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61 Cards in this Set

  • Front
  • Back
What is the primary function of the respiratory system?
To obtain oxygen for use by cells and eliminate CO2 produced by cells.
Respiration involves two separate processes. List them.
1. Internal (cellular) respiration

2. External respiration
Give a general description of internal (cellular) respiration.
1. Mitochondria metabolize foodstuffs

2. Usually involves the use of Oxygen

3. Results in the production of CO2 and H2O
What is exchanged during external respiration?
Exchange of gases between environment and cells.
List 4 steps of external respiration.
1. Ventilation or gas exchange between the atmosphere adn air sacs (alveoli) in lungs

2. Exchange of O2 and CO2 b/n air in alveoli and blood

3. Transport of O2 and CO2 b/n lungs and tissues

4. Exchange of O2 and CO2 b/n blood and tissues

(Steps 1 & 2 involve respiratory system)
(steps 3 & 4 depend upon circulatory system)
List 7 NON-respiratory fns of the respiratory system.
1. Route for H2O loss and heat elimination

2. Enhances venous return (respiratory pump)(inhalation, expiration)

3. Contributes to maintenance of normal acid-base balance

4. Enables vocalizations

5. Defends against inhaled foreign matter

6. Modifies, activates, and inactivates materials passing through the circulatory system.

7. Nose: organ for smell
How does the respiratory system defend against inhaled foreign matter?
Has cilia and mucus that act as physical barriers. Macrophages also reside in the lungs.
What happens to prosataglandins in the lung?
It is inactivated.
What happens to angiotensin in the lung?
Describe the general structure of the lungs?
Two, left and right, each with several lobes.
List the 8 connecting air passages of the respiratory system?
1. Nasal passage/oral cavity

2. Pharynx

3. Larynx

4. Trachea

5. Bronchi (2)

6. Bronchioles (32): Terminal bronchioles (60,000), respiratory bronchioles (500,000).

7. Alveolar ducts (500,000)

8. Alveolar sacs (8 million)
The respiratory system and circulatory system is basically a series of what?
A series of branching tubes.
What are the sites of gas exchange?
How many alveoli are present?
~300 million
Other than a series of branching tube structures the respiratory system also has associated ? for movement.
The pharynx is aka what?
Vocal cords
Where are the cartilaginous rings seen? Why?
Seen in the trachea to keep it open.
The bronchioles are surrounded by what?
Cartilage, smooth muscle
The bronchioles are regulated by what?
By autonomic innervation, also sensitive to hormones and local neurotransmitters to dilate or constrict bronchioles.
The alveolar sac is very important to ? ? and is surround by ? ?.
Important to gas exchange and surrounded by pulmonary capillaries.
What is the purpose of the Pores of Kohn that are observed in the alveolus?
So 1 alveolus is able to move gas to another collateral ventilation (side by side)
Alveoli general structure?
Thin-walled, inflatable sacs.
What is the main function of the alveoli?
Gas Exchange
The alveoli is encircled by what?
Pulmonary capillaries
What is important for the great rate of gas exchange seen in the alveoli?
The proximity to capillaries and tremendous surface area gives a great rate of gas exchange by DIFFUSION.
What does diffusion in general depend upon?
1. Thickness

2. Surface area

3. Differences in [conc]

4. Permeability
Describe the walls of the alveoli?
Single layer of flattened type I alveolar cells.

Alveolar epithelium also contains type II alveolar cells that secrete pulmonary surfactant that facilitates lung expansion and keeps them open.

Alveolar macrophages are also present (immune defense).
What is Fick's Law?
For diffusion

(^C)(p)(SA) / (MW)(^thickness)
What lines the entire internal surface of an alveolus?
Pulmonary surfactant.
The alveolus has a single layer of what kind of cells?
A single layer of epithelial cells.
The lung tissue consists of what?
A series of highly branced airways, alveoli, pulmonary blood vessels, and lots of elastic connective tissue. This is important for inhalation and exhalation.
The muscle of the lungs is subject to what control?
In the walls of arterioles and bronchioles, both are subject to the control of the ANS. Local chemical mediators and hormonal control. So different areas can be opening while others can be closing.
What amount of the thoracic cavity is occupied by the lungs?
Most of the volume of the thoracic cavity is occupied by the lungs.
What protects the lungs?
Outer chest wall. 12 pairs of curved ribs, which join the sternum and thoracic vertebrae. This protects all teh soft tissue in the thoracic cavity.
What is the diaphragm?
Skeletal muscle for breathing. Also separates the thoracic cavity from the abdominal cavity.
What is the pleural sac?
Separate each lung from the thoracic wall (chest wall).
What is the pleural cavity?
The inside of the pleural sac. Pleural surfaces secrete fluid into this cavity which prevents pain and allows for the expansion and closing of it.
Describe the parietal and visceral pleura of the pleural sac.
1. Parietal Pleura = outer membrane = attached to chest wall

2. Visceral pleura = inner membrane = attached to internal organs
Respiratory pressures involves the exchange of what?
The exchanging of gases with the environment.
What is atmospheric (barometric) pressure?
P produced by weight of the air on objects on the surface of earth.

