Respiratory System II Flashcards
Gas composition in the alveoli determines rate of __ and ___ diffusion between alveoli and capillaries
O2, CO2
PO2 and PCO2 remain relatively constant during _____ respiration
quiet
Alterations in ventilation rate independent of changes in the CV system will alter partial pressures of O2 and CO2, thus altering _____
diffusion
As alveolar ventilation increases, alveolar ___ increases and ___ decreases. The opposite occurs as alveolar ventilation decreases
Po2, Pco2
Ventilation and alveolar blood flow (perfusion) are ____
matched
What is the first step of external respiration?
Bringing O2 from the atmosphere into the alveoli
More negative intrapleural pressure due to gravity at apex means alveoli are _____ open and filled even at rest and therefore ?
partially, do not take in much air during ventilation
_____ helps to ensure that ventilation and perfusion is matched within larger sections of the lung
Gravity
Blood pressure is the highest at the ___ of the lung
base
Ventilation is highest at the ___ of the lung
base
Perfusion is ______ at the apex, ______ in the middle, and _____ at the base of the lung
absent, sporadic, constant
There is very _____ autonomic innervation of the pulmonary arterioles
little
Pulmonary arterioles primarily influenced by decreasing ___ levels around them
O2
In the pulmonary arterioles, decreases in O2 cause ______.
Low O2→___ channel closure →________
constriction, K+, depolarization
Bronchioles are sensitive to ____ levels, increases causes _____ or decreases causes _____
CO2, dilation, constriction
If ventilation decreases in a group of alveoli, Pco2 _____ and Po2 _____. Blood flowing past those alveoli does not get ______
increases, decreases, oxygenated
Decreases tissue Po2 around under-ventilated alveoli _____ their arterioles, diverting blood to better ventilated alveoli
constricts
When Pco2 increases, the bronchioles _____, when Pco2 decreases, the bronchioles ____
dilate, constrict
When Po2 decreases, the pulmonary arteries ____
constrict
Arteriole smooth muscle sensitive to decreases in O2 and _____
constricts
What is hypoxia?
Too little oxygen
What is hypoxia often paired with? and what is it?
Hypercapnia, excess CO2
Hypercapnia causes ___ level changes in your body which can cause proteins to ____ and ?
pH, unfold, irregular cellular function
Order these statements according to “pulmonary gas exchange and transport:”
1. Oxygen is transported in blood dissolved in plasma or bound to hemoglobin inside RBCs
2. Oxygen diffuses into cells
3. CO2 enters alveoli at alveolar-capillary interface
4. CO2 diffuses out of cells
5. Oxygen enters the blood at alveolar-capillary interface
6. CO2 is transported dissolved, bound to hemoglobin, or as HCO3-
5, 1, 2, 4, 6, 3
To avoid hypoxia and hypercapnia the body has sensors to monitor the arterial blood and respond to three variables: ?
Oxygen: ATP production
Carbon dioxide: CNS depressant/ acid precursor
pH: denaturing of protein
What is the normal systemic blood value for Po2?
Arterial: ?
Venous: ?
Arterial: 95 mmHg (85-100)
Venous: 40 mmHg
What is the normal systemic blood value for Pco2?
Arterial: ?
Venous: ?
Arterial: 40 mmHg (35-45)
Venous: 46 mmHg
What is the normal systemic blood value for pH?
Arterial: ?
Venous: ?
Arterial: 7.4 (7.38-7.42)
Venous: 7.37
What is the definition and typical causes of Hypoxic hypoxia?
Definition: considered widespread (the whole body), low arterial Po2
Causes: high altitude, alveolar hyperventilation, decreased lung diffusion capacity, abnormal ventilation-perfusion ratio
What is the definition and typical causes of Anemic hypoxia?
Definition: decreased total amount of O2 bound to hemoglobin
Causes: blood loss, anemia, carbon monoxide poisoning
What is the definition and typical causes of Ischemic hypoxia?
Definition: reduced blood flow
Causes: heart failure (whole body hypoxia), shock (peripheral hypoxia), thrombosis (localized hypoxia)
What is the definition and typical causes of Histotoxic hypoxia?
