The Functions of the Central and Peripheral Nervous System - Assignment Example

COORDINATION and Coordination Task One: Understand the Central and Peripheral Nervous System and their Functional units; the Neurons 1.1 Explain the Structures and the Functions of the Central and Peripheral Nervous System The nervous system is divided into two core components; the central and the peripheral nervous systems. The peripheral nervous system comprises nerves that are outside the brain and the spinal cord while the central nervous system entails the spinal cord and the brain. The spinal cord which is a major part in the CNS is found the vertebral column and has only one bone (Bear, Connors, & Paradiso, 2007 p. 46). It is directly linked to the brain medulla and it therefore sends sensory messages to the brain. The brain is divided into the hind brain, midbrain and forebrain. The hind brain consists of pons, cerebellum and medulla; medulla links the backbone to the pons and the pons bridge the cerebrum to the cerebellum. The cerebellum is directly behind the brain stem and it therefore maintains posture, balance and movement. Midbrain handles the eye movement reflexes (Bear, Connors, & Paradiso, 2007 p. 54). The forebrain is divided into telencephalon and diencephalon. Telencephalon comprises of the cerebral cortex, basal ganglia and the limbic system. The cerebral cortex is mainly for memory, understanding and spatial processing. Basal ganglia aids in regulating movement and the learning of skills whereas the limbic system is for processing emotions, formation of long term memories and maintaining homeostasis (Bear, Connors, & Paradiso, 2007 p. 63). The peripheral nervous system mainly links the central nervous system o the environmental stimuli so as to allow the body to respond to the different environment changes. The PNS has neurons are nerve cells that communicate with each other through neurotransmitters. The sensory neuron are for vision and smell and pass message to the CNS while the motor neurons are for hearing and carry their signals to the internal body organs from the CNS. Motor cells are divided into somatic and autonomic cells. The somatic cells link the environment to the CNS whereas the autonomic cells are divided thrice into; sympathetic, parasympathetic and enteric (Bear, Connors, & Paradiso, 2007 p. 87). The sympathetic cells increase body functions while the parasympathetic reduce the body functioning. The enteric cells are involved with the functioning of the gallbladder and pancreas. The autonomic cells majorly control the involuntary muscles referred to as the smooth muscles. 1.2 Explain the structures and functions of a neuron distinguishing between the three main types found in the human body A neuron is a nerve cell, there are only three main types of nerve cells in the human body that is the motor, sensory and relay neurons. Nerve cells have nerve fibers called axon which carry nerve impulses from the cell body of the neuron. The cell body has lysosomes and nucleus which breakdown all neural proteins and membranes. Dendrites are the shorter branches to the neurons which receive the chemical signals from the axon and transfer the impulses into the cell body. The myelin sheath is a layer comprising of protein and phospholipid fats, they are meant for protection and insulation of the nerve fiber, the sheath also increases the rate at which the nerve impulses are transmitted (Bear, Connors, & Paradiso, 2007 p. 43). The nodes of Ranvier are gaps that occur in the myelin sheath they allow entrance of nutrients and the removal of waste materials from the neuron. The Schwann cells are cells that envelop the axon as it grows. The sensory neuron transmits impulses to the CNS from the sense organs; relay neuron transmits electrical signals to other nerves from the stimuli generating the impulses while the motor neurons transmit signals from the CNS to the entire body. 1.3 Explain a reflex arc and nerve impulse A reflex arc is a nerve pathway used during the reflex action and controls it. It is divided into somatic and autonomic reflex arcs. The autonomic reflex affects inner organs while the somatic reflex arc affects the muscles nerve impulse is an electrical signal that passes in an axon (Brodal, 2010 p. 36). Neurons that are used to transmit these electrical signals are shielded with the myelin sheath which acts as an insulator. 1.4 Discuss two diseases/disorders of the central nervous system mentioning causes, symptoms and treatment The central nervous system disorders can affect either the spinal cord or the brain. The hyperactivity disorder of the nervous system is caused by the biochemical imbalances in the brain specifically the low levels of the neurotransmitters which are involved in the controlling and maintaining attention and locomotion. Some of its symptoms are persistent headache, memory loss and slurred speech. Surgery and prescribed medications can be used for treatment (Brodal, 2010 p. 48). The bipolar disorder is a type of nervous disorder its major symptoms are mood swings from mania to depression, can be caused by certain brain infections and autoimmune disorders. Can be treated through surgery and prescribed medications. 