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163 Cards in this Set

  • Front
  • Back
What is the primary function of the respiratory system?
to obtain oxygen for cellular use and to remove carbon dioxide
What are the two types of respiration?
Internal and external
What is internal respiration?
cellular mitochondrial respiration
What is external respiration?
exchange of gas between cells and the environment
What are the four steps of external respiration?
1) gas exchange between the atmosphere and the alveoli
2) exchange of oxygen and carbon dioxide between air in alveoli and blood
3) transport of oxygen and carbon dioxide between lungs and tissues
4)exchange of oxygen and carbon dioxide between the blood and the tissues
What are the nonrespiratory functions of the respiratory system?
1)water loss and heat elimination
2) enhance venous return
3) maintenance of normal acid base balance
4) enable vocalizations
5) defend against foreign matter
6) modify, activate, and inactivate materials passing through circulatory system
7) nose = organ for smell
What are the sites for gas exchange?
What is the main respiratory organ?
The lungs
Name the connecting air passages.
nasal passage/oral cavity, pharynx, larynx, trachea, bronchi, bronchioles, alveolar ducts, and alveolar sacs
What helps keep the trachea open?
Cartilaginous rings
What branch of the nervous system innervates the smooth muscle in the respiratory tract?
The autonomic nervous system
What are the Pores of Kohn?
pores in the alveoli that allow for collateral ventilation
What encircles the alveoli?
pulmonary capillaries
What secretes pulmonary surfactant?
Type II cells in the alveolar epithelium
What is the immune defense of the alveoli?
Alveolar macrophages
What is the importance of the elastic connective tissue in the lung?
Allows for expansion during inhalation
Tru or fals, the lungs ocupy most of the volume of the thoracic cavity?
What is the diaphragm?
skeletal muscle for breathing that seperates the thoracic and abdominal cavities
What seperates each lung from the thoracic wall?
The pleurl sac, which forms the pleural cavity into which fluid from the pleural surface is secreted
What is the atmospheric (barometric) pressure?
pressure produced by weight of air on objects on earth's surface, 760 mm Hg at sea level, decreases with increasing altitude
What is the intra-alveolar/intra-pulmonary pressure?
The pressure in the alveoli
What is the intrapleural/intrathoracic pressure?
The pressure in pleural sac
What is the average intrapleural pressure at rest?
756 mm Hg (or -4 below 760 mm Hg) a slight vaccume compared to normal atmospheric pressure
What happens during a pneumothorax?
The intrapleural pressure is lost
What is transmural pressure?
Pressure accross the cavity wall
What is the transmural pressure gradient accross the lung wall?
net outward P diference b/n intra-alveolar and intrapleural pressure
What happens to the lungs when the intra-alveolar pressure is greater than the intrapleural pressure?
lungs are pushed out
What is the transmural pressure gradient accross the thoracic wall?
The net inward pressure difference b/n the atmospheric and intrapleural pressure
Why does the transmural pressure on the lung wall have a greater effect?
Because the lungs contain highly condensible soft tissue
What produces air flow in and out of lungs?
changes in the intra-alveolar pressure
What happens when intr-alveolar pressure < atmospheric pressure?
air flows into lung
What happens when intra-alveolar pressure is > atmospheric pressure?
air leaves the lungs
What is Boyle's law?
there is an inverse relationship between pressure and volume
What is the major muscle of inspiration?
What are the muscles of active respiration?
internal intercostal muscles and abdominal muscles
Is expiration and active or passive process?
Dos inspiration require work?
Yes, it is an active process
What nerves innervate the diaghram?
phrenic nerves
What innervates the external intercostal muscles?
intercostal nerves
What is most of the enlargement of the thoracic cavity during quiet respiration due to?
Contraction and flattening of the diaphragm
What effect does expansion of the thoracic cavity have n intrapleural pressure?
It decreases it
What happens when the lungs are drawn into an area of lower pressure?
they expand
What happens to intra-alveolar pressure when lung volume increases?
intra-alveolar pressure lowers below atmospheric pressure
What happens when the inspiratory muscles relax?
chest cavity siz decreases (due to relaxation of diaphragm, chest wall muscles, and elastic recoil of alveoli)
What happens when the intrapleural pressure increases?
the lungs are compressed
What happens to the intr-alveolar pressure with decreased lung volume?
it increases above atmospheric pressure and forces the air out
What is forced expiration?
An active process where contraction of expiratory muscles further increses teh pressure gradient between alveoli and atmosphere, forcing the air out
What influences the rate of airflow?
airway resistance
What happens when the difference between atmospheric and intra-aveolar presures are increased?
air flow increases, flow rate and change in presure are directly proportional
What happens when airway resistance is increased?
airflow decreases, flow rate and resistance are inversely proportional
What is the major determinant of resistance?
the radius of conducting airways, R=1/r^4
What portion of the nervous system controls contraction of smooth muscles in the bronchioles?
autonomic nervous system
What can change the conducting airway radii?
the ANS
What causes bronchdialation?
sympathetic stimulation and epinephrine
What causes bronchoconstriction?
parasympathetic stimulation (at rest) - demand for airflow is low
What two properties allow lungs to behave like balloons?
stretching and recoiling
What is elastic recoil?
how readily lungs rebound if stretched - allows lungs to return to preinspiratory volume when inspiratory muscles relax
What is compliance?
