User:CJManalo25/Final Draft

Week 12: Working towards Final Draft

Plan of Action

• The ones that are underlined will be areas with my revisions
• Words/sentences in bold will be my actual edited changes

Respiratory System

Taken directly from page:

"In the shark anatomy image, it depicts the beginning half of the shark, including the gills. The shark gills are especially important and were evolved from the chordate pharyngeal gill slits synapomorphy. Gills are essential for sharks to breathe underwater. Like other fishes, sharks extract oxygen from water as it passes over their gills. The water enters through the mouth, passes into the pharynx, and exits through the gill slits (most sharks have five pairs, the frilled sharks, cow sharks, and sixgill sawshark have six or seven pairs). Most sharks also have an accessory respiratory opening called a spiracle behind their eyes. In bottom-dwelling sharks such as angel sharks, the spiracle allows them to take in water to breathe without having to open their mouths^{[citation needed]}.

There are two mechanisms that sharks can use to move water over their gills: in buccal pumping, the shark actively pulls in water using its buccal muscles, while in ram ventilation, the shark swims forward, forcing water into its mouth and through its gills. As buccal pumping is more energy-intensive than ram ventilation, the former is generally used by sedentary, bottom-dwelling sharks while the latter is used by more active sharks. Most sharks can switch between these mechanisms as the situation requires. A few species, such as the great white shark, have lost the ability to perform buccal pumping and thus will suffocate if they stop moving forward.

Cardiovascular/Circulatory System

Note: on the Shark Anatomy Page there is no "Cardiovascular System" section but a "Circulatory System" section and I will add information about the cardiovascular system here. I'm unsure if I want to tackle this system as well or should focus on the respiratory system more. Any opinions/insights are appreciated!

Taken directly from page:

Sharks possess a single-circuit circulatory system centered around a two-chambered heart. Blood flows from the heart to the gills where it is oxygenated. This oxygen-rich blood is then carried throughout the body and to the tissues before returning to the heart. As the heart beats, deoxygenated blood enters the sinus venosus. The blood then flows through the atrium to the ventricle, before emptying into the conus arteriosus and leaving the heart.

[Will add a whole new paragraph here] ****There is also an image of a dissection that I plan to replace***

The caption of that image:

A dissected view of the unique four-chambered heart of the shark Chambers: Sinus Venosus, Atrium, Ventricle, Conus Ateriosus

Respiratory System [My version]

"In the shark anatomy image, it depicts the beginning half of the shark, including the gills. The shark gills are especially important and were evolved from the chordate pharyngeal gill slits synapomorphy. Like lungs in other animals, gills are essential for sharks to breathe underwater by extracting oxygen from water. The water enters through the mouth, passes into the pharynx, and exits through the gill slits. Most shark species have five gill slits on each side such as the frilled sharks, cow sharks, however, some species can have up to six or seven like the sixgill sawshark. As part of their respiratory system, sharks also have an accessory respiratory opening called a spiracle behind their eyes. Spiracles are cartilaginous structures located on the top of a shark's head to draw oxygenated water from above in addition to it passing over the gills.

A ventral dissection of a pregnant female dogshark exposing its internal gill slits and internal spiracles.

Gill Structure and Components

Like most fishes, sharks gill slits are located on its external surface on both lateral sides near the head. Inside the gill slits, are long projection-like structures called gill filaments. Gill filaments are lateral to the gill arches and have a high surface area, where they form folds (lamellae) inside the gill slits. Lamellae in the gill slits are thin, membrane folds that have access to blood supplies via arteries and are the site of gas exchange. When oxygen-rich water enters the gills, the blood takes up the oxygen through diffusion at the site of lamellae and expels carbon dioxide. To support the gills in ventilation, spiracles take in more water and ventilate the gill, even when sharks are feeding. Gill rakers are cartilaginous structures inside gill arches that act in filtration in food particles in feeding as water moves in through the gills.

Mechanisms of Breathing

There are two mechanisms that sharks can use to move water over their gills: in buccal pumping, the shark actively pulls in water using its buccal muscles, while in ram ventilation, the shark swims forward, forcing water into its mouth and through its gills. Buccal pumping is more energy intensive than ram ventilation. Sedentary, bottom-dwelling sharks generally use buccal pumping to move water over to their gills compared to more active sharks, who will use ram ventilation and swim to force water to its mouth and gills. Most sharks can switch between these mechanisms as the situation requires depending on the abundance of oxygen in the water. A few species, such as the great white shark, have lost the ability to perform buccal pumping and will suffocate if they stop moving forward due to insufficient oxygen passing over their gills.

Circulatory System [My version]

Sharks possess a single-circuit circulatory system centered around a two-chambered heart containing an auricle and ventricle Blood flows from the heart to the gills where it is oxygenated. This oxygen-rich blood is then carried throughout the body and to the tissues before returning to the heart. As the heart beats, deoxygenated blood enters the sinus venosus. The blood then flows through the atrium to the ventricle, before emptying into the conus arteriosus and leaving the heart.

[Insert image of heart]

The circulatory system and respiratory system interacts closely together. it As water rushes over their gills, shark have a body temperature similar to the water.

****This would be a way to start this new paragraph for this section, but I think I'm trying to bite off more than I can chew*****