Internal Structural Adaptations Essay Research Paper 1

Internal Structural Adaptations Essay, Research Paper

1. In order to grow and survive an organism must metabolize. In order to metabolize, an organism must have access to nutrients and O2 at the cellular level. Within the kingdom Animalia, there are several solutions to the problem of delivery of said nutrients and O2.

Discuss, in a written format, the various internal structural adaptations (their form and function) associated with each of the four heart configurations discussed in class which facilitate the delivery of nutrients starting at the mouth and ending with the diffusion of particles into the cells.

Use diagrams, flow charts and specific examples as appropriate.

Cite your references.

Due: Tuesday, December 2nd

I will begin this essay by discussing the various internal structures of animals which possess a four chambered heart. Generally, these animals are more complicated and larger than those whose hearts have three or less chambers. I shall begin by discussing the actual heart, a sort of pump which is used to drive blood throughout the body.

The four-chambered heart, which is shared by most mammals, birds and some of the larger reptiles is the most complicated and the most efficient heart configuration in known existence. Blood which the body has depleted of oxygen enters the heart in one of two ways . either through the superior vena cava, which comes from above the heart, or the inferior vena cava, which comes from below the heart. No matter which of the cavae the blood came from, it next enters the right atrium (or the right auricle). Blood from the right atrium slowly drains down into the right ventricle below it via the tricuspid valve . when the right ventricle is finally full of all the blood it can contain, the valve closes shut, allowing no more to enter from the atrium. The blood-full ventricle suddenly and powerfully contracts, shooting the O2-delpleted blood up through the pulmonary valve, through the pulmonary artery and into the lungs. Oxygen contained within the lungs. alveoli diffuses into the blood, CO2 that the blood picked up in the body diffuses into the alveoli, and the blood then re-enters the heart via the pulmonary veins. The pulmonary veins drain into the left atrium of the heart which then, in a manner similar to that of the right atrium, drains through the mitral valve into the left ventricle. When it is full of blood, the valve shuts and the left ventricle contracts once more, shooting the blood out to the body via the aorta. Oxygen-rich blood travels through the body in various different arteries (the .pulse. that you feel is from the blood-filled arteries moving and carrying your blood . a common misconception is that pulse is felt in your veins). These arteries continue to branch into smaller and smaller arteries throughout your body until they become known as capillaries. Since capillaries are so small the walls which contain the blood within them are very thin . so thin that the blood can almost come in contact with the various tissues of the body. When this occurs, the nutrients and oxygen from the blood diffuse across into the cells of the tissues, and the waste products from the cells of the tissues diffuse across into the blood. This new blood, devoid of O2 and carrying only waste, travels through more capillaries which slowly branch together forming larger capillaries and eventually forming veins. Veins, carrying their O2-malnourished blood, travel back into the heart where the blood collects new O2 and deposits its old wastes. And the process repeats once more.

Much like their hearts, the lungs of those animals with four-chambered hearts are far more complicated and efficient than those of any others. The purpose of the lungs and their surrounding respiratory systems is twofold: firstly, they collect oxygen which then diffuses into the blood and is passed on to various body cells and secondly they collect CO2 and other wasteful gasses from the blood and vacate them from the body. The process by which air enters the lungs is known as inspiration. Inspiration occurs when the muscles in the rib cage contract, forcing the ribs to lift themselves upwards. This in turn causes the entire chest cavity, including the lungs, to expand . this expansion, in turn, causes the lungs to have a lower air pressure than their outside surroundings . air, in turn, must rush into the vacuum-like lungs, balancing the pressures out (approx. . litre of air enters the body with every breath). Air enters the lungs via a long sequence of tubes and passageways. From the external nostrils or mouth, it travels down the throat, past the larynx and into the trachea. The trachea eventually branches into two bronchial tubes, the right and the left, which each lead to a different lung. Within the lungs, the bronchial tubes continue to break down, fractal-like, into smaller and smaller parts. First they become the bronchioles, next they become the alveolar ducts and finally these tubes terminate with small, grape-like clusters of alveoli. Although the alveoli themselves are small, as a whole they certainly are not . the surface area of these air sacs is about 50 times larger than the surface area of the skin).

It is within the alveoli that the important process of respiration takes place. Every cluster of alveoli is surrounded by capillaries coming from the left ventricle of the heart, full