2. Understand the Main Glands of the Endocrine System 2.1 Discuss the role of the hormones secreted by the main endocrine glands in the human body and their effects Hormones play a very crucial role in the development of various conditions in the human body. For instance, hormones are very influential in the development of dwarfism as well as gigantism. Specifically, growth hormones affect the development of an individual and determine whether one will become a dwarf or a huge person. Growth hormones affect the development of new tissues in the body. For example, a deficiency of secretion of growth hormones before one reaches puberty can result in a condition known as pituitary dwarfism. An example of growth hormones that affects dwarfism is the deficiency of dwarfism. Hormones are also influential in the development of myxedema. This is a skin condition that occurs mostly in hypothyroidism. Cushing’s disease also arises from the changes in hormone levels in the body. The disease refers to a collection of various symptoms that result from one’s prolonged exposure to cortisol. This condition arises from the benign tumors in the pituitary gland. The benign tumor releases a hormone called adrenocorticotropic hormone, which affects the glands and causes them to release cortisol hormone in excess amounts (Squire, 2013 p. 56). Hormones also play a vital role in controlling milk production in lactating mothers. Prolactin hormone, which is produced in the pituitary gland is responsible for regulating the production of milk among breastfeeding women. A deficiency in production of the prolactin hormone affects the levels of milk produced. The breastfeeding mothers are likely to experience low milk production in instances where the levels of prolactin from the pituitary glands is very low. Diabetes mellitus is one of the most common long term conditions. Type 1 diabetes mellitus results from low production of insulin in the body, which creates a condition of high sugar levels in blood. Insulin is a hormone charged with the responsibility of regulating blood sugars in the body (Brodal, 2010 p. 63). However, when the levels of insulin production are very low, it may be difficult to regulate the levels of sugar in blood, thereby resulting in type 1 diabetes mellitus. Finally, hormones are also very useful in regulating an internal biological clock also known as the circadian rhythm. This internal clock helps one’s body to adjust itself in terms of the daily lives and activities that humans do day and night. 3. Understand Sensory Perception 3.1 Explain the structure and function of the eyes Light enters the eye through the pupil which is a small hole in the eye and then focused on the retina. Images on the retina are focused on from different distances by the eye lens. The iris which resembles a colored ring regulates the amount of light which enters the eye, when the light is too bright it closes and when it’s dim it widely opens. There is a transparent white tough sheet around the eye called sclera which allows light to enter the eyes cornea. Moreover, it acts as a protective layer for the eyes (Brodal, 2010 p. 64). The cilliary muscles control the adjustments of the lens during image focusing. Nutrients in the eyes structure is supplied by the choroid. Images formed on the retina are transmitted to the brains by the optic nerve. Then the brain perceives that image. Vitreous humor which is a jelly like fluid fills the space between the lens and the retina (Squire, 2013 p. 43). Aqueous humor is a fluid that nourishes the lens iris and cornea. The right balance of the aqueous humor production and absorption controls the eye pressure. 3.2 Explain the Mechanism of Visual Perception in the eyes As light enters the eyes it is refracted though the cornea and controlled by the iris as it passes through the pupil then further refracted by the eye lens. An inverted image is then projected on the retina which has a high number of photoreceptor cells that have opsins and protein molecules. Opsins absorb light particles and then transmit the signal to the cells leading to the hyper-polarization of the photoreceptors (Brodal, 2010 p. 45). Rods are used to see dim light while cons are for color distinction and found at the Centre of the retina while the rods are found in the periphery of the retina. The photoreceptor cells in the retina directly synapse onto the bipolar cells which turn the synapse on the ganglion cells that will conduct action potentials to the brain cells. The information about the image formed reaches the brain through the optical nerve; the optic nerves meet the optic chiasm at the base of the brains hypothalamus. 3.3 Explain the structure and function of the ears The ear is divided thrice into the inner outer and middle ear. The outer ear has the pinna, auditory canal and the eardrum. The pinna collects the sound waves and funnels it into the auditory canal which is a funnel shaped ear passage that leads it to the eardrum. The middle ear has the malleus, incus and the stapes which transfer sound waves to the inner ear (Brodal, 2010 p. 33). The inner ear has the cochlea which is a coiled structure that contains the auditory receptor cells. The pinna has hair that traps dust preventing the eardrum from damage. The auditory canal determines the intensity of sound that reaches the eardrum. The eardrum has the ossicles which transmit vibrations to the inner ear. The cochlea has the sound receptors and the vestibular apparatus mainly for a sense of balance. 3.4 Explain how sound is perceived in the ears The pinna cause sound reflection thus changing the direction of the sound making the brain to establish the precise direction from which the sound came. The sound waves enter the auditory canal which amplifies the sound into the eardrum which is placed in the middle ear. Sound waves from the eardrum are carried along through the hammer, anvil and the stirrup bones (Brodal, 2010). At the oval window this bones convert the low pressure vibrations from the eardrum into high pressure vibrations. On the cochlea there is a membrane that is like a round window, it pulsates according to the vibrations entering the cochlea from the oval window therefore allowing the fluid in the cochlea to move. The fluid movement stimulates the hair cells of the cochlea that act as hearing mechanoreceptors. References Bear, M. F., Connors, B. W., & Paradiso, M. A., 2007, Neuroscience: Exploring the brain. Lippincott Williams & Wilkins, Philadelphia, PA. Brodal, P., 2010, The Central Nervous System, Oxford University Press, USA, Oxford. Squire, L. R., 2013, Fundamental neuroscience, Elsevier/Academic Press, Amsterdam. Read More