Gas Exchange

Question 1

What is ventilation?

Answer 1

The movement of a respiratory medium (air, water, etc..) over a respiratory surface.

Question 2

What are the three requirements for a respiratory to properly function?

Answer 2

1. Moist
2. Thin
3. High surface area

Question 3

What two types of respiratory surfaces were desribed in class?

Answer 3

1. A dense network of capillaries beneath the skin (cutaneous respiration): used by earthworms and amphibians
2. Highly folded body surfaces (gills, trachea, lungs): used by most other animals

Question 4

How much lower vs air is the oxygen content of water? What does this mean for aquatic animals?

Answer 4

40x lower

Aquatic animals must be very efficient in gas exchange.

Question 5

What are the two ways a fish can ventilate its respiratory surface?

Answer 5

1. Swimming with its mouth open
2. Coordinated movements of the mouth and operculum (gill covers).

Question 6

What mechanism is used to extract O2 from water? What percentage of O2 is extracted from water by gills? What is the pressure gradient that gas flows in?

Answer 6

Countercurrent exchange - see reference picture

About 80% of water

High pressure to low pressure.

Question 7

What are lamella in fish?

Answer 7

These are flattened plates full of capillaries in the gills that water runs by and O2 is extracted.

Question 8

What are the 4 structures in the tracheal system of an insect?

Answer 8

Spiracles - external openings

Tracheae - tubes that connect to spiracles

Tracheoles - smaller, branched tubes that deliver air directly to body cells

Air sacs - enlarged portions of the trachaea that are found near organs that require a lot of O2

Question 9

How do mammalian lungs differ from the insects tracheal system?

Answer 9

Lungs are a localized respiratory organ while the tracheal systems run throughout the insects entire body.

Question 10

Are the lungs an in-folding of a body surface?

Answer 10

Yes

Question 11

What is the trachea of a mammal reinforced by? Why?

Answer 11

Cartilagenous rings

To keep the airway open

Question 12

How do we produce sound?

Answer 12

Air is exhaled and elastic muscles of the larynx vibrate to allow sound to be produced.

Question 13

Why do epithelial cells lining the air ducts have cilia and mucus?

Answer 13

Mucus traps dust, debris, and bacteria

Cilia beat to move the mucus up the the pharynx where it can be swallowed or coughed out.

Question 14

What are at the end of bronchioles?

Answer 14

Alveoli

Question 15

How many alveoli do humans have?

Answer 15

millions, amount to 50x the surface area of the skin

Question 16

How thick are alveoli? What are they surrounded by?

Answer 16

1-cell thick

Surrounded by capillaries

Question 17

What are alveolar epithelial cells covered by? What is its purpose?

Answer 17

Surfactant - to prevent the alveoli from collapsing

Question 18

What is the definition of breathing?

Answer 18

The alternating of inhalation and exhalation of air.

Question 19

What is the difference between how amphibians breath, how birds breath, and how mammals breath?

Answer 19

Amphibians - positive pressure breathing

Birds - Negative pressure, but anterior and posterior sacs act as bellows to keep air flowing through lungs

Mammals - negative pressure breathing

Question 20

Describe negative pressure breathing of birds.

Answer 20

1. Air is inhaled and fills posterior air sac upon first inhalation.
2. First exhalation pushes air into lungs.
3. Second inhalation air passes through lungs and fills anterior air sacs
4. second exhalation anterior sacs contract and push air out of the body.

ANTERIOR AND POSTERIOR SACS ACT AS BELLOWS TO KEEP AIR FLOWING

Question 21

Describe positive pressure breathing, or how amphibians breath.

Answer 21

Air is pushed into the lungs

Air is drawn in through norstril and mouth

mouth closes and oral cavity rises and pushes air into the trachea

elastic recoil pushes air out of the lungs.

Question 22

Describe negative pressure breathing of mammals.

Answer 22

Air is pulled into the lungs

Inhalation - ribs and diaphragm contract and rib cage expands moving the thoracic cavity down, this lowers pressure in thoracic cavity relative to the atmosphere so air rushes into the cavity

Exhalation - rib and diaphragm relax and air is forced out of lungs.

Question 23

What is the pressure gradient of air? What is boyles law?

Answer 23

Air flows from high to low pressure

Boyles law: there is an inverse relationship between pressure and volume.

Question 24

So when a mammal inhales the thoracic cavity volume increases, according to boyles law the pressure in the thoracic cavity then will?

Answer 24

Decrease, allowing air to flow in.

Question 25

When a mammal exhales the thoracic cavity decreases in volume, so the pressure?

Answer 25

The pressure increases in the thoracic cavity and the air is forced out.

Question 26

What is tidal volume? Vital capacity? Residual volume? What happens to residual volume as we age?

Answer 26

Tidal volume - volume of air breathed in in one breath (about 500ml) Vital capacity - the maximal tidal volume Residual volume - air that remains in lungs after forced exhalation. Residual volume increases as we age due to decreased pulmonary function.

Question 27

What is the relationship of RV to TV and VC?

Answer 27

As residual volume increases, tidal volume and vital capacity decrease INVERSE RELATIONSHIP

Question 28

What part of the brain regulates breathing?

Answer 28

medulla oblongata (BCC, breathing control center)

Question 29

Look at this picture and understand pH control via the medulla oblongata.

Answer 29

DO IT.

Question 30

What is the definition of partial pressure?

Answer 30

The pressure exerted by a particular gas in a mixture of gases.

Question 31

What is atmospheric pressure at sea level?

Answer 31

760mmHg

Question 32

What percentage of the atmosphere is composed of O2?

Answer 32

21%

Question 33

Sine we know the pressure of the atmosphere and we know the percentage of oxygen in the atmosphere, what is the partial pressure of oxygen in the atmosphere?

Answer 33

160mmHg 760mmHg x 0.21 = 160

Question 34

What is the partial pressure of CO2 in the atmosphere?

Answer 34

0.29 mmHg

Question 35

Look at this picture and understand how the differences in partial pressure allow for gas exchange in different parts of the body.

Answer 35

DO IT. Refer to steps in the book as well.

Question 36

What is the purpose of respiratory pigments?

Answer 36

These circulate with the blood or hemolymph the oncrease the amount of O2 carried in the circulatory fluid.

Question 37

What is the difference between hemocyanin and hemoglobin?

Answer 37

Hemocyanin - uses copper to bind and carry O2, blood will be blue consequently. This is found in arthropods and mulloscs. Hemoglobin - four subunits each with a heme group, each containing an iron atom at its center that can bind one molecule of O2. MAX OF 4 O2 MOLECULES CARRIED

Question 38

Be able to interpret this graph that shows the oxyhemoglobin dissociation curve.

Answer 38

DO IT.

Question 39

What happens when one molecule is bound to hemoglobin? What about when one is released?

Answer 39

One binds - it encourages O2 to bind to other groups One releases - it encourages the rest to release

Question 40

What is a Bohr shift? What is its significance?

Answer 40

This occurs with a low pH. decreases the affinity of hemoglobin for O2. Important becasue this shows that where CO2 production is greater, hemoglobin will release more O2 in support of cellular respiration.