Unit 14 The Brain and Nervous System (Psychology) Academic Report PDF

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Unit 14 The Brain and Nervous System (Psychology)

An Academic Report By Emma Bushnell

Terms of Reference This academic report has been written by Emma Bushnell for Unit 14 (The Brain and Nervous System) for LearnDirect in April 2021. The purpose of this report is to demonstrate understanding of the key aspects of the brain and the nervous system. In Section One, the major structures and functions of the brain, the differences between the central nervous system, the peripheral nervous system, and the two branches of the autonomic system are explained in detail with references. In Section Two, the differences between glial cells and neurons, the role of neurotransmitters and the process of communication between neurons is described with references.

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Terms of Reference Contents Research Methodology

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Section One

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Structures and functions of the brain The Central Nervous System, Peripheral Nervous System and the Autonomic System Section Two The structure and function of glial cells and neurons The process of communication between neurons The role of neurotransmitters Conclusions Recommendations References Bibliography Appendices

Research Methodology This report has been created using secondary qualitative research collected from LearnDirect materials, relevant websites and e-books on the anatomy of the brain and nervous system, cited in the bibliography section. Where quotations or citations have been made, references are provided in the references section.

Section One Structures and functions of the brain There is a lot of activity going on inside the brain, according to J Bollow (date unknown), 20 million billion bits of information move around the brain every second. The brain is made up of different parts which function together. The limbic system, in the centre of the brain, is responsible for much of human cognition, emotion, perception and memory. It consists of the following parts: the amygdala, mammillary body, olfactory bulbs, septum, cingulate gyrus, thalamus, fornix, dentate gyrus and hippocampus. The cerebral cortex, or grey matter/cerebrum, connects with the limbic system via nerve pathways from the central and peripheral systems. The following lobes are present in the cerebral cortex: The frontal lobe, which is primarily responsible for human speech, motor control (via the primary motor cortex) and sense of smell. The parietal lobe, which controls touch and pressure (via the primary somatosensory cortex), body awareness, taste, hearing abilities and language. The occipital lobe, which aids vision. The temporal lobe, which allows humans to read and recognise faces. The cerebellum, which controls balance and coordinated movement. The medulla oblongata is found at the top of the spinal cord in the brain stem. It contains neurons which transmit electrical impulses to the heart and lungs thus controlling heartbeat, breathing rate and peristalsis. The midbrain and pons are also located in the brain stem. “Centres in the brain stem produce automatic behaviours necessary for survival”. Marieb, E.N. et al, (2015). The Central Nervous System, Peripheral Nervous System and the Autonomic System The central nervous system (CNS) is made of all neurons found inside the brain and spinal cord which occupy the dorsal body cavity. The CNS functions to interpret sensory information received via electrical impulses from sensory and motor neurons. Differences within the CNS include how the brain and spinal cord function; in that the brain provides conscious awareness and the spinal cord provides simple reflex responses. Also, the brain is made up of distinct parts which are responsible for different functions whereas the spinal cord has only one main function. The peripheral nervous system (PNS) includes “the sensory receptors, peripheral nerves and their associated ganglia and efferent motor endings”. Marieb, E.N. et al, (2015). Sensory receptors transmit information to the brain from a stimulus, for example, touch, temperature, smell, and pain. There are different receptors for each of the stimuli, see Appendix 1. Differences between the CNS and PNS include the components of the systems themselves; in that the CNS includes the nerves of the brain and spinal cord whereas the PNS includes all the other nerves in the body. Also, the CNS acts as the central processing unit for information whereas the PNS is responsible for transmission of such created information. Another difference is in the protective structures that surround the systems; the CNS is protected by the skull and the PNS is protected by the vertebral column.

The autonomic nervous system (ANS) is the part of the PNS that controls muscular movements such as the size of the pupil for sight and the contraction of cardiac muscles. The ANS has two subsystems, the afferent (sensory) division and the efferent (motor) division. The efferent division conducts impulses from the CNS to muscles and glands and the afferent division conducts impulses from receptors to the CNS. There are two further subsections of the ANS which are sympathetic and parasympathetic systems. Differences in the sympathetic and parasympathetic divisions are the sympathetic system is responsible for the well-known ‘fight or flight’ reflex and uses noradrenaline. Whereas, the parasympathetic system, responsible for slowing down processes within the body, encourages rest and digestion, using acetylcholine. The work systems work together to maintain an internal balance, this is called homeostasis.

