Circulation and Gas Exchange

Question 1

What is the difference between unicellular and multicellular exchange with environment?

Answer 1

In unicellular organisms, exchange occur directly with the environment. In multicelullar organisms, there exists a specialized exchange system of internal transport and gas exchange.

Question 2

What are three reasons why an internal transport system is important?

Answer 2

1. Diffusion is too slow for more complex body plans
2. Higher metabolic rates demand faster and easier access to materials
3. Larger body sizes demand easier access to materials

Question 3

What pumps the circulatory system? What does it carry, where does it carry it to and from?

Answer 3

A muscular pump (heart) uses metabolic energy to generate hydrostatic pressure to force fluid through the circuit. It carries:

1. Gases from respiratory surface to deep tissues
2. Nutrients from digestive tract to body
3. Hormones from endocrine cells.

Question 4

What are the three components of a circulatory system?

Answer 4

1. Circulatory fluid: blood or hemolymph
2. Muscular pump: heart
3. Sets of tubes: blood vessels

Question 5

What is the pathway of the circulatory system starting from the right atrium?

Answer 5

1. DeO blood goes from right atrium to right ventricle, then right ventricle to the lungs
2. Lungs oxygenate blood and return to the heart in the left atrium to the left ventricle.
3. Oxygenated blood on left ventricle exits through the aorta and is distributed among the cells through the aorta and arteries.
4. Arteries become capillaries which exchange molecules with the cells and become deoxygenated.
5. Capillaries become veins which travel back to the heart through the inferior and superior vena cavae and enter the right atrium.

Question 6

How does an open circulatory system work?

Answer 6

Blood and interstitial fluid are one fluid called hemolymph that bathe the organs directly. There is lesser hydrostatic pressure as it is less energetically expensive.

Question 7

How does a closed circulatory system work?

Answer 7

Blood is distinct from the interstitial fluid and is confined to vessels. They are more efficient at transporting circulatory fluids to tissues and cells and use high blood pressure to lead to effective delivery of oxygen and nutrients.

Question 8

What are the 5 main types of blood vessels in the cardiovascular system?

Answer 8

1. Arteries: send blood away from heart to arterioles
2. Arterioles: smaller extensions of arteries that send blood to capillaries
3. Capillaries: thin and porous walls for the exchange of molecules with body cells
4. Venules: smaller extensions of veins that send blood from capillaries to veins
5. Veins: sends blood from venules to the heart.

Question 9

What are capillary beds?

Answer 9

Networks of capillaries that act as the sites of chemical exchange between the blood and interstitial fluid based on diffusion. They infiltrate every tissue and pass within a few cell diameters of every cell.

Question 10

What are the chambers of the hearts of vertebrates and what do they do?

Answer 10

Atria: receive blood
Ventricles: pump blood

Question 11

What heart does a single circulation use? How does the system work?

Answer 11

It uses a two chambered heart (venricle and atrium). The ventricle pumps blood to the arteries innervating gills to become oxygenated. The blood travels to the rest of the body and is deoxygenated at capillary exchange, and returns to the atrium.

Question 12

What are the advantages and disadvantages of single-circulation system?

Answer 12

It has low metabolic demands, but the efficiency of circulation is low and the heart must rely on deoxygenated blood for its metabolic needs.

Question 13

What is double circulation? How does double circulation work?

Answer 13

Double circulation is a circulatory system where oxygen-poor and oxygen-rich blood are pumped separately from the right and left sides of the heart.

Question 14

What occurs during gas exchange?

Answer 14

Gas exchange supplies oxygen for cellular respiration and disposes of carbon dioxide through diffusion as a result of differences in partial pressure.

Question 15

What is partial pressure? How does it affect concentration gradient

Answer 15

Pressure exerted by a particular gas in a mixture of gases. A gas diffuses from a region of higher partial pressure to a region of lower partial pressure.

Question 16

Where is oxygen obtained in animals?

Answer 16

Sources include air or water, though there is less O2 available in water than air.

Question 17

What are the qualities of respiratory surfaces? What are some examples?

Answer 17

Must be moist, large, thin, and folds or branches (e.g. Gills, trachea, lungs)

Question 18

What is ventilation? What are types of ventilation?

Answer 18

The act of moving the respiratory medium over the respiratory surface. (E.g. countercurrent exchange system, tracheal system)

Question 19

How does the countercurrent exchange system work?

Answer 19

Blood flows in the opposite direction to water passing over the gills.

Question 20

How does the tracheal system in insects work?

Answer 20

Branching tubes supply O2 directly to body cells and removes CO2, but is separate from the circulatory systems. They ventilate by rhythmic body movements.

Question 21

Why are lungs different than the trachael system?

Answer 21

Lungs are localized respiratory systems and O2 is transported via circulatory system from the lungs to the rest of the body. Size and complexity of lungs correlate with an animals metabolic rate.

Question 22

What is the map of the respiratory system in the mammalian respiratory system?

Answer 22

Nostrils - Pharynx - Larynx - Trachea - Bronchi - Bronchioles - Alveoli

Question 23

What is the difference between positive pressure breathing and negative pressure breathing?

Answer 23

Positive pressure: ventilation occurs by forcing air down the trachea

Negative pressure: ventilation occurs by pulling air into the lungs by varying volume/air pressure (reducing air pressure in the lungs)

Question 24

What is the difference between tidal volume, vital capacity, and residual volume?

Answer 24

Tidal volume: volume of air inhaled with each breath (500 mL)

Vital capacity: maximum tidal volume

Residual volume: amount of air remaining in the lungs after exhalation

Question 25

How do birds inhale and exhale?

Answer 25

Inhalation: Air passes through the lungs in one direction only, filling 8-9 air sacs acting as bellows.

Exhalation: Air travels out of the lungs as air from bellows travel into the lungs, completely renewing the air.

Question 26

What two regions in the brain are the main breathing control centres located in? What does each region do?

Answer 26

Medulla: adjusts breathing rate and depths in response to pH changes in cerebrospinal fluid, and to match metabolic demands

Pons: regulates the tempo of breathing

Question 27

What are respiratory pigments? What are two examples?

Answer 27

Proteins that transport oxygen and increase the amount of oxygen blood can carry.

E.g. hemocyanin in arthropods and molluscs (copper binding), hemoglobin in vertebrates (iron binding)

Question 28

What is the bohr shift?

Answer 28

At high CO2 concentration, blood pH drops and decreases affinity of hemoglobin for O2.

Question 29

What are the 6 adaptations of Diving mammals that allow them to retain O2 for long amounts of time?

Answer 29

1. High blood to body volume ratio
2. Slow depletion of stockpiled O2
3. Storage of O2 in muscles in myoglobin proteins
4. Changing buoyancy to glide passively and use less O2
5. Decreasing blood supply to muscles
6. Deriving ATP muscles from fermentation once oxygen is depleted.