Respiratory System

Question 1

What is Anaerobic Respiration?

Answer 1

Respiration that does not require oxygen to create ATP. One glucose molecule gives (net) two ATP through glycolysis.

Question 2

What is Aerobic Respiration?

Answer 2

Oxygen is needed to create ATP; more ATP can be generated (net 34 ATP).

Question 3

What are Respiratory Gases?

Answer 3

Ventilation, how we exchange gas with the environment. Glucose + oxygen = carbon dioxide + water + 34 ATP.

Question 4

Why is there a need for a respiratory system?

Answer 4

The skin of many organisms is too thick, and diffusion would be too slow to provide energy for the body. Diffusion only works in very small animals.

Question 5

What is the physics of gas exchange? (Diffusion of O2)

Answer 5

Diffusion is the main mechanism for the delivery of oxygen to cells.
Fick’s Law.
[Rate of Diffusion (Q) = ({P1-P2}AD)/DeltaX]
D = diffusion coefficient
DeltaX = thickness
A = Area

Question 6

What is Diffusion?

Answer 6

Transports from a region of high concentration/partial pressure to a region of lower concentration/partial pressure (gas molecule in gas mixture).

Question 7

What happens to diffusion is there is no pressure difference?

Answer 7

There is no diffusion because there is no difference in concentration.

Question 8

What is partial pressure?

Answer 8

How much of the air is actually oxygen.

Question 9

What happens when you increase the thickness of skin by a factor of two in Fick’s law?

Answer 9

The rate of diffusion decreases by half.

Question 10

What happens when you increase the area of diffusion by two in Fick’s law?

Answer 10

The rate of diffusion increases by two.

Question 11

What type of animals is diffusion alone good for?

Answer 11

Very small animals like rotifers.

Question 12

What happens with diffusion as organisms get larger?

Answer 12

The oxygen requirement increases with mass, but there is an increased diffusion distance and the surface area gets proportionally smaller. More mass but less space to exchange gas with.

Question 13

What do respiratory organs have that helps deal with larger organism’s diffusion issues?

Answer 13

Large surface areas and short diffusion distances. For example, human lungs have a respiratory surface of 50-100m^2 and a diffusion distance of about .3 micrometers.

Question 14

What do most vertebrate’s gas-transfer systems involve?

Answer 14

Breathing movements to allow for bulk transport (convection - or bulk flow - refers to the movement of all gas species at the mean velocity of the airstream and is the principle mechanism of gas transport in the conducting airways during normal tidal breathing - it requires a pressure gradient).
Diffusion of gases across the respiratory epithelia.
Circulatory system to allow for bulk transport of gases (convection).
Diffusion of gases across capillary walls.

Question 15

What is the structure of the gas-transfer system influenced by?

Answer 15

The properties of the medium the animal lives in (air versus water) and the requirements of the animal.

Question 16

From most efficient to least efficient, list which animals can obtain the most O2 from the medium (best respiratory systems):

1. Birds
2. Fish
3. Humans

Answer 16

Fish, birds, humans. Fish need advanced methods to obtain air from water.

Question 17

What does high altitudes do to air as a respiratory medium?

Answer 17

High altitudes reduces the inspired pressure of oxygen (partial pressure of oxygen reaching the lungs), not the percent of oxygen in the atmosphere.

Question 18

In contrast with air, water can contain ____ concentrations of ____ __.

Answer 18

In contrast with air, water can contain varying concentrations of dissolved oxygen. This is diurnal variation. Solubility of oxygen falls as temperature increases (in water).

Question 19

Air versus water as a respiratory medium:

Answer 19

1. The oxygen content in water is less than in air
2. Diffusion rate is higher in air
3. Water is more dense than air
4. Most fish have unidirectional, continuous ventilation
5. Most mammals have tidal ventilation
6. Fish are able to use up to 80% of oxygen in water (versus mammals uses 25% in air)
7. Water is more viscous than air

Question 20

What is the gas exchange performance (efficacy) of the Mammalian lung?

Answer 20

When the air gets in contact with blood, the air loses oxygen to blood. When the blood enters the alveoli it has low oxygen, when it exits the alveoli it has a lot of oxygen. When the partial pressure of blood is equal to the partial pressure in air/alveoli, then the maximum oxygen potential is reached. P1 = P2.

Question 21

What system of exchange do fish gills have?

Answer 21

Counter-current.

