Search results
Results from the WOW.Com Content Network
Not all animals have neurons; Trichoplax and sponges lack nerve cells altogether. Neurons may be packed to form structures such as the brain of vertebrates or the neural ganglions of insects. The number of neurons and their relative abundance in different parts of the brain is a determinant of neural function and, consequently, of behavior.
The human brain has evolved around the metabolic, environmental, and social needs that the species has dealt with throughout its existence. As hominid species evolved with increased brain size and processing power, the overall metabolic need increased. Compared to chimpanzees, humans consume more calories from animals than from plants.
The brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals.It consists of nervous tissue and is typically located in the head (cephalization), usually near organs for special senses such as vision, hearing and olfaction.
The somatic part consists of the nerves that innervate the skin, joints, and muscles. The cell bodies of somatic sensory neurons lie in dorsal root ganglia of the spinal cord. The visceral part, also known as the autonomic nervous system, contains neurons that innervate the internal organs, blood vessels, and glands.
Genes involved in the neuro-development and in neuron physiology are extremely conserved between mammalian species (94% of genes expressed in common between humans and chimpanzees, 75% between humans and mice), compared to other organs. Therefore, few genes account for species differences in the human brain development and function. [15]
Cephalization is a characteristic feature of the bilaterians, a large group containing the majority of animal phyla. [3] These have the ability to move, using muscles, and a body plan with a front end that encounters stimuli first as the animal moves forwards, and accordingly has evolved to contain many of the body's sense organs, able to detect light, chemicals, and gravity.
On the organ and tissue scale in mammals and other animals, examples include the circulatory system, the respiratory system, and the nervous system. On the micro to the nanoscopic scale, examples of biological systems are cells , organelles , macromolecular complexes and regulatory pathways.
The expensive tissue hypothesis (ETH) relates brain and gut size in evolution (specifically in human evolution).It suggests that in order for an organism to evolve a large brain without a significant increase in basal metabolic rate (as seen in humans), the organism must use less energy on other expensive tissues; the paper introducing the ETH suggests that in humans, this was achieved by ...