9/23a Pulmonary Physiology I (Biomedical Sciences)

Question 1

Functions of the pulmonary system

Answer 1

1. Main function: gas exchange of O2 and CO2 between cells and the environment; adapt to changing demands; pulmonary processes
2. Speech
3. Metabolic Functions - blood reservoir

Question 2

Anatomical components of gas exchange

Answer 2

1. Pump - thoracic cavity/wall is the home of the pump. The motion and changes in volume drive ventilation
2. Airways - conduction and respiratory zones
3. Control System - sensors, processors, effectors

Question 3

the importance of the pump

Answer 3

1. the motion and changes in volume of the thoracic cavity drive ventilation.
2. the volume changes drive pressure gradients
3. the movement is driven by muscle
   - Inspiration (primary, secondary/accessory)
   - Expiration (passive)
4. Lung

Question 4

primary muscles of inspiration

Answer 4

1. diaphragm completes 2/3 of vital capacity

2. intercostal muscles are important to stabilize the thoracic cavity

Question 5

secondary/accessory muscles of inspiration

Answer 5

1. sternocleidomastoid

2. scalenes

Question 6

muscles of expiration

Answer 6

1. usually passive, diaphragm relaxes

2. force exhalation is helped by the abs contracting and pushing the diaphragm superiorly

Question 7

Anatomy of the lungs

Answer 7

lobes of the lung are split by fissures

1. right lung: 3 lobes
   - superior
   - middle
   - inferior
2. left lung: 2 lobes
   - superior
   - inferior
3. pleura
   - visceral lines surface of the lung
   - parietal lines inside
   - intrapleural space is in between the two above filled with fluid that acts as a lubricant as the thoracic wall moves over the surface of the lung

Question 8

two components of the airways

Answer 8

1. conduction zone: bulk air flow to the site of gas exchange
2. respiratory zone: diffusion/gas exchange

Question 9

conduction zone

Answer 9

bulk air flow to the site of gas exchange

1. no gas exchange, so often called anatomical dead space
2. diameter is regulated by ANS (opposite of vasculature); want airways to open up and decrease resistance from airflow when symp NS hits
   - beta2 receptors excited by NE > dilation via sympathetic
   - muscarinic receptors excited by Ach > constriction via parasympathetic
3. large areas (like trachea and bronchi) are supported by cartilage rings that help keep airways open and prevent collapse

Question 10

Respiratory zone

Answer 10

diffusion/gas exchange

1. alveoli are where gas exchange takes place (50-100m^2 of surface area, but the volume itself is really SMALL, membrane is really thin, surrounder by pulmonary capillaries)
   - Pulmonary capillaries vasoconstrict in response to hypoxia (low oxygen in lungs) to direct blood away from that region and match delivery of blood via perfusion
2. Acinus - respiratory bronchiole with corresponding ducts and sacs
3. Bronchioles and Ducts - no supported by cartilage rings, but they are embedded in the parenchyma

Question 11

sensors of the respiratory system

Answer 11

part of the control system

• mechanoreceptors in the airways
• chemoreceptors in aortic and carotid arteries sense pO2, pCO2, and pH

Question 12

processors of the respiratory system

Answer 12

medulla and pons cause a change through effectors

Question 13

effectors of the respiratory system

Answer 13

signal that indicates ventilation needs to increase, it sends increase activity to the nerves and muscles of ventilation and potentially the smooth muscle for bronchodilation

• muscles of ventilation
• smooth muscle in airways

Question 14

what is an example of the pulmonary system adapting to changing demands?

Answer 14

during rest, VO2 is 250 ml/min and minute ventilation is 5 L/min
during exercise, VO2 is 5000 ml/min and minute ventilation is 100 L/min

Question 15

what are the main pulmonary processes?

Answer 15

• ventilation
• gas exchange
• gas transport to tissues
• ventilation-perfusion matching
• defense systems

Question 16

how are lung volumes and capacities measured?