Question 22

What system of exchange do bird lungs have?

Answer 22

Cross-current.

Question 23

What system of exchange do mammalian lungs have?

Answer 23

Pool.

Question 24

What system of exchange do amphibian lungs have?

Answer 24

Open.

Question 25

What is the gas exchange performance (efficacy) of Fish gills?

Answer 25

When the blood comes in contact with the gills, it never allows P1 to equal P2 - there is always a gradient, and more exchange is always possible. The exhale oxygen content is lower than what the blood has. The counter current arrangement allows for better extraction of oxygen.

Question 26

What is the gas exchange performance (efficacy) of the Bird lung?

Answer 26

Bird lungs have individual spots where the air capillary and the blood capillary come into contact, and this is where gas is exchanged. It’s not a proper countercurrent since there is no continuous movement of oxygen. The arteries can collect a lot more oxygen from the air than humans can.

Question 27

What is the gas exchange performance (efficacy) of Amphibian skin?

Answer 27

It’s the least efficient respiratory system. Diffusion; the skin that separates it from the environment is thicker than the skin around human lungs. Partial pressure in air is constant.

Question 28

What is included in the Mammalian Lung/Respiratory system?

Answer 28

The Mammalian lungs are surrounded by the pleural cavity, which is filled with intrapleural fluid, and surrounded by the thoracic wall.

Question 29

What is significant about Boyle’s law?

Answer 29

P1V1=P2V2, as pressure increases the volume decreases and as the pressure decreases the volume increases.

Question 30

What happens during inhalation of the mammalian lungs?

Answer 30

The diaphragm contracts and moves down. There is an inward bulk flow of air. The external intercostal muscles contract and lift the rib cage upward and outward. The lung volume expands.

Question 31

What happens during exhalation of the mammalian lungs?

Answer 31

The diaphragm and external intercostal muscles return to the resting positions. There us an outward bulk flow of air. The rib cage moves down, lungs recoil passively.

Question 32

What is the Total Lung Capacity (TLC) of humans?

Answer 32

The maximum amount of air that the lungs can hold (approximately 5.7 L).

Question 33

What is the Tidal Volume (TV) of humans?

Answer 33

Volume of air entering or leaving the lugs during a single breath (resting TV = approximately 0.5 L).

Question 34

What is the Functional Residual Capacity (FRC) in humans?

Answer 34

The volume of air in the lungs at the end of a normal passive expiration (approximately 2.2L).

Question 35

What is the Residual Volume (RV) in humans?

Answer 35

The minimum amount of air remaining in the lungs after a maximal expiration (approximately 1.2 L).

Question 36

What is the Vital Capacity (VC) of Humans?

Answer 36

The maximum volume of air that can be moved out during a single breath following maximal inspiration (approximately 4.5 L)

Question 37

What structures are involved in the respiration of fish gills?

Answer 37

Secondary lamellae, ventilatory water flow, blood capillaries (countercurrent system), continuous flow.

Question 38

What is involved in the respiratory system of fish gills?

Answer 38

In bony and cartilaginous fish, there is a double pumping mechanism.
Ram Ventilation: pelagic fish like some sharks and mackerel (and remora). Mackerel can’t fully oxygenate their blood if prevented from active swimming.

Question 39

Describe the Fish Breathing Cycle.

Answer 39

The mouth and opercular flap act as passive flap valves, open open and one closed. The floor of the mouth acts as a suction pump (negative) in phase 1 as it is lowered, and as a positive in phase 2 as it is raised. The operculum acts as a suction pump in phase 1, situated behind the curtain of secondary lamellae, and a positive pressure pump in phase 2, expelling water from the operculum. All inspired water passed through the gill curtain for gas exchange.
The flow of water is unidirectional, which is energy efficient.

Question 40

In countercurrent exchange, blood leaving the capillaries has the same ___ ___ as fully oxygenated water entering the gills.

Answer 40

Oxygen content.

Question 41

How does ventilation and countercurrent exchange work in bony fishes?

Answer 41

Water flows around the gill filaments; water and blood flow in opposite directions though the gill filaments. Oxygen from the water diffuses into the blood, raising its oxygen content.

Question 42

What does the countercurrent exchange entail?

Answer 42

The anatomical arrangement is such that water and blood flows in opposite directions. At no point are P1 and P2 the same, there is always at least a small difference. The oxygen in the blood will always be lowered than the oxygen in the water. The water coming in has a lot of oxygen and encounters blood that has already been though oxygenation; the pressure difference exists throughout the entire exchange.

