Chapter 8 - Respiration

Question 1

Vital Capacity (VC)

Answer 1

The maximal volume of air that can be inhaled by the lungs with each breath. This is the amount of air we actually (or vitally) use.

Question 2

Total lung capacity (TLC)

Answer 2

The maximum volume of air that the lungs can hold, which include the vital capacity (VC) and the residual volume (RV)

Question 3

Residual volume (RV)

Answer 3

The amount of air that must remain in the lung at all times in order to prevent lung collapse

Question 4

What is the relationship between total lung capacity (TLC), residual volume (RV), and vital capacity (VC)?

Answer 4

Total lung capacity (TLC) is the vital capacity (VC) plus the residual volume (RV)

TLC = RV + VC

Question 5

Expiratory Reserve Volume (ERV)

Answer 5

The amount of air that can be forcibly exhaled after a normal exhalation.

Question 6

Tidal volume

Answer 6

The volume of air that is normally inhaled or exhaled with each breath

Question 7

Inspiratory reserve volume (IRV)

Answer 7

The amount of air which can be taken into the lungs, beyond one’s tidal volume, using a forced inspiration.

Question 8

What is the relationship between tidal volume (TV), vital capacity (VC), inspiratory reserve volume (IRV), and expiratory reserve volume (ERV)?

Answer 8

Vital capcity (VC), the total amount of gas that can be moved, is equal to the sum of the inspiratory reserve volume (IRV), expiratory reserve volume (ERV), and tidal volume (TV).

VC = TV + IRV + ERV

Question 9

Label the regions of the lung capacity graph and understand their relations

Answer 9

Question 10

Where does gas exchange occur in adults?

Answer 10

gas exchange occurs in the lungs. Specifically, it occurs in the alveoli of the lungs.

Question 11

What is the passage that air takes through the respiratory tract during inhalation

Answer 11

external nares → nasal cavity → pharynx → larynx → trachea → bronchi → bronchioles → alveoli (site of gas exchange)

Question 12

What important purposes do the mouth and nose serve during breathing?

Answer 12

They act as a filtration system by removing dirt and particulate matter from the air (via mucous membranes, nasal hairs, and cilia).

They warm and humidify the air before it reaches the lungs.

Question 13

Each alveolus is coated in surfactant. What is it, and what function does it play in respiration?

Answer 13

A liquid substance produced by the lung that reduces surface tension in the alveoli. Surfactant prevents lung collapse and decreases the effort needed to expand the lungs (inhale).

Question 14

What filtration mechanisms are present in the bronchi and trachea?

Answer 14

The bronchi and trachea contain ciliated epithelial cells to catch material that may have made it past the initial filtration mechanisms in the nasal cavity.

Question 15

What function does the branching and continual subdivision of the bronchi, bronchioles, and alveoli play in gas exchange?

Answer 15

The branching and minute size allow for an exceptionally large surface area for gas exchange—approximately 100 m².

Question 16

Describe the interface of gas exchange in the alveoli.

Answer 16

A network of capillaries surrounds each alveolus to carry oxygen and carbon dioxide for gas exchange between the respiratory and circulatory systems.

Question 17

What is the function of the epiglottis?

Answer 17

The epiglottis keeps food out of the respiratory tract by covering the opening of the larynx (glottis) during swallowing.

Question 18

Thoracic cavity

Answer 18

The chest cavity that contins the lungs

Question 19

What role do the diaphragm and intercostal muscles play during breathing

Answer 19

generate the relatively negative pressure differential between each intrapleural space and its associated lung

Question 20

Regarding nervous system control, what is interesting about respiration?

Answer 20

Although breathing is controlled autonomically by smooth muscle cells, the diaphragm is composed of skeletal muscle and therefore is under somatic control. Muscular contraction and expansion of the diaphragm regulates inspiration, which is necessary for air intake.

Question 21

What are the membranes within the thoracic cavity that surround the lungs called?

Answer 21

The pleurae (singular pleura) are the membranes that surround each lung, and are a closed sac against which the lung grows. The surface adjacent to the lung is the visceral plerua, while all other parts of the sac are parietal. The pressure differential between the intrapleural space and the lungs is critical for breathing.

Question 22

Intrapleural space

Answer 22

The space between two membranes (visceral pleura and parietal pleura) that cover the lungs

Question 23

What physical principle and associated equation is used during ventilation?

