Ch. 6: The Respiratory System Flashcards
func: thoracic cavity
where the lungs and heart are located
its structure is specially designed to perform breathing
where does gas exchange occur in the respiratory tract?
in the lungs
what is the pathway of air through the respiratory system? + what happens to air when it is in the nasal cavity
- enters through external nares of the nose
- passes through the nasal cavity where it is filtered by mucous membranes and nasal hairs
- pharynx
- larynx
- trachea (cartilaginous)
- into one of the two mainstem bronchi
- lungs: bronchi continue to divide into bronchioles
- which divide into alveoli
aka: vibrissae
nasal hairs!
location + pathway contents: pharynx vs. larynx
PHARYNX
- behind the nasal cavity, at the back of the mouth
- pathway for air and food
LARYNX
- lies below the pharynx
- pathway for air only
aka: glottis
larynx
defn + func: epiglottis
covers the larynx during swallowing to keep food out of the respiratory tract
where are the vocal cords located and how are they maneuvered?
where: in the larynx
maneuvered using skeletal muscle and cartilage
what is the purpose of ciliated epithelial cells in the bronchi and trachea?
to catch material that has made it past the mucous membranes in the nose and mouth
defn: alveoli
tiny balloon-like structures in which gas exchange occurs
defn + func: surfactant
coats each alveolus
a detergent that lowers surface tension and prevents the alveolus from collapsing on itself
what does the network of capillaries surrounding each alveolus do?
carry oxygen and CO2
why do the alveoli have such a large surface area?
the branching and minute size allow for a large surface area for gas exchange
defn: pleurae
membranes that surround each lung
pleura form a closed sac against which the lung expands
defn: visceral vs. parietal pleura
VISCERAL PLEURA = the surface adjacent to the lung
PARIETAL PLEURA = the outer part associated with the chest wall
defn: diaphragm
a thin, muscular structure that divides the thoracic cavity from the abdominal cavity
do the lungs fill passively?
no they require skeletal muscle (most importantly the diaphragm) to generate the negative pressure for expansion
is the diaphragm under somatic or autonomic control?
somatic (even though breathing is autonomic)
defn: intrapleural space
the space within the sac, contains a thin layer of fluid which helps lubricate the two pleural surfaces
what ultimately drives breathing?
the pressure differentials that can be created across the pleura (between the intrapleural space and the lungs)
defn: external intercostal muscles
one of the layers of muscles between the ribs
how does inhalation work? (steps: 7)
- we use our diaphragm and external intercostal muscles to expand the thoracic cavity
- as the diaphragm flattens and the chest wall expands outward, the intrathoracic volume (chest cavity volume) increases
- specifically, because the interpleural space closely abuts the chest wall, its volume increases first
- this leads to low pressure in the intrapleural space
- the gas in the lungs is initially at atmospheric pressure (which is now higher than the pressure in the intrapleural space)
- the lungs will therefore expand into the intrapleural space and the pressure in the lungs will drop
- air will then be sucked in from a higher pressure environment (the outside world)
why is the inhalation method called negative-pressure breathing?
the driving force is the lower (relatively negative pressure) in the intrapleural space compared with the lungs
how does simple exhalation work? (steps: 3)
- relaxation of the diaphragm and external intercostal muscles decreases the volume of the chest cavity
- the pressure in the intrapleural space goes up (is now higher than the lungs which are still at atmospheric pressure)
- air will be pushed out (exhalation)
does the diaphragm contract or relax during inhalation? during exhalation? what about the chest wall and rib cage?
INHALATION
- diaphragm contracts
- chest wall and rib cage expand
EXHALATION
- diaphragm relaxes
- chest wall and rib cage contract
is inhalation active? is exhalation active?
inhalation: yes
exhalation: doesn’t have to be
how do we speed up the process of exhalation during active tasks? how + effect?
- the internal intercostal muscles and abdominal muscles are used to oppose the external intercostals and pull the rib cage down
- this actively decreases the thoracic cavity volume
why do the lungs recoil as the chest wall relaxes?
due to the intrinsic elastic quality of the lungs and surface tension of the alveoli
defn: spirometer
an instrument used to assess lung capacities and volumes
defn: total lung capacity (TLC)
the maximum volume of air in the lungs when one inhales completely (usually around 6 to 7 liters)
defn: residual volume (RV)
the volume of air remaining in the lungs when one exhales completely
defn: vital capacity (VC)
the difference between the minimum and maximum volume of air in the lungs (TLC - RV)
defn: tidal volume (TV)
the volume of air inhaled or exhaled in a normal breath
defn: expiratory reserve volume (ERV)
the volume of additional air that can be forcibly exhaled after a normal exhalation
defn: inspiratory reserve volume (IRV)
the volume of additional air that can be forcibly inhaled after a normal inhalation
defn + func + how: ventilation center
a collection of neurons in the medulla oblongata that is the primary regulator of ventilation
these neurons fire rhythmically to cause regular contraction of respiratory muscles and contain chemoreceptors that are sensitive to CO2 concentration
what is the effect on breathing of the partial pressure of CO2 in the blood rising? + aka for this
aka: partial pressure of carbon dioxide in blood = hypercarbia = hypercapnia
respiratory rase will increase so that more carbon dioxide is exhaled, causing CO2 levels in the blood to fall
when do these cells in the ventilation center respond to changes in oxygen concentration?
during periods of significant hypoxemia (low oxygen concentration in the blood)
what are three functions of the lungs other than gas exchange?
