissues
- > Partial pressures and diffusion gradients are reversed compared to external respiration
- Po2 in tissue is always lower than in systemic arterial blood
- Po2 of venous blood is 40 mm Hg and Pco2 is 45 mm Hg
Respiratory transport- O2
- > Molecular O2 is carried in the blood
- 1.5% dissolved in plasma (poorly soluble in water)
- 98.5% loosely bound to each Fe of hemoglobin (Hb) in RBCs
- 4 O2 per Hb
Even the most forceful exhalation leaves air in the lungs; this is called the _______ and is needed to _______.
residual volume; keep alveoli patent
If there is an increase in alveolar CO2, the body will adjust by:
dilating the bronchioles in the lungs
An increase in temperature or CO2 will cause
- a shift in the curve to the right
- an increase in O2 unloading
*(bohr effect)
O2 and hemoglobin
- rate of loading and unloading of O2 is regulated by
- Po2
- Temp
- Blood pH
- Pco2
-oxygen-hemoglobin disassociation curve
other factors influencing hemoglobin saturation
-increases in temp, H+ and Pco2, enhance O2 unloading
- occur in systemic capillaries
- shift the O2-hemoglobin dissociation curve to the right (Bohr effect)
-decreases in these factors shift the curve to the left
factors that increase release of O2 by hemoglobin
- as cells metabolize glucose:
- PCO2 and H+ increase in blood
- declining pH (acidic) enhances O2 unloading (Bohr effect- shift to right)
- heat production increases
- increasing temp causes HB to unload more O2 to working muscles
CO2 transport
CO2 is transported in the blood in 3 forms
- Plasma (7 to 10%)
- Bound to globin of hemoglobin 20%
- bicarbonate ions (HCO3-) 70% in plasma
Haldane effect
- the amount of CO2 transported is affected by the Po2
- at tissues: the lower the Po2 and O2 saturation the more CO2 the blood can carry
- at lungs: uptake of O2 facilitates release of CO2
influence of CO2 on blood pH
- > CARBONIC ACID-BICARBONATE BUFFER SYSTEM:
- CO2 + H20-> H2CO3-> H+ HCO3
- > IF H+ CONCENTRATION IN BLOOD RISES, EXCESS H+ IS REMOVED BY COMBINING WITH HCO3–
- > IF H+ CONCENTRATION BEGINS TO DROP, H2CO3 DISSOCIATES, RELEASING H+
influence of C02 on blood pH
- changes in RR or depth can change blood pH
- short shallow breaths- increases CO2, lowers pH
- deep breaths-> reduce CO2
- can use this to adjust blood pH during:
- increased lactic acid during exercise
-FATTY ACID METABOLISM (KETONE BODIES) IN UNCONTROLLED DM
voice production
- speech: intermittent release of expired air while opening and closing the glottis
- pitch: determined by the length and tension of the vocal cords. faster virbation-higher pitch, boys in puberty
- loudness: depends on the force of air
- sounds: is shaped into language by muscles of the pharynx, tongue, soft palate, and lips
larynx
vocal ligaments (true vocal cords)
-vestibular folds (false vocal cords)
larynx (voice box)
9 CARTILAGES OF THE LARYNX
- THYROID CARTILAGE (ADAM’S APPLE)
- RING-SHAPED CRICOID CARTILAGE
- 3 PAIRED CARTILAGES
EPIGLOTTIS: ELASTIC CARTILAGE; COVERS THE LARYNGEAL INLET DURING SWALLOWING
larynx (voice box)
attaches to the hyoid bone and opens into the laryngopharynx
functions:
- provides a patent airway
- routes air and food into proper channels
- voice production
pharynx (throat)
- NASOPHARYNX – AIR PASSAGE, UVULA PREVENTS FOOD FROM ENTERING CAVITY, EUSTASCIAN TUBE
- OROPHARYNX – PSEUDOSTRATIFED COLUMNAR PROTECTS AGAINST FRICTION AND CHEMICAL TRAUMA
- LARYNGOPHARYNX – LIES POSTERIOR TO EPIGLOTTIS
nasal cavity
VESTIBULE: NASAL CAVITY SUPERIOR TO THE NOSTRILS
*Superior, middle and inferior nasal conchae
-> OLFACTORY MUCOSA (SMELL RECEPTORS)
- > RESPIRATORY MUCOSA
- GOBLET CELLS (CONTAIN LYSOZYME AND DEFENSINS)
- CILIA – MOVES CONTAMINATED MUCUS
- WARMS INSPIRED AIR
***filter, heat, and moisten air
the nose
functions:
-PROVIDES AN AIRWAY FOR RESPIRATION
- MOISTENS AND WARMS THE ENTERING AIR
- FILTERS AND CLEANS INSPIRED AIR
- SERVES AS A RESONATING CHAMBER FOR SPEECH
- HOUSES OLFACTORY RECEPTORS (HUMANS – 5 MILLION SCENT RECEPTORS, BLOODHOUND HAS 300 MILLION)
respiration
Respiratory system:
PULMONARY VENTILATION: *MOVEMENT OF AIR INTO AND OUT OF THE LUNGS
EXTERNAL RESPIRATION:
*O2 AND CO2 EXCHANGE BETWEEN THE LUNGS AND THE BLOOD
Circulatory System:
TRANSPORT: O2 AND CO2 IN THE BLOOD
INTERNAL RESPIRATION: O2 AND CO2 EXCHANGE BETWEEN SYSTEMIC BLOOD VESSELS AND TISSUES
Influence of CO2 on blood pH
- changes in RR or depth can change blood pH
- short shallow breaths- increased CO2 lowers pH
- deep breaths- reduce CO2
- can use this to adjust blood pH during:
- increased lactic acid during exercise
- fatty acid metabolism (ketone bodies) in uncontrolled DM
Even the most forceful exhalation leaves air in the lungs; this is called the _______ and is needed to _______.
