Crash Course Psychology #3 is the first step looking into how everything psychological is biological.
For context, Crash Course inspired me to learn the basics of psychology, so I’ve made it my mission to watch the entire Crash Course Psychology playlist and paraphrase each episode in my own words. This journey wouldn’t have been possible without the Crash Course team, so many thanks to them! To showcase what I learnt, here is my personal paraphrase of episode 3:
Introduction: Brain Chemicals
We often discuss psychology as a process separate from our bodies. In actuality, our mental activities are spurred by our biological condition. Psychologists like to say, everything psychological is biological.
One way to understand how your mind works is to look at how the chemistry of your body influences how you think, sense, and feel about the world around you. (For example, the brain releases chemicals in response to getting startled, and that influences your next course of acton).
To do that, we look at the system with the smallest parts; the neurons (nerve cells). The brain alone has billions of neurons, and to understand why we do what we do, we first have to understand how these work.
Neurons (Nerve cells)
Neurons (nerve cells) are the building blocks that comprise our nervous systems. Made like other cells, but added with electrochemical stuff that lets them transmit messages to each other. We have several different types of neurons, but they all have the same basic parts;
- Soma
- The cell body! Does what all cells do to keep it alive, so it houses the mitochondria, nucleus, DNA, etc. If the Soma dies, the whole neuron dies.
- Dendrites
- Bushy and branch like, receive messages from other cells. They listen for the Soma.
- Axon
- Long cable like extension, transmits electrical impulses from the cell body out to other neurons or glands or muscles. The talker for the neuron. Depending on the neuron, it may be encased in a protective layer of fatty tissue called the myelin sheath.
- The myelin sheath speeds up the transmission of messages. If this degrades, those signals degrade as well. This leads to lack of muscle control. Often associated with those affected with Multiple Sclerosis.
- Multiple Sclerosis is a chronic, typically progressive disease involving damage to the sheaths of nerve cells in the brain and spinal cord.
Neurons transmit signals either when stimulated by sensory input or triggered by neighbouring neurons.
How they transmit signals
The dendrites pick up the signal first, which is the listening. This activates the neuron’s action potential / firing impulse, that shoots an electrical charge down the axon’s terminal branches, which do the talking to the neighbouring neurons.
The contact points between neurons are called synapses. Those bushy dendrites are covered in synapses, and they almost but don’t quite touch the neighbouring axon. That microscopic cleft is called the synaptic gap. When the action potential / firing impulse runs down the end of an axon, it activates the chemical messengers to jump that tiny synaptic gap and land on the receptor sites of the receiving neuron. We call these chemical messengers neurotransmitters. Though they slide right in to their intended receptors, they don’t stay bonded to the receiving neuron. After exciting or inhibiting the receiving neuron’s trigger, they immediately get reabsorbed by their original neuron, in a process called reuptake.
So neurons communicate with neurotransmitters which enable us to pretty much do everything we do. We have over 100 different kinds of these neurotransmitters, some are excitatory and others are inhibitory. All of which are good reminders that everything psychological is also biological.
Crash Course Psychology #3 terminology related to neurons and their definitions
- Endorphins
- natural, opiate like neurotransmitters linked to pain control and pleasure
- Excitatory neurotransmitters
- rev neurons up. Increases the chances it will fire off an action potential
- Norepinephrine
- an example of an excitatory neurotransmitter. Helps control alertness and arousal
- Glutamate
- an example of an excitatory neurotransmitter. Involved with memory
- Inhibitory neurotransmitters
- chill neurons out. Decreases the chances of firing an action potential
- Gamma-aminobutyric acid (GABA)
- a major inhibitory neurotransmitter
- Seratonin
- an example of an inhibitory neurotransmitter. Affects your mood, hunger, and sleep. Low amounts of Seratonin are linked to depression, which is why some class of antidepressants work to boost Seratonin levels in the brain.
- Alzheimer’s
- progressive neurological deterioration that can occur in middle or old age, due to generalised degeneration of the brain. Alzheimer’s patients experience a deterioration of their Acetylcholine producing neurons.
