Human Biology - Parts of the Nervous System - Coursework Example

HUMAN BIOLOGY al Affiliation) Key Words: Neuron, reflex arc, ear, eye TAQ a) Complete the boxes below for each part of the nervous system. b) For each of the subdivisions you have labelled above (the ones originally marked by?) explain their functions within the nervous system and in the case of certain answers their relationships to each other. The brain Its primary function is to regulate all the activities of the human body. It is composed of three regions namely the cerebellum, cerebrum and the advanced marrow (Mader, 2006). The cerebrum serves in conscious actions such as speech, movement, sight, and memory. The cerebellum performs the role of body balance regulation and muscle coordination for movement. The spinal cord It is regarded as a brain extension in which it performs the function of linkage between the lower regions of the body and the brain (Mader, 2006). The somatic nervous system It is also known as the skeletal nervous system that is consistent with sensory nerve receptors that enables the perception of feeling the world and perception in humans (Mader, 2006). The autonomic nervous system It is a component of the peripheral nervous system and as such it performs the function of regulating internal organs like the heart, stomach, bladder; glands and blood vessels (Mader, 2006). The sympathetic and parasympathetic nervous systems These two are components of the autonomic nervous system. These two systems work in a reverse manner to the body so as to enhance its adaptability to the environment (Mader, 2006). In this regard, the parasympathetic nervous system assists in the conservation of the body’s physical resources and the maintenance of normal body functions. The sympathetic nervous system is responsible for the regulation of ‘flight or fight’ responses such as increasing the heart rate and enabling an individual to escape a potential dangerous situation. (W0RD COUNT: 310) TAQ 2: Using web based diagrams (which must be referenced correctly) explain the function of the three neurons (sensory, relay and motor) Motor neuron The motor neuron performs the role of impulse transmissions from the Central Nervous System to other glands and muscles spread within the body (Mader, 2006).. It is composed of dendrites, cell body, myelin sheath, node of ranvier, and synaptic knobs. The dendrites facilitate the transportation of nerve impulses from neighbouring neurons into the cell body. The myelin sheath assists in the nerve fiber protection, insulation as well as a faster transmission rate of the nerve impulses. The nodes of Ranvier assist in nutrient uptake and expulsion of waste products. Figure 1: Motor neuron (Neuron. n.d.) Sensory neuron It is in charge of the inward transmission of impulses from sensory organs of sight, tastes, smell, touch, and hearing to the central nervous system. Figure 2: sensory neuron (Source: Nervous System Intro. (n.d.). Relay neuron It is composed of a cell body and synaptic knobs. It is responsible of the transmission of electrical impulses created by stimuli reaction from other nerves. In this regard, it assists the brain in the processing of information. Figure 3: Relay neurone(Source: Nervous System Intro. (n.d.). (WORD COUNT 156) TAQ 3 a) Explain the changes that occur within a nerve cell and across its membrane during the process of nerve impulse initiation Nerve impulse initiation from one end to the other along a neuron is made possible due to the electrical differences across the neuron’s membrane (Mader, 2006). In this regard, an un-stimulated neuron is normally polarized. In this regard, there is an electrical charge difference between the inner parts and outer region of the membrane. The polarization of the membrane is achieved by the maintenance of surplus potassium ions on the inner region and surplus sodium ions on the exterior region of the membrane (Mader, 2006). Leakage channels allow the leaking of specific amounts of potassium and sodium ions across the membrane. At resting potential, the unstimulated neurone is normally around -70 millivolts (Mader, 2006). The change in the resting potential of a membrane is regarded as graded potential which occurs in response to a stimulus that opens up the potassium ions or sodium ions gated channels. In the event that the sodium ions gated channels opens up, it results to an influx of positive sodium ions which causes depolarization of the membrane. If the gated