Answer:
atmospheric nitrogen, Industrial Nitrogen and biological nitrogen
Explanation:
atmospheric nitrogen: During lightning, the high temperatures and pressures created in the air convert nitrogen into oxides of nitrogen.
Industrial Nitrogen: is done in the fertilizer manufacturing industries in which nitrogen and hydrogen from atmosphere is used to form ammonia which is further used to manufacture fertilizers .
biological nitrogen :
is done by few forms of bacteria (which may be free living like Azotobacter or symbiotic bacteria like Rhizobium) which can convert insert nitrogen molecule into forms like nitrates and nitrites which can be taken up by plants and used to make the required proteins.
In an effort to bring mean arterial pressure back to normal after a hemorrhage, total peripheral resistance increases because the blood flow to most organs decreases. However, blood flow to the brain and heart is maintained because these organs are not greatly influenced by the baroreceptor reflex.
Baroreceptor reflex is one of the body's homeostatic mechanisms that helps to maintain blood pressure at nearly constant levels. They are mechanoreceptors located in the carotid sinus and in the aortic arch. They function to sense pressure changes by responding to change in the tension of the arterial wall.
It's no longer the dead-end of the carbon cycle. Since the industrial revolution, this material has been taken out of the ground (by Oil and Gas companies) which is for the most part subsequently burned - of which the final by-product is CO2. This fossil material also goes into making plastics and other chemicals - so the "dead-end of the carbon cycle" is not quite so straight forward anymore.
Answer:
reduced thrombogenicity.
Explanation:
For patients with significant heart valve disease, surgical options for treatment include valve repair or replacement. The choice between repair and replacement is influenced by a number of factors including age, type of the valve disease and other medical conditions. When valve replacement is performed, there are options of mechanical or tissue heart valves. These two classes of valves confer different characteristics and each have their advantages and disadvantages.
Mechanical valves: Mechanical heart valves are made from materials such as titanium and carbon. They usually consist of two leaflets and a metal ring surrounded by a ring of knitted fabric, which is sewn onto the heart in place of the original valve.The main advantage of mechanical valves is that they are very durable. However, these valves provide a surface on which blood clots can form easily. As a result, anyone who has been implanted with a mechanical valve needs to be on lifelong blood-thinning medication, such as warfarin, to prevent the development of blood clots that can cause heart attack or stroke
Tissue valves, also known as biological or bioprosthetic valves, are composed of animal or human tissue. The valves are derived from animal tissue such as porcine (pig), bovine (cow) and equine (horse) models, and then fixed with a preserving solution that may be mounted on a flexible frame to assist in deployment during surgery. As with mechanical valves, the bottom of a tissue valve is often surrounded by a ring of knitted fabric that is sewn onto the heart. In addition to animal-derived valves, a human tissue valve from a donor human heart, known as an allograft or homograft, may also be used as a replacement valve. Tissue valves can be used in open heart surgery or in a minimally invasive aortic operation known as transcatheter aortic valve implantation (TAVI).
Advantages of tissue valves compared to mechanical valves include the avoidance of lifelong warfarin therapy to prevent the development of blood clots.
<span>The actions of sleep and dreaming are influenced by the pons. This portion of the brain is located above the medula, and connects the upper and lower parts of the brain. In addition to driving sleep and dreaming, it also synthesizes signals to control movements on the two sides of the body.</span>
