Neural Physiology and Function - Assignment Example

Neural Physiology and Function Biological evolution of the human brain and factors leading to the development of the modern humanbrain Human brain biological evolution is a gradual, complex and proactive process that involves a change of the human brain genetic material, structure and function caused by natural selection or pressure resulting in physical, cognitive and behavioral traits variation. The new acquired characteristics of the brain are then modified, inherited and passed from one generation to another while others are lost depended on natural pressure to be reinforced, eliminated or undergo a series of mutation(Rubenstein & Rakic, 2013). The modern human brain development is caused by physical factors such as exercise, hereditary and environmental factors such as radiation, pollution and climatic changes and personality traits. In addition, socio-economical factors in a cultural context that gives the human being the ability to interact communicate and position presented in the society such as education, wealth and the place of residence. However, nutrition factors or metabolic factors determine the rate human growth and development in the form of physical and cognitive characteristics. In addition, technology development plays a crucial role in the modern human development in the manner in which human beings acquire and control other factors such as environmental pollution, hereditary factors as well as social factors such as occupation (Rubenstein & Rakic, 2013). 2) The description of the divisions and systems of the mammalian nervous system, e.g. the central nervous system (areas of the brain, spinal cord) and peripheral nervous systems and their respective function (s) The gross organization of the Nervous System is divided into two divisions, the peripheral and the central nervous and their respective subdivisions both in functions and architecture. As single unit, the mammalian nervous system is responsible for the production, control as well as guidance on all mammalian actions, thoughts, and responses to their daily activities. However, each division and system is differentiated by different architecture and function. The peripheral nervous system division consists of the nerves connected directly to the mammalian skin, muscles, body organs as well as blood vessels excluding those nerves that are attached to the skull and the spinal column (Rubenstein & Rakic, 2013). Peripheral nervous system divisions include the somatic nervous system and automatic nervous system. Somatic nervous system is further subdivided into afferent and efferent nerve fibers responsible for mammalian physical sensation and voluntary movements. Afferent nerve fibers transmit impulses or sensory information towards the central nervous system while the efferent nervous division of the Somatic nervous system transmits locomotive impulses away from the CNS allowing locomotion of the limbs and facial features. Similarly, the autonomic nervous system is an involuntary division part of the peripheral nervous system that is subdivided into parasympathetic and sympathetic sub-division responsible for motor and sensory function beyond the mammalian voluntary control such as the functions of the internal body organs and glands. The sympathetic sub-division is responsible for energy expenditure preparation through fight or flight while the parasympathetic sub-division is responsible for production and energy restoration for a balanced mammalian activity (Rubenstein & Rakic, 2013). Comparatively, the central nervous system division is subdivided into the brain, and the spinal cord encased in the bone mainly for mammalian protection. The spinal cord subdivision is responsible for the transmission of sensory nerve impulses to the brain and motor impulses to the PNS. The Brain as a division of Central Nervous System control and guide the mammalian behavior by processing, storing and executing actions or information from various body parts. The brain is subdivided into the ventricles and the hemispheres responsible for cerebrospinal fluid (CSF) production and analytical task or emotional processing respectively (Rubenstein & Rakic, 2013). 3) The production of an action potential and its conduction along a myelinated axon and the process involved in neurotransmitter release The production of action potential begins with a stimulus initiation from a sensory nerve or cell or from a nearby neuron causing the targeted cell to be depolarized towards a threshold potential. Alternatively, a neuron gets stimulated by binding of neurotransmitters to the specific receptors. However, if a threshold excitation potential (-50mV) is reached, the entire sodium ion channels open into the cell causing the membrane to depolarize in favor of the concentration gradient -35mV. At the peak of action potential, the potassium channel (K+) open causing the K+ to exit as the sodium channels (Na+) closes causing the membranes to become hyperpolarized. At this stage, the K+ channels are closed while the Na+/K+ transporters are restored as a refractory phase to begin a new phase. In a myelinated axon, an action potential production occurs at the nodes of Ranvier that permit saltatory conduction process that allows impulses to skip from one node to another. The conduction process is achieved when the depolarized node of Ranvier stimulates an increase in membrane permeability to the Na+ channels that cause a corresponding depolarization in the adjacent node of Ranvier. The process involved in the neurotransmitter release are neurotransmitter freeing process, docking, fusion and the exocytosis processes by the stimulation of influx calcium ions (Rubenstein & Rakic, 2013). 4) Classes of neurotransmitters description inside the central nervous system Neurotransmitters inside the central nervous system are classified into two groups, inhibitory and excitatory neurotransmitters. Within the same classification, the transmitters are grouped into various classes that include amino acids such as GABA, diamines such as histamine, monoamines such as epinephrine and serotonin. In addition, classes of gas include nitric oxide and nitrogen (II) oxide while others fall into other categories such as ATP and acetylcholine (Rubenstein & Rakic, 2013). 5) Description and discussion of the involvement of dopamine and the “reward pathway” in addition according to the wanting-and-liking theory Reward pathway consist of a neural projection termed as mesocorticolimbic system that originate from the dopaminergic cell bodies were dopamine served an essential role in wants, novelty, as well as expectations. The reward experience such as a natural desire for sex and food are always accompanied by stimulation of mesolimbic dopaminergic pathway due to the increase in mesolimbic dopamine extracellular concentration. For the case of drugs intake such as cocaine consumption, the drugs increases the synaptic dopamine concentration gradient by blocking the DAT (presynaptic dopamine transporter) causing a corresponding increase in mesolimbic dopamine concentration at the synaptic site. However, the prolonged effect upon which the dopaminergic function produces a reward of want and liking is dependent on the dopamine function (Rubenstein & Rakic, 2013). Conversely, the concept of the dopamine sensitization and depletion causes a transitional shift from reward to addiction. Therefore, as dopamine remains the principal component and modulator of the reward and addiction centers, dopamine plays a critical role in the motivation processes such as drugs craving and other wants. In addition, dopamine being the crucial factor in the VTA-NAc pathway it plays an essential role in determining whether an induced stimulus is rewarding or averse in conjunction to mediating the rewarding effects of natural rewards as well conditional forms of learning (Rubenstein & Rakic, 2013). References Rubenstein, J. L. R., & Rakic, P. (2013). Neural circuit development and function in the healthy and diseased Brain: Comprehensive developmental neuroscience. Burlington: Elsevier Science. Read More