Lab 6: Respiratory Physiology

Question 1

What is the objective of this experiment?

Answer 1

a) to measure chest dimension during respiratory cycle
b) to study effects of changes in PO2, PCO2 and pH on breathing movement
c) to preform Valsalva’s manoeurve
d) examine neural inout of respiration
e) to determine a subject’s respiratory capacity and volumes

Question 1

The Law of LaPlace

Answer 1

• explains why two ballons behave as they do

P= 2T / r

P = pressure inside each balloon
T = surface tension
r = radius

Question 2

How do surfactants work in lungs?

Answer 2

• by reducing the surface tension of liquid that lines the alveoli from a value of about 50 dynes/cm2 to 2 dyes/cm2
• the concentration of surfactant is slightly higher in smaller alveoli than in larger

Question 3

What are the two separate motions responsible for filling up the lungs?

Answer 3

• lowering the floor of the chest cavity by contraction of the diaphragm
• increasing the diameter of the chest cavity by expansion of the ribcage through the contraction of the set of external intercostal muscles found between adjacent ribs

Question 4

How do the lungs empty out?

Answer 4

through revising the motions which fill them up

Question 5

A. Chest measurements

Answer 5

• using callipers measure from anteroposterior and lateral diameters of the chest cavity during:
  quiet inspiration and extirpations and forced inspirations and expiration

Question 6

What element is measured to indicate the body’s respiratory requirements?

Answer 6

the level of carbon dioxide in the arteries is monitored

Question 7

Chemical formula of respiration

Answer 7

CO2 + H20 <–> H2CO3 <–> H+ +HCO3-

Question 8

What do the central chemoreceptors in the brain’s medulla sense?

Answer 8

a drop in blood pH which can be caused by the rate of production of CO2 exceeding it’s rate of elimination

Question 9

What in the brain detects changes in the aorta and carotid arteries?

Answer 9

peripheral chemoreceptors

Question 10

What is the main purpose of the peripheral chemoreceptors?

Answer 10

to sense acidity which arises not from CO2 but from lactic acid

Question 11

How would you know to increase your depth and rate of breathing?

Answer 11

from info sent from central and peripheral chemoreceptors to the brain

Question 12

Which level does the partial pressure of oxygen in the arteries have to fall to in order to trigger the breathing centre?

Answer 12

60 mmHg

Question 13

B. Regulation of Ventilation

Answer 13

• sit on a stool and breath as deeply as you can with your mouth open at the rate of 1 breath/ 4 seconds
• do this without a large bag tightly over your nose then with the bag

Question 14

Apnea

Answer 14

the suspense of breathing due to no desire to breathe after having had forced breathing

Question 15

The Valsalva manoeuvre

Answer 15

• forced expiration against a closed glottis
• illustrates how respiration can markedly influence circulation

Question 16

Tachycardia

Answer 16

acceleration of heartbeat

Question 17

Cyanosis

Answer 17

blood stagnation (and consequently slower delivery of O2) due to the reduced venous return
- bluing of the skin

Question 18

Cerebral hypoxia

Answer 18

insufficient delivery of O2 to the brain

Question 19

What is responsible for rhythmic breathing?

Answer 19

the brains respiratory centre

Question 20

How does the brain respiratory centre work?

Answer 20

• in order to bring inspiration, it sends excitatory impulses to the motor neuron which control the muscles of inspiration and simultaneously sends inhibitory impulses to the motor neuron of opposing groups of muscles
• for forced exhalation, excitatory impulses are sent to the motor neurons of the expiratory muscles and inhibitory impulses to the opposing muscles

Question 21

What muscles are stimulated to contract during exhalation when the body is at rest?

Answer 21

diaphragm, internal intercostal muscles and abdominal muscles

Question 22

The Hering-Breuer Inflation Reflex

Answer 22

receptors located in the visceral pleura (chest wall), bronchi, bronchioles and the alveoli are stimulated by stretching; the resultant neural transmission (via vagus nerve) inhibits the inspiratory centre and thereby prevents further inflation of the lungs

Question 23

The Hering-Breuer Deflation Reflex

Answer 23

reduced (unstretched) receptor activity removes the inhibitory influence of inspiratory centre and therefore allows inspiration to begin again

Question 24

Under normal circumstances...

Answer 24

strenuous exercise can lead to increases acidity in the blood because of the muscles production of CO2 and lactic acid - this drop in pH signals the brains respiratory centre to accelerate and deepen the breathing motions - the same effect can be also seen as soon as the exertion begins before the blood can show any signs of increased pH

Question 25

What are two explanation that cause the response of increased acidity?

Answer 25

1. exercise stimuli from contracting muscles or moving joints causes impulses to be relayed directly to the respiratory centre to increase ventilation 2. motor impulses originating in the cerebral cortex an sent to the muscle may cause collateral impulses to be sent to the respiratory centre to increase the movements of ventilation

Question 26

D. Neural Control of Respiration

Answer 26

1. see how long you can hold your breath for 2. return to normal breathing then run in place for 30 second redetermine how long you can hold your breath

Question 27

Deglutition Apnea

Answer 27

inability to breath while eating or drinking and serves to prevent the passage of substance into the trachea

Question 28

Tidal volume

Answer 28

the amount of air that moves in or out of the lungs during one breathing cycle

Question 29

Inspiratory reserve volume

Answer 29

the ability to breath in additional air after normal inspiration

Question 30

Expiratory reserve volume

Answer 30

the amount of air that can be forcibly exhaled beyond the tidal volume

Question 31

Residual volume

Answer 31

the volume of air in the lungs which is present even if the expiratory reserve volume is fully expelled from the lungs and cannot be exhaled - has low oxygen and high carbon dioxide concentration

Question 32

Equipment

Answer 32

- laptop - black iWorx case containing IXTA-ROAM - A-FH-300L Spirometer flow head and plastic tube

Question 33

Spirometer setup...

