Lesson 13-14a Part 2 - Respiratory System Flashcards
breathing depends on…
repetitive stimulation of skeletal muscles from the brain
breathing is controlled at two levels of the brain
- one is cerebral and conscious
- other is unconscious and automatic
automatic, unconscious breathing is controlled by…
respiratory
two pairs of respiratory centers are located where?
medulla oblongata?
which respiratory center is the primary generator of the respiratory rhythm?
ventral respiratory group (VRG)
where is the ventral respiratory group (VRG) located?
medulla oblongata
the ventral respiratory group (VRG) is a collection of reverberating circuits of…
- inspiratory (I) neurons
- expiratory (E) neurons
what rhythm does the VRG produce?
12 breaths per minute
the dorsal respiratory group (DRG) is also called…
the inspiratory center
what does the inspiratory center stimulate?
inspiratory muscles
which respiratory group functions in both quiet and forced breathing?
dorsal respiratory group (DRG)
the dorsal respiratory group (DRG) modifies what? how?
(1) the rate and depth of breathing by (2) affecting the VRG
the dorsal respiratory group receives influence from…(4)
external sources like the pons, medulla, receptors in the lungs, and higher brain centers
central chemoreceptors
brainstem neurons that respond to changes in pH of cerebrospinal fluid (CSF)
the pH of cerebrospinal fluid reflects what?
the CO2 level in the blood
the lower the pH in the CSF the……in blood?
more CO2 in blood
central chemoreceptors regulate respiration to maintain…(2)
stable pH/stable CO2 levels in blood
where are peripheral chemoreceptors?
carotid and aortic bodies
what do peripheral chemoreceptors respond to? (3)
O2 and CO2 content and the pH of blood
stretch receptors are located where in the lungs? (2)
- smooth muscle of bronchi and bronchioles
- visceral pleura
what do stretch receptors in the lungs respond to?
inflation of the lungs
inflation (Hering-Breuer) reflex
protective reflex that inhibits inspiratory neurons and stops inspiration to stop excessive inflation/stretching of lung tissue
what is the Hering-Breuer reflex triggered by?
excessive inflation
irritant receptors
nerve endings amid the epithelial cells of the airway
irritant receptors respond to (6)
- smoke
- dust
- pollen
- chemical fumes
- cold air
- excess mucus
irritant receptors trigger protective reflexes such as…(4)
- bronchoconstriction
- shallower breathing
- breath-holding
- coughin
apnea
breath-holding
where does voluntary control over breathing originate?
in the motor cortex of the frontal lobe of the cerebrum
what does the motor cortex of the frontal lobe of the cerebrum send?
impulses down corticospinal tracts to respiratory neurons in the spinal cord, bypassing the brainstem
the 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 slow, pressure, and resistance as blood flow
the flow of a fluid is _____ proportional to the pressure difference between two points
directly
the flow of fluid is _____ proportional to the resistance
inversely
atmospheric (barometric) pressure
the weight of the air above us
where is atmospheric pressure lower?
higher elevations
intrapulmonary pressure
air pressure within the lungs
intrapulmonary pressure changes with lung volume according to what law?
Boyle’s law
- P = 1/V
Boyle’s Law
at a constant temperature, the pressure of a given quantity of gas is inversely proportional to its volume
- P = 1/V
if the lungs contain a quantity of gas, and the lung volume increases, what happens to internal pressure?
it falls
what happens if the intrapulmonary pressure falls below atmospheric pressure?
air moves into the lungs
what happens if intrapulmonary pressure rises above atmospheric pressure?
air moved out of the lungs
during inspiration, the lungs expand and…
follows the expansion of the thoracic cage due to the intrapleural pressure
intrapleural pressure
the slightly negative pressure that exists between the two pleural layers (parietal and viseral)
what causes the lungs and chest wall to be pulled in opposite directions? (2)
(1) recoil of lung tissue and (2) tissues of the thoracic cage
the potential space between the parietal and visceral pleurae contains?
a small amount of watery serous fluid called pleural fluid
how do the layers of the pleura stay together?
