Ch 6 - The Respiratory System

Question 1

List the structures in the respiratory pathway, from where air enters the nares to the alveoli

Answer 1

nares –> nasal cavity –> pharynx –> larynx –> trachea –> bronchi –> bronchioles –> alveoli

Question 2

What are alveoli?

Answer 2

small sacs that interface with pulmonary capillaries, allowing gases to diffuse across a one-cell-thick membrane

Question 3

What do surfactant in the alveoli do?

Answer 3

reduces surface tension at the liquid-gas interface, preventing collapse

Question 4

What is pleura? What is the difference between visceral, parietal, and intrapleural pleura?

Answer 4

• cover the lungs and line the chest wall
• viscera: lies adjacent to the lung itself
• parietal: lines the chest wall
• intrapleural: lies between these 2 layers and contains a thin layer of fluid that lubricates the two pleural surfaces

Question 5

What is the diaphragm?

Answer 5

a thin skeletal muscle that helps to create the pressure differential required for breathing

Question 6

What is the active process of inhalation?

Answer 6

• diaphragm and external intercostal muscle expand the thoracic cavity, increasing the volume of the intrapleural space, decreasing intrapleural pressure
• this pressure differential ultimately expands the lungs, dropping the pressure within and drawing in air from the environment (negative-pressure breathing)

Question 7

What is the difference between passive and active exhalation?

Answer 7

• passive: relaxation of the muscles of inspiration and elastic recoil of the lungs allow the chest cavity to decrease in volume, reversing the pressure differentials seen in inhalation
• active: internal intercostal muscles and abdominal muscles can be used to forcibly decrease the volume of the thoracic cavity, pushing out air

Question 8

What is a spirometer?

Answer 8

used to measure lung capacities and volumes

Question 9

What is total lung capacity (TLC)?

Answer 9

maximum volume of air in the lungs when one inhales completely

Question 10

What is residual volume (RV)?

Answer 10

volume of air remaining in the lungs when one exhales completely

Question 11

What is vital capacity (VC)?

Answer 11

difference between the minimum and maximum volume of air in the lungs
VC = TLC - RV

Question 12

What is tidal volume (TV)?

Answer 12

volume of air inhaled or exhaled ina normal breath

Question 13

What is the difference between expiratory and inspiratory reserve volume (ERV)?

Answer 13

• ex: volume of additional air that can be forcibly exhaled after a normal exhalation
• in: volume of additional air that can be forcibly inhaled after a normal inhalation

Question 14

What regulates ventilation?

Answer 14

ventilation center, a collection of neurons in the medulla oblongata

Question 15

What do chemoreceptors respond to and how do they affect the respiratory rate?

Answer 15

• respond to carbon dioxide concentrations

- increase respiratory rate when there is a high concentration of CO2 in the blood (hypercarbia or hypercapnia)

Question 16

How does the ventilation center respond to hypoxemia?

Answer 16

ventilation venter can also respond to low oxygen concentrations in the blood (hypoxemia) by increasing ventilation rate

Question 17

Other than the medulla oblongata, what can control ventilation?

Answer 17

• consciously through the cerebrum

- although the medulla will override the cerebrum during extended periods of hypo- or hyperventilation

Question 18

How do the lungs perform gas exchange with the blood through simple diffusion across concentration gradients?

Answer 18

• deoxygenated blood with a high carbon dioxide concentration is brought to the lungs via the pulmonary arteries
• oxygenated blood with a low carbon dioxide concentration leaves the lungs via pulmonary veins

Question 19

What does the large surface area of interaction between the alveioli and capillaries allow?

Answer 19

the respiratory system to assist in thermoregulation through vasodilation and vasoconstriction of capillary beds

Question 20

What mechanisms help filter the incoming air and trap particulate matter?

Answer 20

multiple including vibrissae, mucous membranes, and mucociliary escalator

Question 21

How do lysozyme in the nasal cavity/saliva protect the respiratory system from potential pathogens?

Answer 21

they attack peptidoglycan cell walls of gram-positive bacteria

Question 22

How do macrophages protect the respiratory system from potential pathogens?

Answer 22

they can engulf and digest pathogens and signal to the rest of the immune system that there is an invader

Question 23

What are mucosal surfaces coverd with?

Answer 23

IgA antibodies

Question 24

How do mast cells protect the respiratory system from potential pathogens?

Answer 24

• they have antibodies on their surface that, when triggered, can promote the release of inflammatory chemicals
• often involved in allergic reactions as well

Question 25

How id the respiratory system involved in pH control through bicarbonate buffer system?

Answer 25

• when blood pH decreases, respiration rate increases to compensate by blowing off CO2 causing a left shift in the buffer equation reducing H ion concentration
• when blood pH increases, respiration rate decreases to compensate by trapping CO2, causing a right shift in the buffer equation, increasing H ion concentration

Question 26

Which muscles are involved in inhalation v exhalation and state whether they relax or contract and how this affects the thoracic cavity volume?

Answer 26

• in: diaphragm contracts and flattens while the external intercostal muscles contract, pulling the rib cage up and out (overall increase in volume of thoracic cavity); in labored breathing, muscle of the neck and back also
• passive ex: both diaphragm and external intercostal muscles relax, causing a decrease in thoracic cavity volume; active ex also uses the internal intercostal muscles and abdominal muscles, both contracting to force out air

Question 27

What is the mathematical relationship between vital capacity, inspiratory reserve volume, expiratory reserve volume, and tidal volume?

Answer 27

VC = IRV + ERV + TV

Question 28

What is the chemical equation for bicarbonate buffer system?

Answer 28

CO2 (g) + H2O (l) H2CO3 (aq) H+ (aq) + HCO3- (aq)

Question 29

Respiratory failure refers to inadequate ventilation to provide oxygen to the tissues. How would the pH change in respiratory failure?

Answer 29

• in respiratory failure, ventilation slows, and less CO2 is blown off
• as this occurs, the buffer equation shifts to the right, and more hydrogen ions are generated resulting in lower pH of the blood

Question 30

What are the 3 main facilitators of gas exchange in the lungs?

Answer 30

• gas exchange in the lungs relies on passive diffusion of O2 and CO2 which is accomplished easily because there is always a difference in partial pressures of these 2 gases and because the subdivision of the respiratory tree creates a large surface area of interaction between the alveoli and the circulatory system
• also, thin alveolar walls allow for fast diffusion and gas exchange

Question 31

Between which pleura of the lungs would blood most likely be located in a patient with collapse of both lobes of the left lung due to blood collection?

Answer 31

the intrapleural space, bounded by the parietal and visceral pleura, is a potential space that is normally collapsed and contains a small amount of fluid
- introducing fluid to this space can cause collapse of lung

Question 32

How is gas exchange in the lungs affected if an entire lobe is filled mucus/pus (from pneumonia for example)?

Answer 32

• if an area of the lungs becomes filled with mucus and inflammatory cells, the area will not be able to participate in gas exchange
• because no air will enter or leave the area, the concentration gradient will no longer exist, and neither oxygen nor carbon dioxide will be able to diffuse across the alveolar wall

Question 33

Why is it recommended for people who are hyperventilating to breath in a bag?

Answer 33

• when people hyperventilate, their respiratory rate increases, meaning more carbon dioxide is blown off causing a shift to the left of the bicarbonate buffer equation and the blood becomes more alkaline
• breathing into the bag allows some of this carbon dioxide to be returned to the bloodstream in order to maintain proper pH