Respiratory System

Question 1

What are different mechanisms different vertebrates utilized for gas exchange?

Answer 1

-simple diffusion through the skin (needs to wet)
Amphioxus

Through Gills- some fish

Lungs - most tetrapods

Question 2

Pharynx

Answer 2

Short segment of the gut tract

Well-developed in fish

Just caudal of the oral cavity and anterior to the gut tube
-leads into the esophagus

Presence of pharyngeal pouches, arches and slits

In fish - gas exchange system

Question 3

Lamprey respiratory system and Gill slits

Answer 3

Pharynx divided into dorsal esophagus and ventral respiratory tube.

Respiratory tube has spherical pouches that are open to the tube through internal gill slits
To the exterior with external gill slits

Lined with gill lamellar

• highly vascularlized
• where gas exchange occurs

Question 4

Gills

Answer 4

Open to pharynx by internal gill slits and exterior by external gill slits

Filter feeding system that was redesigned for gas exchange

All vertebrate embryos develop with gill slits

Each gill associates with skeletal, muscular, vascular and nerve component

Question 5

In Gills what’s the difference between holobranch, hemibranch and pseudobranch?

Answer 5

Holobranch:
Gill with gill lamellar on both sides of the supporting septum

Hemibranch:
Septum has gill lamellae on only one side

Pseudobranch:
Gills receive oxygenated blood

Question 6

What are the support mechanisms for gill lamellae?

Answer 6

Fleshy septum extending out of the gill arch

Pairs of stiffer gill rays

Question 7

In chondrichthyes why is the first gill slit typically reduced?

Answer 7

Because the hyoid element of the first gill arch swings up to branch the upper jaw against the braincase - hylostylic jaw articulation.

Spiracle.

Question 8

Compare spiracles between modern/open water fish and bottom dwelling fish? How many gil slits pairs do modern fish have? What are the exceptions?

Answer 8

Spiracles are reduced or lost in open water fish

Spiracle is quite large in bottom dwelling sharks and skates

Five

The exceptions to the rule are lampreys and hagfish, which have many gill slit pairs

Question 9

What mechanisms are use by sharks and teleosts to force water over their gill slits?

Answer 9

Sharks:
-suction pump mech: inspiration with mouth closed cause volume of pharynx to expand which forces the water across the gill surfaces.

Positive pressure ventilation: ram ventilation- fast swimming sharks

Teleosts
Alternating negative-positive pressure
-wate drawn in by open mouth and lowered floor, mouth closes flow raises, pressure lowers, pressure changes draws water from pharynx across gill surfaces and out.

Question 10

Swim Bladders

• development
• function

Answer 10

Most actinepterygian fish have a swim bladder AND gill slits

Develops as a dorsal outgrowth from wither the pharnyx or anterior gut.
-from the gut then it is initially connected to gut tube by pneumatic duct

Hydrostatic organ used to control depth in water with little muscular effort. by fluctuations of gas volume

Question 11

In fish that lose the pneumatic duct the swim bladder is controlled by?

Answer 11

Red Body

• gas gland
• system of capillaries called “rete mirabile”

Keeps the gas from being reabsorbed back into the blood from the swim bladder

• located anteriorly
• gas-absorbing tissue in at the posterior end

Question 12

What is the fate of the pneumatic duct in those fish that retain the structure?

Answer 12

In acrinopterygian fish it
Extends from the roof of the pharynx
With paired sacs which position is identical to lungs in tetrapods

Lungs in fish preceded the swim bladder. Swim bladders may have evolved from lungs in primitive fish that no longer needed them.

Question 13

What fish, other than actinopterygian, form lung like structures from the pneumatic duct?

Answer 13

Sturgeon, the gar, the bowfin and some other teleosts

Primitive teleost it’s lateroventrally located

Question 14

Respiratory system in Amphibians

• anurans
• necturus

Answer 14

Adult anurans - larval gills replaces by lungs. Also the skin and floor of buccal cavity undergo gas exchange

Larval anurans: external gills

Some salamanders retain their larval gills (neoteny)

Lungs not efficient enough to be the only source of gas exchange

Question 15

how do frogs breathe?

Answer 15

ALternating negative-positive pressure system

Air into buccal cavity throug valves nostrils and buccal flor lowers

Nostrils closed, buccal floor raises

Postive pressure forces air into the lungs through glottis

Repeat

Utilize air in lungs for several minutes before emptying and refilling

Question 16

How is the general respiratory system in mammals arranged?

Answer 16

Trachea, opens into the pharynx and larynx. At the top of the larynx is the glottis, the epiglottis keep food particles out.

Two halves of the lung, supplied by the primary bronchi (first split)

Lungs are divided into 2 or 3 lobes. A secondary broncos supplies them both.

Lobes are divided into lobules are subdivided into smaller and smaller units. The smallest is Alveoli, which is where the gas exchange occurs.

Question 17

What muscles do we use to breath?

Answer 17

A diaphragm which is under voluntary control but can be controlled through breathing centers.

Movement of the diaphragm is done by muscles originating from the sternum, ribs and lumbar vertebrae

Question 18

How is air pushed in and out of the lungs?

Answer 18

Movements by the diaphragm and ribs create a vacuum that draws air into the lungs. The elasticity of these same structures pushes air out.

Diaphragm flattened and contracts, lowers and increases the volume of the pleural cavitys (around the lungs) this decreases air pressure in the cavities, that is what draws the air in.

Movement of the ribs also lower air pressure in the area having the same effect. (Movement by intercostal muscles)