- thermoregulation (from the many capillaries lining the lungs)
- immune function (prevent invaders from gaining access to the bloodstream, represent a pathway into the body)
- control of blood pH (by controlling carbon dioxide concentrations)
what is the overarching pathway of gas exchange in the alveolus? (3 steps)
- each alveolus is surrounded by a network of capillaries which bring deoxygenated blood from the pulmonary arteries (which originate from the right ventricle of the heart)
- the walls of the alveoli are only one cell thick –> facilitates the diffusion of carbon dioxide from the blood into the lungs and oxygen into the blood
- the oxygenated blood returns to the left atrium of the heart via pulmonary veins
what is the driving force for gas exchange + how does this work (2)?
driving force = pressure differential of the gases
- when blood initially arrives at the alveoli, blood has relatively low partial pressure of oxygen and a relatively high partial pressure of CO2
- this facilitates a transfer of each down its respective concentration gradient
since the gradient between the blood and air in the lungs is already present as the blood enters the lung, what does this imply about energy required for gas transfer?
no energy is required for gas transfer!
how do our respiratory systems adjust if we move to higher altitudes where less oxygen is available? (2)
- we breathe more quickly to try to avoid hypoxia
- the binding dynamics of hemoglobin to oxygen would be altered to facilitate the unloading of oxygen at the tissues
how is gas exchanged maximized?
there is a tremendous surface area over which the alveoli and capillaries interact
defn: thermoregulation
regulation of body temperature
why can the respiratory tract be used for thermoregulation?
because the entire respiratory tract is highly vascular
how is heat (the transfer of thermal energy) regulated via the body surfaces (2 processes)?
- vasodilation
- vasoconstriction
defn + effect: vasodilation
as capillaries expand, more blood can pass through these vessels and a larger amount of thermal energy can be dissipated
defn + effect: vasoconstriction
as capillaries contract, less blood can pass through them, conserving thermal energy
what are the main (3) and secondary (3) methods of thermoregulation for humans?
how do other animals (like dogs) take advantage of one of these ?
MAIN
1. capillaries in the skin
2. sweat glands in the skin
3. rapid muscle contraction (shivering)
SECONDARY
1. nasal capillaries
2. tracheal capillaries
3. evaporation of water in mucous secretions
dogs take advantage of the last cooling mechanism (secondary, 3) by panting
what is the first line of immune defense of the respiratory function? how?
the nasal cavity!
it has small hairs (vibrissae) that help to trap particulate matter and potentially infectious particles
also contains lysozyme
func + loc: lysozyme
able to attack the peptidoglycan walls of gram-positive bacteria
found in the nasal cavity, tears, and saliva
how do internal airways have an immune function?
the mucociliary escalator
process: mucociliary escalator (2)
- internal airways are lined with mucus which traps particulate matter and larger invaders
- underlying cilia then propel the mucus up the respiratory tract to the oral cavity where it can be expelled or swallowed
what kind of immune cells are contained within the lungs? (3)
- macrophages
- IgA antibodies
- mast cells
func: macrophages
engulf and digest pathogens and signal to the rest of the immune system that there is an invader
func: IgA antibodies
help to protect against pathogens that contact the mucous membranes
func: mast cells
have preformed antibodies on their surfaces
releases inflammatory chemicals into the surrounding area to promote an immune response when the right substance attaches to the antibody
eqn: bicarbonate buffer system
CO2 (g) + H2O (l) <–> H2CO3 (aq) <–> H+ (aq) + HCO3- (aq)
what pH range does the body try to maintain a balance in?
7.35 - 7.45
defn/char + effect + role of respiration: acidemia
pH is lower, hydrogen ion concentration is higher
acid-sensing chemoreceptors just outside the blood-brain barrier send signals to the brain to increase the respiratory rate
also shifts the bicarbonate buffer system, generating additional carbon dioxide –> which also promotes an increase in respiratory rate
defn/char + effect + role of respiration: alkalemia
the blood is too basic
the body will seek to increase acidity
if the respiratory rate is slowed, then more CO2 will be retained, which shifts teh bicarb buffer equation right, producing more hydrogen ions and bicarbonate ions which results in a lower pH
