What are the 3 steps of external respiration?
1.Ventilation or gas exchange between the atmosphere and air sacs (alveoli) in the lungs
2.Exchange of O2 and CO2 between air in the alveoli and the blood.
3.Transport of O2 and CO2 between the lungs and the tissues.
How is the respiratory system responsible for water loss and heat loss?
-breathe over more surface during exercise and evaporate water in lungs= water loss= cooling
Does the respiratory system have an effect on the maintenance of acid-base balance?
-yes as blowing off CO2 has effect on it!
Is respiratory system important for speaking?
-yes, enables vocalization
How does breathing enhance venous return?
-breathing in= effect on heart rate= effect on venous return
Does respiratory system act as a defense against inhaled foreign matter?
Does the respiratory system change materials in the circulatory system?
-inactivates and activates, modifies the materials e.g.: angiotensin conversion
How can be flow in bronchioles affected by muscle?
-the small bronchioles are surrounded by smooth muscle and contraction of these will decrease diameter of the bronchioles= so effect on flow
Is there any flow of air in terminal bronchioles?
No. Only diffusion.
How do lungs interact with the circulatory system?
-the alveolar sacs are surrounded by fine capillaries there the exchange of O2 and CO2 takes place
What is special about the arteries and veins in the lungs?
-arteries have low oxygen and veins have high oxygen= the opposite of the rest!
Are there difference in appearance of the lungs in different species?
Degree of separation of lungs into secondary lobules by
connective tissue differs among mammalian species
Complete separation: Pigs & cattle
Partial separation: Horses & sheep
No separation: Dogs & cats
black area= pneumonia, the separation better so it prevents the infection of spreading
cats and dogs don't have separation= better flow overall
Can pathways of airflow vary?
Nose & mouth breathers: cattle & dogs (can cool down that way more)
Obligate nose breathers: e.g. horse( if can't really mouth breathe= sign of illness, also
-don't lose much heat thriugh brathing so more relying on sweat )
Is there a difference in the Stiffness of the thorax in animals?
Greater in large animals (i.e. less compliant) eg horse & cow
-stiffer thorax= so more energy to move it out
Whic alveolar cells produce surfactant?
Type II alveolar cells
Describe the anatomy of an alveolus:
What are pleural surfaces?
plural surfaces hold it in the thorax
lungs full of gas and if it goes out= collapse, they are covered by the plural sacs= keeps them inflated
in fluid= only few mms, surround and attach it to the thorax= no physical attachment but if expanded much more it would have to push out the fluid= similar to vacuum sort of
also no friction against the thorax or the plural surface and when thorax changes shape the lungs will follow eventough no actual physical attachment
great system unless you get a hole in the thorax wall=air goes in and the lungs collapse, stay collapsed till the air sucked out and close the hole
the plural surfaces also full of lymphatic fluid and white cells and part of the protective system of the lungs
How do Intrapleural fluid & transmural pressure gradient hold lungs & thoracic wall in tight opposition?
-plural cavity slightly lower pressure than outside and in the lungs= keeps the lungs inflated
transmural pressure= the difference between inside and outside only needs to be only small to work
What is pulmonary ventilation?
Pulmonary ventilation (breathing) is the process by which air is exchanged between the alveoli in the lungs and the external environment. Breathing has two stages: inspiration (breathing in) and expiration (breathing out). Pulmonary ventilation is the first stage in respiration.
What is the position of the diaphragm and the intercostal muscles before inspiration?
The external intercostal muscles are relaxed and the diaphragm is relaxed. The ribcage is not expanded.
What happens during inspiration?
During inspiration the external intercostal muscles contract, elevating the ribcage upwards and outwards and increasing the size of the thoracic cavity. At the same time the diaphragm contracts and flattens, further increasing the size of the thoracic cavity. The lungs expand, following the shape change in the thoracic cavity. The sudden shape change causes an area of low pressure inside the lungs, and air rushes in to fill the newly available space.
What happens during expiration?
Expiration (breathing out)
During expiration the external intercostal muscles and diaphragm relax. The tissues of the ribcage are elastic and return the thoracic cavity to its original, smaller shape. The ribcage falls back down and inwards and the diaphragm relaxes into a domed shape. The air pressure increases inside the lungs and air is forced out of the body.
During active expiration, which is a forceful expelling of the air from the lungs (such as during coughing), the internal intercostal muscles contract and the abdominal muscles contract, quickly decreasing the size of the thoracic cavity and forcing air out of the lungs.
What causes flow of air into and out of lungs?