channel for potassium ions opens up, the positive potassium ions move out across the membrane resulting to a more negative charge or hyperpolarization (Mader, 2006). On the other hand, an action potential occurs when a neuron transmits information for longer distances down an axon (Mader, 2006). In this regard, the gated channels of positive sodium ions are triggered open if there is a sufficiently large depolarized graded potential. In this regard, there is a depolarization of the sodium ions on the outer parts of the membrane. In the event that there is a stronger stimulus, there is supplementary opening of the positive sodium ion gates and an influx of more sodium ions that result to total depolarization of action potential. This consequently, triggers the opening of more positive sodium ion gates downwards along the axon. (WORD COUNT 300) b) What is a synapse? They are specialized sites which allow neurons to transmit information in one direction to facilitate the communication process with other cells (Mader, 2006).. c) Explain how the synapse is involved in transmitting the nerve impulse from one neurone to the next. The synapse functions as a gateway that allows the flow of information from one neurone to the next. In this regard, the gap between two neurons is regarded as the synapse. The synapse is composed of a pre-synaptic ending in which there are neurotransmitters, cell organelles and mitochondria; a post synaptic ending in which receptor sites are found for the neurotransmitters and a synaptic cleft which is a gap between the postsynaptic and pre-synaptic endings (Mader, 2006).. The neurotransmitter carries the nerve impulses which are received by the post-synaptic neuron. Evidently, the post synaptic neuron contains neuroreceptors that are essentially chemical gated ion channels. The neuroreceptors possess definite binding sites for the neurotransmitters (Mader, 2006).. The presynaptic neurone contains calcium paths that are voltage gated at the ends. Once an action potential arrives at the synapse, the paths open up and there is an influx of calcium ions into the cell. The calcium ions catalyze the fusion of synaptic vessels with the cell membrane. The result is the release of neurotransmitter chemicals via a process known as exocytosis (Mader, 2006).. Consequently, diffusion of the neurotransmitters occurs across the synaptic cleft. The next phase is the binding of the neurotransmitters to neuroreceptors contained in the post-synaptic membrane. This results into the opening up of sodium pathways that allows the influx of sodium ions. Consequently, the post synaptice cell membrane undergoes depolarization and can trigger an action potential once the threshold is achieved. A certain enzyme contained in the synaptic cleft breaks down the neurotransmitter. For example, the neurotransmitter acetylcholine is broken down by an enzyme known as acetylcholinesterase (Mader, 2006).. The products of the breakdown process are absorbed through a process known as endocytosis within the pre-synaptic neurone. This is consequently used in the regeneration of additional neurotransmitter by energy derived from the mitochondria. The net effect is the control over the functioning of the synapse. (W0RD COUNT, 307) TAQ 4 Using a diagram, describe the reflex arc. Figure 4: Reflex arc (Source: Spinal Reflex Arc, vector illustration (for basic medical education, for clinics) A reflex arc denotes a nerve conduit in the human body that bypasses the brain by linking certain groups of muscles with others. This essentially initiates involuntary actions in reaction to a stimulus. The reflexes are hence automatic and involuntary movement of muscles that are occur along the reflex arc in response an external stimulus. The arc is situated in the spine or brain and it is normally shorter than the conventional nerve channels. In a reflex situation, in the event of an external stimulation, the nerve impulse moves along the sensory neurons upto the brain or spinal cord and back again towards the region of stimuli action along motor neurons. Other reflex arcs are normally linked to the motor neurons via connector neurons. However, the major fact is the lack of control by the brain. An example of the reflex action is the ‘knee jerk; reflex. (WORD COUNT: 147) TAQ 5 Name of endocrine gland Location Hormones released Function (s) of hormones released Pituitary Located in a hollow bony region known as the pituitary fossa. The pituitary fossa is situated