Answer 33

1. firmly push the tube to the outlets of the flow head 2. connect the other end of the flow head with the wire to the IXTA-ROAM Channel A1 (red port to red connector) 3. plug power supply for IXTA-ROAM

Question 34

What software file on labscribe is used?

Answer 34

Human Spirometer folder and "Breathing-Rest-Exercise" file

Question 35

How can you calibrate the spirometer?

Answer 35

by ensuring that in the setup settings, that the type of spirometer is IXTA and the flow head is 300L, that it is set to " No Reset Time" and the that the temp for air exhaled is 37

Question 36

Exercise 1: Breathing while resting

Answer 36

goal: to measure breathing parameters in a healthy, resting individual procedure: 1. sit quietly and breath through the spirometer 2. hold it so the outlets are held upward 3. ensure that the flowhead is properly in the subjects mouth so no air gets out 4. record subject breathing normally then record 5 forced exhalation breaths

Question 37

Exercise 1: Breathing while resting Analysis what info do you obtain from this?

Answer 37

V2-V1, T2-T1, Max_dv/dt, Min_dv/dt - to get this place cursors on a complete breathing cycle -Tidal volume: place one cursor in the long narrow opening prior to inhalation and the second on the peak of the cycle (V2-V1) -Max Inspiration Flow Rate (the max rate of air movement during inhalation): cursors in same position as tidal volume and the Max_dv/dt is the max insp. flow rate -Max Expiratory Flow Rate (max air movement during expiration): place one cursor at one peak of a breathing cycle and the second at a long narrow opening to the right of the peak and observe the value Min_dv/dt -Breathing Period (the duration of each breathing cycle): place one cursor at the peak of a breathing cycle and the other at the peak of an adjacent breathing cycle

Question 38

Equation for calculating normal breathing rate of the subject at rest (breaths/min)

Answer 38

= 60 (sec/min) / mean breath period (sec/breath) -mean breath period: mean of tidal volume, rates and breath periods

Question 39

Analyzing Forces Respiration at rest

Answer 39

- Tidal Volume (TV): place one cursor in the long narrow opening prior to inhalation and the second on the peak of the cycle (V2-V1) - Inspiratory Reserve Volume (IRV): one cursor on the peak of the normal breath prior to the max inhalation and the second at the peak of the forced breath cycle (V2-V1) - Forced Inspiratory Flow Rate : keeping cursors in same position as IRV but look at Max_dv/dt value - Forced Vital Capacity (FVC): place one cursor at peak of the forced breathing cycle and the second cursor on the flatline after the subject has expelled all the air from their lungs (V2-V1) function - Forced Expiratory Flow Rate: keeping cursors in same place as FVC but looking at Min_dv/dt value - Expiratory Reserve Volume (ERV): placing one cursor in the long narrow opening prior to the maximal inhalation and the second cursor on the flatline after the subject has expelled all the air from their lungs (V2-V1) - Forces Expiratory Volume at 1 Second (FEV1): placing one cursor at the peak of the max breath cycle and the second on the data point that is one second after the peak (V2-V1) - Forced Expiratory Volume at 3 Seconds (FEV3): placing one cursor at the peak of the max. breath cycle and the second on the data point that is 3 seconds after the peak use T2-T1 to determine where 3 seconds is but observe V2-v1 for results

Question 40

How to calculate FEV1/FVC

Answer 40

divide FEV1 by FVC - expected : 0.80

Question 41

How to calculate FEV3/FVc

Answer 41

divide FEV3 by FVC - expected: 0.95

Question 42

In obstructive airway diseases like asthma, bronchitis or emphysema both FVC and FEV1 are normally what value?

Answer 42

reduced and to a value usually less than 0.70

Question 43

In restrictive lung diseases like fibrosis

Answer 43

FVC is reduced but the FEV1/FVC ratio may be normal (0.80) or greater than normal (> 0.85)

Question 44

Expected results (for average sized human male)

Answer 44

- Tidal volume (TV): 500 mL - Inspiratory Reserve Volume (IRV): 3100 mL - Expiratory Reserve volume (ERV): 1200 mL - Forced Vital Capacity (FVC): 4800 mL - Residual Volume (RV): 1200 mL

Question 45

Exercise 2: Breathing Immediately After Exercise

Answer 45

1. subject is instructed to exercise to sufficiently increase breathing rate and this is to be recorded

Question 46

Exercise 3: Breathing Parameters from Other Students

Answer 46

1. repeat exercise 1 with a new subject

Question 47

Results (before vs after exercise)

Answer 47

- what decreased: tidal volume, mean breath periods, max normal air flow rate during exhalation, inspiratory reserve volume, forced vital capacity and forced expiratory volume 1 second, forced air flow rate during exhalation - what increased: breathing rate, mean tidal volume minute air flow rate, flow rate during inhalation, expiratory reserve volume, forced expiratory volume 3 seconds, forced air flow rate during inhalation, FEV1/FVC ratio, FEV3/FVC ratio