Neurons Flashcards
What are neurons responsible for?
How our brain and boy’s function
What is the function of the dendrite in a neuron?
the extensions which receive the message from other neurons to take to the cell body to trigger an action potential
A)what is the function of the cell body/soma?
B) what does it contain?
A)it provides the neuron with energy
B)the nucleus and mitochondria
A)What is the Node of Ranvier?
B)What is the function of the Node of Ranvier?
A) the gaps between the myelin sheath
B)allows electric messages to transmit across neurons more effectively by forcing the impulses to jump
A) what is the function of the axon terminal
connects to the other neurons to pass information (not physically connected)
What is the function of the schwann cell?
produces myelin for the sheath
A) what is the myelin sheath?
B) what is the function of the myelin sheath?
A) a fatty substance which surrounds the axon to protect the nerve
B) helps speed up the transmission of information
A) what is the axon?
B) what is the function of the axon?
A) tube like part B) which transports information away from the cell body to the end of the axon terminals
A) what is the function of the nucleus?
Contains chromosomes which are a part of DNA which decides how we develop
A)What is the function of sensory neurons?
B) what do they look like?
A) they carry messages from sensory receptors along the nerves in the peripheral nervous system to the CNS
B) they have long dendrites and short axons?
A)What is the function of motor neurons?
B) what do they look like?
A) Carry messages from the CNS along nerves in the PNS to effectors in the body.
B) they have short dendrites and long axons
A) What is the function of relay neurons?
B) what do they look like?
A) Connects sensory and motor neurons and connects other relay neurons also.
B) they have short dendrites and short axons.
How are neurons charged in the resting state?
the inside of the cell is negatively charged relative to the outside
When activated, what is the charge of a neuron?
when sufficiently activated by a stimulus, the inside becomes positively charged for a second.
What is depolarisation?
the rapid switch from negative to positive charge and it creates an electrical impulse that travels down the axon towards the terminal buttons
What is action potential?
an electrical signal that travels down a neuron’s axon, allowing it to send messages
How does action potential generate?
once depolarisation reaches a certain threshold an AP fires
what happens if the threshold for AP is not met?
there is no AP
What happens to the membrane during action potential generation?
As an AP travels down the axon, the polarity changes across the membrane
What is a synapse?
the tiny gap between the axon terminal of a neuron and the dendrite of another neuron
What are neurotransmitters?
brain chemicals which relay signals from one neuron to another across a synapse.
What are the 2 categories of neurotransmitters?
1) those than perform an excitatory function
2) those than perform an inhibitory function
Where are neurotransmitters released from?
synaptic vesicles
what is synaptic transmission?
a chemical process using neurotransmitters. When the action potential reaches the end of the neuron, it triggers the release of a neurotransmitter from synaptic vesicles.
what is the function of neurotransmitters?
allow neurons to communicate with each other
what are the stages of synaptic transmission?
1)When a neuron is excited, an electrical pulse travels down the axon
2) This causes neurotransmitters to be released from the vesicles
3) Neurotransmitter Binding – Neurotransmitters bind to receptors on the postsynaptic neuron.
4) Signal Transmission – If enough neurotransmitters bind, a new action potential may be triggered.
5) Reuptake or Breakdown – Neurotransmitters are reabsorbed or broken down to stop the signal.
Where are the receptors on a neuron?
on the dendrite
what happens if the neurotransmitter ‘fits’ the receptor?
the message is passed on to the neuron
what happens if the neurotransmitter doesn’t ‘fit’?
the receptor is blocked and the message isn’t passed on
what happens when enough neurotransmitters are received at the dendrite?
the next neuron becomes excited/stimulated and and synaptic transmission will occur
what is reuptake?
where a neurotransmitter which is not used by the receptors is taken up again to be reused
What does reuptake regulate?
the amount of neurotransmitters in the synapse and recycles them, they are picked up by transport proteins
What happens to the neurotransmitters which are not used?
they’re destroyed by enzymes in the synaptic gap
how are neurotransmitters unique?
each neurotransmitter has its own specific molecular structure and fits perfectly into a specific type of post synaptic receptor
what is inhibition in neurons?
caused by the neurotransmitter serotonin in the postsynaptic neuron making the neuron more negatively charged and less likely to fire
what is excitation in neurons?
it’s caused by dopamine which increases the neurons positive charge making it more likely to fire
what is the net effect in in synaptic transmission in neurons?
the overall outcome of excitatory and inhibitory inputs on a neuron
what happens if the net effect is excitatory?
depolarisation takes place and the AP travels down the dendrite towards the cell body and then along the axon
what is synaptogenesis in neurons?
the process by which new synapses are formed between neurons due to the axons and dendrites growing towards each other for networks
what is Exuberant synaptogenesis?
possibly 1million new synapses are created each second by time of birth
the more synapses the more _____ ?
the more synapses the more neurotransmitter activity
what are the benefits of Exuberant synaptogenesis?
1) major contribution to cognitive processes such as thinking
2) promotes flexibility as brains are less fixed at birth
3) more open to alteration by experience and learning
What is myelination and how does it develop in the brain?
Myelination is the process where a fatty substance (myelin) forms around neurons, helping them transmit electrical impulses more efficiently.
It starts at birth, with the brain weighing 25% of an adult brain, and reaches 75% by age 2. Myelination is rapid in the first 2 years and continues through adolescence.
What is synaptic pruning?
After 3 years of exuberant synaptogenesis follows a period of synaptic loss which ‘fine tunes’ brain structure and functioning. This is where inactive synapses die off and what remains grows back stronger.
What is the benefit of synaptic pruning?
creates organisation in the brain so areas become specialised for certain functions
What are the 4 credibility points for neurons?
- Falsifiable: use of neurotransmitters to explain behaviour is credible scientifically as they can be observed and measured
- Face validity: provides an explanation as to why substances effect human behaviour and people with mental disorders
- Seeman et al (2000): showed higher densities of dopamine receptors showed a cause of schizophrenia
- brain scanning and surgery provides clear and unquestionable evidence of the effect of neurotransmitters
what are the 4 opposition points of neurons?
- Reductionist: psychologists reduce what makes us human (emotion) down to chemistry and biology
- ignores effects of society, nurture and our own cognitive abilities
- side effects of medication that has an effect on other cognitive functions
- higher chance of patients to become suicidal when taking medication, it shouldn’t happen if the theory is true
what are the 3 different points of neurons?
- Becks cognitive triad (1966): suggests depression is due to faulty schemas and negative thought patterns
- therapies such as CBT have been based on cognitive theories and have been proven to be highly effective
- programs focused on putting people in positive groups instead of anti-depressants has been proven just as effective
what are the 3 applicability points of neurons?
- anti-depressants and psychiatric medication used around world to treat mental health issues
- psychosurgery involves using an implant device that stimulates serotonin in the brain
- to help reduce drug withdrawal treatments which excite neurotransmitters without causing damage to health or being as addictive
