In this section we'll take a look at the circulatory systems of 5 different organisms
The circulatory system functions with other body systems to provide the transportation of materials throughout the body contain cells that help fight infection, helps stabilize pH and ionic concentration of the body fluids and helps maintain body temperature. In this module I will discuss the different circulatory systems of the fetal pig we dissected (mammal), a Bee (insect), snail, crow, lizard, fish. Although the overall purpose remains the same the method of completing circulatory function can be quite different.
In the fetal pig we dissected the heart is actually two separate pumps. The left side pumps blood to the body (systemic circulation) and the right side pumps blood to the lungs (pulmonary circulation). Each side has an atrium and a ventricle. Mammals and birds have a four-chambered heart which acts as two separate pumps. After passing through the body, blood is pumped under high pressure to the lungs. Upon returning from the lungs, it is pumped under high pressure to the body. The high rate of oxygen-rich blood flow through the body enables birds and mammals to maintain high activity levels.
Organism #1 Crow (Bird)
Crows like other birds have evolved circulatory systems needed to provide the energy necessary to continually flap their wings. Crows have evolved such a system and it is very similar to a mammal's. Bird blood is similar to ours in that it contains both red cell and white blood cells called. The red blood cells are iron-based proteins like ours and do the work of moving oxygen around the system and taking the waste carbon dioxide away from the muscles and other organs. However, unlike ours, bird’s red blood cells have a nucleus where our red corpuscles have no nucleus.
Flight muscles need a lot of oxygen on a regular basis and to get it the blood must be kept moving rapidly around the system. To achieve this birds have, like mammals, evolved a four chambered heart (reptiles have only a three chambered heart). Two of these chambers are basically receiving vessels called atria; into them the blood flows at the end of its journey around the body, or to and from the lungs. The other two chambers, called ventricles, are the pumping power houses that send the blood off on its endless journey again. Thus the blood travels in a figure 8 as in mammals.
The oxygenated blood is pumped out to the various parts of the body by the left ventricle, where after giving up its life fuelling oxygen and collecting the carbon dioxide, it returns, as deoxygenated blood to the right atrium through three large veins called the caval veins - (left caval, right caval and post caval). From here it is shunted to the right ventricle which pumps it out to the bird's lungs via the pulmonary arch where the carbon dioxide is dumped to be exhaled (breathed out) and a new load of oxygen picked up. This newly reoxygenated blood returns to the left atrium of the heart via four large pulmonary veins. (We mammals only have two pulmonary veins). From here it is shunted to the left ventricle so that the cycle can start all over again. The possession of four pulmonary veins, along with the fact that a bird's heart is generally larger and more muscular per pound of body weight than ours, explains why a bird's circulatory system is more efficient than ours. The left ventricle in a bird's heart is by far the largest chamber and has to work exceptionally hard in small birds which have hovering flight such as humming birds.
Fun Fact - Because of their exceptional intelligence and resilience crows can survive in a variety of habitats. A study made in 2004 revealed that crows are more intelligent than bonobo chimpanzees. This basically means that crows are the smartest creatures on earth after humans.
Flight muscles need a lot of oxygen on a regular basis and to get it the blood must be kept moving rapidly around the system. To achieve this birds have, like mammals, evolved a four chambered heart (reptiles have only a three chambered heart). Two of these chambers are basically receiving vessels called atria; into them the blood flows at the end of its journey around the body, or to and from the lungs. The other two chambers, called ventricles, are the pumping power houses that send the blood off on its endless journey again. Thus the blood travels in a figure 8 as in mammals.
The oxygenated blood is pumped out to the various parts of the body by the left ventricle, where after giving up its life fuelling oxygen and collecting the carbon dioxide, it returns, as deoxygenated blood to the right atrium through three large veins called the caval veins - (left caval, right caval and post caval). From here it is shunted to the right ventricle which pumps it out to the bird's lungs via the pulmonary arch where the carbon dioxide is dumped to be exhaled (breathed out) and a new load of oxygen picked up. This newly reoxygenated blood returns to the left atrium of the heart via four large pulmonary veins. (We mammals only have two pulmonary veins). From here it is shunted to the left ventricle so that the cycle can start all over again. The possession of four pulmonary veins, along with the fact that a bird's heart is generally larger and more muscular per pound of body weight than ours, explains why a bird's circulatory system is more efficient than ours. The left ventricle in a bird's heart is by far the largest chamber and has to work exceptionally hard in small birds which have hovering flight such as humming birds.
Fun Fact - Because of their exceptional intelligence and resilience crows can survive in a variety of habitats. A study made in 2004 revealed that crows are more intelligent than bonobo chimpanzees. This basically means that crows are the smartest creatures on earth after humans.
Organism #2 Bee
Unlike larger animals the bee’s blood is not contained within tubes but simply fills all spaces within its body, thereby surrounding all of its organs. This is called an open circulatory system, unlike our own which is a closed circulatory system. Blood circulation in a bee is achieved through a simple heart, which is an elongated organ laying just under the roof of the abdomen. It has muscular walls and has five pairs of openings with one-way valves which allow blood to enter the heart when it dilates. When the heart contracts, the valves close and the blood is forced forwards into the aorta which extends through the thorax and into the head where it ends just behind the brain.
