Lesson 3: Respiratory System: Structure and Function 2 Flashcards
what is the pleural sac?
a double-walled, closed sac that separates each lung from the thoracic wall
where is the pleural cavity?
interior of pleural sac
what is intrapleural fluid secreted by?
surfaces of the pleura
what does intrapleural fluid do?
lubricates pleural surfaces
where are the lungs found?
in the thoracic cavity
what is the lungs divided into?
several lobes, each supplied by one of the bronchi
what does lung consist of?
a series of highly branches airways, the alveoli, the pulmonary blood vessels, the large quantities of elastic connective tissue
what form does the lung want to be?
deflated
- because the elastic tissue allows us to not have to use muscles to breathe out
- this allows us to manage our chest and the volume of air we allow in
what are airways?
tubes that carry air between the atmosphere and the air sacs
what are our airways?
- nasal passages
- pharynx (common passageway for respiratory and digestive systems)
- larynx
- trachea
- right and left bronchi
- bronchioles
what is the tracheas structure?
- fairly rigid, non-muscular tubes
- rings of cartilage preventing collapse from large pressure
- very stiff, very hard to make it wider or narrower
does the bronchioles have cartilage to hold them open?
no
bronhiole walls contain smooth muscle innervated by the ______________________________.
autonomic nervous sytem
where are alveoli clustered?
at ends of terminal bronchioles
why do we have smooth muscles in the small areas of our airways (bronchioles)?
- to be involuntary
- allows for them to dilate or constrict for air
are the bronchioles sensitive to certain hormones and local chemicals?
yes
why does air sacs constrict?
- protective mechanism to avoid the alveoli from getting exposed to extreme temperatures, chemicals, etc.
- size of airway can change (critical to have efficient breathing)
what is critical to have effective breathing?
size of airway can change
what does the puffer do?
its a bronchiole dilator to open up the airways
- relaxes smooth muscle to open the airways by targeting beta receptors in the airways
what is the scientific name of a puffer?
ventolin inhaler salbutamol
- short acting beta agonist
what is targeted when taking a puffer?
smaller airways like the bronchioles
** what are alveoli?
- thin-walled, inflatable sacs that function in gas exchange
- walls consist of single layer of flattened type 1 alveolar cells
- pulmonary capillaries encircle each alveolus
- type 2 alveolar cells secrete pulmonary surfactant (located in the lumen of the alveolus)
- alveolar macrophages guard lumen
- pores of Kohn permit airflow between adjacent alveoli (maintain tone)
where are type II alveolar cells located?
in the lumen of the alveolus
what is the surface of an alveoli?
a single, flattened layer of Type 1 alveolar cells
what does pulmonary surfactant do?
- secreted into the alvelous for decreasing surface tension of the type 1 wall
- this is to help the pressure be equal in each of the alveolar sacs
why does the pressure have to be equal in each of the alveolar sacs?
the alveolus will collapse
what happens if too many alveolus collapse?
becomes really hard to breath
what does alveolar macrophages do?
guard the lumen
what does the pores of Kohn do?
they permit airflow between adjacent alveoli to help maintain tone across alveoli, within and between sacs (communication to make sure everything is properly inflated)
the wall of the alveolus is?
one type 1 cell that is stretched across, very thinly
what is a single alveolus?
a bulb in the sac
how big is the space in the alveolus?
300 micrometers (um)
- very very very small
what is elastic fibre?
helps us get the elastic, stretchiness of the lung
why do we need to have thin walls in the alvelus?
for gas exchange
where is the type 2 cells?
a cluster somewhere in the lumen and secretes the surfactant into the lumen
the distance between pulmonary capillary and the alveolar wall is? (air and blood barrier)
very thin (0.5um)
- this is to maximize gas exchange
- allows for easy O2 in and CO2 out diffusion
- interstitial space is the small space in between them. can have interstitial fluid that leaks into the space (minimally because it is very small)
where may the interstitical space be widened?
- high altitude pulmonary edema
- leads to fluid accumulation in the interstitial space. causes fluid leakage a little in the alveoli but mostly in the interstitial space
what is the issue with having a widened interstitial space between alveoli and capillaries?
there is going to be more resistance and there is going to be issues getting the oxygen across which will affect gas exchange (because the space is now thicker)
example of disease where there is an accumulation of something in the interstitial space?
pulmonary fibrosis
what is a disease where the interstitial space is compromised?
interstitial lung disease
- like pulmonary fibrosis
does the chest wall move air and out?
no, but it facilitates the lung changing its shape to help move the hair
what does the outer chest wall (thorax) consist of?
- formed by 12 pairs of ribs that join sternum anteriorly and thoracic vertebrae posteriorly
what contains muscles involved in generating pressure that cause airflow?
chest wall
what protects lungs and heart?
rib cage
what pulls the lung walls open when it stretches?
the chest wall
- they are very dependent on each other
the chest wall is an opposing force to?
the lung tissue
- ribs want to go out and lungs want to go in
key muscles in the chest wall?
- diaphragm for inspiration
- sternocleidomastoid
- external intercostals that slope towards sternum
- parasternal intercostals
what is the most important key muscle for inspiration?
the diaphragm
what muscles are used for inspiration?
- sternocleidomastoid
- scalenes
- external intercostals
- parasternal intercostals
- diaphragm
what muscles are used for expiration?
- internal intercostals
- external abdominal oblique
- internal abdominal oblique
- transversus abdominis
- rectus abdominis
when we do not contract any muscles in our chest wall, why does air leave?
because the lungs want to be deflated, they are only inflated because of the inspiration muscles
what are the key muscles for expiration in resting breathing?
- it is passive so none
when is the only time we do not use our expiration muscles?
when we are rest breathing
what is 75% of the enlargement of the thoracic cavity during quiet respiration is due to?
the contraction and flattening of the diaphragm
***** onset of expiration begins with?
relaxation of inspiratory muscles
what decreases intra-alveolar pressure to a level below atmospheric pressure?
the expansion of the chest wall
- allows for air to enter the lungs
what is the pleural sac?
double-walled, closed sac that separates each lung from the thoracic wall
- both the visceral and parietal pleaura and the fluid in between them
what is the intrapleural fluid secreted by?
surfaces of the pleura
what does intrapleural fluid do?
lubricates pleural surfaces
where is the pleura space?
space between chest wall and lung
what is the visceral pleura?
where the pleura is attached to the lungs outer space
what is the parietal plerua?
where the pleura is attached to thoracic wall and diaphragm
when we open the lungs, what happens to the pressure in the lungs?
decreasing pressure in the lung, the intrathoracic space, and the pressure will be lower than atmospheric, so it will draw air in
are the pleura attached?
no, they are very close to each other
what does the pleural sac compose of?
the visceral and parietal pleura and the intrapleural fluid
there is pressure in the pleura, what is it called?
the intrapleural pressure