Section Two The structure and function of glial cells and neurons A neuron is a cell with a single nucleus and many of the typical organelles found inside cells except centrioles. Neurons have tentacle-type projections radiating from its centre called dendrites and an axon, which is the longest projection, or process. The dendrites receive nerve impulses and axons transmit nerve impulses. See Appendix 2. Glial cells, or neuroglia, are found in the CNS and the PNS. In the CNS, the types of neuroglia found are ependymal cells, oligodendrocytes, astrocytes, and microglia. In the PNS, satellite cells and Schwann cells can be found. The neuroglia has so many functions that it is not surprising the ratio of neuroglia to neurons is 10:1. Neurons and neuroglia are different by definition, function, and significance. Neurons are tiny, specialised cells responsible for the transmission of nerve impulses between the CNS and the rest of the body. Whereas neuroglia cannot transmit signals but provide support and protection to neurons and maintain homeostasis. Neuroglia plays a critical role in signal transduction as they surround the neurons, form myelin, provide nutrients, remove dead cells, oxygen and provide insulation and protection. Finally, but with no less importance, the neuroglia increase transduction speed by myelination of axons. Lakna, (2019). The process of communication between neurons Neurons communicate between each other by a process called neurotransmission which uses electrical impulses and chemical substances, called neurotransmitters. The neurotransmitters are released by one neuron (the pre-synaptic neuron) to send information to the neighbouring neuron (the post-synaptic neuron) across the synaptic cleft. This happens upon arrival of action potential (changes in chemical or electrical structures) at the pre-synaptic axon terminal of a neuron. Stimulation by chemical changes in the cell body generates electrical charges created by internal negative charges and positive potential on the outside of the cell body. The chemical stimuli cause the cell body to become permeable to sodium and thus the positively charged sodium ions can pass through into the cell, leaving the outside of the cell membrane negative. This is called depolarisation. Inside the cell, negative potassium ions and positive sodium ions react to cause an electrical charge which creates an impulse along the axon. Neurotransmitter substance is then released into the synaptic cleft when a vesicle (the bulb of the synapse) and the pre-synaptic membrane create a

fusion. As the chemical diffuses across the synaptic cleft it binds with receptor proteins on the postsynaptic plasma membrane of the dendrites. The substance then triggers the whole process to start over again in the post-synaptic neurone and thus the information is passed along. Lumen, (date unknown). Meanwhile, the neurotransmitter substance re-enters the pre-synaptic neurone by a reuptake mechanism involving astrocytes to ensure only the correct amount of information is sent forward. If chemicals are left over in the synaptic cleft, the information will continue to be sent, resulting in excessive amounts of chemical in the system.

The role of neurotransmitters Neurotransmission plays an important role in the way the human brain interprets information from the nervous system. Commonly occurring neurotransmitters include dopamine, GABA, glutamate, serotonin, acetylcholine, norepinephrine, and epinephrine (or, adrenaline). See Appendix 3. Serotonin is produced in the gastrointestinal tract and the brain and affects mood, social behaviour, sleep, and other important human functionalities. Symptoms of low serotonin levels include craving sweet or starchy foods, cognitive impairment, anxiety, fatigue, digestive troubles, insomnia, and low sex drive. Conditions associated with low serotonin include autism, anxiety disorders, IBS, major depression, sleep disorders and migraines. Corticotrophin releasing factor (CRF) is a neurotransmitter and a hypothalamic hormone which stimulates corticotrophin. Its main role is to act as the central driver of the hypothalamic-pituitaryadrenal axis (the stress hormone system). CRF acts within the brain and links with the endocrine system to suppress appetite, increase anxiety to aid the fight or flight response, and improves memory. These effects coordinate and regulate the body’s response to stress. Stress can be emotional, physical or behavioural. The most common effects are headaches, muscle tension, anxiety, restlessness, over or under eating, and angry outbursts, but there are many others. The unhealthy habits linked to stress, such as smoking and excessively consumption of alcohol or junk food, can cause high blood pressure or heart disease, but stress alone cannot cause this. Dopamine, like the other neurotransmitters, is made in the body and sends messages using the nervous system. It helps us focus and plays a role in how we feel pleasure due to its links with the pleasure centres in the brain. Dopamine also assists with learning, motivation, heart rate, sleep, mood, and pain processing. Mental health disorders such as schizophrenia and ADHD and diseases such as Parkinson’s disease and obesity are linked to low or high levels of dopamine in different parts of the brain. In Parkinson’s disease, dopaminergic neurons degenerate, and although the cause of the disease it unknown, the symptoms are recognised as tremors, bradykinesia (slowness of movement), limb rigidity, and gait. According to Parkinson’s UK, around 145,000 people in the UK live with Parkinson’s and that it is the fastest growing neurological condition in the world. Conclusions This report has summarised the major structures and functions of the brain with explanation of how the nervous system works to communicate messages around the body. Exploring the roles of neurotransmitters and how increased or decreased levels can impact behaviour and other functionalities has been both useful and relevant.

