Unit 5; Respiratory System Flashcards
What are the 4 functions of the respiratory system
- exchange of gases between atmosphere and blood
- homeostatic regulation of body pH
- protection from inhaled pathogens and irritating substances
- vocalization
What is the first exchange in the respiratory system
gas exchange between atmosphere and lungs
What is the second exchange in the respiratory system
gas exchange between lungs and blood
What occurs between exchange 2 and 3
transport of gases by blood
What is the third exchange in the respiratory system
exchange of gases between blood and tissues
What is another term for the transport of gases between atmosphere and lungs
ventilation
What is it called when air moves into lungs
inspiration or inhalation
What is it called when air moves out of the lungs
expiration or exhalation
What is the conducting system of the respiratory system
airways
What is the exchange surface of the respiratory system
alveoli
What is the pumping system of the respiratory system
bones and muscle of thorax
What are the components of the upper respiratory system
mouth, nasal cavity, pharynx, larynx
(above trachea)
What are the components of the lower respiratory system
trachea, bronchi, bronchioles, lungs
(below trachea and at lungs)
What are alveoli
tiny sacs found at the ends of terminal bronchioles wrapped in capillary network - gas exchange occurs between alveoli and capillaries
Why does gas exchange occur specifically at the alveoli
small surface area and connected to huge capillary network - allows for efficient diffusion
What are the two types of alveolar cells
type 1 and type 2
What are type 1 alveolar cells
large but thin
- allow for rapid gas diffusion (thin layer = faster diffusion)
What are type 2 alveolar cells
small but thick
- synthesize and secrete surfactant
Where does low oxygen blood exit the heart
right ventricle
Where does low oxygen blood travel once it has left the right ventricle
pulmonary arteries via the pulmonary trunk
Why is the rate of blood flow high in pulmonary circulation
all blood leaving the heart goes to the same place: the lungs
Why is the rate of blood flow lower in systemic circulation
the blood leaving the heart flows all around the body, not all to the same place (unlike exchange 2)
Why is blood pressure low in pulmonary circulation
right ventricle doesn’t have to contract as hard since its only sending blood to one place
Why is blood pressure higher in systemic circulation
left ventricle has to contract harder since it is pushing blood around the body, and not just to one location
Which ventricle pumps more forcefully in the heart
the left ventricle (systemic circulation)
What is another term for the chest
the thorax
What makes the thorax (chest) a closed compartment
- closed off at top by neck muscles and connective tissues
- closed off at bottom by the diaphragm
What is the wall of the thorax formed by
ribs and intercostal muscles
(costal=ribs, therefore intercostal muscles are literally just muscles at the ribs)
What are the neck muscles involved in the closed compartment of the thorax
sternocleidomastoids and the scalenes
What happens when the intercostal muscles contract
inspiration
What happens when the intercostal muscles relax
passive expiration
What muscles are required for active expiration
internal intercostals and the diaphragm
What shape is the diaphragm when relaxed
dome
What shape is the diaphragm when contracted
flat
When does the volume of the thorax increase
when the diaphragm contracts and flattens (inhalation)
When does the volume of the thorax decrease
when the diaphragm relaxes and expands (exhalation)
What surrounds the lungs
pleural sac
What is found within the pleural sac, and what is its purpose
pleural fluid; acts as a lubricant
What is the equation for total gas pressure
total pressure = sum of partial pressures
Gas moves from areas of _____ pressure to ______ pressure
high to low
What two factors determines if a gas will dissolve in a liquid
- partial pressure of the gas
- solubility of the gas in liquid
What is the law applied to pressure-volume relationships
Boyle’s law
What is the driving force of airflow
changes in alveolar pressure
Can the lungs change volume on their own?
no!
