Biological Flashcards
(27 cards)
What is Action Potential
-Occurs when neurotransmitters are released in the synaptic gap, electrical chemical messengers are released to perform various brain functions
What are neurotransmitters
-Chemicals that diffuse across the synapse to the neurone in chain
-When NT crosses a synapses it fits into matching repair sites on postsynaptic neurone
-Each NT has its own specific molecular structure and fits perfectly into a type of postsynaptic receptor and have a specific function
What is a neuron
A nerve cell which is the basic unit of the nervous system
-When in resting state inside of cell is negatively charged relative to outside
-When neurone is sufficiently active by stimulus, inside becomes positively charged for a second
-Rapid switch from - to + is called depolarisation
-Creates an electrical impulse (action potential) that travels down axon
Types of Neuron
SENSORY: Carry messages from sensory receptors along peripheral NS to CNS- long Dendrites & Short axon
MOTOR: Carry msgs from CNS Along PNS to Effectors- short dendrites, long axons
RELAY: Connect sensory and motor neurons- short dendrites, short axons
Excitatory Neurotransmitters
Dopamine causes excitation of postsynaptic neuron by increasing its positive charge making it more likely to fire
Inhibitory Neurotransmitters
Serotonin causes inhibition of postsynaptic neurone by increasing its negative charge making it less likely to fire
Brain structure and Aggression
-Brain is made of different regions which have many roles in human behaviour.
-Some regions manage our aggressive behaviours
-Damage or dysfunction to these areas can cause person to be at risk of increased aggression
Prefrontal Cortex & Aggression
-Important role in higher cognitive functions e.g. rational thinking/ decision making
-Involved in self-control, impulse regulation & inhibition of aggressive behaviour
-Not fully developed until 25
Limbic System & Aggression
-Made up of number of structures that acts as our emotion centres
-Controls basic urges e.g. appetite, sleep, fear, sex drive
Corpus Callosum & Aggression
-Links both left and right hemisphere of brain together
-Helps them communicate with each other about long term planning, past events & consequences
Amygdala & Aggression
-Part of limbic system
-Takes info from thalamus and interprets whether it’s threat or not
-Controls fear response by producing fear or aggression
-Small amygdala= lack of fear & emotion
Credibility for Brain Struc and Aggression
-Brain scans show correlation between aggressive people brain and inaggressive
-Raine study shows link between brains of murderers- lack of fear & consequences
-Found small amygdala in murderers- lack of fear/ consequence
-11% less activity in PFC
Objections to Brain Structure
-Brain scans may lack validity as some brain structures may do multiple jobs
-Amygdala regulates for both fear and aggression
-Reductionist as doesn’t take into account cause of brain abnormality
Differences of Brain structure
Freud believes that everyone has an unconscious that stems from childhood to cause certain behaviours- not explanable by brain scans
Hormones & Aggression
-Hormones are chemical messengers
-Released by endocrine glands in our bloodstream
-Slower then NT but can travel all over body
What is Testosterone
-Hormone linked to aggression
-Higher levels in males than females- see aggression more in men then women
What is cortisol
-Plays a role in managing Stress
-Secreted by adrenal gland to help body w effects of stress
-If too low a person will struggle to deal w stress and may act out
What is Dual Hormone theory
-High levels of Testosterone lead to aggression only when levels of cortisol are low
-When cortisol is high, testosterone’s influence on aggression is blocked
Credibility for Hormones & Aggression
-Wagner found that castration reduces Testosterone
-Wagner Castrated mice, and observed aggression drop
-When Mice were injected with Testosterone, levels of aggression rose to pre-castration levels
Objections of Hormones
-Cannot generalise animal studies to humans, humans have more complex cognition
-Animals don’t have the same PFC as humans and may not be capable of planning/ self-awareness
Drugs & The Brain
-Recreational drugs include stimulants, sedatives, hallucinogens and opioids.
-Each drug operates in a particular way, increasing or decreasing specific NT at Synapse
Agonistic and Antagonistic drugs
-Antagonistic Drugs= Boost amount of normal NT
-Agonistic= Limiting natural NT- fools brain into activating its pleasure centres
Cocaine and the brain
-Has a stimulant effect on CNS
-Blocks reuptake of dopamine by binding w dopamine transporter molecule
-Prevents recycling of dopamine- synapse flooded with large amount of dopamine- euphoric high
-After repeated use receptors become downregulated- explains withdrawal and higher doses for same high
Heroin and The Brain
-Depressant effect on CNS
-Agonistic Drug, slows down CNS activity + neurones involving pain
-Injected intravenously- once reaches brain binds with receptors of opioid system to enhance natural response
-Regular use, desensitises the effect which leads to addiction
