Lecture 9

Question 1

How do fish breathe?

Answer 1

From the Buccal cavity, into the opercular cavity. This is done by the transport of water Flow across the the gill slits where in the secondary lamellae there are filaments that allow for blood flow, when the water crosses the gills, this will get taken and the water will flow into the opercular cavity

Question 2

How is pressure achieved in fish?

Answer 2

This is due to the buccal pressure pump, when water moves from high to low pressure this occurs. Allowing for suction, and the pump to open, also the opercular pressure pump plays a role as well.

Question 3

What does breathing in amphibians look like in juvenile and adults

Answer 3

juvenile - The gills of all young larval amphibians are
external to the body. In salamanders, they
remain external, in frogs and toads, they
become enclosed by the operculum and
breathing occurs via buccal pumping. Some
species maintain these gills as adults

adults - Paired lungs develop from the ventral side of
the pharynx during metamorphosis. Each lung
is a single chamber (unicameral). The internal
wall of the chambe

Question 4

how do frogs breathe?

Answer 4

1. Fills the buccal cavity with air by sealing
   the glottis and lowering the buccal floor
   (the lungs are full of air at this point)
2. The glottis is opened and air passes out
   of the lungs through the nares.
3. The nares are then shut and the buccal
   floor is raised, pushing

Question 5

what does breathing in non-avian reptiles look like?

Answer 5

• a unicameral lung: the folds of the lung and vascularization occur at the posterior end of the lung in some species – this is the location of most gas exchange.
• Rather than buccal pressure, ventilation in non-avian reptiles is achieved by suction: this is done by air being drawn into the lung by expanding the lung space (volume) with thoracic muscles, which decreases the pressure inside the lung and draws gas in.

Question 6

components of breathing in mammals

Answer 6

Tidal volume - it is the volume of air inhaled and exhaled per breath

Expiratory reserve volume - it is the maximum volume of air that an individual can expel
beyond the resting expiratory level

Inspiratory reserve volume- It is the maximum volume of air that an individual can inhale
beyond the resting inspiration level

Question 7

Mechanically how does breathing in mammals work?

Answer 7

Breathing is achieved by actively via the muscles along the ribs and the diaphragm
expanding and contracting
This is modulated to meet the demands for oxygen or carbon dioxide exchange
- Chemoreceptors near the ventral surface of the medulla detect the levels of CO2 and
H+ in the blood, and send signals to adjust breathing accordingly to return levels to
normal – negative feedback
- O2 concentrations are detected by two chemoreceptive bodies – cartid bodies and
aortic bodies