cohesion of water
what happens to the pleura when the ribs swing upward/outward during inspiration?
the pleura follows!
in quiet breathing , the thoracic cage moves a few _____ in each direction, which is enough to increase its volume by 500ml
mm (millimeter)
the _____ pleura clings to and follows the _____ pleura
visceral, parietal
what happens when the visceral pleura stretches?
the alveoli near the surface of the lungs stretches, and because they are coupled to deeper alveoli they got pulled too
as alveoli increase volume, the ______ (______) pressure drops below atmospheric pressure
intrapulmonary (alveolar)
another force that expands lungs is…
the warming of inhaled air
Charles’s Law
the volume of a gas is directly proportional to its absolute temperature
is expiration a passive or active process in quiet expiration?
passive
how is expiration achieved in quiet expiration?
mainly by elastic recoil of the thoracic cage
elastic recoil of the thoracic cage _____ the lungs
compresses
in normal lungs, the intrapleural pressure is always _____ in both inhalation and exhalation
negative
pneumothorax
presence of air in the pleural cavity
describe how a pneumothorax occurs (2)
- thoracic wall is punctured
- inspiration sucks air through the wound into the pleural cavity
the potential space a pneumothorax creates causes what?
an air-filled cavity causing the loss of negative intrapleural pressure allowing the lungs to recoil and collapse
atelectasis
collapse of part of all of a lung
potential causes of atelectasis (4)
- lung tumor
- aneurysm
- swollen lymph node
- aspirated object into airways
how does an aspirated object lead to atelectasis?
an airway obstruction causes blood to absorb gases from the alveoli causing a decrease in alveolar volume and subsequent alveolar collapse
two factors influence airway resistance
- bronchiole diameter
- pulmonary compliance
bronchodilation
increase in diameter of bronchus or bronchiole
bronchoconstriction
decrease in diameter of bronchus or bronchiole
pulmonary compliance
ease with which the lungs can expand; change in lung volume relative to a given pressure change
compliance is reduced by…
degenerative lung diseases in which the lungs are stiffened by scar tissue
lung diseases that cause scar tissue (2)
- tuberculosis
- black lung disease
compliance of the lungs is limited by…
the surface tension of the water film inside the alveoli
what does surfactant do?
disrupts hydrogen bonds between water molecules and thus reduces the surface tension, making them easier to fill with air
surfactant is secreted by..
great cells of the alveoli
infant respiratory distress syndrome (IRDS)
premature babies lacking surfactant are treated with artificial surfactant until they can make their own
what air is available for gas exchange?
the air that enters the alveoli
about how much air fills the conducting zone of the airway?
150ml
anatomical dead space
the conducting zone of the respiratory system in which no gas exchange occurs
the anatomical dead space can be altered somewhat by what?
sympathetic dilation which increases dead space but allows greater flow
spirometry
measuring pulmonary ventilation
spirometry aids in what?
diagnosis and assessment of restrictive and obstructive lung disorders
restrictive disorders include (3)
- black lung disease
- tuberculosis
- any disease that produces pulmonary fibrosis
restrictive disorders
reduction in pulmonary compliance, limiting how much lungs can inflate
obstructive disorders of the lungs
interfere with airflow by narrowing or blocking the airway making it harder to inhale or exhale a given amount of air
obstructive disorders include (2)
- asthma
- chronic bronchitis
_____ bombines both elements of both restrictive and obstructive disorders
emphysema
eupnea
relaxed, quiet breathing
apnea
temporary cessation of breathing
dyspnea
labored, gasping breath/shortness of breath
hyperpnea
increased rate and depth of breathing in response to exercise, pain, or other conditions
hyperventilation
increased 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, diabetes-related ketoacidosis
air contains
- 78.6% nitrogen
- 20.9% oxygen
- 0.04% carbon dioxide
- 0-4% water vapor
air contains minor amounts of…(5)
- argon
- neon
- helium
- methane
- ozone
Dalton’s Law
total atmospheric pressure in the sum of the contributions of the individual gases
partial pressure
the separate contribution of each gas in a mixture
composition of inspired and alveolar air differs because of three influences
- air is humidified by contact with mucus membranes
- alveolar air mixes with residual air
- alveolar air exchanges O2 and CO2 with blood
air is humidified by contact with mucous membranes
alveolar PH2O is more than 10x higher than inhaled air
alveolar air mixed with residual air
oxygen gets diluted and air is enriched with CO2
alveolar air exchanges O2 and CO2 with blood (2)
- PO2 of alveolar air is about 65% that of inspired air
- PCO2 is more than 130x higher
alveolar gas exchange
the movement of O2 and CO2 across the respiratory membrane
for oxygen to get into the blood, it must…
dissolve in the alveolar epithelium (water) and pass through the respiratory membrane separating the air from the bloodstream
for carbon dioxide to leave the blood, it must…
pass the other way and then diffuse out of the water film into the alveolar air
gases diffuse down their own gradients until…
the partial pressure of each gas in the air is equal to its partial pressure in water
what is the first step in alveolar gas exchange?