Definition: failure of cells to use O2 because cells have been poisoned
Causes: cyanide and other metabolic poisons
In the alveoli:
Po2 = ____ mmHg
Pco2 = ____ mmHg
Po2 = 100 mmHg
Pco2 = 40 mmHg
In the arterial blood:
Po2 = ____ mmHg
Pco2 = ____ mmHg
Po2 = 100 mmHg
Pco2 = 40 mmHg
In the cells:
Po2 ≤ ____ mmHg
Pco2 ≥ ____ mmHg
Po2 ≤ 40 mmHg
Pco2 ≥ 46 mmHg
In the venous blood:
Po2 ≤ ____ mmHg
Pco2 ≥ ____ mmHg
Po2 ≤ 40 mmHg
Pco2 ≥ 46 mmHg
Alveolar gas exchange is influenced by 3 variables: ?
- O2 reaching the alveoli
- Gas diffusion between alveoli and blood
- Adequate perfusion of alveoli
O2 reaching the alveoli is influenced by 2 variables: ?
Composition of inspired air, and alveolar ventilation
Alveolar ventilation is influenced by 3 variables: ?
Rate and depth of breathing
Airway resistance
Lung compliance
Gas diffusion between alveoli and blood is influenced by 2 variables: ?
Surface area and diffusion distance
Diffusion distance is influenced by 2 variables: ?
Barrier thickness and amount of fluid
________ _______ is a major cause of opioid overdoses, as it shuts down the respiratory center
Alveolar ventilation
If atmospheric PO2 normal and alveolar PO2 still low then it must be a ______ issue (hypoventilation).
ventilation
What 4 variables are going to affect the random movement of gas molecules between the alveoli and capillaries?
- Concentration gradient
- Surface area
- Barrier permeability/solubility of gas
- Diffusion distance
Technically when we are looking at the concentration gradient of gases, we are referring to _____ ____ gradients
partial pressure
Diffusion rate ∝ ______ ____ × _____ _____ × ______ _____
surface area, concentration gradient, barrier permeability
Diffusion rate ∝ 1 / _______^2
distance
Under normal conditions surface area, diffusion distance and barrier permeability are ______
constant
In a healthy individual concentration gradient is variable and the main determinant of _____
diffusion
______: destruction of alveoli means less surface area for gas exchange
Emphysema
______ _____ _____: thickened alveolar membrane slows gas exchange. Loss of lung compliance may decrease alveolar ventilation. Aka decreased barrier permeability
Fibrotic lung disease
_______ _____: fluid in interstitial space increases diffusion distance. Arterial Pco2 may be normal due to higher CO2 solubility in water
Pulmonary edema
______: increased airway resistance decreases alveolar ventilation, aka decreased concentration gradient
Asthma
The movement of gas molecules from air to liquid is directly proportional to three factors: ?
The pressure gradient of the gas
Solubility of gas in liquid
Temperature-relatively constant
CO2 is very soluble, _____ diffusion distance doesn’t affect PCO2
increased
Why do we use partial pressure gradient and not concentration gradient when referring to gases?
Because oxygen is not readily soluble in liquid
Usually when you have hypoxia you have hypercapnia, but what pathology is an exception?
pulmonary edema
Oxygen transport in circulation and oxygen consumption by tissues illustrate the general principles of ____ ___ (movement of X per minute) and ____ ______ (any substance in the body must remain constant).
mass flow, mass balance
How to calculate Mass Flow?
O2 transport = CO × O2 concentration
How to calculate Mass Balance?
Qo2 = Arterial O2 transport - Venous O2 transport
What is the Fick Equation?
Qo2 = CO × (Arterial [O2] - Venous [O2])
What is Qo2?
Cellular oxygen consumption, or O2 consumption by systemic tissues
Generally, we only use about ___ of the oxygen brought to us
25%
More than __% of the oxygen in blood is bound to hemoglobin in RBCs, and less than __% is dissolved in plasma
98, 2
Within each globin protein there is a ____ group which is has perforin ring with an iron atom in the center that oxygen can reversibly bind to
heme
Each heme group can bind __ globulins
4
Oxygen binding obeys the law of ___ ____
mass action
As the concentration of free O2 increases, more oxygen binds to Hb producing ____. Free O2 will be taken up until the plasma and Hb reach _____ for that given partial pressure of oxygen that it is exposed to
HbO2, equilibrium
Transfer of O2 from alveoli air, to plasma, to red blood cells, onto hemoglobin occurs very ____
rapidly
Blood travels to the tissues that have a low ____, this draws O2 out of the plasma, which disrupts the equilibrium and causes Hb to release its O2 into the ____
PO2, plasma
_______ ensure that equilibrium is not reached right away because it would be and would cause inadequate amounts of oxygen
Hemoglobin
At rest we consume about ___ml O2/min
250
Plasma O2 is determined by alveolar PO2 which depends on 3 variables: ?