Question 43

What does concurrent flow entail?

Answer 43

Everything moves in the same direction, and P1 and P2 start out with a great difference and end up with no difference. The best you can do in a concurrent flow (or in humans) is have P1 equal P2.

Question 44

Why is countercurrent gas exchange so efficient?

Answer 44

Because, in the fill gill, the PaO2 (arterial blood) is higher than PeO2 (expired water).

Question 45

What structures are involved in the respiratory system of birds?

Answer 45

Trachea, anterior sacs, lungs (not going to change shapes), thoracic sacs, posterior sacs. Crosscurrent system, unidirectional. Air comes into very close contact with blood.

Question 46

What is the lung cycle of the bird?

Answer 46

Crosscurrent exchange in the lungs (lungs do not expand or contract, changes in pressure moves air in and out), air flows in one direction; two cycles of inhalation and exhalation are needed to move a specific volume of air through the system. Gas exchange occurs at the bronchi of the lungs, the anterior sac has deoxygenated air.

Question 47

What happens in Cycle One of the Bird breathing cycle?

Answer 47

Cycle One: during the first inhalation, most of the oxygen flows directly to the posterior air sacs. During the following exhalation, both anterior and posterior air sacs contract.

Question 48

What happens in Cycle Two of the Bird breathing cycle?

Answer 48

During the next inhalation, air from the lung (not deoxygenated) moves into the anterior air sacs. During the next exhalation, air from the anterior sacs is expelled to the outside through the trachea.

Question 49

How does the gas exchange in the parabronchus of birds work?

Answer 49

Blood flow is crosscurrent, i.e. at 90 degrees to air flow. Gas flows through parabronchi unidirectionally, and not tidally.
Air flow is driven by changes in pressure within the respiratory system.

Question 50

True or False: The serial arrangement of blood capillaries running from the periphery to the lumen of the parabronchus and the air capillaries radially depart from the parabroncial lumen.

Answer 50

True. There is a barrier between the blood capillary and the air capillary. There are multiple sites for gas exchange to occur, each site reaches an equilibrium, but the gas exchange is higher than humans.

Question 51

Air flow in birds is driven by changes in pressure within the respiratory system. During inspiration:

Answer 51

The sternum moves forward and downward while the vertebral ribs move cranially to expand the sternal ribs and the thoracoabdominal cavity .
This expands the posterior and anterior air sacs and lowers the pressure, causing air to move into those air sacs.
Air from the trachea and bronchi moves into the posterior air sacs and, simultaneously, air from the lungs moves into the anterior air sacs .

Question 52

How does Amphibian Skin respiration work?

Answer 52

It’s an ‘open’ system, the demands for oxygen works through diffusion gas exchange. Organisms are restricted to aquatic or damp environments. External gills can work with the skin. Cutaneous gas exchange represents an “open” model. In vertebrates, it’s most important in amphibians with thin, well vascularised, moist, naked skin.

Question 53

How does Insect Ventilation work?

Answer 53

They depend on the trachea, which are internal tubes with finer branches that extend to all parts of the body. They may become functionally intracellular in muscles. They are opened to the outside due to holes called Spiracles. The taenidium prevents collapse. The tracheoles are the finer (distal) tubes that appear intracellular, they invaginate a muscle cell (Tracheolar cells), are intimately associated with tissue, and deliver oxygen directly to muscle.
Spiracles are the opening of the trachea that contain closing mechanisms. They are missing in some aquatic insects, who have an array of trachea close to a thin cuticle.
Ventilation is done by air movement produces by changing shape of tracheal system; collapse and expansion of air sacs.

Question 54

What is the importance of Physical Gills?

Answer 54

They are a different way for insects to get air. Some insects carry a bobble of air when they dive to provide short-term oxygen supply, they ‘collect’ oxygen from water.

Question 55

What is Plaston (insects)?

Answer 55

A different way to get air; film or air outside the body held by specialized structures (hydrophobic). Volume is constant, and it functions as a gill. The insect does not need to surface.

Question 56

What is the importance of Tracheal Gills?

Answer 56

They are a different way for insects to get air; a close tracheal system. Oxygen diffuses across a very thin cuticle. It works as an actual gill, no direct contact with outside except for trachea gill for gas exchange.