Lesson 13/14 Exam 5 Flashcards
breathing depends on
repetitive stim of skeletal muscles from brain
breathing will cease if
spinal cord is severed high in neck
what are the two levels of the brain where breathing is controlled
- cerebral and conscious
- unconscious and automatic
brainstem respiratory centers (2)
- automatic unconscious breathing
- controlled by respiratory centers in reticular formation
what are the two pairs of respiratory centers in the medulla oblongata
- ventral respiratory group
- dorsal respiratory group
ventral respiratory group (3)
- primary generator of the respiratory rhythm
- reverberating circuits I neurons and E neurons
- 12 breaths per minute
dorsal respiratory group (4)
- inspiratory center stims inspiratory breathing
- functions in both quiet and forced breathing
- modifies the rate and depth of breathing
- receives influences from external sources
what are the input receptors to the respiratory centers
- central chemoreceptors
- peripheral chemoreceptors
- stretch receptors
- irritant receptors
central chemoreceptors
- brainstem neurons respond to changes in pH of CSF
- regulate respiration to maintain stable pH
- ensure stable CO2 levels in blood
pH of CSF reflects the ____ level in blood
CO2
peripheral chemoreceptors
- located in carotid and aortic bodies
- respond to O2 and CO2 content and pH of blood
stretch receptors
- smooth muscle of bronchi and bronchioles and the visceral pleura
- respond to inflation of lungs
- inflation (Hering-Breuer) reflex
inflation (Hering-Breuer) reflex
- triggered by excessive inflation
- protective reflex inhibits inspiratory neurons and stops inspiration to stop excessive inflation/stretching of lung tissue
irritant receptors
- nerve endings amid epithelial cells of the airway
- trigger protective reflexes
- respond to foreign bodies
examples of what irritant receptors respond to
- smoke
- dust
- pollen
- chemical fumes
- cold air
- excess mucus
what are the protective reflexes triggered by irritant receptors
- bronchoconstriction
- shallower breathing
- breath holding
- coughing
voluntary control over breathing originates in
motor cortex of frontal lobe of cerebrum
what does the voluntary control of breathing do in regards to the nervous system
send impulses down corticospinal tracts to respiratory neurons in spinal cord bypassing the brainstem
breaking point
when CO2 levels rise to a point where automatic controls override one’s voluntary will
respiratory airflow is governed by
the same principles of flow, pressure, and resistance as blood flow
the flow of a fluid is ___ to the pressure difference between two points
directly proportional
the flow of fluid is ____ to the resistance
indirectly proportional
atmospheric pressure
the weight of the air above us
what is the atmospheric pressure at sea level
- 760 mmHg
- 1 atm
_____ atmospheric pressure at higher elevations
lower
intrapulmonary pressure
air pressure within lungs
intrapulmonary pressure changes with ___
lung volume
Boyle’s Law
- governs air flow into and out of the lungs
- at constant temp the pressure of a given quantity of gas is inversely proportional to its volume
if lung volume increases what happens to intrapulmonary pressure
it decreases
if the pressure inside the lungs falls below atm pressure
air moves into the lungs
if lung volume decreases intrapulmonary pressure
increases
if lung pressure rises above atm pressure
air moves out of the lungs
during inspiration what happens
the lungs expand and follow the expansion of the thoracic cage because of intrapleural pressure
intrapleural pressure
slightly negative pressure that exists between the two pleural layers
recoil of lung tissue and tissues of the thoracic cage causes
lungs and chest wall to be pulling in opposite direction
about ____ if intrapleural pressure results from layers of pleura staying together
-5 cm H2O
in quiet breathing
thoracic cage increases only a few mm in each direction
during inspiration, the visceral pleura does what?
stretches the alveoli near surface of lungs which are coupled to deeper alveoli which get pulled too
as alveoli increases in volume
the intrapulmonary pressure drops below atm pressure
what is another force that expands lungs during inspiration?
warming of inhaled air
Charles’s Law
the volume of a gas is directly proportional to its absolute temp
on a cool day 60°F air will do what during inspiration
increase its temp by 39°F
inhaled air is warmed to _____ by the time it reached the alveoli
99°F
inhaled volume of 500ml will expand to 536ml. what does this do to the lungs?
