Respiration
Vertebrate Zoology
SCBI 305
• External respiration—การแลกเปลี่ยนแก๊ส (O2 extraction)
ระหว่างสิ่งแวดล้อม (น้ํา อากาศ) & เลือด
• Internal respiration—การแลกเปลี่ยนแก๊สระหว่างเลือด &
เนื้อเยื่อ
Respiratory System
ที่มา: Piiper, J. 1982. J. Exp. Biol. 100: 5-22
• ความหมาย respiration ในมุมของ biochemists
• Respiration = chemical respiration, cellular
respiration, the aerobic degradation of substrates
in biochemical pathways
– Kreb’s cycle
– Electron transfer
– Mitochondria
• Respiration vs. Breathing vs. Ventilation
– การหายใจ?
• Ventilation, breathing = active process of moving
the respiratory medium (water/ air) across the
exchange surface
1
• Ventilation ในปลา  ทิศทางเดียว (unidirectional)
• O2 flow ในปลา
Water  mouth  cavity  operculum  outside
• Ventilation ในสัตว์มีกระดูกสันหลังอื่นๆ  ไป-กลับ
(bidirectional)
อวัยวะในระบบหายใจ
• Gills
• อื่นๆ  modified gill arches
– labyrinth organs (suborder Anabantoidei)
– suprabranchial chamber (ปลาช่อน)
• Cutaneous respiratory organs
• Gas bladders
• ปอด
ที่มา: Kardong, KV. 2009. Vertebrates: Comparative Anatomy, Function, Evolution (5th ed.).
McGraw-Hill, Inc., New York.
Gills
•
•
•
•
พบมากที่สุดสําหรับการหายใจในน้ํา
ปลาอ้าปาก น้ําผ่านเข้าปาก & gills
โครงสร้างค้ําจุนโดย branchial arches
Internal gills associated with pharyngeal slits usually
covered by
– inter branchial septum (in chondrichthyans)
– operculum (osteichthyans)
ที่มา: Helfman et al. 1997. The Diversity of Fishes. Blackwell Science.
2
External gills ยื่นออกไป
สัมผัสน้ํา, พบในตัวอ่อนของ
สัตว์มีกระดูกสันหลังหลาย
ชนิด เช่น ปลาปอด ปลาที่มี
ครีบก้าน สัตว์ครึ่งบกครึ่งน้ํา
ที่มา: Kardong, KV. 2009. Vertebrates: Comparative Anatomy, Function, Evolution (5th ed.). McGraw-Hill, Inc.,
New York.
Cutaneous respiration
• หายใจทางผิวหนัง
– Simple and direct gas exchange
– Surface cilia for creating respiratory current
• พบใน ปลาไหลยุโรป ตัวอ่อนของปลาในกลุ่ม teleosts
สัตว์ครึ่งบกครึ่งน้ํา
• Modified gill arches
– labyrinth organs  1st gill arch (พบในปลากระดี่ ปลากัด
ปลาแรด—suborder Anabantoidei)
– Other suprabranchial organs  fan-like structure (พบในปลา
ช่อน)
ที่มา: Helfman et al. 1997. The
Diversity of Fishes. Blackwell
Science.
Gas/air/swim bladders
• พบในปลาที่มีครีบก้าน
• Outpocketing of pharynx/
esophagus
• Filled with CO2, O2, N2 ใน
อัตราส่วนที่แตกต่างกัน
ที่มา: Helfman et al. 1997. The Diversity of Fishes. Blackwell Science.
3
•
•
•
•
มี pneumatic duct เชื่อมต่อกับระบบทางเดินอาหาร = physostomous
ไม่มี pneumatic duct = physoclistous
Gas gland  secreting lactic acid
Rete mirabile = looping bundle of capillaries, high
concentration of gases and metabolic byproducts
ที่มา: Kardong, KV. 2009. Vertebrates: Comparative
Anatomy, Function, Evolution (5th ed.). McGraw-Hill,
Inc., New York.
Lung
• Same origin as gas bladders
• For air breathing
• Found in many fishes and
other vertebrates
Gas gland  secreting lactic acid  lower blood pH  reduce
solubility of gases in blood  releasing of O2 bound to Hb
ที่มา: Helfman et al. 1997. The Diversity of Fishes. Blackwell Science.
• Controlling buoyancy (aka swim bladders)—fish tend
to sink due to ossified bones
– Absent in bottom dwelling fishes and open water species
(e.g. tuna)
– Absent in sharks, cyclostomes
– Why do sharks not sink?
• Occasionally serving as respiratory organs
– Original function
ที่มา: Kardong, KV. 2009. Vertebrates: Comparative Anatomy, Function, Evolution (5th ed.). McGraw-Hill, Inc.,
New York.
• Connecting to hearing apparatus in some fishes,
producing sound within swim bladders เช่น ปลาตะเพียน
ปลาปิรันย่า
4
Examples of air-breathing fishes
• Comparison with lungs
Lung
catfish
lungfish
Location Ventral to digestive tract Dorsal to digestive tract
Number pair
catfish
eel
eel
Gas bladder
Single, except
Australian lungfish
Blood
Blood returning to heart Blood returning to
pathway directly
heart through
circulation
ที่มา: Kardong, KV. 2009. Vertebrates: Comparative Anatomy, Function, Evolution (5th ed.). McGraw-Hill, Inc.,
New York.
