Wednesday, 17 April 2024 ------------------------ Hello. All is well. In chapter three, we briefly cover genetics and neurons. Genetics makes sense of the theory of natural selection. With genes, we can have variation in trait. Genes that express traits that are adaptable to environment, have a higher chance of reproducing, carrying on the genes to offspring. Each genetic parent contributes 23 chromosomes to their offspring. A chromosome is a string of DNA, a helix shaped molecule. Sequences in these strings make up our genes. When an egg cell and sperm cell team up, we get a zygote cell, containing 46 (23x2) chromosomes. Genes have variations, known as alleles. We've got dominant and recessive alleles. A dominant allele will take priority, but if both parents carry a recessive allele, their offspring will get the trait of that gene. Having the same allele is known as homozygous, opposite being heterozygous. A lot of traits are polygenic, meaning they involve many genes, allowing for more variation. Genes alone do not determine traits. How genes are expressed depends on the environment. For example, schizophrenia will usually only occur if they're predisposed to it, and they grow up in a stressful environment. While identical twins share same genetic makeup (genotype), how it's expressed, the person's appearance and characteristics (phenotype), will depend on environment. That was genetics, onwards to neurons. In the nervous system, we got two main types of cells. Neurons, the carriers, and glial cells, the supporters. Glial cells support neurons by providing scaffold, insulation, and transportation (nutrients, waste). Neurons are the carriers of information, making up a vast network of interconnections throughout the body. Neurons have a semipermeable membrane, the structure separating the inside (intracellular) space and outside (extracellular) space of the cell. Being semipermeable means some molecules dependent on size and charge can pass the membrane. The membrane itself allows for different charge of the inside and outside fluid, and the permeability allows for changes in the charges. The nucleus of the neuron is in the cell body (soma). Branches of dendrites (input sites) extend out around the cell body, and the axon, along the cell body, extends out to branches of terminal buttons (output sites). Axon length can vary, I assume it depends on where the neuron is located, how close it needs to be to other neurons. I imagine the neurons connecting the brain to the rest of the body have longer axons. So, neurons communicate with other neurons. Within a neuron, the signal is electric, while across neurons it's chemical. It's electrochemical. We've got charged fluid (dissolved ions) inside and outside the cell with different charges, resulting in a difference in charge, known as membrane potential. I won't go into too much detail, but I gather by change in concentration of different charged molecules, Na+ and K+ by membrane openings, difference in electric charge shifts, allowing an electric signal to move across the axon from dendrites to terminal buttons. This is an all-or-nothing event, a threshold of excitation must be met for the signal to move across. When signal crosses, membrane potential goes from resting potential to activation potential (threshold of excitation) by depolarization causing positive charge inside, reaching peak action potential, then back to resting potential by repolarization, returning inside to a negative charge. I guess the signal inside neuron is also chemical in a sense, at least to allow for electrical signal to happen. Glial cells help cover parts of axons with myelin sheath for insulation to improve signal. Some neurons communicate by electrical signal, passing the current. Anyhow, at the terminal buttons, you've got synaptic vesicles, small balls containing neurotransmitters. When a signal reaches here, some neurotransmitters leave the vesicles, to flow across the synaptic cleft, the gap between two neurons, to attach to a receptor of the other neuron. Neurotransmitters and receptors have a lock-key-relationship, as in a particular neurotransmitter will only attach to a fitting receptor. After attaching, the neurotransmitter will dissolve into smaller parts or sent back to vesicles by reuptake. Psychoactive drugs influence this process as agonists, antagonists, or reuptake inhibitors. An agonist is a molecule that mimics the neurotransmitter causing signal, promoting signals, while an antagonist is a molecule that will attach but not cause a signal, essentially blocking signals. A reuptake inhibitor will block reuptake, causing the neurotransmitter to stay in the synapse to be reused more, promoting signals. The book mentions seven neurotransmitters: acetylcholine, beta-endorphins, dopamine, norepinephrine, serotonin, glutamate, gamma-aminobutyric acid (GABA). I've now finished reading the secondary book. In the last chapter, they talked about being practical, looking at the strengths of a person and how that can be applied in school and work setting. If you have good vibes today, I'd recommend not reading further. From experience, it can be uncomfortable to read what I'm going to write about. I'm not sure why, but I felt a tiredness reading the last chapter. I'm not sure if I'm tired because of my experiences or a debilitation. I don't find my issue to be that I can't function. I just don't enjoy it, and I don't care enough to do it regardless of enjoyment. I've been able to live life without a coherent sense of enjoyment for a long time, but after losing hope of becoming more normal, I can't make the same effort I once could. Right now I just exist. A lot has become strange to me. I don't really know anyone nor do I care to know anyone. I'm not depressed, I don't feel sad or anxious. I just exist, being practical, waiting. I guess you could say I'm a little apathetic. I think it's a state I can be content with. It's calm for me, but it might come across as uncomfortable if you're not in this state. Then again, I follow routines, the bare minimum I guess, whatever that means to me. I floss and brush my teeth. Do you? You better. I prefer being healthy. I like to walk, run, and do calisthenics. My body feels young but my mind feels old. I mainly read and write to avoid mental decline, but I don't care too much about it. Having a plan of publishing some writing each day makes this routine easier to follow. What part of me cares about what I write. Maybe some curiosity that remains in me, about how I function and the external world. I think I enjoy the exercise itself. I don't have anything I want to achieve, just something to fill up the time with that works for me. I noticed some get confused when they talk with me, because they see me talk as if I care about things, but it's mainly intellectual or an adoption of prosocial speech. In a dialogue, I will usually picture what is right for the other person, what they should do, and talk about that, but I realize some interpret this as if I also care or think it's the right thing for me. I don't want to mislead, so it can be awkward for me to then try and correct what I meant without sounding bonkers, heh. I'm happy when I'm nothing. My honeymoon phase of being nothing is over, but it's still where I find contentment. I take a practical approach, maintaining my body and mind while not being a menace to my surroundings, doing the right thing if confronted by something important. I'll care to help someone in distress, but I won't care to casually socialize with people apart from formal civility, like please and thank you. Nor do I expect anything in return, except peace. Perhaps I'll care more one day, who knows, eh.