Absence of circulatory system
Circulatory systems are absent in some animals, including flatworms and unicellular animals. Flatworms lack enclosed fluid or lining in their body cavity, but a muscular pharynx instead that leads to an extensively branched digestive system where nutrients and oxygen diffuse directly to all cells with ease. This is enabled by the reduced distance of body cells from the digestive system because of the flatworm’s dorso-ventrally flattened body shape. Thus every cell obtains water, oxygen and nutrients, water and oxygen without the need of a transport system. The gastrovascular cavity of some animals, like jellyfish, have more extensive branching allowing bodily fluids to reach the outer layers, since the digestion begins in the inner layers. Thus functions as both a form of circulation and a place of digestion.
Open circulatory systems
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In this system, hemocoel (fluid in a cavity) bathes the organs directly with oxygen and nutrients and there is no distinction between interstitial fluid and blood.
The combination of these is called hemolymph or haemolymph. It consists of a heart, vessels, and hemolymph. The hymolymph is first pumped into the aorta through the heart, dispersed into the head and throughout the hemocoel. It then travels back through the ostium that are located in the heart, where the process is repeated. Muscular movements by the animal during locomotion facilitate hemolymph movement around the body in all directions. The hemolymph bathes the organs directly supplying oxygen and removing waste. Blood flows at a very slow speed because of absence of smooth muscles that are responsible for contraction of blood vessels. Blood is drawn back toward the heart through open-ended pores (ostia) when the heart relaxes. Most invertebrates (Arthropoda and Mollusca) have an open circulatory
system. To understand how open circulatory systems work, try to imagine a bucket with two hoses coming out of it and these hoses connected to a squeeze bulb. Squeezing the bulb will force the water along to the bucket. One hose will be shelling water into the bucket, whilst the other is sucking water out of the bucket. Unfortunately this is a very inefficient system. Arthropods can get by with this type system because they have (spiracles numerous openings) in their bodies that allow the hemocel to come into direct contact with air. Closed Circulatory System In closed circulatory systems the blood never comes in direct contact with the body cells, it always remains inside the blood vessels. The materials get in and out the blood vessels through the walls. In the blood vessels, the blood flows under high pressure to ensure it reaches all the body parts in good time. This system is much more efficient and is found in some mollusks and all higher invertebrates and the vertebrates. An earthworm has one of the simplest types of closed circulatory systems. It has two main blood vessels, dorsal and ventral that carries blood to the head and tail respectively. Movement of blood along the dorsal vessel is by peristaltic pumping. There are five pairs of vessels in the anterior region of the worm that are loosely referred to as "hearts," and these connect the dorsal and the ventral vessels. The system is relatively inefficient and is aided by the epidermis of the earthworm which is so thin and constantly moist, thereby allowing ample opportunity for exchange of gases. An earthworm also has special organs that remove nitrogenous wastes. Blood can flow backward and thus the system is more efficient than the open system of insects.
Fox, R. 2001. Invertebrate Anatomy OnLine: Artemia Franciscana. Lander University. http://webs.lander.edu/rsfox/invertebrates/artemia.html, retrieved February 13, 2011.
The circulatory system and respiratory system share a highly important relationship that is crucial to maintaining the life of an organism. In order for bodily processes to be performed, energy to be created, and homeostasis to be maintained, the exchange of oxygen from the external environment to the intracellular environment is performed by the relationship of these two systems. Starting at the heart, deoxygenated/carbon-dioxide (CO2)-rich blood is moved in through the superior and inferior vena cava into the right atrium, then into the right ventricle when the heart is relaxed. As the heart contracts, the deoxygenated blood is pumped through the pulmonary arteries to capillaries in the lungs. As the organism breathes and intakes oxygenated air, oxygen is exchanged with CO2 in the blood at the capillaries. As the organism breathes out, it expels the CO2 into the external environment. For the blood in the capillaries, it is then moved into pulmonary veins and make
Haven't you ever wondered what would happen if you didn't have a digestive or circulatory system? Well, basically you wouldn't be able to be reading this or even be alive. While there are many important systems in the body, the circulatory and digestive are the two most important. There are many ways that they are similar, different, and how they work together.
The Circulatory System is a transportation and cooling system for the body. The Red Blood Cells act like billions of little mail men carrying all kinds of things that are needed by the cells, also RBC's carry oxygen and nutrients to the cells. All cells in the body require oxygen to remain alive. Also there is another kind of cells called white blood cells moving in the system. Why blood cells protect from bacteria and other things that are harmful. The Circulatory system contains vein arteries, veins are used to carry blood to the heart and arteries to carry the blood away. The blood inside veins is where most of the oxygen and nutrients are and is called deoxygenated and the color of the blood is dark red. However, blood in the arteries are also full of oxygen but is a bright red. The main components of the circulatory system are the heart, blood, and blood vessels.
