Chapter 1/2/3 (Gas Exchange and Gas Transport)

Question 1

Describe the difference between adaptation, acclimatization, and acclimation.

Answer 1

• adaptation: genetic modifications in response to change in external environment, long term
• acclimatization: behavioural modifications in response to change in external environment, short term
• acclimation: behavioural change that occurs in a controlled environment

Question 2

Fick’s first and second laws

Answer 2

• Fick’s first law: solute moves from high to low concentration
• Fick’s second law: amount that diffuses is proportional to surface area and inversely proportional to diffusion distance

Question 3

external respiration

Answer 3

exchange of oxygen and carbon dioxide between external environment and internal animal

Question 4

ventilation vs perfusion

Answer 4

• ventilation: movement of respiratory medium across respiratory surface (oxygen to respiratory tissue)
• perfusion: delivery of oxygen to tissues by blood (blood that reaches alveoli via capillaries)

Question 5

internal respiration (mitochondrial respiration)

Answer 5

use of oxygen to make energy

Question 6

Henry’s law

Answer 6

amount of gas dissolved in liquid depends on partial pressure of gas and solubility of liquid

Question 7

Graham’s law

Answer 7

• diffusion rate is proportional to solubility but inversely proportional to root of molecular weight
• increased solubility increases diffusion rate
• increased molecular weight decreases diffusion rate

Question 8

Boyle’s law

Answer 8

gases move from high to low pressure

Question 9

nondirectional ventilation

Answer 9

• medium flows past respiratory surface in an unpredictable pattern
• e.g. sponges

Question 10

tidal ventilation

Answer 10

• medium flows in and out of respiratory chamber (back and forth)

Question 11

unidirectional ventilation

Answer 11

• medium enters respiratory chamber one way and exits through another
• flow is in a single direction across respiratory surface
  (can be concurrent, countercurrent or crosscurrent)

Question 12

concurrent vs. countercurrent vs. crosscurrent flow

Answer 12

• concurrent flow: same direction
• countercurrent flow: opposite directions
• crosscurrent flow: at an angle

Question 13

Explain the buccal-occular pump used by teleost fish.

Answer 13

1. mouth opens; buccal cavity expanded; opercular valve closed; opercular cavity expands
2. mouth closed; buccal cavity compressed; opercular valve closed; opercular cavity expanded
3. mouth closed; buccal cavity compressed; opercular valve open; opercular cavity compressing
4. mouth open; buccal cavity expands; opercular valve open; opercular cavity compressed (some backflow)
   [flow is unidirectional; negative pressure created inside buccal cavity]

Question 14

Explain the ventilatory cycle in air-breathing fish.

Answer 14

1. mouth opens; buccal cavity expands; air enters buccal cavity
2. mouth closes; buccal cavity compresses; air enters anterior chamber
3. mouth closed; anterior chamber closed; posterior chamber contracts and used air is exhaled from posterior chamber, exiting via operculum
4. mouth closed; anterior chamber opens and contracts; fresh air flows into posterior chamber; gas exchange occurs

Question 15

Explain the ventilatory cycle in a frog.

Answer 15

1. air enters pocket of buccal cavity through open nares
2. glottis opens; elastic recoil of lungs and compression of chest wall reduces lung volume; air forced out through nares
3. nares close; buccal cavity floor rises and air is pushed into lungs
4. glottis closes; gas exchange occurs in the lungs

Question 16

book lungs

Answer 16

• found in chelicerates (tarantula)
• thin plates called lamellae
• oxygen from air diffuses across lamellae into hemolymph
• spiracles are openings in the shell/cuticle that lead to tracheal system

Question 17

muscles used to change thoracic cavity volume and operate suction pumps in lizards vs. chelonians (turtles) vs. crocodilians

Answer 17

• lizards: intercostal muscles
• chelonians: abdominal muscles
• crocodilians: diaphragm

Question 18

Explain the ventilatory cycle in birds.

Answer 18

1. chest expands; first inhalation brings fresh air into posterior air sacs
2. chest compresses; first exhalation pushes fresh air from posterior air sacs to lungs
3. chest expands; second inhalation pushes stale air from lungs to anterior air sacs
4. chest compresses; second exhalation pushes stale air from anterior air sacs out

Question 19

Define the different patterns of ventilation: eupnea, apnea, hypernea, tachypnea, dyspnea, hyperventilation and hypoventilation

Answer 19

• eupnea: normal breathing
• apnea: no breathing
• hypernea: increased ventilation frequency or volume (increase in metabolism/exercise)
• tachypnea: increase ventilation frequency/rate with decrease in ventilatory volume (panting)
• dyspnea: difficult, laboured and uncomfortable
• hyperventilation: increased ventilation in excess of metabolic needs
• hypoventilation: decreased ventilation

Question 20

respiratory pigment

Answer 20

• metalloproteins that circulate in bodily fluids and undergo reversible chemical combination with oxygen
• respiratory pigments in RBCs is hemoglobin

Question 21

oxyhemoglobin vs deoxyhemoglobin vs carbaminohemoglobin

Answer 21

• oxyhemoglobin: heme bound to O2
• deoxyhemoglobin: heme not bound to O2 (after O2 dissociates)
• carbaminohemoglobin: when CO2 binds to globin

Question 22

methemoglobin reductase

Answer 22

• converts ferric (Fe3+) back to normal ferrous (Fe2+) in order to bind to more O2

Question 23

Why is the shape of the O2/Hb saturation curve a sigmoid shape?

Answer 23

cooperative binding: binding of O2 facilitates binding of more O2

Question 24

effect of pH on Hb-O2 affinity (Bohr effect and Root effect)

Answer 24

• decrease pH = increase PCO2 = decrease Hb-O2 affinity = curve shifts right
• Bohr effect: looks at only Hb-O2 relationship; no change in saturation
• Root effect: decrease pH causes Bohr effect AND decreases O2 carrying capacity of Hb (more exaggerated shift)

Question 25

effect of organic modulators (2,3-DPG) on Hb-O2 affinity

Answer 25

• increased 2,3-DPG decreases Hb-O2 affinity to increase O2 delivery
• increased organic modulators = increased metabolic rate so higher oxygen demand

Question 26

effect of temperature on Hb-O2 affinity

Answer 26

• higher temp = higher metabolic rate = higher oxygen demand

- Hb-O2 affinity decreases to increase O2 delivery

Question 27

Haldane effect

Answer 27

• relationship between CO2 and Hb (with effect of O2)

- CO2 saturation in deoxygenation blood higher than oxygenated blood

Question 28

carbonic anhydrase

Answer 28

catalyzes conversion of CO2 + H2O to H2CO3