Respiration

Question 0

Ventilation

Answer 0

• membranes known as pleurae surround each lung, pleurae are closed sac
• The surface adjacent to the lung is visceral and all other parts of the sac are parietal
• this space within the sac is referred to as interpleural space which in our body contains a thin layer of fluid- this fluid helps lubricate the two plural surfaces

Question 1

Anatomy of lungs

Answer 1

Numerous cilia in the nasal pathway trap particulate matter that we don’t breathe it into our lungs

• pharynx and larynx: larynx pathway for air, pharynx for food
• from the larynx air passes into the trachea and then into the bronchi; the bronchi divide into smaller structures named bronchioles which divide further until they end in tiny structures where gas exchange occurs In alveoli
• The bronchia and trachea also contain ciliated epithelial cells catch material that may have made it past the initial check in the nose
• each alveolus is coated with surfactant, a detergent that lowers surface tension and prevent the alveolus from collapsing on itself

Question 2

Stages of ventilation

Answer 2

1. Inhalation
   - we use our diaphragm as well as the external intercostal muscles (one of the layers of muscles between the ribs) to expand the thoracic cavity. As the cavity and enlarges the diaphragm flattens down and the Chest wall moves out
   - interpleural volume increases
   - interpleural pressure decreases
   - The gas in the lungs is at atmospheric pressure which is now higher than the pressure in the intrapleural space. The lungs expand into intrapleural space (increase vol, decrease press) and air will be sucked in from a higher pressure environment into the lungs
   - this mechanism is known as negative pressure breathing because the driving force is the lower pressure in the intrapleural space compared with the lungs
2. Exhalation
   - as the diaphragm and external intercostal muscles relax the chest cavity decreases in size
   - pressure in the intrapleural space is higher than in the lungs which is still at atmospheric pressure. air will be pushed out resulting in exhalation. during highly active tasks we can speed up process by using the internal intercostal muscles which oppose the externals and pull the rib cage down, actively decreasing the volume of the thoracic cavity

Question 3

Control of ventilation

Answer 3

• ventilation is primarily regulated by neurons (ventilation centers) in the medulla oblongata that rhythmically fire causing regular contraction of respiratory muscles. These neurons are primarily something carbon dioxide concentration
• The partial pressure of carbon dioxide rises, the respiratory rate will increase to counter it
• chemoreceptors on the neuron surface monitor changes in the blood pH, this is how carbon dioxide concentration is measured
• extended periods of hypoventilation would lead to increased carbon dioxide levels and an override by the medulla oblongata which will jumpstart breathing. hyperventilation would blow off too much, co2 and inhibit ventilation

Question 4

Total lung capacity

Answer 4

In healthy human being is about 6 to 7 L, if we breathe in as much as possible, the total amount of air in our lungs at this point is the TLC

Question 5

Vital capacity

Answer 5

The total amount of forced air we breathe out, it is the amount that we can actually use

Question 6

Residual volume

Answer 6

The amount left over after we force out all of our air is the residual volume. There will always be some left over because expelling it all require lung collapsed

Question 7

Tidal volume

Answer 7

When we shallowly breathe only what we need; a liter or so with each breath; the air that naturally comes out with exhalation

Question 8

Expiratory reserve volume

Answer 8

If we use respiratory muscles to push air out, the last bit of air that exits is the expiratory reserve volume

Question 9

Inspiratory reserve volume

Answer 9

The amount of extra air we can take in after a title breath

The tidal volume plus the expiratory reserve volume plus the inspiratory reserve volume is equal to the vital capacity

Question 10

Gas exchange

Answer 10

The capillaries bring the oxygenated blood from the pulmonary arteries, which stem from the right ventricle. As they approach the single celled alveolar layers allow for diffusion of carbon dioxide from the blood into the lungs and oxygen in the opposite direction

The driving force is the pressure differential of the gases; blood is deoxygenated as it enters the lungs, has a relatively low partial pressure of oxygen and a relatively high pressure carbon dioxide

Oxygen in the alveoli flows down it’s partial pressure gradient from the alveoli into the pulmonary capillaries, where can bind to the hemoglobin for transport. Meanwhile carbon dioxide flows down it’s partial pressure gradient from the capillaries into the alveoli for expiration