Recommendations There are many books which outline the key aspects of the brain and nervous system in relation to neurotransmission and hormone regulation. It would be recommended to conduct further reading to discover more in-depth information. Mind has many articles of information and advice and also offers a range of services for people who suffer with, or know someone who suffers with, mental health problems such as depression, anxiety, ADHD and schizophrenia. In current times, many people are suffering with mental health problems and Mind have recently declared a mental health emergency due to the coronavirus pandemic. This is an interesting topic and is worth further research.

References Bollow, J. (date unknown). How Fast is Your Brain? [Online] Available at https://thephenomenalexperience.com/content/how-fast-is-your-brain (Accessed on 08/04/2021) James, A. (2021). Using Molecular Psychology in Everyday Life. [Online] Available at https://www.betterhelp.com/advice/psychologists/using-molecular-psychology-in-everyday-life/ (Accessed on 09/04/2021) Lakna. (2019). What is the difference between neurons and glial cells? [Online] Available at https://pediaa.com/what-is-the-difference-between-neurons-and-glial-cells (Accessed on 08/04/2021) Lumen. (date unknown). Neurophysiology. [Online] Available at https://courses.lumenlearning.com/boundless-ap/chapter/neurophysiology/ (Accessed on 08/04/2021) Marieb, E.N. and Hoehn, K.N. (2015). Human Anatomy & Physiology, Global Edition. 10th ed. [ebook] Pearson. Available at: https://www.perlego.com/book/811178/ Parkinson’s UK. (date unknown). What is Parkinson’s? [Online] Available at https://www.parkinsons.org.uk/information-and-support/what-parkinsons (Accessed on 09/04/2021)

Bibliography Bollow, J. (date unknown). How Fast is Your Brain? [Online] Available at https://thephenomenalexperience.com/content/how-fast-is-your-brain (Accessed on 08/04/2021) James, A. (2021). Using Molecular Psychology in Everyday Life. [Online] Available at https://www.betterhelp.com/advice/psychologists/using-molecular-psychology-in-everyday-life/ (Accessed on 09/04/2021) Lakna. (2019). What is the difference between neurons and glial cells? [Online] Available at https://pediaa.com/what-is-the-difference-between-neurons-and-glial-cells (Accessed on 08/04/2021)

Lumen. (date unknown). Neurophysiology. [Online] Available at https://courses.lumenlearning.com/boundless-ap/chapter/neurophysiology/ (Accessed on 08/04/2021) Marieb, E.N. and Hoehn, K.N. (2015). Human Anatomy & Physiology, Global Edition. 10th ed. [ebook] Pearson. Available at: https://www.perlego.com/book/811178/ Parkinson’s UK. (date unknown). What is Parkinson’s? [Online] Available at https://www.parkinsons.org.uk/information-and-support/what-parkinsons (Accessed on 09/04/2021)

Appendices In this appendices section you will find listed relevant information that could not be written into the report due to the tight word limit.

Appendix 1. Sensory Receptors There are multiple sensory receptors classified by the stimulus they receive:     

Mechanoreceptors respond to touch and pressure. Thermoreceptors respond to changes in temperature. Photoreceptors respond to light. Chemoreceptors respond to chemicals, for example, in tasting. Nociceptors respond to the feeling of pain, for example, extreme heat or cold, excessive pressure.

Appendix 2. Types of Neurons Sensory neurons carry nerve impulses from the sensory receptors to the CNS. Motor neurons carry nerve impulses from the CNS to effector organs. Interneurons, found in the brain and spinal cord, connect sensory and motor neurons to bring the whole system together.

Appendix 3. Molecular psychology The study of neurotransmitters and how they moderate behaviour is called molecular psychology which has been investigated since the late 1980s. Molecular psychologists use biochemistry to investigate and explore physical irregularities in the brain to get a better understanding of how behaviours relate to the physical structures of the brain. James, A, (2021)....