␣ Cyclical changes in intra-alveolar pressure brought about indirectly by respiratory muscle activity
␣ Boyles Law: P1V1 = P2V2 (at constant Temp)
-if we change pressure in the thorax that will make gas flow in or out
so change in flow and volume of gas depends on pressure
-how you can change the pressure:
if ribs go forward= bigger volume
don't need much muscular activity for inspiration and expiration
-pulling it forward in inspiration and not much muscle activity for expiration, just sort of returning to the original position
What are the major muscles of inspiration (contract every inspiration; relaxation causes passive expiration)?
External intercostal muscles
Diaphragm- limits how long and fast an animal can run for
What are the Accessory muscles of inspiration (contract only during forceful inspiration)?
What are the muscles of active expiration (contract only during active expiration)?
-internal intercostal muscles and abdominal muscles
What happens during inspiration: picture:
bottom left: Contraction of external intercostal muscles causes elevation of ribs, which increases side-to-side dimension of thoracic cavity
What happens in passive expiration?
What happens during active expiration?
What are the changes in lung volume & intra-alveolar pressure before inspiration:
What are the changes in lung volume & intra-alveolar pressure during inspiration?
the pressure is smaller inside than outside= air goes in (due to muscle contraction)
What are the changes in lung volume & intra-alveolar pressure during expiration?
-the pressure in the plura determines the pressure in the lungs, the plura pressure= because of the muscles
lot of the time "natural" expiration: recoil of the lungs as the muscles relax
but can have more forceful expiration
can get more air in if breathe out more!
What are the airflow and poiseulle equations?
Airflow rate (F) = difference between atmosphere & intra- alveolar pressure (P) /airway resistance (R)
-L = length, viscocity
radius is the most imposrtant factor in airflow rate
- very small change will have a big effect on the resistance to the airflow
bronchioles= the radius controlled by smooth muscle
-so depends on those
What sort of airflow do we have in animals usually?
-Usually laminar / not turbulent
-assuming we get laminar flow, non laminar can happen= galloping horses or interference in the larynhx or so,
What controls the Bronchodilation v. bronchoconstriction?
Sympathetic (mostly dilation) v. parasympathetic (mostly constriction)
Mucus escalator (upper respiratory tract= lining, villi,-moving mucus material toward the pharynx -dust etc will be caught ther= mucus escalator,protecting the respiratory tract from foreign matter past larynx you swallow it and the digestive tract deals with it)
Slow rate = greater efficiency of mucus escalator (the flow through the small bronchioles is slow so foreign matter won't get far and not to the alveoli as we can close the bronchioles during vigorous exercise it can be opened so more flow to there = then there more of a chance of getting foreign matter in= dangerous, natural state of lung= bronchoconstriction= so foreign matter doesn't get in!)
plus smooth muscle can contract and bronchoconstrict even further
asthma= too much bronchocontriction
why not best to have it controlled only by pressure?= contact with the outside air: dust etc
in horses if breathing in poor air long term= bronchoconstriction chronically, hard to breathe= heaves sickness
How are lungs able to behave like a balloon?
-Pulmonary elasticity (in the connective tissue between the alveoli)
-Compliance( Effort required for lungs to distend or stretch
Elastic recoil(Highly elastic connective tissue throughout the lungs, Alveolar surface tension, Alveolar interdependence)
What is the law of LaPlace?
-small alveoli should collapse & expel air into larger alveoli
-more surface tension in the smaller one, pressure in bigger is smaller than in the smaller if just talking about balloons, then the smaller ones should give it to the bigger ones =that's what can happen in smokers and also destroys their mucus escalator
What solves the problem of LaPlace law?
Type II alveolar cells secrete pulmonary surfactant (detergent containing lipids & proteins)
but:change of surface tension is controlled by the surfactant released by Type II alveloar cells
so then pressure is the same in the big and small
surfactant: Lowers alveoli surface tension, pulmonary compliance, lung tendency to recoi
What is different in ventilation of birds?
-separation of ventilation and gas- exchange
-Parabrochii (lined with air capillaries)
-Anterior air sacs
-Posterior air sacs
-2 breath pattern: one way flow through the parabronchii
separation of ventilation and gas exchange
-parabronchi= air flow and air capillaries allow air flow
air sacs- hold the gas breathed in
then valves that allow this to be controlled so only one way flow through the bronchi
both expiration and insipration have gas exchange happening much more efficient than the mammalian system= important for flying they can extract oxygen much more efficiently
flow into the alveoli almost zero in mammals