What does lung volume depend on
- transpulmonary pressure
- degree of elasticity of the lungs
Pressure inside of the lungs is known as ___________ pressure
alveolar
Pressure outside the lungs is known as pressure in the ___________ _________
intrapleural fluid
Difference between the alveolar pressure and the pressure of the intrapleural fluid is known as…
transpulmonary pressure
What is bulk airflow
flow of air between atmosphere and lungs
In what 3 ways do the airways condition the air before it reaches the lungs
- warm to 37 degrees
- add water vapour
- filter out foreign material
What are airways lined with
ciliated epithelia
What do ciliated epithelia secrete
watery saline solution
How do the ciliated epithelia secrete watery saline solution
cells move Cl from ECF into the lumen of the cell (via apical ion channel)
Na moves between cells from ECF to the lumen, and the concentration gradient of NaCl draws water towards the lumen creating a watery saline solution
Cilia are covered with _________
mucus
What cells secrete mucus
goblet cells
What is the mucus escalator
when mucus moves up the pharynx and transfers to the digestive tract where bacteria is destroyed
What disease results from a mutation in the Cl channel
cystic fibrosis
What is the result of the defective Cl channel in cystic fibrosis
insufficient secretion of the watery saline = thick and sticky mucus
What is the subsequent concern with cystic fibrosis
the thick and sticky mucus restrains the cilia, which doesn’t allow for proper movement or removal of bacteria = repeated infections (leads to overactive immune cells)
What does the somatic neuron trigger
contraction of diaphragm and inspiratory muscles - leads to inspiration
During inspiration, thoracic volume ___________ and alveolar pressure ___________
increases, decreases
When impulses from somatic motor neuron stop, what happens
diaphragm and thoracic muscles relax = expiration
During expiration, thoracic volume ____________ and alveolar pressure ______________
decreases, increases
What is elastic recoil
when exhalation occurs, thoracic volume decreases which causes recoil of the lungs and lung volume subsequently decreases
Passive expiration depends entirely on ____________ _________
elastic recoil
Active expiration depends on contraction of __________ ________________ and _________ muscles
internal intercostals and abdominal muscles
What is a pneumothorax
a collapsed lung
What causes a pneumothorax
air gets into the pleural cavity and increases the pressure, causing the lung to collapse (the pressure difference is abolished)
The work required to breathe depends on what 2 factors
compliance (stretchability) of the lungs and resistance to airflow in airways
What is lung compliance
the ability for the lung to stretch
If lung compliance is low, is it more or less difficult to expand the lungs
more difficult
People with LOW lung compliance breathe _________ and __________
rapidly and shallowly
If lung compliance is high, is it more or less difficult to expand the lungs
less difficult
People with HIGH lung compliance breathe ________
easier
What is lung elastance
degree and speed at which the lung can return to resting volume after being stretched
When lung elastance is low, does the lung return to original volume
no, it cannot return to volume passively if lung elastance is low
In the case of low lung compliance, is exhalation active or passive
active: cannot passively return to original volume
What factor most prominently impacts airway resistance
diameter
Increases in CO2 in the airways causes ___________________
bronchodilation (airways open)
Histamine (in response to allergies) in the airways causes ____________________
bronchoconstriction (airways tighten)
Why do people struggle to breathe during anaphylactic shock
bronchoconstriction is so severe that the airway is blocked/restricted
For neural control of bronchioles, what is the main effector
parasympathetic neurons that cause bronchoconstriction
- this is a reflex designed to protect lower respiratory tract from inhaled pathogens
Is there any sympathetic innervation in neural control of bronchioles
no, not anything significant at least
What is the main effector of hormonal control of bronchioles
circulating epinephrine
How does circulating epinephrine impact bronchioles
circulating epinephrine binds to B2 receptors on the smooth muscle of the bronchioles which relaxes muscles to dilate the bronchioles
- this is used as a treatment for asthma
What is the point of pulmonary function assessment
to determine the amount of air a person moves during quiet breathing and maximal breathing effort
What tool is used in pulmonary function assessment
spirometer
What are the 4 lung volumes that can be measured during breathing
tidal volume
inspiratory reserve volume
expiratory reserve volume
residual volume
What is tidal volume
amount of air moved in and out of the lungs in a single normal inspiration/expiration
What in inspiratory reserve volume
max amount of air that can be inspired above tidal volume
What is expiratory reserve volume
max amount of air that can be expired below tidal volume
What is residual volume
amount of air left in the lungs after maximal expiration
The sum of two or more lung volumes is called a…
capacity
What is vital capacity
the max amount of air that can be voluntarily moved into or out of the respiratory system
- VC=IRV+ERV+tidal volume
What is total lung capacity
TLC=vital capacity+residual volume
What is minute volume and how is it calculated
measures the effectiveness of breathing
MV=tidal volume+respiratory rate
Is there gas exchange within the dead space of the airways
no
What is alveolar volume and how is it calculated
since air in trachea, bronchi, and bronchioles is not included in gas exchange, alveolar volume is the amount of air partaking in exchange
alveolar volume=tidal volume+dead space
What is alveolar ventilation and how is it calculated
the amount of air that reaches the alveoli each minute
alveolar ventilation=ventilation rate x alveolar volume
Alveolar ventilation is matched to alveolar _______ ______
blood flow
Why does the body try to match ventilation to alveolar blood flow
to gain optimum gas exchange
Increases in tissue PO2 result in _________________ in the arteriole
vasodilation
If the ventilation of alveoli in one area of the lung decreases, what happens to the tissue O2 in that area
tissue O2 also decreases
Decreases in tissue PO2 result in ___________________ of the arteriole
vasoconstriction
Alterations in blood flow in the lungs depends primarily on what
local control exerted by O2 levels in the interstitial fluid around the arteriole surrounding the alveoli
If max is breathing 10 times per minute, with a tidal volume of 450mL and a dead space of 150mL, what is his alveolar ventilation?
