Respiration: Animal Models Flashcards
ventilation: sponges and cnidarians (2)
- circulate external medium through an internal cavity
- gases diffuse directing in and out of cells
circulation of medium: sponges
- flagella move water in through ostia and out through osculum
circulation of medium: cnidarians
- muscle contractions move water in and out through the mouth
ventilation: echinoderms (2)
- sea cucumbers pump water tidally via the anus
- use muscular contractions of cloaca and the respiratory tree
ventilation: molluscs (2)
- cephalopods use countercurrent flow
- muscular contractions of mantle propel water unidirectionally past the gills in the mantle cavity
ventilation: jawless fishes/agnathans
- lamprey and hagfish have multiple pairs of gill sacs
ventilation: hagfish jawless fish (3)
- uses muscular pump to propel water through respiratory cavity
- water enters mouth and leaves through gill opening
- flow is unidirectional and countercurrent
ventilation: lamprey jawless fish (3)
- when not feeding, ventilation is similar to the hagfish
- when feeding, mouth is attached to prey and cannot intake water
- ventilation is tidal through gill openings when feeding
ventilation: elasmobranchs (sharks)
- blood flow is unidirectional and countercurrent
elasmobranch ventilation steps (4)
- expand buccal cavity
- draws water into buccal cavity via mouth and spiracles
- mouth and spiracles close
- muscles around buccal cavity contract, forcing water past gills and out the gill slits
ventilation: teleost (bony) fishes steps (4)
- mouth open and opercular valve closed, buccal cavity expanded and opercular cavity expands
- mouth and opercular valve closed, buccal cavity compressed and opercular cavity expanded
- mouth closed, opercular valve open, buccal cavity compressed and opercular cavity compressing
- mouth and opercular valve open, buccal cavity expands and opercular cavity compressed
ram ventilation (3)
- used by active fish
- swimming with mouth open, so swimming musculature results in unidirectional water flow over gills
- energetically efficient as no ventilation muscles are required
major animal lineages colonizing terrestrial habitats (2)
- arthropods
- vertebrates
vertebrates (4)
- amphibians
- reptiles
- birds
- mammals
arthropods (2)
- crustaceans
- insects
ventilation: crustaceans (3)
- respiratory structures and ventilation are similar to marine relatives
- gills are stiff so they don’t collapse/stick together
- branchial cavity is highly vascularized and is primary site of gas exchange
ventilation: insects (3)
- extensive tracheal system that is similar to human circulatory system
- gases diffuse over very small distances, which is achievable due to small body size
- contraction of abdominal muscles/movements in thorax lead to expansion/contraction of tracheae
insect tracheal system (3)
- air-filled tubes called tracheae
- system open to outside via spiracles
- tracheae branch to form tracheoles which penetrate the cells throughout the body
disadvantage of tracheal system in insects (2)
- takes up enormous amount of space in body
- does not leave space for a lot of other tissues
insect air flow (2)
- tidal: air flows in and out of same spiracles
- unidirectional: air enters anterior spiracles, flows through tracheae, and exits abdominal spiracles
insects: discontinuous gas exchange (2)
- phenomenon where gas exchange is discontinuous (only 2 “bouts” of ventilation in 60 min)
- adaptive value is unknown
what medium do aquatic insects use to ventilate (2)
- breathe air
- evolution of multiple solutions for air breathing aquatic insects
ventilation: mosquito larvae (2)
- use snorkel-like mechanism to maintain air-filled trachea
- don’t use H20 because it has low O2 content and viscosity is too high to move through fragile/thin tracheal system
ventilation: water beetles (3)
- carry “scuba tank” air bubbles to breathe from during diving
- O2 diffuses in and out of bubble, N2 and CO2 diffuse out
- PO2 and PN2 remain constant in water (incompressible); however, their levels change inside the bubble
water beetle ventilation: start of descent (3)
- PO2 decreases due to O2 consumption by the beetle, O2 enters from water
- PN2 increase as bubble volume decreases due to O2 consumption, N2 exits into water
- CO2 leaves bubble
water beetle ventilation: arrival at 1m depth (3)
- PO2 is elevated due to decreased bubble volume, O2 exits into water
- PN2 is elevated due to decreased bubble volume, N2 exits into water
- CO2 exits into water
water beetle ventilation: later at 1m depth (3)
- PO2 is decreased from bus O2 consumption, so O2 enters bubble
- PN2 is elevated due to decreased bubble volume, N2 exits into water
- CO2 exits into water
water beetle ventilation: advantage
- breathing from bubble can provide 7x O2 content of initial bubble as O2 diffuses in from the water
water beetle ventilation: potential disadvantage (2)
- smaller bubbles results in less buoyancy and sinking