Composition of inspired air
Alveolar ventilation rate
Efficiency of gas exchange
The amount of oxygen bound to hemoglobin depends on 2 variables: ?
Plasma O2 and Amount of hemoglobin
The amount of oxygen bound to hemoglobin depends on plasma O2, which determines ?
% saturation of hemoglobin
The amount of oxygen bound to hemoglobin depends on amount of hemoglobin, which determines ?
Total number of Hemoglobin binding sites
Total number of Hemoglobin binding sites is calculated from?
Hemoglobin content per RBC × Number of RBCs
Individuals whom have lost a lot of blood need transfusion to replace _______
hemoglobin
The amount of O2 bound to hemoglobin at any given PO2 is expressed as the ?
% saturation of hemoglobin
The oxyhemoglobin saturation curve is determined in ____ the laboratory
vitro
In the Oxygen-Hemoglobin binding curve, a resting cell at 40 mmHg has a hemoglobin saturation % of ___?
~75%
In the Oxygen-Hemoglobin binding curve, alveoli at 100 mmHg have a hemoglobin saturation % of ___?
~98%
____ cells can have a lower PO2
Active
What are the 4 physical factors altering hemoglobin’s affinity for O2?
- pH
- Pco2
- Temperature
- 2,3-BPG
What is the Bohr Effect?
Shift in hemoglobin saturation as a result in pH or CO2 change
What would cause a decreasing shift in pH?
Maximal exertion produces excess CO2 and pushes a cell into anaerobic metabolism. Results in increased H+ and lactic acid in the cytoplasm and extracellular space
Describe the effect of pH on hemoglobin’s affinity for O2
The lower the pH, the more H+, the higher the carbon dioxide level and the LESS affinity Hemoglobin has for oxygen.
Increased aerobic metabolism results in increased CO2 production, this increases the PCO2 in the blood which: ?
- readily binds Hb altering conformation
- CO2 is readily converted to acid
Describe the effect of Pco2 on hemoglobin’s affinity for O2
Carbon dioxide increases [H+] and lowers tissue pH. As a consequence, hemoglobin’s affinity for oxygen decreases
Describe the effect of temperature on hemoglobin’s affinity for O2
Increased heat causes a conformational change in Hb leading to decreased affinity and more O2 to be dropped at the very active muscles
? : a by-product of glycolysis in RBC’s
2,3-BPG
Describe the effect of 2,3-BPG on hemoglobin’s affinity for O2
The presence of 2,3-BPG decreases hemoglobin’s affinity for oxygen
Chronic hypoxia _____ 2,3 BPG production; as well as ascent to higher altitude (low atmospheric PO2) and anemia can _____ 2,3 BPG production
increases, increase
RBC’s release ___ during hypoxia
ATP
Fetal hemoglobin has a _____ affinity for oxygen compared to adult (maternal) hemoglobin
higher
______ hemoglobin (2 α (alpha), 2 γ (gamma))
_____ hemoglobin (2 α (alpha), 2 β (beta))
Fetal, Adult (maternal)
The total oxygen content of arterial blood depends on the amount of oxygen ? and bound to ______
dissolved in plasma, hemoglobin
Although very soluble, cells produce far ___ CO2 than plasma is capable of carrying
more
Only about __% of CO2 carried by venous blood is dissolved in plasma
7
Remaining __% of CO2 diffuses into red blood cells
93
Of the 93% of CO2 diffused into RBCs, __% binds to hemoglobin HbCO2, and __% is converted to HCO3-
23, 70
CO2 is transported 3 ways: ?
