gas exchange in fish

• explain the process of ventilation in fish?

  Buccal cavity drops and mouth opens increasing volume of buccal cavity and decreasing pressure so that water flows into the buccal cavity down a pressure gradient. Simultaneously, operculum valve shuts and operculum cavity expands. Volume of the operculum cavity increases and decreases pressure. Fish close mouth and buccal cavity raises, decreasing volume increasing pressure inside the buccal cavity, water in buccal cavity moves over gills. Operculum opens, decreasing pressure in operculum cavity and water moves out the opercular opening.
• other than helping with gas exchange, what does the operculum do?

  protect gills when closed
• where is the site of gas exchange in fish?

  gill lamellae
• how many gill filaments does each gill arch hold?

  2
• gill filaments are thin for a short diffusion distance and their surface is folded into many lamellae, increasing surface area of gills.
• lamellae are a few cells thick and contain capillaries
• other than the common answers of gaseous exchange structures, what 2 adaptations do the gills have?

  tips of adjacent gill filaments overlap, countercurrent flow
• why do the tips of adjacent gill filaments overlap?

  slow movement of water
• what type of circulatory system do fish have?

  single closed