Answer 16

spirometry

Question 17

What are the different lung volumes and capacities

Answer 17

1. TV = tidal volume
2. IC = inspiratory capacity
3. VC = vital capacity
4. I/ERV = Inspiratory/Expiratory Reserve Volume
5. FRC = Functional Residual capcacity
6. RV = Residual Volume
7. TLC = Total Lung Capacity

Question 18

Tidal Volume

Answer 18

volume of normal breathing = 0.5 L and it is measured pretty easily.
Normal volume of air displaced between normal inhalation and exhalation when extra effort is NOT applied
6-8 mL/kg Ideal Body Weight

Question 19

Inspiratory Capacity

Answer 19

the volume of air that can be inspired following a normal, quiet expiration
IC = TV + IRV

Question 20

Inspiratory Reserve Volume

Answer 20

the additional/maximal amount of air that can be inhaled after a normal inspiration (tidal volume)

Question 21

Vital Capacity

Answer 21

the greatest amount of air that can be expelled from the lungs after taking the deepest possible breath
VC = ERV + RV + FRC

Question 22

Expiratory Reserve Volume

Answer 22

the additional amount of air that can be expired from the lungs by determined effort after normal expiration

Question 23

Residual volume

Answer 23

not measured easily

amount of air that remains in a persons lungs after full exhaling

Question 24

Functional Residual Capacity

Answer 24

volume of air in the lungs at the bottom of a normal exhalation (no motion of the system, resting point of lung + thorax)

elastic recoil pressure of the lung inward equals the elastic recoil pressure of the chest wall outward, alveolar and mouth pressure are both ZERO and there is no airflow

Question 25

are the capacities normally sums of multiple compartments?

Answer 25

yes

Question 26

How does air get into the lungs?

Answer 26

- Ventilation = bulk flow of air into and out of the lungs - Air flows from high pressure to low pressure - Pin = Alveolar Pressure; Pout = Barometric Pressure - ----to get air to flow inward, Pin < Pout and it is expelled until pressure is equalized

Question 27

how does air get out of the lungs

Answer 27

Pin > Pout --> volume decreases | -Mechanical ventilation is a form of positive pressure ventilation, use a pump to decrease the outside pressure

Question 28

Properties of the thorax

Answer 28

Passive 1. volume is large at equilibrium, Pin = Pout, expanding forces = collapsing forces 2. Outside forces can cause the thorax to collapse or expand 3. once outside force stops acting, thorax will return to equilibrium - Collapsing > Expanding = crushed tennis ball half - Expanding > Collapsing = expanded tennis ball half

Question 29

Properties of the lungs

Answer 29

BALLOON 1. volume can't be eliminated, but it can be decreased close to 0 2. Outside forces cause the lung to expand and as soon as it stops acting, lung collapses back to equilibrium 3. Lungs have compliance (slinky) (change in Volume/ change in Pressure)

Question 30

High compliance vs low compliance

Answer 30

Very compliant = very stretchy, and as volume of lung decreases (slinky at full length) low compliance = less stretchy, more stiff, and as volume of lung increases (slinky being pulled at last two rings)

Question 31

Do muscles have to work more to stretch when the lung is at a large volume or a small volume?

Answer 31

LARGE volume

Question 32

Properties of the lungs and thorax

Answer 32

Passive! 1. pleura membrane covers/lines the inside of the pleural cavity and the outside of the lungs 2. in between pleural membrane there is a fluid that acts as a cohesive force and allows the lung to be attached to the chest wall (microscope slide comparison) - thorax wants to expand at equilibrium - lung wants to collapse at equilibrium - together, lung expands from thorax and chest wall gets to collapse from their own equilibriums to a new equilibrium (tugging force - pulling apart (-) force)

Question 33

what pressure keeps the alveoli open?

Answer 33

Pip = Intrapleural pressure (-5 at equilibrium) is what holds the alveoli open

Question 34

total lung capacity

Answer 34

the larges volume the lungs can attain

Question 35

Process of ventilation

Answer 35

1. Intrapleural lung pressure = -5cm/water at rest, lung pressure at rest = 0, the difference between Palveoli and Pintrapleaural space = +5cm/water 2. Begin inhalation/tidal volume, alveoli get pulled open, volume increases in thoracic cage and causes alveoli to expand, decreases pressure and air flows in 3. Air continues to flow in until Palveoli = Pout 4. Now, pressure increases inside the lungs as we start to exhale 5. Air continues to flow out until Palveoli = Pout