- Dissolved in plasma (7%)
- Bound to hemoglobin (23%)
- Converted to bicarbonate, HCO3- (70%)
HCO3- moves out of the RBC in exchange for ?, which is known as the _____ ____
Cl-, chloride shift
Order these statements according to “CO2 transport:”
1. Nearly 1/4 of the CO2 binds to Hb
2. By the law of mass action, CO2 unbinds from Hb and diffuses out of the RBC
3. HCO3- enters the plasma in exchange for Cl-
4. CO2 diffuses out of cells into systemic capillaries
5. The carbonic acid reaction reverses, pulling HCO3- back into the RBC and converting it back to CO2
6. At the lungs, dissolved CO2 diffuses out of the plasma
7. Only 7% of the CO2 remains dissolved in plasma
8. 70% of the CO2 load is converted to HCO3- and H+. Hemoglobin buffers H+
4, 7, 1, 8, 3, 6, 2, 5
The conversion of CO2 to HCO3- serves two purposes: ?
Provides an additional means of CO2 transport from cells to the lungs
HCO3- is available to act as a buffer for metabolic acids, stabilizing body’s pH
To ensure equilibrium is not reached two mechanisms exist: ?
one to remove HCO3- from RBC and another mop up excess H+
Hemoglobin acts as a buffer and binds excess H+ ions:
-It prevents large changes in the ____ __
-If blood CO2 is elevated too high Hb cannot soak up all the H+ and ______ ___ can result
body’s pH, respiratory acidosis
When O2 leaves Hb at the tissues, CO2 binds with free hemoglobin at exposed ______ _____ (-NH2), forming carbaminohemoglobin
amino groups
Breathing is a rhythmic process that often occurs ______ similar to the beating of the heart
subconsciously
Skeletal muscles that control ventilation cannot contract ________
spontaneously
There is believed to be spontaneously firing networks of neurons in the brainstem. This network is influenced by _____ and ______, as well as by ?, with the neural control of ventilation considered to be a “_______”
sensory, chemoreceptors, higher brain centers, Blackbox
What is a “Blackbox?”
An area we do not fully understand
There are 4 pieces to our current model for control of respiration:
1. Respiratory neurons in the ____ control inspiratory and expiratory muscles
2. Neurons in the ____ integrate sensory information and interact with ______ neurons to influence ventilation
3. Rhythmic pattern of breathing arises from a neural network with spontaneously discharging neurons – “______”
4. Ventilation is continuously modulated by various _____ and ________-linked reflexes and by ?.
- medulla
- pons, medullary
- pacemaker
- chemo, mechanoreceptor, higher brain centers
Various chemoreceptors in controlling respiration will continuously monitor the _____; mechanoreceptors will monitor the level of ? of the walls of the lungs; and irritant receptors that will monitor the ______
blood, inflation/filling of the lungs/stretching, airways
3 main groups of neurons that are known to be involved in ventilation: ?
- Dorsal Respiratory Group in the medulla
- Ventral Respiratory Group in the medulla
- Pontine Respiratory Group in the pons
Nucleus tractus solitaris (NTS) receives input from the _____ mechano and chemoreceptors
peripheral
NTS of the medulla contains the ? that mainly control inspiratory muscles via phrenic nerve and intercostal nerve
dorsal respiratory group of neurons (DRG)
_____ Respiratory Group: controlling inspiration mainly through muscles, quiet and active, receives sensory input
Dorsal
_______ Respiratory Group: coordinate a smooth respiratory rhythm, not “absolutely” necessary for respiration if you were to cut the brainstem between the PRG and the medulla, ventilation would still occur, but it would be rough and not regulated (gasping)
Pontine
______ respiratory group (PRG): receives sensory info from DRG; provides tonic input to DRG to help the medullary networks coordinate a smooth respiratory rhythm; coordinates but does not create the rhythm
Pontine
______ Respiratory Group: contains the pre-botzinger complex (believed to be the location of the pacemaker neurons that initiate respiration), also controls muscles that are included in the accessory active inspiration and expiration, as well as output that keeps the airways open (usually constant, but slowing down causes the disorders)
Ventral
During inspiration, the activity of inspiratory neurons increases steadily, apparently through a _____ ______ mechanism. At the end of inspiration, the activity shuts off abruptly (it could be that the _____ can shut off the positive feedback loop) and expiration takes place through recoil of elastic lung tissue. Believed to be initiated by a _______: the positive feedback loop recruits more neurons “______” recruiting more outputs to inspiratory muscles
positive feedback, pons, pacemaker, ramping
CO2, O2 and pH influence _______
ventilation
Peripheral chemoreceptors: ____ and _____ ______ sense changes in arterial PO2, PCO2 and pH and adjust ventilation accordingly
aortic, carotid bodies
Where is the location of the aortic and carotid bodies?
