Lecture 17: Resp Flashcards
Describe ways in which vertebrates have met the requirements for gas exchange:
- Sufficient SA
- Vascularization
- Moist for diffusion
- Protection for delicate tissue
Skin for amphioxus, gill slits for fish, lungs for fish and tetrapods.
Main characteristic of the pharynx: presence of pharyngeal pouches, arches, and slits.
Describe the gernealized structure of a fish gill .
Gill slits are elongated and open into the pharynx via internal gill slits and to the exterior via external gill slits.
Filter-feeding system redesigned for gas exchange.
Each gill arch asso. W/ a skeletal , muscular, vascular, and nerve component.
W/ some kind of mechanical support for the actual gas exchange surfaces.
Compare gills in lampreys, sharks, and teleosts.
Lampreys: subdivided pharynx-for sucking/feeding. Spherical pouches.
Sharks: 1st gill slit reduced-spiracle. Mouth closed during inspiration. Pharynx is expanded, drawing water in pharynx. Forced across gill surfaces by closing of the mouth and the contraction of pharynx. Use ram ventilation: +pressure.
Teleosts: water drawn into pharynx by opening the mouth and lowering the pharyngeal floor. Then mouth closed and the operculum raised, lowering the pressure in the opercular chamber. Draws water from the pharynx across the gill surfaces and out.
Differentiate btw hemibranch and holobranch
Holobranch: gill lamellae on both sides of the supporting septum
Hemibranch: The septum is covered only on one side by gill lamellae
Define spiracle and describe its fate in fishes
The hyoid element from the 2nd arch cuts across the gill slit in order to brace the upper jaw
Reduced first gill arch- small external opening that connects to trachea
Describe the function of the swim bladder
Functions as a hydrostatic organ allowing fish to control their depth in the water w/ little muscle effort
Gas volume regulated by gas-producing organ :red body
Describe the anatomy of the pneumatic duct and the pulmonary arteries that supports the origin of the swim bladder from early lungs
The swim bladder develops as an evagination from the foregut region and is initially connected to the gut tube by the pneumatic duct
develops as a dorsal outgrowth from the pharynx or anterior gut
Swim bladders developed from lungs*
Explain why fishes needed lungs and why lungs were no longer needed in many fishes.
One advantage, susceptibility to droughts, can breath and just be a little moist.
Another advantage is energy conservation- can float without using muscle. Can stand idle
Describe the structure and function of the red body.
Consists of gas gland and an extensive system of capillaries called rete mirabile-keep gas from being reabsorbed back into the blood from swim bladder.
Located at the anterior end of the swim bladder. Gas-absorbing tissue is found at the posterior end.
Describe the distribution of external and internal gills among amphibians
Adult anurans replace larval gills w/ lungs and use skin/ floor of buccaneers cavity for exchange.
Amphibian larvae have external gills- these are replaced by internal gills in older larvae but are retained throughout larval life. External gills retained =neotony.
Lungs in anurans -some subdivision-increases SA
Describe the mechanism via which frogs move air into and out of their lungs
Frogs use alternating (-)/(+) pressure system.
Air drawn into into buffalo cavity by opening valved nostrils and lowering the floor buccaneers cavity. Nostrils closed and buccaneers cavity raised creating + pressure and forcing air into lungs through glottis. Repeated several times to fill lungs w/ air. Frog may use air for sev. Min. W/o again emptying/refill lungs
Describe the general anatomy of the mammalian respiratory system from the trachea to the lungs
Pair of lungs, divided into 2 or more lobes. Lobes divided into lobules. Gas exchange occurs in alveoli. Alveolar wall single cell thick.
Gases get to lungs via trachea. Opening of trachea at top of larynx is glottis- Which is guarded against food particles by epiglottis. When swallowing the epiglottis deflects particles that might otherwise enter and possibly block the trachea.
Trachea bifurcates into a pair of primary bronchi. Into 2ndary bronchi. 16-17 levels of branching.
Separated from heart by pericardial membranes. Tranverse septum separates lungs from abd contents- creating pleural cavity on either side of the heart.
List and describe the muscles mammals use to breath.
Diaphragm-under voluntary control. But breathing centers in brain stem as well. Originate in sternum, ribs, and lumbar vertebrae. Innervated by phrenic nerve.
Also, muscles attach to rib cage-intercostal muscles and accessory muscles can use to breath: such as, scalenes and serratus anterior.
Describe the mechanism by which the diaphragm is able to move air into and out of the lungs.
Increases volume when contracted decreasing pressure= cause air to enter lungs.
Relaxing diaphragm but mostly recoil of lungs causes the air to move back to exterior.
