Habitat, community, ecosystem,biome, biosphere
<span>Levels of OrganizationIn unicellular (single-celled) organisms,
the single cell performs all life functions. It functions independently.
However, multicellular (many celled) organisms have various levels of
organization within them. Individual cells may perform specific
functions and also work together for the good of the entire organism.
The cells become dependent on one another.Multicellular organisms have
the following 5 levels of organization ranging from simplest to most
complex:<span><span>LEVEL 1 - Cells<span><span>Are the basic unit of structure and function in living things.
</span>May serve a specific function within the organismExamples- blood cells, nerve cells, bone cells, etc.</span></span><span>LEVEL 2 - Tissues<span>Made up of cells that are similar in structure and function and which work together to perform a specific activity
Examples - blood, nervous, bone, etc. Humans have 4 basic tissues: connective, epithelial, muscle, and nerve.</span></span><span>LEVEL 3 - OrgansMade up of tissues that work together to perform a specific activityExamples - heart, brain, skin, etc.</span><span>LEVEL4 - Organ Systems
<span>Groups of two or more tissues that work together to perform a specific function for the organism.
Examples - circulatory system, nervous system, skeletal system, etc.
The
Human body has 11 organ systems - circulatory, digestive, endocrine,
excretory (urinary), immune(lymphatic), integumentary, muscular,
nervous, reproductive, respiratory, and skeletal.</span></span><span>
LEVEL 5 - Organisms
<span>
Entire
living things that can carry out all basic life processes. Meaning they
can take in materials, release energy from food, release wastes, grow,
respond to the environment, and reproduce.
<span>Usually made up of organ systems, but an organism may be made up of only one cell such as bacteria or protist.
</span>Examples - bacteria, amoeba, mushroom, sunflower, human</span></span></span></span>
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).
Environmental Threats have come upon Madagascar lately like, Deforestation and habitat destruction. Agricultural fires. Erosion and soil degradation. Overexploitation of living resources including hunting and over-collection of species from the wild. Its a very sad thing :(