air in the alveolus is in contact with a film of water covering the alveolar epithelium
Henry’s Law
at the air-water interface, for a given temperature, the amount of gas that dissolves in the water is determined by its solubility in water and its partial pressure in air
the _____ the PO2 in the alveolar air, the ____ O2 the blood picks up
greater, more
because the blood arriving at the alveolus has…
a higher PCO2 than air, so it releases the CO2 in the air
at the alveolus, the blood is said to
unload CO2 and load O2
the unloading of CO2 and loading involves…
erythrocytes
efficiency of the alveolar gas exchange depends on…
how long an RBC stays in the alveolar capillaries
how long does a RBC need to stay in the alveolar capillaries to reach equilibrium?
0.25 seconds
at rest, RBC spend _____ seconds in the alveolar capillaries
0.75
in strenuous exercise, RBCs stay for ___ seconds
0.3
each gas in a mixture behaves _____
independently, one gas does not influence the diffusion of another
variables affecting alveolar gas exchange efficiency (5)
- membrane thickness
- membrane surface area
- solubility of gases
- pressure gradients of the gases
- ventilation-perfusion coupling
normally, the PO2 is…
= 104 mmHg in the alveolar air versus 40 mmHg in blood
normally, the PCO2 is…
= 46 mmHg in blood arriving versus 40 mmHg in blood arriving versus 40 mmHg in alveolar air
how do pressure gradients differ at high altitudes?
partial pressure of all atmospheric gases are lower; pressure gradient for oxygen is lower so less diffuses into blood
hyperbaric oxygen therapy
treatment with oxygen at greater than 1 atm of pressure
what is hyperbaric oxygen therapy used for? (2)
- gangrene
- carbon monoxide poisoning
by the time blood reaches the left atrium, the PO2 is…
95 mmHg
why is PO2 95 mmHg by the time it reaches the left atrium?
caused by a mixing of oxygenated blood from the pulmonary vein with deoxygenated blood from the bronchial vein
variables affecting alveolar gas exchange efficiency: solubility of gases
equal amounts of O2 and CO2 are exchanged across the respiratory membrane because CO2 is much more soluble and diffuses more rapidly
CO2 is _____ time as soluble as O2
20
what disease decrease surface area for gas exchange? (3)
- emphysema
- lung cancer
- tuberculosis
the respiratory membrane is only _____ thick
0.5um
what would happen if the respiratory membrane was thicker?
gases have father to travel between blood and air and cannot equilibrate fast enough to keep up with blood flow
what diseases cause thickening of the respiratory membrane? (2)
- pulmonary edema
- pneumonia
ventilation-perfusion coupling
gas exchange requires both good ventilation of alveolus and good perfusion of the capillaries
pulmonary blood vessels change diameter depending on…
air flow to an area of the lungs
bronchi change diameter depending on…
blood flow to an area of the lungs
if an area of the lungs is well perfused, what occurs?
bronchodilation
gas transport
the process of carrying gases from the alveoli to the systemic tissues and vice versa
how much O2 does blood carry?
