Unit 4- Respiratory Phys.

Question 1

VC

Answer 1

vital capacity (4,500 ml) - maximum amount of air a person can exhale after taking the deepest breath possible

VC = TV + ERV + IRV
= tidal volume + expiratory reserve vol. + inspiratory reserve volume

Question 2

TLC

Answer 2

Total Lung Capacity 5,700 ml) -

TLC = VC + RV
= vital capacity + residual volume

Question 3

TV

Answer 3

Tidal Volume (500 ml) - amount of air that enters lungs during a normal, quiet inspiration.

TV = VC - (IRV + ERV)
= vital capacity - (inspiratory reserve vol + expiratory reserve vol)

Question 4

RV

Answer 4

Residual Volume (1,200 ml) - even after a forceful expiration, some air remains in the lungs. Prevents lungs from collapsing.

RV = FRC - ERV
= functional residual capacity - expiratory reserve vol

Question 5

Dead space

Answer 5

About 150 ml - air entering the respiratory tract that fails to reach the alveoli. Air remains in trachea, bronchi & bronchioles where gas exchange cannot take place.

Question 6

How is Carbon Dioxide transported in the body?

Answer 6

~60% as bicarbonate ion (HCO3-) in the plasma
~30% as bound to the protein portion of Hb in RBC (cabaminohemoglobin, HbCo2)
~10% dissolved in plasma

Question 7

What is the OD Curve?

Answer 7

• oxygen dissociation (sigmoid) curve

- shows the relationship between Po2 and % Hb saturation

Question 8

What is the significance of the Plateau Portion of the OD curve?

Answer 8

• Top part of the curve (on the right)
• Where the P02 is high (lungs)
• Even with a 40% decrease in P02, O2 content of blood is only slightly reduced (from 97.5% to 90%)

Question 9

What is the significance of the Steep Portion of the OD curve?

Answer 9

• left side of curve

- only a small drop in blood PO2 can make large amounts of O2 available to active tissues

Question 10

A right shift of the OD curve indicates higher oxygen……

Answer 10

unloading (reduced affinity)

Question 11

carbonic anhydrase

Answer 11

• causes C02 to combine with H20 to make bicarbonate ions w/in red blood cells
• in this version is how 60% of C02 travels in RBC

Question 12

Chloride Shift

Answer 12

• Diffusion of bicarbonate ions (HCO3-) out of RBC into plasma & Cl- ions into the RBC
• important to keep the charge of the cell stable

Question 13

Haldane Effect

Answer 13

• Deoxygenated Hb has a greater affinity to CO2 than oxygenated Hb
• overall effect:
  1. O2 unloading in tissues causes CO2 loading to Hb
  2. O2 loading in lungs causes CO2 unloading from Hb

Question 14

hypoxia

Answer 14

insufficient oxygen at cellular level

• hypoxic hypoxia: due to a low Po2 in arterial blood
• anemic hypoxia: due to reducted O2-carrying capacity in blood
• stagnant hypoxia: inadequate oxygen delivered to tissues

Question 15

hyperoxia

Answer 15

an above-normal partial pressure of Po2

Question 16

hypercapnia

Answer 16

an excess of CO2 in blood caused by hypoventilation

Question 17

hypocapnia

Answer 17

below-normal level of CO2 in the blood due to hyperventilation

Question 18

respiratory acidosis

Answer 18

decrease in pH due to increased H+ produced when CO2 accumulates b/c of hypoventilation

Question 19

What are the PHYSICAL factors influencing ventilation?

Answer 19

1. Airway resistance: relationship between Flow, pressure & resistance
2. Elastic behavior of lungs: compliance (expand) & elastic recoil
3. Alveolar surface tension: influences elastic behavior of lungs

Question 20

compliance

Answer 20

• ability to stretch; ease with which lungs can be expanded
• determined by (1) distensibility of lung tissue _ thoracic cage, and (2) surface tension of alveoli
• High compliance = stretches easily
• Low compliance = requires more force

Question 21

elastic recoil

Answer 21

• returning to its resting volume when stretching force is released
• surface tension of alveolar fluid draws alveoli to their smallest possible size
• ELASTANCE: measure of how readily the lungs rebound after being stretched.

Question 22

Neural control of respiration

Answer 22

1. Medullary respiratory centers

2. Pons respiratory centers

Question 23

Medullary Respiratory center

Answer 23

1. dorsal respiratory group (DRG)

2. ventral respiratory group (VRG)

Question 24

Dorsal Respiratory group (DRG)

Answer 24

• Part of Medullary Respiratory center

- Excites inspiratory muscles

Question 25

Ventral respiratory group (VRG)

Answer 25

• Part of Medullary Respiratory center

- Active when ventilation demands increase

Question 26

Pre-Botzinger complex

Answer 26

• Neurons show pacemaker activity: sends signals to DRG

Question 27

Pontine respiratory group (PRG) [aka Pons Respiratory centers]

Answer 27

Has greater influence on respiration than the medulla

1. pneumotaxic center
2. apneustic center

Question 28

pneumotaxic center

Answer 28

sends impulses to DRG that help “switch off” inspiratory neurons, limiting the duration of inspiration

Question 29

apneustic center

Answer 29

prevents inspiratory neurons from being switched off

Question 30

Hering-Breuer (inflation) reflex

Answer 30

• triggered to prevent overinflation of lungs

- pulmonary stretch receptors

Question 31

Where are the peripheral chemoreceptors located and what do they do?

Answer 31

• Located in the carotid & aortic bodies
• respond to low levels of Po2
• used only in dire situations; as will only respond when Po2 goes below 60 mmHg
• stimulate the medullary centers - increase ventilation

Question 32

Where are the central chemoreceptors located & what do they do?

Answer 32

• in the brain (medullary center)
• sensitive to CO2-induced H+ concentration in the brain ECF that bathes them.
• increased H+ increases ventilation

Question 33

What 3 pressures are involved in ventilation?

Answer 33

1. atmospheric
2. intra-alveolar
3. intra-plueral pressure