(5) The Respiratory Cycle (Karius)

Question 1

What is PaO2 measuring?

Answer 1

Partial Pressure of Oxygen in the arterial blood

Question 2

What are the major muscles of inspiration?

Answer 2

• Diaphragm
• Intercostal Ms.

Question 3

What is the diaphragm innervated by?

Answer 3

Phrenic n.

Question 4

When the diaphragm contracts, it moves _______

Answer 4

DOWN into the abdomen to increase volume of the thorax

Question 5

What type of motion do the external intercostal ms. demonstrate?

Answer 5

Bucket handle motion

(increase the anteroposterior diameter of the thorax)

Question 6

What are considered accessory muscles of inspiration?

Answer 6

• Scalene
• Sternomastoids
• Additional muscles in head and neck

Question 7

What are the functions of these accessory ms of inspiration?

Scalene:

Sternomastoids:

Answer 7

Scalene: Raise 1st and 2nd ribs

Sternomastoids: Raise sternum

Question 8

What kind of muscles are the respiratory muscles?

Answer 8

Skeletal muscle

Question 9

What are the pros for the respiratory muscles being skeletal m.?

Answer 9

Rapid

Uniform activation

Ability to respond rapidly to changes in conditions

Question 10

What are the cons for the respiratory muscles being skeletal?

Answer 10

Brain or spinal cord damage can stop breathing

Length-tension curve (if lungs get too big, can stretch the muscle)

Question 11

What is the first step in inspiration?

Answer 11

Contraction of inspiratory ms.

-Increase the thoracic volume

Question 12

T/F

Under normal conditions, the lungs and the muscles/ribs are NOT physically connected to one another

Answer 12

TRUE

Question 13

Inn between the visceral and parietal pleura there is ______

Answer 13

fluid

Question 14

At rest, the intrapleural pressure is _________

Answer 14

-5cm H2O

Question 15

As the thorax increases in volume, the intrapleural pressure will decrease to about _______

Answer 15

-8cm H2O

Question 16

As the lungs increase in size, the alveolar pressure ________

Answer 16

decreases

Question 17

At rest, alveolar pressure is _________

Answer 17

the same as atmospheric (O cm H2O)

Question 18

During a normal inspiration, alveolar pressure will go to _______

Answer 18

-1cm H2O

Question 19

Describe when air flows into the lungs

Answer 19

When alveolar pressure drops below atmospheric pressure

Question 20

Draw the graphs for:

INSPIRATION AND EXPIRATION

Volume Change (liters)

Alveolar pressure (cm H2O)

Intrapleural Pressure (cm H2O)

Air Flow (L/sec)

Answer 20

Question 21

What is the lowest point that intrapleural pressure will reach?

Answer 21

-8cm H2O

Question 22

What is tidal volume abbreviated as?

Answer 22

V (subscript T)

Question 23

What is the approximate volume of a typical breath?

(V subscript T)?

Answer 23

500 mL

Question 24

What are the expiratory muscles?

Answer 24

Abdominal Muscles

Internal intercostals

Question 25

T/F Expiration is an active process

Answer 25

FALSE!!! Expiration is PASSIVE \*Like a balloon

Question 26

What is the intrapleural pressure at the start of inspiration?

Answer 26

-5cm H2O

Question 27

LO: Compare and contrast intrapleural and alveolar pressures DRAW both Alveolar and Intrapleural pressure graphs

Answer 27

Question 28

How do you calculate **minute ventilation?**

Answer 28

How much air is inhaled every minute V(dot)= Vt x frequency

Question 29

A patient's respiratory rate is 14 breaths/min and their tidal volume is 500 mL/breath. What is their minute ventilation (V(dot))?

Answer 29

14 breaths/min x 500 mL/breath = 7,000 mL/min or 7 L/min

Question 30

How do you estimate **anatomic dead space?**

Answer 30

Estimated by knowing the patient's weight in pounds Example: A 150lb individual is estimated to have an anatomic dead space of 150mL

Question 31

How do you calculate the **minute alveolar ventilation?**

Answer 31

Subtracting the anatomic dead space volume from the tidal volume V alv= Vt-Vds example: A 150lb person who breaths in 500mL with each breath: 500-150= 350 mL of every breath gets to the alveoli

Question 32

# Define: Intrapleural Pressure (P ip)

Answer 32

Pressure in the intrapleural space

Question 33

# Define: Alveolar pressure (P ALV)

Answer 33

Pressure in the alveoli

Question 34

# Define: Transpulmonary pressure

Answer 34

Alveolar pressure - Intrapleural pressure P(alv)-P(ip)

Question 35

# Define: Tidal volume

Answer 35

How much air you take in during inspiration

Question 36

# Define: Anatomic dead space

Answer 36

The volume of air that remains in the conducting airways

Question 37

# Define: Alveolar ventilation

Answer 37

Vt- V (ds)

Question 38

# Define: Minute ventilation

Answer 38

Vt x f

Question 39

# Define: Minute alveolar ventilation

Answer 39

V (dot) a x (frequency)