The effort required to stretch lungs
What decreases lung compliance?
fibrotic lungs
What two factors effect pulmonary elastic behavior?
-pulmonary elastic connective tissue
-alveolar surface tension
What does alveolar surface tension depend on?
it is determined by a thin liquid film lining each alveolus
What does the film lining each alveolus do?
-allows alveolus to resist expansion
- squeezes alveolus producing recoil
What prevents the alveolus from collapsing from surface tension?
pulmonary surfactant
What is pulmonary surfactant?
mixture of proteins and lipids secreted by Type II alveolar cells
Where is pulmonary surfactant found?
b/n water molecules in fluid lining of alveolus
What are two important benefits of pulmonary surfactant reducing alveolar surface tension?
-increases pulmonary compliance, reducing work needed to inflate lung
-reduces lungs tendency to recoil so they do not readily collapse
What percentage of total energy expenditure is normally required for breathing?
What 4 situations increase the work needed for breathing?
- decreased pulmonary compliance
- increased airway resistance (COPD)
-decreased elastic recoil (emphysema)
-need for increased ventilation (excercise)
How is tidal volume measured?
a spirometer
What is tidal volume (TV)?
air entering or leaving the lungs in a single breath
What is pulmonary (minute) ventilation?
volume of air breathed in and out in 1 minute
What is the respiratory rate?
# of breaths/minute
How is pulmonary ventilation calculated?
tidal volum X respiratory rate
What is the average pulmonary ventilation?
6 liters
What is anatomic dead space?
not all inspired air reaches the alveoli where gas exchange can occur, some remains in conducting airways
Why is alveolar ventilation less than pulmonary ventilation?
because of dead space
How is the alveolar ventilation calculated?
(tidal volume - dead space volume) / breath X respiratory rate
What is the average alveolar ventilation?
4200 ml/min
What can effect alveolar ventilation?
breathing patterns - deep slow breaths increase alveolar ventilation
True or flase - resistance of individual alveoli can be adjusted independently?
What do local controls on resistance act on?
smooth muscle of the airways
What decreases airway resistance by causing airway supplying alveoli to relax?
accumulation of carbon dioxide in alveoli
What does decreased carbon dioxide do to airflow?
reduces airflow by increasing the contraction of airways supplying the alveoli
True or false, ventilation and perfusion should match?
What are the stages of gas transfer?
-breathing movements
-diffusion of oxygen and carbon dioxide across the respiratory epithelium
-transport of gases
-diffusion of oxygen and carbon dioxide across capillary walls between blood and tissue cells
How does oxygen and carbon dioxide exchange occur at pulmonary and tissue capillaries?
simple diffusion
What does the partial pressure of each gas in the air depend on?
the % of that gas in the total atmospheric pressure
What is a partial pressure gradient?
2 partial pressures for a gas in different regions of the body
Where is the partial pressure of oxygen higher, the alveoli or the blood of pulmonary capillaries?
the alveoli, thus oxygen diffuses from alveoli to capillaries
Where is the partial pressure of carbon dioxide greater?
greater in the blood if the pulmonary capillaries, thus carbon dioxide diffuses into the alveoli from the capillaries
Which direction does oxygen move between the alveoli and capillaries?
It flows from the alveoli into the capillaries
Which direction does carbon dioxide flow between the capillaries and alveoli?
it diffuse into the alveoli from the capillaries
which direction does oxygen flow between blood and tissue cells?
it diffuses from blood into tissue cells
Which direction does carbon dioxide flow between tissue cells and blood?
it diffuses from tissue cells into the blood
How does surface area effect the rate of gas transfer?
increases the rate of gas exchange, alveoli collectively have a tremendous surface area, increased pulmonary blood pressure = increased cardiac ourput = increased surface area
How does distance affect the rate of gas transfer?
thin walls lead to rapid gas exchange
What disease states decrease gas exchange by thickening areas for gas exchange?
pulmonary edema, pulmonary fibrosis, penumonia
How does the gas diffusion coeffecient affect gas transfer?
gas exchange is directly proportional to diffusion coefficient for a gas
How is oxygen and carbon dioxide transported?
in blood between alveoli and tissues
What percentage of oxygen is bound to hemoglobin?
What % of carbon dioxide is physically dissolved?
What percentage of carbon dioxide is bound to hemoglobin?
What percentage of carbon dioxide is in the form of bicarbonate ion?
Does the oxygen bound to hemoglobin contribute to its partial pressure?
