Respiration (Gas Exchange main functions (4))
- Requires surfaces between the environment and respiratory organs
- Transport of gases in blood to capillaries
- Exchange surface between capillaries and tissues
- Respiratory and circulatory systems work together
What is Gas Exchange?
Follows physical rules of diffusion of air
What does Gas Exchange (Diffusion) Need:
- Large surface area between environment (water or air) and blood
- Thin and moist barrier
- Effective ventilation (gradient)
Fish Gills - Basic Structure
Gill arches composed of gill rakers on the pharyngeal edge with gill filaments on the distal edge
What are Gill Rakers?
Debris filters
What are Gill Filaments responsible for?
Involved in respiration
Are Gill Filaments Primary or Secondary Lamellae?
Primary Lamellae
What are secondary Lamellae?
Further increase surface area on gill filaments
Evolution of Internal Gills (Pouched Gills)
- No gill covering
- Adults sea lamprey feed by latching onto prey for a blood meal (cannot draw water through mouth at the same time
- Tidal ventilation
What is Tidal Ventilation?
Of gill pouches through muscle compression and relaxation of brachial apparatus
Evolution of Internal Gills (Septal Gills)
- Dual Pump ventilation
- Water is pumped in through the mouth, around the gills, and out the sides
- Separated gill arches
Holobranch vs. Hemibranch Gills
What is Dual Pump Ventilation?
Pushes water unidirectionally over the gills
The Gill Arches Separated by What?
Interbrachial septa
What are Spiracles Used for (Sharks)?
Sharks and other cartilaginous fishes use top-opening spiracles to ventilate gills while buried in the sand
Evolution of Internal Gills (Opercular Gills)
- Dual pump ventilation
- Water enters the mouth, pumped over the gills and out the external gill openings on the sides
- Gill arches protected by bony operculum
Dual Pump Ventilation Pushes Water:
Unidirectionally over the gills
Gill Arches Protected by:
Bony Operculum
Dual Pump Gill Ventilation Components and How They Function:
Buccal and opercular components act like a two-stroke pump with alternating cycles of negative and positive pressures
Swim Bladders and Lungs Develop From:
Outpocketing of pharynx (endoderm)
Lungs in Boney Fishes:
Paired structures ventral to the gut
Swim Bladders in Boney Fishes:
-Single elongated sac dorsal to the gut
- Used for buoyancy
- Sometimes also help with respiration and well as sound production and reception
Methods for How Swim Bladders Get Filled?
- Physostomous
- Physoclistous
What is the Physostomous Method of Filling the Swim Bladder:
- Filled by gulping air into the digestive tract
- May also serve as a respiratory gas bladder
What is the Physoclistous Method of Filling the Swim Bladder:
Filled by gas gland, emptied at the oval window
