The ileum contains villi that project into the lumen and increase the amount of surface area.
Villi are small finger-like structures that project into the lumen of the small intestine. Villi increase the surface area of the intestinal walls for easy and quick absorption of digested food with the addition of digestive secretions. Villi vary in length from about 0.5 to 1 mm. They are usually found in large numbers at the beginning of the small intestine and they reduce toward the end of the tract.
Answer:
These species form part of the Trophic chain - Trophic web. By the "predator-prey" relationship, they get to balance the ecosystem, keeping their populations in a controlled size.
Explanation:
White-tailed deer consume many different plant species. Deers are herbivores that seem to easily overpopulate different areas in the absence of their predators, reaching the carrying capacity. The population increase causes too much damages, affecting different plant species survival, structure, and composition. And by doing this, they also end affecting other wild animals and invertebrate species that also depend on the same plant species, not only for food but for refuge and nesting sites.
Natural controllers of deer populations are the coyote and the cougars, considered key-species, important in keeping healthy natural areas. Their presence is an indicator of the good state of an ecosystem. These animals act as a major limiting factor, decreasing deep population or keeping it below forage carrying capacity. This natural control increases and maintain the population of other species affected by deers, mainly plants.
The deer is an important item for both the coyote and the cougar, being probably a reason for interspecific competition between these two species.
The equilibrium is very delicate. When key-species populations fluctuate, it also does the deep population, and hence, plants populations. By the cascade effect in the trophic chain, the fluctuation in one species population affects the other species too. A small reduction in key-species such as the coyote might implicate an automatic increase in the deer population. Although a sharp increase in coyote or cougars population might result in severe damage to the deer population. These opposite effects have been described in many different studies.
A cold region of the earth, know as the north pole usually around green land, and alaska
Answer:
air temperature, air pressure, humidity of the air, amount and kind of cloud cover, amount and kind of precipitation, and speed and direction of the wind.
Sexually transmitted diseases caused by virus are the hardest to treat. It is difficult to treat viral infections because they usually hide inside the host's cells, they become so deeply integrated into the host's genome such that inhibiting them will amount to inhibiting the host cells.