Lecture 16 Flashcards

1
Q

Cutaneous Respiration in Amphibians (Keratinization):

A
  • Low keratinized of the skin is required for efficient gas exchange
  • Low keratinization = water loss in air
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2
Q

Cutaneous Respiration in Amphibians:

A
  • requires keritinization
  • Water or moisture needed to maintain integument
  • Requires blood capillaries close to surface of exchange and increased surface area
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3
Q

Tetrapods (Generally):

A
  • Paired, high surface area-to-volume-ratio, joined to larynx and buccal cavity by trachea
  • Leads to increased compartmentalization associated with increased body size and metabolic rate
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4
Q

Buccal Pump of Amphibians (Process):

A

Inspiration:
1. Nostrils open buccal cavity expands
2. Nostrils close, glottis open, buccal cavity contracts, lungs expand

Expiration:
1. Buccal cavity expands, lungs contracts
2. Nostrils open, glottis closes, buccal cavity contracts

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5
Q

Buccal Pump of Amphibians (Pressure):

A

Air is forced into the lungs with positive pressure

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6
Q

Aspiration Pump of Amniotes Properties and Process (3):

A
  1. Ribs and inercostal muscles power the pump in most reptiles
  2. Diaphram muscle and rib cage participate in lung ventilation in mammals
  3. Air is sucked into the lungs because of negative pressure (tidal air flow)
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7
Q

Bird Lungs Properties:

A
  1. Aspiration pump (like other amniotes) but lungs are coupled with air sacs –> unidirectional air flow
  2. Air flow in the lungs is dorsobronchus –> parabronchus –> ventobronchus, but complex network of air sacs involved
  3. Gas exchange occurs in small capillaries in the walls of the parabronchi
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8
Q

Bird Lung Ventilation - Properties of Two-cycle Breathing (2):

A
  1. Inhaled air is divided into lungs and posterior air sacs; the latter perfuses lungs during first exhalation.
  2. Second inhalation similar, but pushes air in the lungs into anterior air saca, which is vented out during second exhalation
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9
Q

Gas Transfer at Respiratory Surfaces (Mammals):

A

Blood encounters relatively constant gas concentration (uniform pool)

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10
Q

Gas Transfer at Respiratory Surfaces (Birds):

A

Blood encounters increasing gas concentrations allowing progressive loading of oxygen in a coss-current exchange system.

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11
Q

Gas Transfer at Respiratory Surfaces (Fish):

A

Blood first encounters lower gas concentrations and is fully equilibrated with oxygenated water in a counter-current system

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12
Q

Evolution of Lung Ventilation (2):

A
  1. Alveolar lung = many levels of branching
  2. Faveolar lung = 2-3 levels of branching
    - Faveolare is not unidirectional
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13
Q

Tetrapod Circulation:

A
  • Blood passes through the heart twice during each circuit (double-circuit system)
  • To/from body = systemic circulation
  • To/from lungs = pulmonary circulation
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14
Q

Variations on Double-Circuit Pump Pattern (Amphibian) (4):

A
  1. 3-chambered heart (two atria, one ventricle)
  2. De-oxygenated blood from the body (systemic) enter the heart at the right atrium
  3. Oxygenated blood from the lungs (pulmonary) enters the heart at the left strium
  4. Mixed-oxygenated blood in the ventricle is surprisingly low (but oxygenated blood coming from skin already mixed in)
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15
Q

Variations on Double-Circuit Pump Pattern (Reptiles) (5):

A
  1. 3-chambered heart (two atria, one partially divided ventricle)
  2. Ventricle partially divided into 3 cava (cavum pulmonale, cavum ateriosum, cavum venosum)
  3. De-oxygenated blood from the body (systemic) enters the heart at the right atrium
  4. Oxygenated blood from the lungs (pulmonary) enters the heart at the left atrium
  5. Ventricular cava allow transfer of deoxygenated blood to the lungs when breathing air and a lung bypass when diving, saving energy
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16
Q

Variations on Double-Circuit Pump Pattern (Birds/Mammals) (5):

A
  1. 4-chambered heart (two atria, two ventricles)
  2. Complete separation of pulmonary and systemic circulation (no mixing)
  3. De-oxygenated blood from the body (systemic) enters the heart at the left atrium
  4. Oxygenated blood from the lungs (pulmonary) enters the heart at the left atrium
  5. Absence of cardiac shunt probably an adaptation to allow different arterial pressure in lungs vs body in active animals
17
Q

Fetal Circulation in Mammals:

A
  • Uptake of oxygen and nutrients occurs at the placenta
  • Need to shunt most of blood away from developing lungs and into systemic circulation
  • Bypass 1: Blood enters right atrium and exits through foramen ovale to left atrium and left ventricle then to head and upper body
  • Bypass 2: Remaining blood enters right ventricle and exits pulmonary artey, travels through ductus arteriosus to lower body and placenta to be oxygenated