residual volume; keep alveoli patent
If there is an increase in alveolar CO2, the body will adjust by:
A greater partial pressure of carbon dioxide in the alveoli causes the bronchioles to increase their diameter as will a decreased level of oxygen in the blood supply, allowing carbon dioxide to be exhaled from the body at a greater rate.
an increase in temperature or CO2 will cause
a shift in the curve to the right
-an increase in O2 unloading
factors that shift the oxygen dissociation curve
to the left: inc. pH inc. PCO2 dec. temp dec DPG dec. HbF dec COHb
-to the right
dec. pH
inc PCO2
inc. temp
inc. DPG
control of respiration
- > pontine respiration center:
- influence and modify activity of the VRG
- smooth out transition between inspiration and expiration and vice versa
- > Medullary respiration centers:
- DRG- (DORSAL)- integrates input from baroreceptors (peripheral stretch) and chemoreceptors
*VRG- (VENTRAL)- sets RR at 12-15 BPM. inspiratory neurons excite. expiratory neurons inhibit.
Pontine respiratory centers
interact with the medullary respiratory centers to smooth the respiratory pattern
- Ventral respiratory group (VRG) contains rhythm generators whose output drives respiration
- dorsal respiratory group (DRG) integrates peripheral sensory input and modifies the rhythms generated by the VRG
chemical factors
influence of PCO2:
-if PCO2 levels rise (hypercapnia), CO2 accumulates in the brain
- elevated H+ stimulates the central chemoreceptors of the brain stem
- chemoreceptors synapse with the respiratory regulatory centers, increasing the depth and rate of breathing
slide 88
flow chart of what happens when increase in CO2
depth and rate of breathing
hyperventilation: increased depth and rate of breathing that exceeds the bodys need to remove CO2
- causes CO2 levels to decline (hypocapnia)
- may cause cerebral vasoconstriction and cerebral ischemia
chemical factors
influence of PO2:
*peripheral chemoreceptors in the aortic and carotid bodies are O2 sensors
*substantial drops in arterial PO2 (to 60 mm Hg) must occur in order to stimulate increased ventilation
summary of chemical factors
- rising CO2 levels are the most powerful respiratory stimulant
- normally blood PO2 affects breathing only indirectly by influencing peripheral chemoreceptor sensitivity to changes in PCO2
INFLUENCE OF HIGHER BRAIN CENTERS
- HYPOTHALAMIC CONTROLS ACT THROUGH THE LIMBIC SYSTEM TO MODIFY RATE AND DEPTH OF RESPIRATION
- EXAMPLE: BREATH HOLDING THAT OCCURS IN ANGER OR GASPING WITH PAIN
-A RISE IN BODY TEMPERATURE ACTS TO INCREASE RESPIRATORY RATE (REVERSE OCCURS – JUMP IN COLD WATER)
- CORTICAL CONTROLS CAN BYPASS MEDULLARY CONTROLS
- EXAMPLE: VOLUNTARY BREATH HOLDING
inflation reflex
Hering-Breuer reflex:
-stretch receptors in the pleurae and airways are stimulated by lung inflation
- these receptors send message to respiratory center (vagus nn) to end inhalation
- protective response
homeostatic imbalances of respiratory system
COPD:
- chronic bronchitis
- emphysema
RESTRICTIVE LUNG DISEASE:
- als/ md
- scoliosis
- obesity
- sarcoidosis
