Biological Flashcards
Define the spinal cord
Links the peripheral nervous system (PNS) to the CNS via the brain stem, which is responsible for reflex actions.
What is the Thalamus?
It is a relay station, which receives and passes on sensory information. It acts as a filter. It passes the information to the appropriate areas of the cerebral cortex for higher-level processing. Plays a role in sleep, wakefulness, and obsessive compulsive disorder.
What is the hypothalamus?
It controls motivational behaviours, stress response, homeostasis, endocrine system and can produce some hormones. Below the thalamus. Maintains bodily functions like body temperature (homeostasis) and regulates the endocrine system (hormones) via its connection with the pituitary gland.
What is the limbic system?
It controls memory and learning and interconnected with the cortex. It includes the amygdala, which processes emotions.
What is the cerebellum?
There are two hemispheres. It controls balance and coordination, integrate information from the brain and spinal cord. 10% of the brains weight but holds 50% of the brains neurons.
What is the fontal lobe?
It is responsible for cognitive functions like thinking, problem solving and planning. Motor cortex which controls controlling voluntary movements.
What is the parietal lobe?
Somatosensory cortex processing sensory information from the skin.
What is the temporal lobe?
Auditory cortex processing sound information and has a role in understanding languages. Also deals with with sound information coming mainly from the opposite ear. They also process the location and volume and pitch of sounds.
What is the occipital lobe?
Visual cortex for processing visual information. It is initially being processed in the left part of the occipital lobe then the right occipital lobe.
Define the structure of neurons.
It is a cell body that contains dendrites (carry impulses/action potential from neighbouring neurons towards the cell body), axons with myelin sheath (protects the axon and speeds up the transmission as they potential action will jump in between the gaps) , nodes of Ranvier (gaps between the myelin sheath), terminal buttons (communication across the gap know as a synapse), and the nucleus (contains genetic material).
What is the sensory neuron?
It is the receptors to the CNS. They have long dendrites and short axons.
What is the motor neuron?
It connects the CNS to the effectors. It has short dendrites and long axons.
What is the relay neuron?
Connects the sensory, other relay, and the motor neuron together. They have a short axon.
What is the function of the neuron?
It is for cell depolarises, which creates an electrical impulse called action potential. It carries action potential down the axon to terminal buttons, which causes our body to react.
What is the synaptic transmission?
It is where neurons have a gap (synaptic cleft) and the action potential triggers the release of chemical neurotransmitters, that then bind to the postsynaptic receptors. Each neurotransmitter has its own specific molecular structure and fits perfectly into a specific type of postsynaptic receptor and have specific functions. They can either fit into 2 main categories excitatory (increasing the positive charge and making it more likely to fire) or inhibitory (making the neuron negative and less likely to fire).
What is the function of neurotransmitters?
Fit receptors like lock-and-key fit. They trigger the release of potential action in the postsynaptic neuron.
What is ethology?
A research method were animals are observed in their natural environment.
What was the theory that Charles Darwin came up with?
Evolution and how we have evolved. This can be used to show evidence for social behaviours and cognitive thinking.
What is reductionist?
Making an idea or theory or an explanation more simple and less complex
What is the difference between a genotype and a phenotype?
A genotype is an individuals collection of genes and a phenotype is an individuals observable trait.
What is the corpus callosum?
This is a dense collection of nerve cells physically connects the two hemispheres below the cerebral cortex. It allows communication between the hemispheres by passing signal back and forth. Integrates activities for both sides of the brain.
What are recreational drugs?
Recreational drugs include stimulants, sedatives, hallucinogens and opioids. Each kind of drug ‘operates’ in a particular way, increasing or decreasing the specific neurotransmitters at the synapse.
What effect does cocaine have on the brain?
It is a stimulant effect on the central nervous system, especially on the brain’s reward system. It achieves this effect as altering the synaptic transmission involving several neurotransmitters, such as noradrenaline, serotonin and acetylcholine, most of all on dopamine. Creates a sense of pleasure when activated. Cocaine blocks the reuptake channels of dopamine by binding with dopamine transporter molecules. Responsible for recycling dopamine back to the neuron that produced it. Cocaine prevents this process as floods the synapse with surplus quantities of dopamine available for binding to the postsynaptic receptors. Causes a euphoric ‘high’. Causes dopamine receptors to downregulate- fewer receptors are active- damaged and shut down. Quantity of dopamine produced declines. Explain withdrawal and craving for the drug and the higher doses needed to get the same effect (tolerance)
The effect of THC on the brain
THC mimics cannabinoids and inhibits GABA release by binding to cannabinoid receptors. GABA cannot inhibit dopamine release. GABA normally regulates dopamine production, THC stops this by stopping the release of GABA. More dopamine is released. It can effect mood and enhance the feeling of pleasure. It can cause memory issues, anxiety, depression, lower dopamine production and lung damage.
The effect of heroine on the brain
Heroine has depressant effects on the CNS. It slows down the CNS activity, including the activity of neurons involved in pain. This is why opiates are valued as analgesics (painkillers). It is injected, once it has and travels to the brain it acts a lot like morphine. Morphine binds with a specific opioid receptor at the synapse found in the cerebral cortex, limbic system and hypothalamus. We have receptors for these as our body/CNS has our own opioid system. Endorphins and enkephalins are produced by the body as natural painkillers , a system that heroine readily taps into. It binds to the natural opioid system to massively enhance natural response. Agonist and antagonist. Heroine is an agonist drug as it mimics the action of another natural biochemical. Naloxone blocks opiate receptors. Effects: downregulation- opioid receptors on the postsynaptic neurons are constantly binding with morphine molecules, which desensitises them to effects of the drug. Tolerance
Evaluating the effects of recreational drugs (strengths)
Research supports with non-human animal studies. One commonly-used procedure involves deliberately damaging the mesocorticolimbic pathway in mice brains (Weinshenker and Shroeder 2007). This means neurons are unable to produce levels of dopamine normally associated with reward. When this is done mice then fail to self administer cocaine intravenously. This does not occur when lesions are performed on other parts of the mouse brain. This shows that cocaine’s effects are due to the activity of dopamine in the brain’s reward system.
It is valid as it is shown by drug users and self-reports from drug users tend to match what the neurobiology of recreational drugs would predict. For example the sensation of euphoria when the drug is taken and desensitisation and addiction in long term use.
Evaluating the effects of recreational drugs (Weaknesses)
You can’t generalise non-human animal studies to humans as basic transmission processes in mammals are similar but the human brain is more complex than a rats brain. For example, isolating the effects of just one neurotransmitter oversimplifies the process, unlikely to be explained by just one mode of action of a drug. The interaction of dopamine with other neurotransmitter systems (noradrenaline, serotonin, GABA) are not well understood.
There is also the idea of the PLACEBO EFFECT, when a person experience physiological and biological changes when they believe they are taking a drug rather than any chemical agent being used. Jones and Stone (1990) gave regular cannabis users either marijuana or the placebo and they couldn’t tell the difference.
Application of the effects of recreational drugs
More treatments are more available for addiction. Once heroine was identified as an agonist that binds to opiate receptors, other drugs were developed with a reverse mode of action. Naloxone is an antagonist drug that blocks opiate receptors and prevents heroin (morphine) from occupying them. Naloxone does not produce the rewarding euphoria associated with heroin use, so it can help manage the withdrawal process and reduce symptoms. Greater knowledge of the transmission effects of drugs.