• Amphibian lungs
– Most have lungs but major respiratory organ is skin
• Reptilian lungs
– Simple sacs in Sphenodon & snakes
– Lots of chambers and sub-chambers in other reptiles
• Bird lungs
– Air sacs extensively
distributed throughout body
– Unidirectional flow
Lung
ที่มา: Kardong, KV. 2009. Vertebrates: Comparative Anatomy, Function, Evolution (5th ed.). McGraw-Hill, Inc.,
New York.
ที่มา: Kardong, KV. 2009. Vertebrates: Comparative Anatomy,
Function, Evolution (5th ed.). McGraw-Hill, Inc., New York.
5
• Mammalian lungs
Trachea
– Multi-chambers
– Bidirectional flow
Evolution of gas bladder & lung
1o bronchi
2o bronchi
3o bronchi
Bronchioles
Alveoli
ที่มา: Kardong, KV. 2009. Vertebrates: Comparative Anatomy,
Function, Evolution (5th ed.). McGraw-Hill, Inc., New York.
Ventilation mechanisms
ที่มา: Kardong, KV. 2009. Vertebrates: Comparative Anatomy, Function, Evolution (5th ed.). McGraw-Hill, Inc.,
New York.
Suction phase
Oral cavity
• Dual pump (water ventilation)
Oral/ buccal cavity
Opercular cavity
Opercular cavity
closed valves, compressed cavities
Water
Oral cavity
Opercular cavity
Oral cavity expands  low pressure
ที่มา: Helfman et al. (1997)
Valve open  water in
6
Oral cavity
Opercular cavity
• Buccal pump (air ventilation)
– Found in air-breathing fishes, amphibians
Opercular cavity expands  lower pressure  water in
Force phase
Oral cavity
Air
Opercular cavity
Buccal
cavity
Lung
Buccal
cavity
Lung
Inhalation
Oral valve closed
Opercular valve opens  water out
Exhalation: muscles near lung force air out to buccal cavity to
outside
• Aspiration (air ventilation)
– Air being sucked in = aspire
– Pump = rib cage, diaphragm (changing pressure)
– Found in amniotes
ที่มา: Kardong, KV. 2009. Vertebrates:
Comparative Anatomy, Function,
Evolution (5th ed.). McGraw-Hill, Inc.,
New York.
ที่มา: Kardong, KV. 2009. Vertebrates: Comparative Anatomy, Function, Evolution (5th ed.). McGraw-Hill, Inc., New York.
Aspiration highly modified in birds, no longer involved buccal cavity,
feeding and ventilation decoupled
7
Ram ventilation—in active swimming fish (open mouth
while swimming)
In sharks, water
intake is through
mouth and spiracle
Patterns of gas transfer
• Orientation of blood flow  increase efficiency of gas
exchange
• Countercurrent
ที่มา: Kardong, KV. 2009. Vertebrates: Comparative Anatomy, Function, Evolution (5th ed.). McGraw-Hill, Inc.,
New York.
ที่มา: Helfman et al. (1997)
• Uniform pool
• Crosscurrent
– Airflow & blood flow crossing obliquely
– Found in bird lungs, air-breathing fish
Lung
– Partial pressure within alvelolar space uniform (frequent
breathing, mixing of gases, no barrier to diffusion)
– Found in mammalian lungs
Lung
Blood capillaries
Blood capillaries
ที่มา: Piiper, J. 1982. J. Exp. Biol. 100: 5-22
8
Skin breathing in
amphibian  direct O2
exchange with air
Comparison 3 patterns of gas transfer
Countercurrent >
Crosscurrent >
CO2
CO2
Uniform pool
CO2
O2
O2
ที่มา: Piiper, J. 1982. J. Exp. Biol. 100: 5-22
Water breathing
O2
Air breathing
ที่มา: Piiper, J. 1982. J. Exp. Biol. 100: 5-22
Moving from water to land
Why?
• Aquatic vs. terrestrial respiration
• Problems of breathing in water
– Low concentration of O2 in water
• [O2] air ~ 21% by volume
• [O2] water < 1% by volume
– High density and viscosity of water
• Water 800x more dense than air
• Water 50x more viscous than air
– Solubility of O2 in water
ที่มา: Kardong, KV. 2009. Vertebrates: Comparative Anatomy, Function, Evolution (5th ed.). McGraw-Hill, Inc.,
New York.
• Decreasing as temperature increases
• Decreasing as salt/solutes increases
9
Adaptation for living on land
• Breath air
• Respiratory organs for air breathing
– Independent evolution
– e.g. swim bladders, part of digestive tract,
specialized compartment to gill chamber, lungs
• Ventilation
– Muscular pumps
– Ventilation mechanisms
• Fishes
– CO2 out through gills, some through skin
– Require water
• Adult amphibians
– CO2 out through skin
– But O2 in through lungs
– Blood pH regulating using kidneys also requiring
large amount of water (must live near water)
Why moving to land?
• True function of respiration ≠ getting O2 from
environment
• Respiration = eliminating metabolic waste (CO2)
by regulating pH in blood
• CO2 not toxic but H+ is
• Blood pH  hemoglobin affinity
– Low pH  low affinity to bind O2
– Enzyme functions
• Connection between sarcopterigians and ancient
tetrapods
– Lungfishes living in seasonal freshwater
environments (dry seasonally)
– Have to breath air (lung for respiration)
• Lungs ≠ adaptation for land living
– Supplement for gill breathing
• Tetrapod ancestors  lung inheritance for air
breathing on land
10
• Advantages of living on land
– No worry for seasonal drying of freshwater habitats
– Amount of O2 in air compared to water
– etc.
Air breathing mechanisms
Air breathing organs
Modified gill arches
Lungs
Buccal pump
Modified buccal pump
Aspiration pump
11