7.19 Comparative Anatomy & Physiology

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These flashcards review the comparative anatomy and physiology of animal respiratory and circulatory systems, emphasizing gas-exchange surfaces, circulatory components, open vs. closed systems, vertebrate heart designs, and the adaptations that support endothermy in birds and mammals.

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35 Terms

1
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How do the circulatory and respiratory systems work together to sustain cellular respiration in animals?

Respiratory surfaces supply O2 and remove CO2 with the environment, while the circulatory system transports these gases to and from every tissue.

2
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Which two gases are primarily exchanged during aerobic cellular respiration?

Oxygen is taken in and carbon dioxide is expelled.

3
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Name the three major components common to almost all circulatory systems.

A circulatory fluid, one or more pumps (hearts), and a network of vessels.

4
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What two structural features increase the efficiency of any respiratory surface?

Large surface area and a thin, moist membrane.

5
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Why must all respiratory membranes remain moist?

Gases must dissolve in water before they can diffuse across biological membranes.

6
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Give an example of an animal group that relies mainly on cutaneous (skin) respiration.

Adult amphibians such as salamanders (many also have simple lungs).

7
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Why do flatworms not require a circulatory system?

Their small size and high surface-area-to-volume ratio allow O2 and CO2 to diffuse directly between cells and the environment.

8
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What specialized respiratory organ do mollusks, crustaceans, and fishes use for gas exchange in water?

Gills.

9
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What are lamellae and where are they found?

Lamellae are the thin, high-surface-area folds of fish gills that contain capillary beds for gas exchange.

10
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Which respiratory system delivers oxygen directly to tissues without using the circulatory system?

The insect tracheal system.

11
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What microscopic structures give mammalian lungs an enormous internal surface area?

Alveoli.

12
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What tubular structures increase the gas-exchange area of bird lungs?

Parabronchi.

13
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Besides parabronchi, what additional structures improve ventilation in the avian respiratory system?

A series of air sacs surrounding the lungs.

14
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What is the name of the oxygen-binding pigment in almost all vertebrates?

Hemoglobin.

15
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Which respiratory pigment containing copper instead of iron is used by many arthropods and some mollusks?

Hemocyanin.

16
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Why do mammalian red blood cells enhance oxygen transport more than those of other vertebrates?

They are biconcave, anucleate, and have a high surface-area-to-volume ratio, maximizing space for hemoglobin and diffusion.

17
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Write the simplified formula that relates flow rate, pressure gradient, and resistance in circulation.

Q = ΔP / R.

18
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In the context of blood flow, what does ΔP represent?

The pressure gradient between two points in the circulatory system.

19
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How does an open circulatory system differ from a closed one in terms of vessels and fluid?

In open systems, hemolymph leaves open-ended vessels and bathes organs in a hemocoel; in closed systems, blood remains inside continuous vessels and is distinct from interstitial fluid.

20
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Which animal groups typically possess open circulatory systems?

Most mollusks (except cephalopods) and arthropods.

21
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Why do closed circulatory systems generally achieve higher flow rates than open systems?

The enclosed vessels maintain higher pressures generated by the heart(s).

22
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Describe the fish circulatory circuit and heart structure.

Fishes have a single circuit with a two-chambered heart (one atrium, one ventricle) that pumps blood from body to gills then directly to systemic tissues.

23
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What limitation results from the fish single-circuit arrangement?

Blood pressure drops after passing through the gills, so flow to systemic tissues is relatively low.

24
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How many circuits and heart chambers are present in amphibians and most reptiles?

Two circuits (pulmonary and systemic) and a three-chambered heart (two atria, one ventricle).

25
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Why do pulmonary and systemic circuits of amphibians and most reptiles operate at the same pressure?

A single ventricle pumps blood into both circuits, so the generated pressure is shared.

26
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What key structural innovation allows birds and mammals to pump blood at vastly different pressures in the two circuits?

A four-chambered heart with completely separated right and left ventricles.

27
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Which ventricle in birds and mammals generates the highest pressure, and why?

The left ventricle, because it pumps oxygenated blood to the entire systemic circuit.

28
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List three adaptations that make bird and mammal lungs exceptionally efficient.

Huge internal surface area (alveoli or parabronchi), extremely thin respiratory membranes, and unidirectional or highly ventilated airflow.

29
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How does endothermy relate to the efficiency of bird and mammal circulatory and respiratory systems?

High metabolic heat production demands rapid and abundant oxygen delivery, selecting for highly efficient lungs and high-pressure circulations.

30
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Define systemic circuit in a double circulatory system.

The set of vessels that carries oxygen-rich blood from the heart to body tissues and returns oxygen-poor blood back to the heart.

31
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Define pulmonary circuit.

The set of vessels that carries oxygen-poor blood from the heart to the lungs (or skin in amphibians) for gas exchange and returns oxygen-rich blood to the heart.

32
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What is the function of capillaries in a closed circulatory system?

They provide thin-walled exchange surfaces where gases, nutrients, and wastes move between blood and tissue fluid.

33
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Which property of respiratory surfaces in aquatic animals like gills offsets low oxygen solubility in water?

Extensive folding or branching to maximize surface area.

34
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Why are lungs located internally in terrestrial vertebrates?

To keep delicate respiratory surfaces moist and protected from desiccation and mechanical damage.

35
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What evolutionary process explains the independent appearance of four-chambered hearts in birds and mammals?

Convergent evolution producing analogous adaptations to meet similar metabolic demands.