underneath the foot of the brain, next to the optical nerves and at the rear of the nose bridge. It releases hormones such as the thyroid stimulatinf hormone, gonadotrophins, adrenocorticotrophic and prolactic hormone, anti-diuretic hormone, and growth hormone Adrenocorticotrophic hormone kindles the adrenal stress hormone known as cortisol. Thyroid stimulating hormones kindles the thyroid gland to produce Thyroxine. Thyroid Largest gland in the neck that is located at the front part of the neck underneath the muscle layers and skin It produces the thyroid hormone. The thyroid hormone enhances cellular activity. Consequently, the thyroid hormone has an effect on growth and development, metabolism, and the body’s temperature. Parathyroids Are four micro glands situated in the neck. Releases the parathyroid hormone. The parathyroid hormone regulates the calcium levels in the body. Consequently, it increases the calcium level in blood through enhancing the body’s capacity for calcium absorption from food, breaking lose of the calcium stored in the bones to stimulate additional release of calcium, enhancing the kidney’s capacity to retain calcium and avoid its loss in urine. Thymus Found between the lungs and behind the sternum Releases the hormone thymosin Thymosin kindles the generation of disease resistant T cells. Adrenal Located at the top part of the kidneys composed of the adrenal cortex and the adrenal medulla. Produces the hormones adrenaline, cortisol and aldosterone. Aldosterone regulates blood pressure, adrenaline assists the body to respond to stress, cortisol controls metabolism and assists the body’s response to stress. Pancreas Situated in the upper abdomen Produces glucagon and insulin hormones. Glucagon and insulin hormones assist in the control of blood sugar level. Ovaries Situated on the both sides of the uterus and opposite regions on the pelvic wall Progesterone and estrogen sex hormones. They work together to facilitate fertility and the healthy development of sex characteristics in the female Testis Situated underneath the penis inside the scrotum. Releases the testosterone hormone. Promotes the development of male characteristics. (word count: 352) TAQ 6 Explain and discuss the effects of insulin, glucagon, T3 and T4 on the metabolism’ Insulin performs a pertinent function of regulating the level of blood glucose in the body. Incidentally, it controls the usage and storage of glucose and fat in the body. Whenever glucose levels in the blood increases, the pancreas releases insulin to control the blood glucose level (Mader, 2006). In terms of controlling the level of blood glucose, insulin triggers the cells in the muscles, liver and fat to absorb blood glucose. Consequently, insulin plays a pivotal role in assisting the cells to absorb glucose for energy. Evidently, an increase in the concentration of blood glucose stimulates insulin secretion. In the event that, secretion of insulin is impaired, a possible result is the manifestation of diabetes mellitus. This disease is characterized by high levels of blood glucose causing excess levels of glucose in urine. Glucagon also works synergistically with insulin to regulate the levels of blood glucose. Incidentally, glucagon has a reverse effect to that of insulin. In this regard, the effect of glucagon results to the elevation glucose levels in the blood. Evidently, a reduction in the blood glucose levels stimulates the secretion of glucagon by the pancreas (Mader, 2006). Glucagon initiates control over two pertinent metabolic channels in the liver causing it to release glucose to the blood. In this regard, whenever there are high levels of glucose in the blood, the liver takes it up and it is stored as glycogen subject to the control of insulin. In the event that, blood glucose levels depreciate, it stimulates the secretion of glucagon. The glucagon hence stimulates the hepatocytes to trigger enzymes that consequently cause the de-polymerization of glycogen. This hence results in the release of glucose in the blood. Glucagon also performs the role of activating hepatic gluconeogenesis. In this regard, gluconeogenesis is in reference to the channel through which non-hexose substrates like amino acids are transformed into amino acids (Mader, 2006). Consequently, it acts as an alternate provision of glucose for blood. In net effect, glucagon is normally secreted in reaction to a condition known as hypoglycemia(Mader, 2006). This condition is characterized by minimal