Answer 23

Ventilation is based on the use of pressure and pressure differentials to do useful work in a system (to move air in and out of the lungs). It is based on Boyles law:

P₁V₁ = P₂V₂

Contraction and expansion of the diaphragm increases or decreases the lung volume (V₂), leading to a decrease or increase in lung pressure (P₂). The associated pressure differentials result in inhalation or exhalation, respectively.

Question 24

What muscles are used during inhalation to expand the thoracic cavity? How does this result in a pressure differential that leads to inhalation?

Answer 24

The diaphragm and external intercostal muscles are used to expand the thoracic cavity and inrease intrapleural volume (decrease intrapleural pressure). The pressure in the lungs (atmospheric) is now higher, than the pressure in the intrapleural space, which results in expansion of the lungs into the intrapleural space (and decreased lung pressure). This results in a pressure differential in the lungs that forces air from the outside world into the lungs (inhalation).

Question 25

What is negative pressure breathing

Answer 25

The contraction of the diaphragm and the intercostal muscles increases the volume of the thoracic cavity, reducing pressure in the intrapleural space. This decrease in pressure creates a vacuum that causes the lungs to suck in air.

Question 26

Compare inhalation and exhalation

Answer 26

Normal exhalation is merely the reverse of inhalation, and so is passive process. Forced exhalation is an active process that utilyzes the internal intercostal muscles to actively decrease the volume of the thoracic cavity (and increase pressure).

Question 27

What neurons regulate ventilation?

Answer 27

Ventilatio is primarily regulated by neurons (ventilation centers) in the medulla oblongata (midbrain) thatrhythmically fire to cause regular contraction of the diaphragm and external intercostal muscles.

Question 28

Hemoglobin

Answer 28

Protein in erythrocytes that combines with four O₂ molecules. Exhibits cooperativity: one O₂ binds (or releases), others do so more easily.

Question 29

Oxygen dissociation curve of Hb

Answer 29

↑ temp, ↑ CO₂ pressure, ↑ H⁺ concentration shift curve RIGHT = Hb has lower affinity for oxygen.

Question 30

What monitors blood CO₂ levels? How is this related to respiration?

Answer 30

Chemoreceptors on the surface of neurons in the medulla and carotid/aorta monitor blood CO₂ levels. These chemoreceptors regulate neuronal signaling that triggers contraction and expansion of the diaphragm and intercostal muscles. As the partial pressure of CO₂ in the blood rises, the respiratory rate will increase to counter it.

Question 31

Define hyperventilation. What drives this process?

Answer 31

An increase in the rate of inhalation. An increase in blood CO₂ or pH promotes hyperventilation to counter and restabilize these levels. Note that CO₂ is carried in the blood as bicarbonate (HCO₃⁻) base.

Question 32

What is the method of controlling blood pH?

Answer 32

Change rate of breathing!

1. Faster (hyperventilation) = expel more CO₂ (reduce acidity).
2. Slower (hypoventilation) = expel less CO₂ (increase acidity).

Note that CO₂ is carried in the blood as bicarbonate (HCO₃^–), a base.

Question 33

Carbonic anhydrase

Answer 33

Enzyme that governs the reaction:
CO₂ + H₂O → HCO₃⁻ + H⁺

and enables waste CO₂ to be soluble in and carried through the circulation.

Question 34

Alveoli (diagram)

Answer 34

Place in lungs where CO₂ / O₂ gas exchange takes place.

Question 35

What is the driving force of gas exchange in the alveoli?

Answer 35

The pressure differential of the gases (CO₂ and O₂) drives gas exchange. The deoxygenated blood from pulmonary arteries has a low partial pressure of oxygen and high partial pressure of carbon dioxide, facilitating the transfer of each down its respective conentration gradients. This is a passive process, no energy is required. The oxygenated blood then returns to the heart via the pulmonary veins.

Question 36

How does our respiratory system adjust as we move to higher altitudes, where oxygen is less available?

Answer 36

1. Initially we hyperventilate to increase gas exchange.
2. Next, more red blood cells are made to carry more oxygen via Hb (polycythemia).
3. In the long term we develop more blood vessels to facilitate the distribution of a higher amount of oxygen to tissues (vasularization).
4. Finally we alter the dynamics of hemoglobin binding oxygen.