contribute to inflation of the lungs
passive process in quiet expiration is achieved by
mainly by elastic recoil of thoracic cage which compresses the lungs
expiration does what to intrapulmonary pressure
raises to about +1cm H2O
in a normal lung the intrapulmonary pressure is always
negative in both inspiration and expiration
pneumothorax (3)
- presence of air in the pleural cavity
- thoracic wall is punctured
- inspiration sucks air through the wound into pleural cavity
what happens to the potential space during a pneumothorax
becomes an air-filled cavity causing the loss of negative intrapleural pressure allowing the lung to recoil and collapse
atelectasis
collapse of part or all of a lung
what can a collapsed lung result from (physiological)
from an airway obstruction as blood absorbs gases from the alveoli causing a decrease in alveolar volume and subsequent alveolar collapse
a collapsed lung can be caused by (diseases) (4)
- lung tumor
- aneurysm
- swollen lymph nodes
- aspirated objects into the airway
what two factors influence airway resistence
bronchiole diameter and pulmonary compliance
bronchodilation
increase in diameter of bronchus or bronchiole
bronchoconstriction
decrease in diameter of bronchus or bronchiole
pulmonary compliance (2)
- ease with which the lungs can expand
- change in long volume relative to a given pressure change
pulmonary compliance is reduced in
degenerative lung disease in which the lungs are stiffened to scar tissue
what are two examples of degenerative lung diseases where the tissue is turned to scar tissue
- TB
- black lung disease
pulmonary compliance is limited by
surface tension of water inside alveoli
what does surfactant do in the alveoli
disrupts hydrogen bonds between water molecules and thus reduced surface tension making ti easier to fill with air
infant respiratory distress syndrome (IRDS)
premature babies lacking surfactant are treated with artificial surfactant until they can make with own
only about ____ of air fills the conducting zone of the airway
150ml
anatomical dead space
the space in the conducting zone where there is no gas exchange
the anatomical dead space can be altered by ______ which increases what?
- sympathetic dilation
- flow into the lungs
spirometry
measuring pulmonary ventilation
what aid in the diagnosis of and assessment of restrictive/obstructive lung disease
spirometry
restrictive disorders of the lungs (2)
- reduction in pulmonary compliance and limit how much lungs can inflate
- any disease that produces pulmonary fibrosis
black lung and TB are what kind of lung disease
restrictive
obstructive disorders of the lungs (2)
- interfere with airflow by narrowing or blocking the airway
- make it harder to inhale or exhale a given amount of air
asthma and chronic bronchitis are examples of what kind of lung disease
obstructive
____ combines elements of both restrictive and obstructive disorders of the lungs
emphysema
eupnea
relaxed, quiet breathing
apnea
temporary cessation of breathing
dyspnea
- labored, gasping breathing
- shortness of breath
hyperpnea
increase rate and depth of breathing in response to exercise, pain, or other condition
hyperventilation
increase pulmonary ventilation in excess of metabolic demand
hypoventilation
reduced pulmonary ventilation leading to an increase in blood CO2
Kussmaul respiration
deep, rapid breathing often induced by acidosis or diabetes-related ketoacidosis
atmospheric air contains (4)
- 78.6% nitrogen
- 20.9% oxygen
- 0.04% carbon dioxide
- 0-4% water vapor depending on temp and humidity
atmospheric air contains minor amounts of what? (5)
- argon
- neon
- helium
- methane
- ozone
dalton’s law
total atmospheric pressure is the sum of the contributions of the individual gases
partial pressure
separate contribution of each gas in a mixture
how is air humidified during inspiration? how much is it humidified by the time it reaches the alveoli?
- contact with mucous membranes
- 10x
the composition of inspired air and alveolar air differ because of what three influences?
