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?