760 mm of Hg at sea level.

Decreases with increasing altitude above sea level. (so decreased pressure with increased altitude)
What is intra-alveolar pressure AKA? What is it?
Intra-alveolar (intrapulmonary) pressure. Pressure in alveoli. It is variable, equilibriates with atmospheric pressure.
What is intrapleural pressure aka? What is it?
Aka intrathoracic pressue. Pressure in the pleural sac.
What does the intrapleural/intrathoracic pressure average at rest?
756 mm Hg at rest.

This is also written as -4.
This is because it is 4 units below 760 mmHg atmospheric pressure.

So there is essentially a slight vacuum compared to atmospheric pressure.

Lost during pneumothorax (air in pleural cavity)
Quick review:

Atmospheric pressure = ?

Lungs pressure = ?

Intrapleural Pressure = ?
Atmospheric pressure = 760 mmHg

Lungs pressure = 760 mmHg

Intrapleural Pressure = 756 mmHg or -4 mmHg
The lungs are normally ?, filling the ?.
The lungs are normally stretched, filling thorax.
The lungs are normally stretched, filling the thorax. This is due, in part, to what?
Due, in part, to intrapleural fluid's cohesiveness. Stickiness pulls lung outwards.
Describe the transmural pressure gradient across the LUNG WALL?
The transmural pressure gradient across the lung wall. There is a net outward P differential b/n INTRA-ALVEOLAR P and INTRAPLEURAL P.

The gradient pushes the lungs outward when intra-alveolar pressure is greater than P outside alveolie (that is the intrapleural P). (also helping to keep lungs open)
Describe the transmural pressure gradient across the THORACIC WALL?
Net inward P differential b/n ATMOSPHERIC P and INTRAPLEURAL P.
What would a lung puncture do?
Interfere with pressure gradients. Pressures would become equal and pushing outward would fail.
Changes in what produces air flow in and out of lungs?
Changes in intra-alveolar pressure produce flow of air in and out of lungs.

Intra-alveolar pressure < atmospheric pressure = air enters lungs

Intra-alveolar pressure > atmospheric pressure = air exits lungs
Intra-alveolar pressure changes according to what? Explain.
Changes according to BOYLE's LAW: (P1)(V1) = (P2)(V2)

There is an inverse relationship between P exerted by a qty of gas and its V.

Increased V = decreased gas P
The changes in the volume of respiratory structures is achieved by what?
Inspiration involves what of the respiratory muscles?
It is an AUTONOMIC response that involves the CONTRACTION of the respiratory muscles.
What muscles are contracted during inspiration?
The respiratory muscles:

Diaphragm (innervated with phrenic nerve)

External intercostal muscles (innervated by intercostal nerves)
75% of the enlargement of the thoracic cavity during quiet respiration is due to what?
Due to the contraction and flattening of the diaphragm.
The expansion of the thoracic cavity does what to pressure?
Expansion of the thoracic cavity decreases INTRAPLEURAL pressure (754 mm Hg0.

-Lungs drawn into area of lower pressure so they expand.

-Increase in lung volume lowers intra-alveolar P below atmospheric p

- P gradient : air enters lung
Expiration is a ? process.
This is a passive process. No contraction involved, just relaxation of inspiratory muscles.
The relaxation of inspiratory muscles during expiration involves what?
Diaphragm and muscles of chest wall, plus elastic recoil of the alveoli, decrease size of chest cavity.
During expiration what happens to intrapleural p?
Intrapleural p INCREASES. The lungs are compressed. Decreased lung volume so increased intra-alveolar P.

The increase is to a level ABOVE atmospheric P, so air is forced out...thus expiration.
What is forced expiration?
The contraction of expiratory muscles further increases P gradient between alveoli and atmosphere.
The intrapleural p is always ? lung p.
It is always less. (see 2nd slide on p. 12 of notes)