- air is humidified by contact with mucous membranes
- alveolar air mixes with residual air
- alveolar air exchanges O2 and CO2 with blood
the partial pressure of O2 in alveolar air is ____ that of inspired air
65%
the partial pressure of CO2 in alveolar air is ____ (higher/lower) than that of inspired air
130x
alveolar gas exchange
- the movement of O2 and CO2 across the respiratory membrane
- air in the alveolus is in contact with a film of water covering the alveolar epithelium
for oxygen to get into the blood what must happen?
it must dissolve in the water covering the alveolar epithelium and pass through the respiratory membrane separating the air from the bloodstream
for carbon dioxide to leave the blood what must happen
it must pass the other direction as O2 and then diffuse out of the water film into the alveolar air
gas diffuses…until…
down their own concentration gradient until the partial pressure of each gas in the air is equal to its partial pressure in the water
henry’s law
at the air-water interface for a given temp the amount of gas that dissolved in the water is determined by its solubility in water and its partial pressure in air
the greater the partial pressure of O2 in the alveolar air
the more O2 the blood picks up
since the blood arriving at the alveolus has a higher ppCO2 than air what happens
blood releases CO2 into the air
the efficiency in unloading CO2 and loading O2 on the erythrocytes depends on
how long an RBC stays in alveolar capillaries
how much time is required to reach equilibrium of O2 and CO2 pp
0.25 sec
at rest how much time do RBCs stay in the alveolar capillaries
0.75 sec
in strenuous exercise how long do RBCs stay in the alveolar capillaries
0.3 sec
each gas in an air mixture acts (independently/dependently) of the other gases in the mixture
independently
what variables affect alveolar gas exchange (5)
- pressure gradients of the gases
- solubility of the gases
- membrane surface area
- membrane thickness
- ventilation-perfusion coupling
what is the normal ppO2 in alveolar air vs in the blood
104mmHg in alveolar air and 40mmHg in blood
what is the normal ppCO2 in alveolar air vs in the blood
46mmHg in the blood and 40mmHg in alveolar air
pressure gradients of gases differ when (2)
- at higher altitudes
- hyperbaric oxygen therapy
at high elevations what happens to pp of atm gases? pressure gradient of oxygen?
- atm: lower
- O2: lower so less diffuse into blood
hyperbaric oxygen therapy
treatment of oxygen at greater than 1 atm of pressure
what happens to the gradients of oxygen in hyperbaric oxygen therapy
larger gradient so more oxygen diffuses into the blood
what is hyperbaric oxygen therapy used to treat
- gangrene
- CO poisoning
by the time blood reaches the left atrium what is the ppO2? what is it caused by?
- 95mmHg
- mixing of oxygenated blood from the pulmonary vein with deoxygenated blood from the bronchial vein
what are the pp of O2 and CO2 of blood when it reaches the tissues
- O2: 95mmHg
- CO2: 40mmHg
what is the ppO2 and ppCO2 in the tissue?
- O2: 40 mmHg
- CO2: 46mmHg
what happens during gas exchange in tissues
O2 is driven to tissue while CO2 is driven to blood so that venous blood leaving will have ppO2 of 40mmHg and ppCO2 of 46mmHg
CO2 if ___ as soluble as O2
20x
why are equal amounts of O2 and CO2 exchanged across the respiratory membrane
because CO2 is much more soluble and diffuses more rapidly
what three diseases of the lungs decrease surface area for gas exchange?
- emphysema
- lung cancer
- TB
what is the surface area of alveoli across the lungs
70m^2
the respiratory membrane is hoe thick?
only 0.5um
when membranes fo rgas exchange are thicker what happens?
gases have to travel farther between blood and air and cannot equilibrate fast enough to keep up with blood flow
what two diseases of the lungs thicken the respiratory membrane
- pulmonary edema
- pneumonia
ventilation perfusion coupling
- air flow and blood flow are matched to each other
- gas exchange requires both good perfusion and good ventilation of the capillaries
_____ change diameter depending on air flow to an area of the lungs
pulmonary blood vessels
_____ change diameter depending on blood flow to an area of the lungs
bronchi
gas transport
process of carrying gases from the alveoli to the systemic tissues and vice versa
arterial blood carries ____ of O2
20ml/deciliter
what are the two ways O2 is transported in the blood and what percentage O2 moves that way?
- 98.5% bound to hemoglobin
- 1.5% dissolved in plasma
how many components are there in a hemoglobin molecule?
four
what are the two parts of each component in hemoglobin?
- globin (protein) chain
- heme group
each heme group can bind ___ O2 to what?
