Archive for the ‘biology’ tag
This week I have continued my reading of Carlson et al. (2007) focusing on psychology, but particularly on the brain and its components, drugs and behaviour, and the controlling of behaviour and the body’s functions.
The brain and its components
The brain is the largest part of nervous system and contains 10billion -100billion nerve cells. All of the nerve cells are different sizes, shapes, functions they carry out and chemicals they produce. To understand the brain we need to look at the structure of the nervous system. The brain has 3 primary jobs: controlling behaviour, processing and storing information about the environment and adjusting the body’s physiological processes. There are two divisions which make up the central nervous system: the spinal cord and the brain. The spinal cord is connected to the base of the brain and runs along the spinal column. The brain contains three major parts:
The brain stem – controls physiological functions and automatic behaviours
The cerebellum – controls and coordinates movements
The cerebral hemispheres – concerned with perceptions, memories
The brain and spinal cord float in a liquid known as cerebrospinal fluid (CSF) that provides a cushion like protection. A blood brain barrier, ensures less substances pass from the blood to the brain to reduce toxic chemicals. A cerebral cortex, which is a 3mm layer of tissue, covers the surface of the cerebral hemisphere and has a billion nerve cells. The brain works with the body through the peripheral nervous system.
Sensory information, decision making, and controlling muscles, are all sent to the brain through neurons which make up the nervous system. To receive, process, and transmit information neurons contain; dendrites, soma, axon, and terminal buttons. Support is provided by glia, that also produces chemicals required by neurons, remove chemicals not required and help protect neurons from infections.
Neurons communicate with cells through synapse. When a message is sent from the presynaptic neuron it is received by the postsynaptic. A neuron accept s messages for lots of terminal buttons which results in terminal buttons creating synapses with several all neurons. Communication between synapses is chemical producing called neurotransmitter. When the axon is fires an actions moves down an axon causing the terminal buttons to release the neurotransmitter chemical.
Drugs and Behaviour
Chemicals that can be found in nature can affect people’s perceptions and behaviours. But some of these chemicals can be useful and are used as therapeutic remedies. By understanding how drugs affect the brain, help us to understand disorders and how to develop new methods of treatment.
Drugs can be said to alter our thoughts, the way we perceive things, the emotions we have, and the behaviour we demonstrate. This is achieved by affecting the activity of the neurons in our brain. Some drugs can stimulate or inhibit the release of neurotransmitters (chemical that is realised when neurons communicate) when the axon is firing, e.g. the venom of a black widow spider. Some drugs can stimulate (e.g. nicotine) or block postsynaptic receptors (e.g. cocaine). Finally, some drugs can impede on the reuptake of the neurotransmitter after it has been released, e.g. botulinum toxin or block receptors all together e.g. curare.
There are two important neurotransmitters that help achieve synaptic communication:
Glutamate – has excitatory efforts, every sensory organ passes messages to the brain through axons with terminals that release glutamate. One type of glutamate receptor – NMDA can be affected by alcohol. This why some ‘binge drinkers’ sometimes say they have no memory of what happened the night before when they were drunk. Likewise if a person has been addicted to alcohol for a long time this receptor can become suppressed, making it more sensitive to glutamate. So if a person stops drinking alcohol then this can strongly disrupt the balance of excitation and inhibition in the brain.
GABA – has inhibitory effects. Drugs that suppress behaviour, cause relaxation, sedation, and loss of consciousness act on a certain GABA receptor. For example if Barbiturates are taken in large quantities they can affect how a person walks, talking, cause unconsciousness, comas and even death.
Muscular movements are controlled by Acetylcholine (ACh) as well as controlling REM sleep (the part of sleep where most dreams occur), activation of neurons in the cerebral cortex and functions of the brain that are concerned with learning. ACh receptors are stimulated by the highly addicted drug nicotine. However the drug curare can block Ach receptors causing paralysis.
Dopamine is important in helping movement and helps in reinforcing behaviours. People with Parkinson’s disease are often given the drug L-DOPA to accelerate the production of dopamine. Drugs such as cocaine and amphetamine stop the uptake of dopamine and with people abusing these drugs would suggest that dopamine plays a role in enforcement.
Norepinephrine is said to increase vigilance and helps control REM sleep. Serotonin helps to control aggressive behaviour and risk taking, and drugs that have an impact on the uptake of serotonin are used to treat disorders concerned with anxiety, depression and obsessive compulsive disorders.
