Respiratory Cycle: Karius Lecture

Question 1

Muscles of inspiration are classified as what kind of muscles

Answer 1

skeletal m.

Question 2

Diaphragm: which direction does it go during contraction?

Answer 2

downward

moves down into the abdomen

Question 3

Diaphragm: which direction does it go when inhaling?

Answer 3

downward

Question 4

Diaphragm: how does it effect volume?

Answer 4

it increases volume of the thorax as it contracts

Question 5

What innervates the diaphragm? What kind of muscle i s the diaphragm?

Answer 5

the phrenic nerve (3, 4, 5 keep diaphragm alive)

muscle of inspiration!

Question 6

External intercostal muscles: the kind of muscle they are, what they do, and how they alter the thorax

Answer 6

they’re skeletal muscle, muscles of inspiration
when contracting they raise the ribs

they increase the anteroposterior diameter of the thorax to make the “bucket handle motion”)

Question 7

Additional muscles of inspiration that participate in inspiration under certain circumstances (excluding diaphragm and external intercostal)

Answer 7

scalene: raises 1st and 2nd ribs
sternomastoids: raise sternum
some muscle in head and neck

Question 8

First step in inspiration (think muscles and the volume of the thorax)

Answer 8

muscles contract, volume of thorax increases, therefore pressure decreases

Question 9

normal conditions: what is the relation of the ribs/muscles to the lungs?

Answer 9

they aren’t physically connected

they’re separated by the intrapleural space, filled with fluid

Question 10

Intrapleural space: boundaries, components, relationship to ribs/muscles

Answer 10

intrapleural space is comprised to of two pleural layers and a serous fluid

visceral pleura layer—intrapleural space—parietal pleura

Question 11

Pressure in the intrapleural space: how it is generated and its significance

Answer 11

lungs and chest wall are constantly trying to separate even at rest

this results in an intrapleural pressure below atmospheric pressure

Question 12

1 cm H20 =

Answer 12

I mmHg

Question 13

atmospheric pressure 760 mmHg =

Answer 13

O cm

Question 14

@ rest, intrapleural pressure =

Answer 14

-5 cm H20

Question 15

@ maximal inspiration, intrapleural pressure =

Answer 15

-8 cm H20

Question 16

lungs increase in size which causes alveolar pressure to

Answer 16

decrease

Question 17

@ rest, alveolar pressure =

Answer 17

0 cm H20

Question 18

@ marximal inspiration, alveolar pressure =

Answer 18

-1 cm H20

Question 19

if alveolar pressure goes from 0 cm H20 to -1 cm H20, which way does air go? does it go at all?

Answer 19

yes, air rushes into the lungs when pressure drops because the volume of the alveolus as increased due to the expansion of the thorax and lungs

Question 20

expiratory muscles: abdominal m.

Answer 20

push into diaphragm, pushing upwards

Question 21

internal intercostal m.

Answer 21

orientated at (more or less) a right angle to the external intercostals, decrease AP diameter of thorax

muscles of expiration

Question 22

what’s the big difference between inspiration and expiration?

Answer 22

expiration is a passive event under normal conditions and doesn’t use expiratory muscles because the lungs “want” want to be smaller (like a balloon)

Question 23

volume changes as inspiratory muscles relax

Answer 23

decreases, diaphragm and rib cage return to starting positions

Question 24

how does expiration alter pressure

Answer 24

by decreasing volume, it increases intrapleural pressure, returning it to its starting point

Question 25

@ maximal relaxation, alveolar pressure =

Answer 25

+1 cm H20

Question 26

intrapleural pressure at rest

Answer 26

-5 cm H20

Question 27

alveolar pressure at rest

Answer 27

0 cm H20

Question 28

alveolar pressure during inspiration

Answer 28

0 --> -1 cm H20 --> 0

Question 29

intrapleural pressure during inspiration

Answer 29

-5 --> -8 cm H20

Question 30

peak negative of alveolar pressure occurs

Answer 30

midway through inspiration

Question 31

when is intrapleural pressure

Answer 31

at peak inspiration

Question 32

when is the alveolar pressure partially +?

Answer 32

midway during expiration

Question 33

minute ventilation?

Answer 33

how much air is inhaled every minute

Question 34

how is minute ventilation calculated

Answer 34

tidal volume x frequency

Question 35

a patient's respiratory rate is 14 breaths per/min. Their tidal volume 500 ml/breath. What is their minute ventilation?

Answer 35

14 X 500

Question 36

Alveolar ventilation: anatomical dead space

Answer 36

dead space because they cannot receive oxygen

Question 37

a 150 Ib individual is "estimated" to have an anatomical dead space of

Answer 37

150 ml, convert Ibs to mls

Question 38

Minute Alveolar ventilation is calculated by

Answer 38

subtracting the anatomic dead space volume from the tidal volume times frequency (Tidal volume - Anatomical Dead Space volume)*f tells you how much air goes to the alveolus every minue

Question 39

V(dot)ALV =

Answer 39

alveolar ventilation Tidal Volume - Anatomical dead space

Question 40

How is minute alveolar ventilation different from minute ventilation?

Answer 40

Minute ventilation tells us how much air is going to the lungs; alveolar ventilation tells us how much air is being used by the alveolus

Question 41

minute alveolar ventilation =

Answer 41

V(ALV) X frequency or (Tidal volume - anatomical dead space) x frequency

Question 42

If a patient weighs 150 Ibs and he's breathing 12 breaths a minute, what is his V(dot)ALV?

Answer 42

(500 ml - 150 ml) x 12 300(12) 4200 ml/min (4.2 L/min)

Question 43

Minute Ventilation Minute alveolar ventilation Alveolar ventilation

Answer 43

MV: Tidal volume x frequency MAV: Tidal volume - anat. dead s * freq. AV: (Tidal volume - anatomical dead space) x frequency