- one
- a ferrous group (Fe2+)
oxyhemoglobin
O2 bound to hemoglobin
deoxyhemoglobin
hemoglobin with no O2
oxyhemoglobin dissociation curve
illustrates relationship between hemoglobin saturation and ambient ppO2
is the hemoglobin dissociation curve linear?
no
what happens to O2 saturation at low ppO2
curve rises slowly then rapid increase in oxygen loading as ppO2 rises farther
why is there an observed rapid increase in O2 loading at low ppO2?
because when hemoglobin binds each other oxygen it makes it easier to bind the next one
what happens to O2 saturation when there is a high ppO2
the curve levels off because hemoglobin approaches 100% saturation and cannot load much more O2
what are the three forms in which CO2 is transported and what percentage of CO2 is transported that way?
- 90% bicarbonate
- 5% carbaminohemoglobin
- 5% dissolved gas
what is the reaction that changes CO2 to bicarbonate
CO2 + H2O -> H2CO3 -> HCO3- + H+
where does the bicarbonate reaction occur?
inside the erythrocytes
carbaminohemoglobin
CO2 bound to hemoglobin
does CO2 compete with O2 to bind to hemoglobin? why?
no because they bind to different moieties
what are the relative amounts of CO2 exchanged between the blood and alveolar air?
- 70% carbonic acid
- 23% carbaminohemoglobin
- 7% dissolved in plasma
what is the hardest form of CO2 in the body to get CO2 from?
bicarbonate
carbon monoxide (CO)
colorless, odorless gas in cigarette smoke, engine exhaust, and fumes from gas furnaces
does CO compete with O2 to bind? why?
yes because it binds to the iron in hemoglobin where O2 binds
carboxyhemoglobin
carbon monoxide bound to hemoglobin
CO binds up to ____ tightly as O2
210x
what is the percentage of CO bound to hemoglobin in a non-smoker?
less than 1.5%
what is the amount of CO bound to hemoglobin in heavy smokers?
10%
what are the treatments for CO poisoning?
- pure oxygen
- hyperbaric oxygen therapy
- blood transfusion
systemic gas exchange
unloading of O2 and loading of CO2 at systemic capillaries
carbonic anhydrase
catalyzes reaction to bicarbonate and hydrogen ions
chloride shift
bicarbonate pumped out of RBC in exchange for chloride ion from plasma
what performs the chloride shift?
chloride-bicarbonate exchanger (antiport protein)
what is the purpose of the chloride shift
- keep the carbonic anhydrase reaction going
- H+ binds to hemoglobin
how is hemoglobin made to let go of O2 during oxygen unloading
- H+ binding to HbO2 reduced its affinity for O2
- O2 moving down its pressure gradient
HbO2 arrives at systemic capillaries ___ saturated and leaves ___ saturated
- 97%
- 75%
utilization coefficient
the giving up of 22% of O2 load by hemoglobin during oxygen unloading
what are the three steps of CO2 unloading in the lungs
- as Hb loads O2, H+ affinity decreases and binds to HCO3-
- reverse carbonic anhydrase
- reverse chloride shift
what is a reverse chloride shift
- HCO3- diffuses back into RBC in exchange for Cl-
- free CO2 is generated and diffuses into alveolus to be exhaled
hemoglobin unloads O2 to match
metabolic needs
four factors that adjust rate of O2 unloading to match need: ambient ppO2
- active tissue has low ppO2
- O2 released from Hb
what are the four factors that adjust rate of O2 unloading to match need?
- ambient ppO2
- temp
- ambient pH
-BPG
four factors that adjust rate of O2 unloading to match need: temperature
active tissue had high temp and promotes O2 unloading
four factors that adjust rate of O2 unloading to match need: ambient pH
active tissue has high CO2 which lowers pH and promotes O2 unloading
what is it called when active tissue has high CO2 which lowers pH and promotes O2 unloading
the bohr effect
four factors that adjust rate of O2 unloading to match need: BPG
RBCs produce biphosphoglycerate which binds to Hb and promotes O2 unloading
what raises BPG levels?
- high body temp
- thyroxine
- GH
- testoterone
- epinephrine
higher temp causes a shift to the ___ of the O2 dissociation curve
right
lower temp causes a ____ shift in the O2 dissociation curve
left
shift to the right of the O2 dissociation curve causes ___ and a shift to the left causes ____
- more O2 release from Hb
- less O2 release from hemoglobin
lower pH shifts the O2 dissociation curve to the
right
higher pH shifts the O2 dissociation curve to the
left
