Lecture 7 (Respiratory System) Flashcards
What is the main function of the respiratory system? (4 things)
- Deliver air for gas exchange
- Protect deep alveolar tissues from damage
- Vocalization
- Where appropriate contain olfactory receptors
What is unique about marine mammal lungs when expiring air?
- conserve water
- expired air much less moist
- Dolphins expired air about 70% less saturated with moister
What structure do seals have to preserve water?
- anterior nasal cavity structure composed of bone with dense mesh
- captures moisture
What are the basic structures in the respiratory system?
- Nasal tract
- Larynx
- Trachea
- Lungs
— Bronchi
— Bronchioles
— Alveoli
In humans what can we do simultaneously with breathing and what can we not do?
- We CAN breath and chew at the same time
- We CANNOT breath and swallow
- We have an epiglottis to prevent both from occuring
What is the respiratory pathway in marine mammals composed of?
What is different?
- Nares or blowholes
- nasal cavity
- larynx (voice box)
- trachea
- lungs
Respiratory system shaped differently depending on species
What are nares/blowholes?
- start of respiratory tract, ending at lungs
How are blowholes regulated?
- passive relaxation keeps blowhole closed
Which mammals have blowholes on the tops of their head and what is the exception???
- Cetaceans
- Sperm whale (blowhole on ANTERIOR part of head and slightly LEFT of center)
How many blowholes do mysticetes have and how many do odontocetes have?
Mysticetes = 2 BLOWHOLES
Odontocetes = 1 BLOWHOLE
What type of nares do sirenians have?
How do they close?
- 2 valved nostrils
- end of nose (Rostrum)
- Passive closure by anterior hinged valves
How do pinnipeds open and close their nares?
- Similar to cetaceans
- Contraction = open
- relaxation = closed
How do polar bears and sea otters open and close their nares?
What muscle is responsible for the nares
- Contration = closed
- Relaxed = open
- Annular muscles surrounding the nares
What is the another name for nasal cavity?
- Nasopharynx
What is the larynx composed of
- an elongated epiglottis
- cartilage
- muscle
What are the two marine mammals that have an epiglottis similar to that of terrestrial mammals?
- Sea otter (mustilidae)
- Polar Bear (Ursidae)
What additional structures does the pinniped have including the epiglottis and what do they do?
- 2 large throat carilages
- arytenoids lie close together to touch posterior part of epiglottis
- Keep water out of trachea
What do odontocetes have that mysticetes don’t?
- Bony septum dividing nasal passage into 2 (right and left) internal nares
- Open into the nasopharynx
- ONE blowhole, TWO INTERNAL nares
What is the goosebeak in the odontocete respiratory tract?
- 2 elongated cartilages that provide direct connection between trachea and blowhole
- appears like a goosebeak
Does the goosebeak obstruct the esophagus in odontocetes?
Is there an epiglottis?
- NO, the esophagus traverses around the blowhole
- No epiglottis
In Mysticetes, how does the larynx differ from other marine mammals?
- Shifted orientation
- extra soft tissue structures
What are the respiratory valves in Mysticetes?
- U-fold
- epiglottis
- conilculate cartilage flap
Which marine mammal species has the largest larynx?
Mysticetes
What are the three important functions of the Hyoid Bones In humans?
- Holds up the tongue which sits above it
- Holds up the larynx, which hangs below it
- Transmits the force of muscles that help open the jaw
In odontocetes, how are the hyoid bones divided and what are the parts within each portion?
Basal portion
= Basihyal, paired thyrohyals
Suspensory portion
= Paired ceratohyals, epihyals, stylohyals, and tympanohyals
Which muscles retract the hyoid apparatus?
- Sternohyoid
Which muscles control the tongue?
- Styloglossus and hyoglossus
Of the muscles that retract the hyoid apparatus or control the tongue, what is the size and function?
- muscles are enlarged
- suggested importance in suction feeding
What can you say regarding the hyoid bones and connections to the tongue in cetaceans?
- They are well developed
In pinnipeds, how do they keep water out of their trachea?