levels of glucose in the blood. T3 and T4 are thyroid hormones derived from tyrosine and iodine. T3 and T4 hormones are reffered to as triiodothyronine and thyroxine (Mader, 2006).. They both exhibit similar effects on the body but the difference comes about in the level of intensity. Evidently, both T3 and T4 exhibit a catabolic reaction on nutrient metabolism in the body. In this regard, the catabolic role of the thyroid hormones is composed of degradation of proteins, lipids and glucides. This results in the release of energy. Glucides degradation causes hyperglycemia in the body that is essentially the increase of blood glucose levels courtesy of T3 and T4. Consequently, the general rate of metabolism is increased and also the heart rate and pulmonary ventilation. The T3 and T4 hormones also merge with mitochondria receptors resulting to a higher rate of ATP production. It equally results to faster gene transcription that facilitates glucose use and production of ATP. This consequently results into greater metabolism rate of the cell. (WORD COUNT; 506) TAQ 7 Write a short essay, discussing and explaining the structure and functions of the eye and the ear. Human Ear The human ear is made up of three parts namely the outer or ear, the middle ear and the inner ear. The outer ear is composed of the pinna and also the external auditory meatus (Mader, 2006). The pinna is the visible part of the ear located on each side of the human head. It is constituted by cartilage and flexible tissue. This structure enables the ear to maintain its shape and also flexibility. The pinna acts like a funnel that captures vibrations of sound from the external environment and directs it to the external auditory meatus. The external auditory meatus is also known as the ear canal (Mader, 2006). The ear canal is linked from the pinna up to the ear drum or tympanic membrane. It assists in comprehension and determination of the source and direction of the sound. The outer part of the ear canal is covered in skin and hair (Mader, 2006). The starting point of the middle ear is at the end of the ear drum. The middle ear is composed of the ossicles which is essentially three small bones that link the tympanic membrane to the inner ear. The three small bones making up the ossicles are namely the malleus, incus and stapes (Mader, 2006). In this regard, the sound waves that are directed from the pinna, strike the tympanic membrane and cause it to vibrate. Consequently, the sound waves are transformed into mechanical vibration. The malleus is linked to the tympanic membrane on one side while the incuse on the opposite side. The malleus is further linked to the third bone and known as the stapes. The mechanical energy resulting from the conversion of sound waves is transmitted through the ossicular chain. There is a tube known as the Eustachian tube that travels from the front wall of the middle ear to the throat and the back of the nose. Its function is to allow ventilation and entry of external air so as to ensure balance of air pressure on all sides of the eardrum. The inner ear provides storage of the sensory organs that assist in hearing and the maintenance of balance. The parts that assist in maintain the body balance is namely the semi-circular canals made up of the utricle and saccule. There is also a structure that appears like a snail in shape and filled with lymphatic fluids known as the perilymph and endolymph. This collectively constitutes what is known as the cochlea. Inside the cochlea, is the Organ of Corti that acts as a sensory receptor. The movement of the middle ear transmits mechanical energy to the cochlea. Consequently, minute hair cells are stimulated owing the movement of the cochlea fluids. Individual hair cells are stimulated by specific sound frequencies. These sound frequencies are translated into nerve impulses that are transmitted to the brain via the acoustic nerve. Human Eye The main parts of the human eye are; cornea, sclera, Iris, lens, retina, optic nerve, pupil, and aqueous humor. The eyeball is protected by two outer skin layers known as the eyelids. The cornea is located at the front of the eye and it is a clear and dome shaped window that allows the passage in of light. It also assists in directing light towards the retina that is situated at the back of the eyeball. The inner layer of the cornea is the sclera. Its function is to protect the eye by acting as a protective coat. The aqueous humor is found behind the cornea