Blood Vessel example essay topic

1) To overcome many of the obstacles on the path of any life function, specifically gas exchange, evolution has provided many adaptations. Some of these are the gills fish have developed, some insects ability to diffuse oxygen to individual cells or a moist diffusion barrier in humans. Fish have developed a trait called countercurrent exchange, in which blood passes through vessels in a direction opposite to that of water flowing over the gills of the fish. This allows the oxygen-rich water to flow over the deoxygenate d blood for the longest possible time and facilitating the greatest possible amount of oxygen to be transferred to the blood. In insects, grasshoppers for example, take in oxygen through spiracles, which are openings in the insects exoskeleton.

From there, the oxygen flows through trachea, that are connective tubes that branch out to every cell in its body. This allows oxygen to diffuse to all cells without the need for a circulatory system. Humans have a moist diffusion barrier in our lungs, which permits oxygen to diffuse into our bloodstream. This, coupled with the alveoli in our lungs to increase the surface area on which oxygen can diffuse and the extensive circulatory into which the oxygen diffuses, make an effective system with which to supply oxygen to all the cells of the body. 2) Xylem Vessels: One component of xylem-made up of shorter, wider, more thinly walled cells (when compared to tracheids) that have perforations to allow water to flow through the xylem freely-Cells are not alive Tracheids: Another component of xylem-made up of longer, thinner cells that move water through pits (areas of space between walls) and are hardened with lignin because tracheids also function as structural support- Cells are not alive Sieve tubes: Located in the phloem of a plant.

Transports organic compounds, sucrose and mineral ions- Cells are living Companion Cells Connected to sieve tubes by plasmodesmata- May have nucleus and ribosomes that provide for cell and surrounding serve cells 3) See graphs 4) Aneurysm: The abnormal widening or ballooning of a portion of a blood vessel. The blood vessel becomes weaker in this area. Thrombus: A clot formed within a blood vessel or heart. Embolism: The blocking of a blood vessel by a foreign abnormal particle. (clot, air bubble, plaque) Deprives the area beyond the obstruction of oxygen. Atherosclerosis: Fatty plaque that builds up on the bore of an artery wall causes this.

Results in narrowing or closing of the artery. Arteriosclerosis: hardening of the armies as a result of plaques and calcium deposits from atherosclerosis. impairment of blood flow. Hypertension: Promotes atherosclerosis and increases the risk of heart attack and stroke-Increases blood pressure by narrowing the bore of the vessels Edema: Swelling of limbs (ankles and feet) because of a lack of albumin, a burn, malnutrition, or pregnancy. Varicose Veins: Veins pushed to the surface of the skin due to increased blood pressure.