- Arytenoids (2 throat cartilages)
- Larynx also has muscles to keep water out
How does the trachae appear in pinnipeds?
- composed of complete or incomplete circles and overlap dorsally
How does the trachae appear in cetaceans?
- short
- consists of several cartilaginous rings (O shaped)
- 5-7 in belugas and sperm whales
- 13-15 in Fin Whales
How does the trachae appear in sirenians?
Dugong = 4 rings
Manatee = 8-12 rings
What adaptation do the cartilaginous rings on the trachae serve?
- diving adaptation
In manatees and cetaceans, where do the lungs sit in comparison to the diaphragm?
- lungs sit above the diaphragm
What organs do the traverse septum separate and is it part of the diaphragm?
- Separates heart from liver
- Traverse septum not part of diaphragm
Does the Manatee diaphragm attach to the sternum?
NO
What are the lungs composed of?
- 2 Bronchi
- Secondary and tertiary bronchi
- Bronchioles
- Alveoli
When adjusted to body mass comparison, do marine mammals have larger lungs than terrestrial mammals?
NO
What are the main differences between marine mammal lungs and terrestrial lungs?
- Flexible chest walls allowing for more complete emptying of air
What is unique about cetacean lungs in terms of size and shape?
- Different shape
- No lobes
- Right lung usually larger, longer, and heavier than left one
- Results in heart being pushed toward left side
How do cetacean lungs compare to terrestrial animal lungs?
- Cetacean lungs are more rigid and elastic due to increased cartilaginous support
- lower lung volume
- Very small residual lung volume
- Gas exchange occurs more fully
- Increased tidal volume
Between Mysticetes and odontocetes, which one has the larger lung?
- Odontocete lungs are larger than mysticete lungs
What advantage does the marine mammal respiratory system have?
efficiency
What is the average tidal volume of marine mammals and what is the maximum?
- Percentages of maximal air capacity
Average = 75%
Maximal = 90%
What is different about the anatomy of the cetacean lung compared to the terrestrial animal in terms of where Alveoli are located?
- respiratory vesicles found along the length of bronchioles and not at end
Describe the lungs and bronchi structure of sirenians
- very long, extend to kidneys
- primary bronchi runs almost whole length of lung
- few secondary bronchi
- arrangement of alveoli different and unique to species
What is unique about sirenian lungs?
- Bronchioles very muscular
- Muscles can close respiratory vesicles
- Allows for lung volume and air density to be compressed and be used to control boyancy w/o flippers or caudal fins
Describe the pinniped lungs and trachea
- both lungs approx. equal size
- Both have 3 lobes except right has small additional lobe
- trachea divided into 2 bronchi imediately after entering chest (runs parallel)
Explain the variation of alveoli in Phocids
- Bronchiole reinforced with muscle and partially in cartilage
- Muscle extends full length of bronchiole to alveoli
Explain the variation of alveoli in Otariids
- Bronchioli mainly reinforced with cartilage
- Cartilage extends to mouth of alveolar sacs
- Muscles DO NOT extend full length of bronchiole to alveoli
Explain the variation of alveoli in Odobenid
Where do the alveoli originate (3 places)
- Bronchiole reinforced with muscle and partially in cartilage
- Muscle extends full length of bronchiole to alveoli
- Alveoli originate in
1. Directly from cartilaginous airway
2. Offshoot on muscle
3. Laterally alveolated ending
How does the human bronchiolar and alveolar organization compare to the pinnipeds?
- Humans have NO cartilage
- Humans have straps of muscle
Describe the lung anatomy of a sea otter
- Thoracic cavity very large
- Right lung has 4 lobes
- left lung has 2 lobes
- lungs are large in relation to body size (2.5 times larger)
- Lungs are used to control buoyancy rather than story O2
Explain the alveolar organization in a sea otter and the 2 places where alveoli originate
- Bronchiole reinforced with muscle and cartilage
- Muscle extends full length of bronchiole to alveoli
Alveoli origins
1. Directly from cartilaginous airways
2. as alveolated endings
Describe polar bear lung anatomy
- No specific adaptations to aid in respiratory system during diving or swimming