20ml of O2 per deciliter
what molecule is specialized for oxygen transport?
hemoglobin
oxyhemoglobin (HbO2)
O2 bound to hemoglobin
deoxyhemoglobin (HHb)
hemoglobin with no O2
oxyhemoglobin dissociation curve
illustrates relationship between hemoglobin saturation and ambient PO2
why does the oxyhemoglobin dissociation curve look the way it does?
occurs because when hemoglobin binds each oxygen, it makes it easier to bind the next one
three forms in which carbon dioxide is transported in the body
- carbonic acid
- carbaminohemoglobin
- dissolved gas
90% of CO2 is carried as…
carbonic acid (H2CO3)
5% of carbon dioxide is carried as either…(2)
dissolved gas or carbaminohemoglobin
70% of exchanged CO2 comes from what form of CO2?
carbonic acid
23% of exchanged CO2 comes from what form of CO2?
carbaminohemoglobin
7% of exchanged CO2 comes from what form of CO2?
dissolved in plasma
blood gives up the dissolved CO2 gas and CO2 from _____ more easily than CO2 in _____
carbaminohemoglobin, bicarbonate
carbon monoxide (CO)
colorless, odorless gas in cigarette smoke, engine exhaust, and fumes from gas furnaces
_____ competes for the O2 binding site on hemoglobin (Hb)
carbon monoxide
what is hemoglobin called when carbon monoxide binds to it?
carboxyhemoglobin (HbCO)
does CO or O2 bind to hemoglobin more tightly?
CO
treatment for CO binding to Hb in smokers (3)
- pure oxygen
- hyperbaric oxygen therapy
- blood transfusion
systemic gas exchange
unloading of O2 and loading of CO2 at systemic capillaries
carbon dioxide loading (2)
- CO2 diffuses into the blood
- carbonic anhydrase catalyzes the reaction to bicarbonate and hydrogen ions
where is carbonic anhydrase found?
red blood cells
chloride shift
bicarbonate pumped out of RBC in exchange for a chloride ion from plasma
how is the chloride shift performed?
an antiport protein called the chloride-bicarbonate exchanger
H+ binding to _____ reduces its affinity for O2
HbO2 (oxyhemoglobin); tends to make hemoglobin release oxygen
HbO2 arrives at systemic capillaries _____% saturated and leave _____% saturated
97, 75
utilization coefficient
22% of HbO2’s load is given up
gas exchange reactions that occur in the lungs are _____ of systemic gas exchange
reverse
CO2 unloading in the lungs
as Hb loads O2, its affinity for H+ decreases causing it to dissociate from Hb and bind with HCO3-
reverse chloride shift
HCO3- diffuses back into RBC in exchange for Cl-, free CO2 that is generated diffuses into alveolus to be exhaled
hemoglobin unloads O2 to match….
metabolic needs of different states of activity of the tissues
four factors that adjust the rate of O2 unloading to match need
- ambient PO2
- temperature
- ambient pH
- BPG
four factors that adjust the rate of O2 unloading to match need: ambient PO2
active tissues have a low PO2 causing Hb to release O2
four factors that adjust the rate of O2 unloading to match need: temperature
active tissues have a higher temperature that promotes Hb to unload O2
four factors that adjust the rate of O2 unloading to match need: ambient pH
active tissue pH is higher due to higher concentrations of CO2, lowering blood pH which promotes unloading of O2
Bohr effect
describes hemoglobin’s lower affinity for oxygen secondary to increases in the partial pressure of carbon dioxide and/or decreased blood pH
four factors that adjust the rate of O2 unloading to match need: BPG
RBCs produce a metabolic intermediate of anaerobic metabolism called BPG which binds to Hb, unloading O2 in the process
BPG aka
bisphosphoglycerate
factors that raise BPG and promote O2 unloading (5)
- raised body temp (fever)
- thyroxine
- growth hormone
- testosterone
- epinephrine
describe the effect of temperature on HbO2
as temperature increases, more Hb unloads O2
describe the effect of pH on HbO2
as pH lowers, HbO2 releases more O2