alveolar volume = 300mL (450 - 150 = 300)
ventilation rate x alveolar volume = alveolar ventilation
10 x 300 = 3000 mL/min
If Katie is breathing 15 times per minute, with a tidal volume of 375mL and a dead space of 150mL, what is her alveolar ventilation?
alveolar volume = 225mL (375 - 150 = 300)
15 x 225 = 3375 mL/min
What is the process by which gas exchange occurs
diffusion
What are the 4 characteristics of the rate of diffusion across the lungs
- proportional to the partial pressure gradient
- proportional to available surface area
- inversely proportional to the thickness of the membranes
- greatest over short distances
What is partial pressure gradient influenced by
Composition of inspired air (affected by altitude)
Alveolar ventilation (changes in airway resistance and/or lung compliance)
What is emphysema
destruction of alveoli
- physical loss of alveolar surface area
In emphysema, what happens to the PO2 in the capillary
low
What is fibrotic lung disease
scarring that thickens the alveolar membrane
In fibrotic lung disease, what happens to the PO2 in the capillary
low
What is pulmonary oedema
increase in interstitial fluid in lungs
What happens as a result of increased interstitial fluid in lungs in pulmonary oedema
leads to an increase in diffusion distance (slow)
In pulmonary oedema, what happens to PO2 in the capillary
low (takes longer to diffuse)
What is asthma
increase airway resistance, decreased ventilation
What occurs as a result of asthma that causes airway resistance
bronchiole constriction
In asthma, what happens to the PO2 in the capillary AND the alveoli
both low
Where are gases transported throughout the body
plasma or RBCs
Since oxygen has low solubility in plasma, most of the oxygen is transported by ________
RBCs
What does oxygen bind to in RBCs
hemoglobin
Blood loss results in ______ O2 carrying capacity
low
Each hemoglobin molecule can bind up to ___ oxygen molecules
4
What part of hemoglobin does oxygen bind to
the iron in the haeme group
Hemoglobin bound to oxygen is called
oxyhemoglobin (HbO2)
Unbound hemoglobin is called
deoxyhemoglobin (Hb)
How to recognize the % saturation of hemoglobin
% of binding sites that are bound to hemoglobin
What is a competitive inhibitor of O2 binding
carbon monoxide (CO)
How does O2 transport in RBCs (explain in a step by step simplified)
- O2 from capillary is dissolved into plasma (small portion will remain but most will go to RBCs)
- O2 then moves into RBCs and binds to hemoglobin (oxyhemoglobin)
- oxyhemoglobin is transported to cells
- O2 unbinds from hemoglobin (deoxyhemoglobin) and enters the cell for cellular respiration
What are the three mechanisms by which carbon monoxide is transported
- dissolved in plasma
- interact with proteins
- converted to bicarbonate
Which is more soluble: CO2 or O2?