It is worth noting that the only blood vessels to be found in a bee are at the base of each antenna, which forces the blood to circulate through them, highlighting the importance of the antennae to a bee.
The bee’s heart pushes the blood forward into the brain until pressure increases forcing it back through the body cavity and to all the organs and tissues. On its way from the head, the blood passes back through the thorax, nourishing the flight muscles, then into the abdominal cavity where more nourishment is picked up from the digestive system before it is drawn back into the heart again. Stem.
Fun Fact - Bees have an incredibly developed set of senses to aid in their daily routines. The honeybee can perceive the difference between images in one 300th of a second, whereas humans are limited to differences in one 50th of a second.
It is worth noting that the only blood vessels to be found in a bee are at the base of each antenna, which forces the blood to circulate through them, highlighting the importance of the antennae to a bee.
The bee’s heart pushes the blood forward into the brain until pressure increases forcing it back through the body cavity and to all the organs and tissues. On its way from the head, the blood passes back through the thorax, nourishing the flight muscles, then into the abdominal cavity where more nourishment is picked up from the digestive system before it is drawn back into the heart again. Stem.
Fun Fact - Bees have an incredibly developed set of senses to aid in their daily routines. The honeybee can perceive the difference between images in one 300th of a second, whereas humans are limited to differences in one 50th of a second.
Organism #3 Snail
The blood system in snails is also open, with blood spaces and no veins. The pigment is colorless and is called haemocyanin, which contains copper. The relatively weak heart consists of a single thick walled ventricle and a single thin walled auricle. The blood takes oxygen from the lung and transports it to the auricle, and then to the ventricle. The ventricle releases blood with oxygen in the arteries, after which the blood goes to the tissues. The tissues take oxygen and food from the blood and excrete waste products. The blood flows back to the lung by means of blood spaces instead of veins. The so-called lung (pulmonary cavity) lies on the inside of the roof of the visceral-sac. Through the breathing-pore, the pneumostome, oxygen reaches the snail’s lung. When the pneumostome is open the roof and bottom of the pulmonary cavity are close together. When the bottom goes down the oxygen can flow into the lung. Then the pneumostome closes and the bottom goes up, pushing the oxygen in the body. It is comparable to the midriff in mammals.
Fun fact – Snails produce mucus internally from special glands. Among other purposes, the mucus secreted by the foot is used to crawl on. The foot mucus of a snail has some of the qualities of glue and some of the qualities of a lubricant, allowing land snails to crawl up vertical surfaces without falling off, and also lubricating rough surfaces to allow the snail to glide easily along the ground without producing excess friction.
Fun fact – Snails produce mucus internally from special glands. Among other purposes, the mucus secreted by the foot is used to crawl on. The foot mucus of a snail has some of the qualities of glue and some of the qualities of a lubricant, allowing land snails to crawl up vertical surfaces without falling off, and also lubricating rough surfaces to allow the snail to glide easily along the ground without producing excess friction.
Organism #4 Lizard
The lizard circulatory system is very interesting. Lizards have a three-chambered heart. Their heart consists of two aortas, two atria and a variably partitioned ventricle. Their heart mixes oxygenated and deoxygenated blood, the degree of which varies from species to species and by their current physiological state.
The ventricles in a lizard’s heart share oxygen back and forth in a constant exchange, but the division of the ventricles vary. However, the hearts atrium is always separated into two chambers; left and right. Their heart allows for the redirection of blood to the body or the lungs allowing for better thermo-regulation.
Fun Fact - An interesting characteristic of lizards and one of their primary defense mechanisms is their camouflage. Camouflage is by far the most effective way to avoid predators. Many lizards exhibit patterns and coloration that blend with their background. Chisel-teeth lizards and chameleons can change in a few seconds from display to camouflage.
The ventricles in a lizard’s heart share oxygen back and forth in a constant exchange, but the division of the ventricles vary. However, the hearts atrium is always separated into two chambers; left and right. Their heart allows for the redirection of blood to the body or the lungs allowing for better thermo-regulation.
Fun Fact - An interesting characteristic of lizards and one of their primary defense mechanisms is their camouflage. Camouflage is by far the most effective way to avoid predators. Many lizards exhibit patterns and coloration that blend with their background. Chisel-teeth lizards and chameleons can change in a few seconds from display to camouflage.
Organism #5 Trout (Fish)
Blood collected from throughout the fish's body enters a thin-walled receiving chamber, the atrium. As the heart relaxes, the blood passes through a valve into the thick-walled, muscular ventricle. Contraction of the ventricle forces the blood into the capillary networks of the gills where gas exchange occurs. The blood then passes on to the capillary networks that supply the rest of the body where exchanges with the tissues occur. Then the blood returns to the atrium.
Fun Fact - There is strong evidence that trout can detect polarization of light, which helps them locate prey which is otherwise difficult lacking stereoscopic vision (eyes either side of the head).
Fun Fact - There is strong evidence that trout can detect polarization of light, which helps them locate prey which is otherwise difficult lacking stereoscopic vision (eyes either side of the head).