Where is oxyhemoglobin formation favored ?
the lungs
When does Hb bind with oxygen?
when oxygen diffuses from alveoli into the pulmonary capillaries
Where does dissociation of oxyhemoglobin occur?
tissue cells
What portion of oxygen contributes to its partial pressure?
The 1.5% dissolved in plasma
What is the main determinant of the percent hemoglobin saturation?
the partial pressure of oxygen
What promotes the net transfer of oxygen at the alveolar and tissue levels?
When does the net diffusion of oxygen from the alveoli to the blood stop?
when the hemoglobin is saturated
What does increased carbon dioxide from tissues cells into systemic capillaries do to Hb dissociation from oxygen?
increses Hb dissociation from oxygen
What is the Bohr (Haldane) effect?
the shift of the dissociation curve to the right, increasing oxygen unloading
How does increased acidity affect Hb-oxygen dissociation?
it increases dissociation (shifts curve to right)
How does increased temp affect oxygen dissociation?
how does BPG production effect oxygen unloading?
increases it
How is most carbon dioxzide transported?
as bicarbonate ion
What is formed when carbon dioxide combines with water?
carbonic acid
What enzyme facilitates the production of carbonic acid in red blood cells?
carbonic anhydrase
What ions does carbonic acid disociate into?
hydrogen ions and bicarbonate ions
Where is carbonic acid dissociation favored?
at the tissue cells
Where does bicarbonae ion form free molecules of carbon dioxide?
in the lungs
What occurs during a chloride shift?
RBC plasma membrane passively facilitates diffusion of bicarbonate and chloride ions
What is the Haldane effect?
oxygen removel from hemoglobin at the tissue cells, which increases ability of Hb to bind to carbon dioxide and hydrogen ion
What is hypoxia?
insufficient oxygen at the cellular level
What is hypoxic hypoxia?
low partial pressure of oxygen in arterial blood
What is circulatory hypoxia?
too little oxygenated blood deleivered to tissues (normal partial pressure of oxygen blood just isn't getting to tissues)
What is anemia hypoxia?
reduced oxygen carrying capacity in the blood, decreased RBCs, CO poisoning
What is histotoxic hypoxia?
oxygen delivery to tissues is normal but cells can't use it
What is hyperoxia?
above normal arterial partial pressure of oxygen
What is hypercapnia?
excess carbon dioxide in arterial blood caused byhypoventilation
What is hypocapnea?
below normal carbon dioxide in arterial blood caused by hyperventilation
What is hyperpnea?
increased need for oxygen delivery and carbon dioxide removal - during times of increased metabolic need
What do the respiratory centers in the brain stem due?
establish rythmic breathing pattern which can be modified via voluntary activity
What is the medullary respiratory center?
an aggregation of neuronal cell bodies in medulla that provide output to respiratory muscles
Name the parts of the medullary respiratory centers.
Pre-Botzinger complex, dorsal respiratory group, ventral respiratory group
What are the two respiratory centers in the pons?
the pneumotaxic center and the apneustic center
What do the respiratory center in the pons do?
infuence output from medullary respiratory center
What are the two types of inspiratory muscles?
phrenic and intercostal
What do the inspiratory neurons do?
signal inspiratory muscles, the diaphragm and external intercostals
Where do impulses from the medullary center terminate?
the phrenic and intercostal motor neurons
Where are cell bodies for the inspiratory neurons located?
in the spinal cord
Where are signals from the inspiratory neurons sent?
to inspiratory muscles
What happens when there is no signal from inspiratory neurons?
What is the dorsal respiratory group responsible for?
When is the ventral respiratory group utilized?
during increased demand for ventilation, particlarly during active expiration
What is responsible for the basic respiratory rythym?
the pre-botzinger complex
What sends the impulses that switch off inspiratory neurons?
pneumotaxic center, it limits the duration of inspiration
What prevents inspiratory neurons from being switched off?
the apneustic center
What is the Hering-Breuer reflex?
stretch receptors in lungs activated with large tidal volumes during inspiration
What are the 3 chemical factors that adjust the magnitude of ventilation?
partial pressure of oxygen
partial pressure of carbon dioxide
hydrogen ion
What is reflective of carbon dioxide?
hydrogen ion concentration
What is the primary regulator of magnitude?
carbon dioxide generated hydrogen ion in the brain
What is monitored by the peripheral chemoreceptors?
arterial partial pressure of oxygen
What are the peripheral chemoreceptors?
Carotid and aortic bodies
When are peripheral chemoreceptors stimulated?
when arterial partial pressure of oxygen is life threateningly low
Where are the central chemreceptors located?
in the medulla
What do the central chemoreceptors monitor?
increased hydrogen ion concentration in the brain ECF
What happens when the central chemoreceptors are stimulated?
ventilation is increased by stimulating the respiratory center
What does elevated arterial hydrogen ion stimulate?
What is apnea?
transient interruption in ventillation
What is sleep apnea?
breathing ceases up to 2 minutes up to 500 times a night
What is dyspnea?
subjective feeling of "shortness of breath" which often accompanies other conditions.