CO2
CO2 is ________ soluble than O2, but cells produce _______ CO2 to be carried
more soluble, produces more to be carried
What compound is formed when CO2 interacts with proteins during transport
carbaminohemoglobin (HbCO2)
Which type of hemoglobin interacts with CO2 better: oxyhemoglobin or deoxyhemoglobin
deoxyhemoglobin
What happens to the majority of CO2 in transport
converted to bicarbonate via reaction catalyzed by carbonic anhydrase
What enzyme catalyzes CO2 in transport in the blood
carbonic anhydrase
What transports bicarbonate ions out of the blood cell
transporter protein that exchanges HCO3 for Cl (chloride shift)
What is the chloride shift
when a transporter protein moves bicarbonate out via exchange of HCO3 and Cl
When venous blood (blood in veins) reaches the lungs, the PCO2 of alveoli is ________ than that of blood
lower
CO2 dissolved in plasma diffuses into __________ and then CO2 in RBCs diffuse into _______
from plasma to alveoli
from RBCs to plasma
When the CO2 diffuses from RBCs to plasma to alveoli, what happens to the reaction
the equilibrium of the CO2-bicarbonate reaction is shifted
What happens during the reverse chloride shift
- bicarbonate ions move from plasma into RBCs
- bicarbonate and H+ form carbonic acid
- carbonic acid forms CO2, which then gets catalyzed by carbonic anhydrase
- CO2 diffuses out of the RBC into the plasma, then alveoli
How does CO2 transport in RBCs (explain in a step by step simplified)
- cellular respiration produces CO2, which moves into plasma, then into RBCs
- CO2 then forms with hemoglobin to form carbaminohemoglobin
- some CO2 is catalyzed with carbonic anhydrase to form carbonic acid
- carbonic acid dissociates into bicarbonate and H+ ions
- bicarbonate shuttles out to plasma via chloride shift, H+ binds to hemoglobin
- HbH and carbaminohemoglobin are then transported to the lungs, where the opposite cascade then occurs
- HbH dissociates into hemoglobin and H+
- Bicarbonate shuttles into the cell via chloride shift, and binds to H+ to form carbonic acid
- carbonic acid is catalyzed via carbonic anhydrase to form water and CO2 (CO2 diffuses into plasma)
- carbaminohemoglobin dissociates into hemoglobin and CO2 (CO2 diffuses into plasma)
- dissolved CO2 then moves into the capillaries
Diaphragm and intercostal muscles are _____________ muscles
skeletal muscles
What are the diaphragm and intercostals innervated by
somatic motor neurons
Where in the brain is contraction of the respiratory skeletal muscle initiated
medulla oblongata
What is the network of neurons called in the medulla oblongata
the central pattern generator
The central pattern generator (network of neurons) have what kind of activity
intrinsic rhythmic activity (fire at a rhythmic rate)
What are the two nuclei in the medulla oblongata associated with respiration
- dorsal respiratory group (DRG): inspiratory neurons (I neurons)
- ventral respiratory group (VRG): active expiratory neurons (E neurons)
What do the “I neurons” control
external intercostal muscles and diaphragm (inspiration)
What do the “E neurons” control
internal intercostal muscles and abdominal muscles (active expiration)
What is the function of chemoreceptors
modify or adjust the rhythmicity of the central pattern generator neurons
What are the 2 types of chemoreceptors
- peripheral chemoreceptors
- central chemoreceptors
Where are peripheral chemoreceptors located
in carotid bodies (glomus cells)
Peripheral receptors sense changes in…
PO2 and pH of plasma
increase in PCO2
Decreased PO2, decreased pH, and increased PCO2 in would result in…
increased ventilation
Are small changes in PO2 enough for signalling to occur
no, PO2 must change radically before a signal is sent
- pH usually has more of an impact for this reason
Where are central chemoreceptors located
in the medulla oblongata
What is the most important chemical controller of ventilation
medulla oblongata
Increased PCO2 in arterial blood (blood carried by arteries) causes what
increased ventilation
When CO2 crosses the brain barrier into the cerebral spinal fluid (CSF), what happens
activates the central chemoreceptors via changes in pH caused by production of carbonic acid
What are the two types of mechanoreceptors
- irritant receptors
- stretch receptors
Where are irritant receptors located
airway mucosa
What is the function of the irritant receptors
stimulation of irritant receptors triggers parasympathetic neurons that innervate bronchiolar smooth muscle
- leads to bronchoconstriction
Where are stretch receptors located
in smooth muscle of airways
