Exercise 18: The Respiratory System

• Respiration - exchange of gases to and from the body
• Respiration is done by various types of respiratory organs such as lungs, tracheary systems, gills, integuments
• For the respiratory organs to be efficient in gas exchange, what are the 4 conditions must be present?

  High surface area, high permeability, contact with oxygen-rich medium, exposure to blood circulation or tissues
• In animals with thin, permeable, or highly vascularized integuments and high body volume-to-surface area ratio, respiration occurs as simple gas diffusion through the integument
• Tracheoles - Microscopic and are in direct contact with the tissues wherein the tracheal trunks branch further into finer tubes and terminate at their end
• Operculum - anterior to the pectoral fins and protects the gills contained within the underlying space, the gill chamber
• Gill filaments house dense networks of capillaries
• The spaces between the arches are referred to as pharyngeal clefts.
• Label the following in the tracheal system of a head lice.

  A) Spiracles

  B) Trachae

  C) Tracheal Trunks

  
• Label the following in the Gill system of a fish.

  A) Operculum

  B) Gill chambers

  C) Gill filaments

  D) Gill arches

  E) Gill rakers

  
• Lungs - derived from the inner wall of the digestive tract, developed from its outpocketings into the coelom
• The air coming through the external nares enter the buccal cavity via what openings?

  Internal nares
• In the buccal cavity of the toad, where can the Eustachian tube be found?

  Angles of the jaw
• In male toads, slit-like openings to vocal sacs can be found ventral to each Eustachian tube opening
• Glottis - slit-like opening on the ventral midline of the buccal cavity which is surrounded by two cartilages
• What immediately flanks the glottis?

  arytenoids
• What forms a ring around the arytenoids?

  Cricoid
• Since the lumen of the arytenoids form a hemisphere which is continuous with the lumen of the cricoid ring, together these form the chamber of what?

  Larynx
• The larynx also houses thin flaps of connective tissue called what?

  vocal cords
• Vocal cords - produce the croaking sound of the animal through vibrations caused by the passage of the air through the larynx
• The air passing through the larynx comes from the lungs which are connected to the larynx by a pair of bronchial tubes
• Label the following in the lung system of the toad.

  A) Internal nares

  B) Cricoid

  C) Arytenoid

  D) Glottis

  E) Larynx

  F) Vocal sacs

  G) Eustachian tube

  H) lungs