Answer:
Leptin is a protein hormone composed of 167 amino acids of the cytosine family, it is synthesized mainly by white adipose tissue. The leptin receptor is related to that of receptors for cytosines (since it uses Janus or JAK type kinases and STAT-3 proteins as intracellular mediators of transcription pathway), it is predominantly found in the hypothalamus (particularly in the arcuate nucleus and to a lesser extent in the nuclei dorsomedial and ventromedial), hippocampus and cerebellum. There is evidence that leptin acts at the level of the arcuate nucleus, preventing the formation of NPY.
Explanation:
Leptin is produced exclusively in adipose tissue cells in a wide variety of species, including humans, and its concentration is higher in overweight than in lean individuals. The biological actions of leptin can be classified into two groups, those that are exerted in the tissues of the central nervous system, mainly the hypothalamus, and those that are carried out on the peripheral tissues. The former regulate body weight downward, decrease food intake, increase basal energy expenditure and modify some neuroendocrine functions such as reproduction, while the latter have effects on proliferation, differentiation and metabolism of peripheral tissues. The leptin that reaches the hypothalamus, in addition, inhibits protein synthesis and the secretion of neurons producing NPY / AgRP of the arcuate nucleus and stimulates the synthesis and secretion of those containing POMC. NPY (neuropeptide Y) is produced in the hypothalamic arcuate nucleus. This neurotransmitter arrives through the projections of the neurons of said nucleus to the paraventricular nucleus, which is the area where it is released. There are several studies that have shown that an increase in NPY leads to an increase in the sensation of hunger and thus to hyperphagia and obesity. Leptin acts at the level of the arcuate nucleus, preventing the formation of NPY. The leptin receptor lacks enzymatic activity in its intracellular domain. Instead, it is linked to members of the janus kinase family, which belong to a class of tyrosine kinases. The binding of the ligand activates the Jak kinase and leads to the phosphorylation of certain cytoplasmic proteins. Within these proteins there is a class of cytoplasmic transcription factors called signal transducers and activators of transcription (STAT).
The answer is; C
It is a woody plant with a flexible stem that can grow extremely long. Its stem cannot stand vertically on its own hence uses other trees for support and climbs up the canopy for good sunlight. They are common plants in rainforests and play a significant role in the ecosystems. They provide support for weaker trees from strong winds and provide bridges for arboreal animals such as monkeys.
Answer:
The death rate is higher than the birth rate. The birth rate is higher than the death rate.
Explanation:
Answer:
Deep zone, surface zone and transition zone.
Explanation:
Open sea zone is the area of the coastal areas above the sea bed and cover the continental shelf where large Marine organism are present and there is enough sunlight algae organism use to photosynthesize and produce food for the Marine organisms by converting carbondioxide and water into carbohydrates.
The zone stretches from the surface , to the middle and depth of 200 m.
The surface zone is the area where light penetrates most , the transition stretches from the surface zone downward, in this zone light penetrates bit not as much as surface zone and in the deep zone, it stretches from the transition zone downward to a depth of 200 meters and don't have enough light penetration compare to surface and transition.