Flatworms belong to the phylum Platyhelminthes. They have the simplest body plan of all bilaterally symmetrical animals. They are called flatworms because their bodies are compressed. The mouth is the only opening into the digestive cavity the flatworms have. Food is taken in through this hole and wastes are discharged also through this hole. Flatworms have a well-defined nervous, muscular, excretory, and reproductive system. The flatworm distributes the food it digests through a digestive tube that branches throughout all of its body parts. The fact that the worm’s body is flat serves many purposes. It allows the worm to hid in small spaces, to fit into the opening of other animals if the worm is parasitic, and it means that all the cells are close enough to the surface for exchange of oxygen and carbon dioxide with the environment (Meinkoth 399).
In order for this breakdown to happen, the ‘tube’ through which the food travels requires assistance from a number of other digestive organs starting with the salivary glands, and later receiving
Lymph is the name given to the fluid of plasma proteins that escape the circulatory system at the sites of the capillary network and diffuse into the cells around the capillaries. To enable the body to maintain a homeostatic fluid level and pressure, the lymph must be returned to the circulatory system. The way this happens is for the the network of lymph vessels to pick up the fluid which has escaped, and been absorbed by the cells at open ends of the lymph vessels, and carry it to a point where it can be put back into the circulatory system. Two points in the shoulders called the left and right subclavian ducts are where the lymph is reintroduced to the cardiovascular system.
The heart serves as a powerful function in the human body through two main jobs. It pumps oxygen-rich blood throughout the body and “blood vessels called coronary arteries that carry oxygenated blood straight into the heart muscle” (Katzenstein and Pinã, 2). There are four chambers and valves inside the heart that “help regulate the flow of blood as it travels through the heart’s chambers and out to the lungs and body” (Katzenstein Pinã, 2). Within the heart there is the upper chamber known as the atrium (atria) and the lower chamber known as the ventricles. “The atrium receive blood from the lu...
is, then it is brought back to the heart by the four pulmonary veins, which
They arise in the interstitial spaces of organs and tissues and they then join with the large veins just before they enter the vena cava of the heart. These lymphatic vessels tend to run parallel with the veins which allows filtration to occur. The vessels are non- muscular and contain valves which stop the fluid from going back. (Hastie, 2012).
Here, deep in the lungs, oxygen diffuses through the alveoli walls and into the blood in the capillaries and gaseous waste products in the blood—mainly carbon dioxide—diffuse through the capillary walls and into the alveoli. But if something prevents the oxygen from reaching t...
There are many similarities and differences between organisms of different species’ digestive systems. The digestive system of an organism is the system that makes food absorbable into the body. The food that the organism takes into their body is broken down through an organ to make it easier for the body to take the nutrients it needs from the food. The food that is broken down in the digestive system is then turned into energy for the organism.
The human digestion system is very complex. It starts with the mouth, salivary glands, pharynx, esophagus, stomach, liver, pancreas, gallbladder, small intestine, large intestine, then ends/exits with the anus. Each step is essential to the whole system. For example, the mouth chews food and mixes it with saliva produced by the salivary glands, and then the pharynx swallows chewed food mixed with saliva, this is followed by the food traveling through the esophagus to the stomach where the food gets a bath and mixes with acids and enzymes. After the stomach, the liver, pancreas, and gallbladder produce, stores, and releases bile and bicarbonates. Bile is produced in the liver and aids in digestion and absorption of fat while the gallbladder stores bile and releases it into the small intestine when needed. Following the process into the small intestine, this is where nutrients will be absorbed into the blood or lymph (most digestion occurs here). Next is the large intestine this is where water and some vitamins and minerals are absorbed. Finally, it is the end of the road, the anus. At...
the aortic valve, between the left ventricle and the aorta. heart_chambers.jpg Each valve has a set of "flaps" (also called leaflets or cusps). The mitral valve normally has two flaps; the others have three flaps. Dark bluish blood, low in oxygen, flows back to the heart after circulating through the body. It returns to the heart through veins and enters the right atrium.
Most reptiles have ventricles that are mostly separated, but still allow right to left shunting of the blood. Crocodiles have ventricles that are completely separated, but can still shunt blood between the pulmonary and systemic circuits (Axellson, Franklin). This shunting can be completed using the foramen of Panizza, which allows and regulates blood flow from either the left or right ventricle into the left or right aorta. Blood flows from the left ventricle to the right aorta, dorsal aorta, right subclavian artery and the common carotid artery. The right ventricle moves blood into the pulmonary trunk which then separates blood into the left and right pulmonary arteries (Axellson, Franklin). During diving, crocodiles develop a slight bradycardia and develop a right to left shunt once right ventricular pressure rises to a certain threshold. Resting rates of oxygen consumption are maintained and muscular lactate levels do not increase (Grigg). This ability to dive for extended periods of time is made possible by right to left shunting by way of the foramen of Panizza, in addition to the ability to maintain muscular lactate levels. Crocodilian hearts have the ability to keep oxygenated and deoxygenated blood within the heart. Blood pressures are also kept higher in the systemic circuit than the pulmonary circuit (Grigg). These heart adaptations are not seen in other reptiles, but rather in mammalian and avian