Lecture 13- Respiratory 1

Question 1

What are the 3 steps of external respiration?

Answer 1

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.

Question 2

How is the respiratory system responsible for water loss and heat loss?

Answer 2

-breathe over more surface during exercise and evaporate water in lungs= water loss= cooling

Question 3

Does the respiratory system have an effect on the maintenance of acid-base balance?

Answer 3

-yes as blowing off CO2 has effect on it!

Question 4

Is respiratory system important for speaking?

Answer 4

-yes, enables vocalization

Question 5

How does breathing enhance venous return?

Answer 5

-breathing in= effect on heart rate= effect on venous return

Question 6

Does respiratory system act as a defense against inhaled foreign matter?

Answer 6

• yes!

Question 7

Does the respiratory system change materials in the circulatory system?

Answer 7

-inactivates and activates, modifies the materials e.g.: angiotensin conversion

Question 8

Annotate:

Answer 8

Question 9

Annotate:

Answer 9

Question 10

How can be flow in bronchioles affected by muscle?

Answer 10

-the small bronchioles are surrounded by smooth muscle and contraction of these will decrease diameter of the bronchioles= so effect on flow

Question 11

Is there any flow of air in terminal bronchioles?

Answer 11

No. Only diffusion.

Question 12

How do lungs interact with the circulatory system?

Answer 12

-the alveolar sacs are surrounded by fine capillaries there the exchange of O2 and CO2 takes place

Question 13

What is special about the arteries and veins in the lungs?

Answer 13

-arteries have low oxygen and veins have high oxygen= the opposite of the rest!

Question 14

Are there difference in appearance of the lungs in different species?

Answer 14

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

Question 15

Can pathways of airflow vary?

Answer 15

-yes:

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 )

Question 16

Is there a difference in the Stiffness of the thorax in animals?

Answer 16

Greater in large animals (i.e. less compliant) eg horse & cow

-stiffer thorax= so more energy to move it out

Question 17

Whic alveolar cells produce surfactant?

Answer 17

Type II alveolar cells

Question 18

Describe the anatomy of an alveolus:

Answer 18

Question 19

What are pleural surfaces?

Answer 19

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

Question 20

How do Intrapleural fluid & transmural pressure gradient hold lungs & thoracic wall in tight opposition?

Answer 20

-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

Question 21

What is pulmonary ventilation?

Answer 21

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.

Question 22

What is the position of the diaphragm and the intercostal muscles before inspiration?

Answer 22

The external intercostal muscles are relaxed and the diaphragm is relaxed. The ribcage is not expanded.

Question 23

What happens during inspiration?

Answer 23

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.

Question 24

What happens during expiration?

Answer 24

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.

Question 25

What causes flow of air into and out of lungs?

Answer 25

␣ 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

Question 26

What are the major muscles of inspiration (contract every inspiration; relaxation causes passive expiration)?

Answer 26

Sternum
Ribs
External intercostal muscles
Diaphragm- limits how long and fast an animal can run for

Question 27

What are the Accessory muscles of inspiration (contract only during forceful inspiration)?

Answer 27

Sternocleidomastoid Scalenus

Question 28

What are the muscles of active expiration (contract only during active expiration)?

Answer 28

-internal intercostal muscles and abdominal muscles

Question 29

What happens during inspiration: picture:

Answer 29

bottom left: Contraction of external intercostal muscles causes elevation of ribs, which increases side-to-side dimension of thoracic cavity

Question 30

What happens in passive expiration?

Answer 30

Question 31

What happens during active expiration?

Answer 31

Question 32

What are the changes in lung volume & intra-alveolar pressure before inspiration:

Answer 32

Question 33

What are the changes in lung volume & intra-alveolar pressure during inspiration?

Answer 33

the pressure is smaller inside than outside= air goes in (due to muscle contraction)

Question 34

What are the changes in lung volume & intra-alveolar pressure during expiration?

Answer 34

-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!

Question 35

What are the airflow and poiseulle equations?

Answer 35

Airflow rate (F) = difference between atmosphere & intra- alveolar pressure (P) /airway resistance (R)

-L = length, viscocity

r-radius

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

Question 36

What sort of airflow do we have in animals usually?

Answer 36

• Usually laminar / not turbulent
• assuming we get laminar flow, non laminar can happen= galloping horses or interference in the larynhx or so,

Question 37

What controls the Bronchodilation v. bronchoconstriction?

Answer 37

Sympathetic (mostly dilation) v. parasympathetic (mostly constriction)

Catecholamines (adrenalin)

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

Question 38

How are lungs able to behave like a balloon?

Answer 38

• 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)

Question 39

What is the law of LaPlace?

Answer 39

• 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

Question 40

What solves the problem of LaPlace law?

Answer 40

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

Question 41

What is different in ventilation of birds?

Answer 41

• 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