Located on the aortic arch, as well as the carotid artery
? : the ones responsible for sensing the changes, neuronal like cells, excitable cells and contain neurotransmitters. Usually, they synapse on a sensory neuron that goes back to the respiratory control center.
Type I (glomus) cell
______ ______: allow glomus cells to be exposed to systemic arteries. Capillaries that allow glomus cells to sense these variables in the blood
Sinusoidal capillaries
Glomus cells function through inhibition of ___ channels
K+
Glomus cells have an ___ sensitive potassium channel, where if levels drop (takes a significant drop to trigger) within that systemic arterial blood that’s being fed through the carotid bodies then the cells themselves would be exposed to a low ____ that would cause ______ of a potassium channel within the glomus cell which causes ______ of potassium which causes the cell to ______, which would open voltage-gated _____ channels. This leads to the exocytosis of ________ (there is a variety)
O2, Po2, closure, retention, depolarize, calcium, neurotransmitters
It takes a ____ drop in arterial PO2 to trigger peripheral chemoreceptors in glomus cells
large
Glomus cells respond to PO2 in ______ changes, not the overall carrying capacity
plasma
Glomus cells can also respond to increases in ___/___, and decreases in ___
H+, CO2, pH
_____ _______: are located in the medulla, provide continuous input to respiratory control center and respond mainly to changes in Pco2
Central chemoreceptors
_____ _______: tonically active neurons that are always firing action potentials at some level, they will increase their firing rate in response to increased CO2 and will decrease their firing rate in response to CO2
Central chemoreceptors
In central chemoreceptors, the neurons themselves that are in the ______ do not respond directly to CO2 they respond to changes in pH in the ______ ____ caused by CO2
medulla, cerebrospinal fluid
Neurons in central chemoreceptors contain ? that become activated and transmit AP’s to the respiratory control center
H+ sensitive channels (ASIC),
In central chemoreceptors:
______ CO2 = increased H+ = increased activity
______ CO2 = decreased H+ = decreased activity
Increased, Decreased
Order these statements according to “decreased arterial O2:”
1. Increased firing of peripheral chemoreceptors
2. Decreased alveolar Po2
3. Increased ventilation
4. Decreased arterial Po2
5. Decreased inspired Po2
6. Increased contractions in respiratory muscles
7. Return of alveolar and arterial Po2 toward normal
5, 2, 4, 1, 6, 3, 7
Order these statements according to “increased arterial H+:”
1. Decreased alveolar Pco2
2. Increased firing of peripheral chemoreceptors
3. Decreased arterial Pco2
4. Increased ventilation
5. Increased arterial [H+]
6. Return of arterial [H+] toward normal
7. Increased contractions in respiratory muscles
8. Increased production of non-CO2 acid
8, 5, 2, 7, 4, 1, 3, 6
____ changes in arterial Pco2 cause very _____ changes in ventilation
Small, drastic
Arterial CO2 is mediated by both central chemoreceptors (___%, primary) and peripheral chemoreceptors (___%)
70, 30
Very high Pco2 will actually _____ ventilation
depress
Protective reflexes guard the ______
lungs
Lungs contain ______ receptors that respond to inhaled particles or noxious gases
irritant
Irritant receptors send input into the ____, parasympathetic outputs then respond by causing ___________ which leads to rapid shallow breathing and turbulent airflow to deposit irritant in mucosa
CNS, bronchoconstriction
Protective reflexes can initiate _____ or _______
coughing, sneezing
______ receptors in the lung prevent over inflation of the lungs
Stretch
What is the Hering-Breuer inflation reflex?
a reflex triggered to prevent the over-inflation of the lung
How can the Limbic system and Hypothalamus influence breathing?
If you’re embarrassed/excited you may start breathing heavier or shallower
? : can control breathing patterns where we can selectively control ventilation to a certain degree (we can actively hold our breath (until chemoreceptors take over and override the higher brain centers) and we can breathe out for set amounts of time indicating higher control)
Higher brain centers
We have a feedforward mechanism (anticipation response) that kicks in at the onset of ______
exercise