- beetle must balance between buoyancy and respiration
why has air breathing likely evolved so many times independently
- likely in response to periods of aquatic hypoxia
what types of respiratory structures have developed in air breathing fish (5)
- reinforced gills that do not collapse in air
- highly vascularized mouth/pharyngeal cavity
- highly vascularized stomach/intestine
- specialized pockets of the gut
- lungs
what is air breathing in fish characterized by (2)
- ventilation of air breathing organ is usually tidal
- uses buccal force similar to other fish
air breathing fish: where does the majority of O2 uptake occur
- across the air breathing organ
air breathing fish: where does the majority of CO2 excretion occur
- across the gills
air breathing fish: heart structure (2)
- possess partial separation of blood flow within heart
- first step towards completely divided hear
air breathing fish: blood flow through heart (2)
- deoxygenated blood passes through gills
- oxygenated blood coming back from the lung passes through non-functional gill arches
air breathing fish: why does oxygenated blood pass through non-functional gill arches (2)
- excrete oxygen for larvae
- conserve oxygenated blood
how do lungfish prevent O2 loss across the gills when air-breathing in hypoxic water
- reduce their gill surface area
ventilation: amphibians (2)
- tidal ventilation
- use of a buccal force pump
amphibians: respiratory structures (3)
- cutaneous respiration
- external gills
- simple, bilobed lungs
- tidal ventilation
- two phases: inspiration and expiration
- separation of feeding and respiratory muscles
- several mechanism change the volume of the chest cavity
reptile: tidal ventilation (2)
- generally relies on suction pumps to create negative pressure for aspiration
- differs from fish and amphibians that rely on buccal pumps, although the buccal pump may act as a supplement
ventilation: birds (3)
- blood flow is crosscurrent
- unidirectional flow using lungs and air sacs
- gas exchange occurs as air flows through parabronchi in lungs
bird ventilation: lungs (3)
- stiff and change little in volume
- located between series of air sacs that act as bellows
- posterior and anterior air sacs that drive movement through lungs
bird ventilation: first inhale (2)
- air sacs expand
- air enters mouth/nares, trachea, and into the posterior air sacs
bird ventilation: first exhale (2)
- air sacs compress
- air leaves posterior air sacs and enters lung tissue/parabronchi
bird ventilation: second inhale (2)
- air sacs expand
- air leaves lung tissue and enters the anterior air sacs
bird ventilation: second exhale (2)
- air sacs compress
- air leaves anterior air sacs, and exits through the trachea and mouth
ventilation: mammals (3)
- two main respiratory system parts: upper and lower respiratory tract
- alveoli are the site of gas exchange
- tidal ventilation
mammal ventilation: upper respiratory tract (4)
- mouth
- nasal cavity
- pharynx
- trachea
mammal ventilation: lower respiratory tract (2)
- bronchi
- gas exchange surfaces (alveoli)
mammal ventilation: alveoli
- types (2)
- general characteristic
- type I alveolar cells have a thin wall
- type II surfactant cells secrete fluid
- outer surface of alveoli are covered in capillaries
mammal ventilation: how does blood enter and leave the lungs (2)
- enters through the pulmonary artery
- leaves through the pulmonary vein
mammal ventilation: pleural sac
- location
- structure
- contents
- pressure
- each lung surrounded by pleural sac
- consists of two layers of cells with a small space, the pleural cavity, between them
- contains small volume of pleural fluid (incompressible)
- intrapleural sac pressure is sub-atmospheric (negative pressure)
mammal ventilation: pleural sac
- function (2)
- transmits chest wall forces evenly across the lungs
- negative pressure keeps lungs expanded, due to elastic pull of lungs or of the chest wall
mammal ventilation: lung puncture (3)
- air enters intrapleural space
- chest wall can still expand, but it cannot pull lung to expand
- lung collapses to unstretched size and is non-functional
mammal ventilation: inspiration muscles (3)
- motor neurons stimulate inspiratory muscles
- contraction of external intercostals and diaphragm
- ribs move outwards and the diaphragm moves downward
mammal ventilation: inspiration (3)
- volume of thorax increases, intrathoracic pressure decreases
- transpulmonary pressure gradient increases
- lungs expand and air is pulled in
mammal ventilation: exhalation muscles (3)
- nerve stimulation of inspiratory muscles stop
- muscles relax
- ribs and diaphragm return to original positions
mammal ventilation: exhalation (2)
- volume of thorax decreases, intrathoracic pressure increases
- passive recoil of the lungs pushes air out
mammal ventilation: exhalation during rapid, heavy breathing
- forced exhalation is by contraction of the internal intercostal muscles