Control of behaviour and the body’s physiological functions
Figure 1 shows how the cerebral cortex part of the brain is split up into four parts also known as lobes – the frontal lobe, parietal lobe, temporal lobe and the occipital lobe. The areas of the cerebral cortex that receive information from the sensory organs are the primary visual cortex (concerned with visual information), the primary auditory cortex (concerned with auditory information), and the primary somatosensory cortex (concerned with information with regards to body senses).the area of the cerebral cortex concerned with the control fo movement is the primary motor cortex and the association cortex is concerned with learning, perceiving, remembering, planning and moving.
Some functions within the brain are lateralized both hemispheres are responsible for different functions. The left hemisphere takes part in analysis of information, and controls serial events (e.g. talking, understanding speed of other people, reading and writing). Whereas the right hemisphere is responsible for synthesis, puts separate elements together to create the bigger picture e.g. draw sketches, read maps. It is also involved in understanding the meanings of certain statements, and damage to this hemisphere can alter these abilities. Although they are responsible for different tasks, these hemispheres combine information through a bundle of axons connecting the two, known as the corpus callosum.
Behind the central fissure are lobers that are reponsisble for learning, perceving, and remembering:
Occipital lobe as well as lower lobes – information concerned with seeing/vision
Upper temporal lobe – information concerned with hearing/auditory
Parietal lobe - information concerned with movement/sensory
However these lobes also perform other functions such as processes concerned with perception and understanding of the body. the lobes situated at the front are responsible for motor movements, such as planning strategies for action. Similarly, the Broca’s area (left front of he cortex) is used to control speech.
Situated in the Cerebral hemispheres is the limbic system which is key when it comes to learning, memory and emotions. This is made up of lots of areas of the limbic cortex as well as the hippocampus and amydala, both of which can be found in the temporal lobe. The latter is concerned with emotions and such behaviour, e.g. aggression and the hippocampus takes part in learning and memory. People who damage the hippocampus are unable to learn anything new but can remember and recall past memories.
The brain stem is made up of three parts:
The Medulla – manages heart rate, blood pressure, rate of respiration
The Pons - manages sleep, and how awake someone is
The Midbrain – manages movements when fighting and when involved in sexual behaviour
Sensory information is received by the hypothalamus, this includes information about changes in the body’s physiological status, e.g. body temperature. It also manages the pituitary gland which is attached to the bottom of the hypothalamus. It also manages the endocrine system (endocrine glands).
Hormones are similar to neurotransmitters as there effects can be seen by stimulating receptors, but they work over a much larger distance. When these hormones combine with receptors they result in physiological reactions in the target cells (receptors in certain cells). The hypothalamus manages homoeostatic processes by its control of the pituitary gland and the autonomic nervous system. However, it can also cause neural circuits in the cerebral cortex to perform more complicated, learned behaviour.
My blog post on criminology will follow shortly
Figure 1 taken from http://samedical.blogspot.com/2010/08/nervous-system-cerebrum.html
So I have been thinking alot about how to tackle the reading for this topic, and have identified some key texts for biology and sociology. These are, as suggested, first year recommended reading ‘essential primers’. They are heavy, and thick, and nice easy reads. So I am going to work my way through them initially to get some ideas on what the main approaches to gender are from biologists’ and sociologists’ perspectives. This is a massive oversimplification I know, but I think it is the best way to begin. So this week and next week I am going to be reading:
Longenbaker, Susannah Nelson. (2008) Mader’s understanding human anatomy & physiology. 6th Edition. McGraw-Hill: London
Mader, Silvia S. (2009) Human Biology. 10th edition. McGraw Hill: London
Smith, Stephen W. and Ronan Deazley (eds.) (2009) The legal, medical and cultural regulation of the body : transformation and transgression. Ashgate Publishing: Farnham
Abbott, Pamela, Claire Wallace and Melissa Tyler (2005) An introduction to Sociology. Feminist Perspectives. Third edition. Routledge: London
Haralambos, Michael and Martin Holborn (2008) Sociology. Themes and Perspectives. Seventh edition. Collins: London
Marsh, Ian, Mike Keating, Samantha Punch and Jeni Harden (2009) Sociology: making Sense of Society. Fourth edition. Pearson Education: London
Not the whole books of course; just the most relevant bits. Then I am going to pull out of those books, some ideas for key approaches, and therefore key texts, around gender from those disciplines’ perspectives. I have a list in my head already of books that I think look relevant (from Google searches and a couple of visits to the university library), but this may change as I work through the introductory texts. In fact one would hope that it will, as that is in a way the whole point of this task, to develop our understandings of these disciplines.