and is a transparent liquid that provided nutrients to the cornea. The light then travels through a minute hole in the middle of the eye known as the pupil. The pupil is surrounded by a circular, pigmented layer known as the iris. The function of the iris is to dictate the colour of an individual’s eyes. Consequently, it does not allow the passage of light. The muscles of the iris contract and relax to regulate the size of the pupil. The function of the pupils is to regulate the amount of light entering the eye. The lens is situated immediately after the iris. The lens has a structure that is bi-convex, transparent and with a flexible disc linked to the ciliary muscles by suspensory ligaments. The lens functions by focusing light onto the retina. The retina is located at the back of the eye and it is a lining that contains photoreceptor cells of two types. These are cones and rods. The cones are exhibit sensitivity to color and provide detailed, sharp and centralized vision. The rods exhibit sensitivity to black and white as well as dim light. The optic nerve is also present at the back of the eye and it is composed of a bundle of sensory neurons. The primary function of the optical nerve is to direct impulses from the eye to the brain. (WORD COUNT, 803) References Mader, S. S. (2006). HYPERLINK "http://www.bibme.org/book"Human biology HYPERLINK "http://www.bibme.org/book" (9th ed.). Dubuque, IA: McGraw-Hill. Nervous System Intro. (n.d.). HYPERLINK "http://www.bibme.org/book"Nervous System Intro HYPERLINK "http://www.bibme.org/book". Retrieved September 11, 2014, from http://www.biologymad.com/nervoussystem/nervoussystemintro.htm Neuron. (n.d.). HYPERLINK "http://www.bibme.org/book"Neuron HYPERLINK "http://www.bibme.org/book". Retrieved September 11, 2014, from http://www.infovisual.info/03/041_en.html Spinal Reflex Arc, vector illustration (for basic medical education, for clinics HYPERLINK "http://www.bibme.org/book"& HYPERLINK "http://www.bibme.org/book" Schools). (n.d.). HYPERLINK "http://www.bibme.org/book"Spinal Reflex Arc, Vector Illustration (For Basic Medical Education, For Clinics HYPERLINK "http://www.bibme.org/book"& HYPERLINK "http://www.bibme.org/book"Amp; Schools) HYPERLINK "http://www.bibme.org/book". Retrieved September 11, 2014, from http://www.shutterstock.com/fr/pic-139529258/stock-vector-spinal-reflex-arc-vector-illustration-for-basic-medical-education-for-clinics-amp-schools.html ASSESMENT CRITERIA Page number/s on which you feel you have achieved the assessment criteria For a Pass 1.1 Differentiate the parts of the nervous system 3-4 1.2 Describe and outline the function of each type of neurone. 5-7 1.3 Explain the process of nerve impulse initiation and transmission. 9-10 1.4 Describe and illustrate the nerve reflex pathway. 11-12 2.1 Locate the major endocrine organs and outline some of their function 12-14 2.2 Explain the effects of specific hormones on metabolism 15-16 3.1 Describe and explain the structure and functions of sensory organs 17-19 ASSESMENT CRITERIA Page number/s on which you feel you have achieved the assessment criteria For a Pass 1.1 Produce plans to meet the requi rements of the title, ensuring the plans are relevant, complete, sequenced logically and prioritised. 3-4 2.1 Use appropriate academic vocabulary 12-14 2.2 Express ideas clearly 12-14 2.3 Ensure the chosen style is appropriate to the type of essay e.g. discursive, narrative 12-14 2.4 Sustain a transactional academic register where this is required 12-14 3.1 Use clear, coherent and logical structure and paragraphing. 17-19 4.1 Write in fluent, accurate English observing the conventions of grammar, punctuation and spelling 3-19 5.1 Evaluate issues and points of view referred to in essays. 2-19 6.1 Acknowledge all research sources quoted or paraphrased within the essay 17-19 6.2 Provide suitable bibliographies and correctly apply a referencing system. 17-18 PART 4: Your Comments on this assignment I have been to succinctly achieve the following differentiate the parts of the nervous system. Describe and outline the function of each type of neurone. Provide and explanation on the process of nerve impulse intiation and transmission. Offer a description and illustration of the nerve reflex pathway. Indicate the major endocrine organs and their functions. Provide an explanation of the specific hormones responsible over metabolism Provide a description and explanation over the structure and functions of the sensory organs Read More