So at the moment, I think that I am going to be reading something like this when I start to look at the disciplines when applied broadly to the topic of Gender:
BIOLOGY and GENDER
Baron-Cohen, Simon (2004) The Essential Difference. Penguin: London
Fausto-Sterling, Anne (2001) Sexing the Body: Gender Politics and the Construction of Sexuality. Basic Books: London
Keller, Evelyn Fox (2000) The Century of the Gene. Harvard University Press: Cambridge, MA
Schiebinger, Londa (1995) Nature’s Body: Gender in the Making of Modern Science. Beacon Press: Boston and London
SOCIOLOGY and GENDER
Archer, John and Barbara Lloyd (2002) Sex and Gender, Second Edition. Cambridge University Press: Cambridge
Backett-Milburn and Linda McKie (2001) Constructing Gendered Bodies. Palgrave: Basingstoke.
Butler, Judith (1993) Bodies That Matter: On the Discursive Limits of ‘Sex’.Routledge: London
Mills, Sara (ed.) (1994) Gendering the Reader. Harvester: London
But who knows. This is an exciting experiment in learning something completely new and anything could happen…
Given the fact it helps understand so many of the issues I am interested in it is very difficult for me to avoid sociology. For alternatives, I am thinking about psychology/social psychology/neural psychology/biology. I need an issue that requires different explanations from these fields. Addiction, for example is understood as a biological phenomenon but it also needs certain environmental conditions before it escalates. I am sceptical about claims that overuse of the web can somehow alter the chemistry or structure of the brain. Therefore, I am also interested in investigating neural plasticity. This would give me an entry point into neural psychology however; it is hard to think of another discipline that would intersect this research. Perhaps a telescopic view would understand why this issue is given any attention at all. I.e. why does the media endorse and thrive on such stories?
So… I have chosen ‘gender’ as my topic for consideration. Why am I looking at gender? Over the past few years, whilst using social networking systems, and generally being ‘online’, I have become increasingly interested by the representation of identity online, in particular in virtual communities, and the ways in which social constructs in the real world, impact on, and in some cases dictate, social constructs in the online world. I am going to be looking at the topic of gender over the next few weeks, concentrating on the ways in which gender (and perhaps also sexuality) are represented on the web, and how traditional ideas about gender are being challenged by the way that the web ‘works’. By this I mean the ways in which the communities of the web work; how these communities communicate with one another, how they promote themselves, and how they understand one another through online profiles.
Some of the questions that I have been thinking about in the lead up to putting together my research question and looking to identify the best approaches to tackling these questions:
In some instances, is gender constructed online and then reified in the real world, rather than, as we would imagine, the other way round? Are the possibilities identified in online communities really a way to escape hegemonic gender representations? Does removal from the corporeal constraints of the real world allow for a reaffirmation of notions of gender, or do the social constructs that bind gender in the real world apply within those worlds that we have created on the web? What are the differences online between actual and perceived gender and how do these manifest themselves? How would we begin to look at these from different perspectives to try to analyse the effects of adopting different genders online, or the effects of having to abide by the gender rules online, to which you are traditionally bound offline?
Themes in online communities like dynamics, harassment, recommendations, are all impacted on by understandings and interpretations of gender. Sociology seemed like an obvious approach to tackling this issue, and I have chosen also to look at gender (and therefore identity) from the perspectives of biologists. I think that this will provide me with two seemingly diametrically opposed perspectives to the construction of gender in the real world (although I am sure that this will not be the case when I start digging into the methods and methodologies of these two disciplines), and this could lead to some useful tools for looking at the construction of gender in the online world. The use of gender to compartmentalise online users of virtual communities, for targeted advertising, gaming experiences, etc. could benefit from a better understanding of the ways in which gender can be constructed, and also deconstructed, online from both sociological and biological perspectives.
That’s all a bit repetitive! I am going to put together a more concise research question and a list of expected key readings and key discipline perspectives later, I just thought I’d get my first thoughts up while they were fresh in my mind.