- Acetylcholine (ACh)
- enables muscle action, influences learning and memory. Can both excite or inhibit neurons, depending on the receptor.
- Dopamine
- influences movement, learning, attention, and emotion. Can both excite or inhibit neurons, depending on the receptor. Excessive amounts of it are linked to schizophrenia as well as addictive and impulsive behavior.
- Schizophrenia
- a long term psychiatric disorder of a type involving a breakdown in the relation between thought, emotion, and behavior.
- Endocrine System
- the body’s “slow” chemical communication system; a set of glands that secrete hormones into the bloodstream.
- Hormones
- chemical messengers that are manufactured by the endocrine glands, travel through the bloodstream, and affect other tissues. Like neurotransmitters, hormones act on the brain. Some of them are chemically identical to certain neurotransmitters. Hormones affect our moods, arousal, and circadian rhythm. Hormones regulate our metabolism, monitor our immune system, signal growth, and help with sexual reproduction.
Endocrine System & Hormones
So while the nervous and endocrine systems are similar in that they both produce chemicals destined to hit up certain receptors, they both however operate at very different speeds. The analogy is that the nervous system will send you a text, while the endocrine system sends you a letter by mail. However, faster isn’t always better, and your body will remember that letter longer than the text. Hormones linger, which help explain why it takes longer for the body to cool down after a moment of severe fright or anger.
The endocrine system has a few important hormone brewing glands.
- Adrenal glands
- Placed near our kidneys. Inner part helps trigger ‘fight-or-flight’ response by secreting the adrenaline hormone. This hormone increases our heart rate, blood pressure, and blood sugar. This gives us that energy to either run or attack.
- Pancreas
- Sits right next to our adrenal glands. Oozes insulin and glucagon hormones that monitor how you absorb sugar, your bodies main source of energy. Thus regulates level of sugar in blood.
- Thyroid gland
- At the base of your throat. Secretes hormones that affects & regulate metabolism.
- Parathyroids
- At the base of your throat. Secretes hormones that help monitor & regulate level of calcium in blood.
- Testes & Ovaries
- Male and female respectively. They secrete your sex hormones like estrogen and testosterone.
- The Pituitary Gland
- While all mentioned glands are super important, this one gland rules them all. A pea-sized nugget hidden deep in the bunker of the brain, it is the most influential gland in the system. It releases a vital growth hormone that stimulates growth in animal or plant cells, spurring physical development. Also releases Oxytocin, the love hormone that promotes feelings of trust and social bonding. What really makes the pituitary gland the master gland is that its secretions boss around the other endocrine glands. However, even the pituitary has a master, in the hypothalamus region of the brain.
- Hypothalamus
- The brain region controlling the pituitary gland, which will be discussed in the next episode.
Conclusion of Crash Course Psychology #3
- The nervous and endocrine systems work together. First, sensory input goes to the brain, such as the hypothalamus. Then it goes down the chain of command from the pituitary gland to the adrenal glands, to the hormone adrenaline to the rest of the body and then back to the brain. The whole journey is a feedback loop; your nervous system directs your endocrine system which directs your nervous system. These systems are complex and way more complicated than we can get into here.
Danniel’s thoughts on Crash Course Psychology #3
- Despite Structuralism, the school of thought by Wilhelm Wundt and Edward Bradford Titchener, not lasting since there were no found structures pertaining consciousness, how much of those conceptual structures could be unfolded by neurons? Unless, they work separately and only influence the other, instead of neurons having access to those conceptual structures?
- The video never talked about what is an action potential / firing impulse. I wonder, could it be our next course of action wrapped in the form of an electrical message? Is that what it is? Or could there be more?
Enjoyed this learning of Psychology? Test your knowledge against these quick custom Kahoot! quizzes I’ve made based on the episode above: This is the easy mode and this is the hard mode for Crash Course Psychology #3.
Also, do check out what else Psychology related I’ve learnt from my Psychology blog!
Credits for Crash Course Psychology #3
Original Content & Media by Crash Course
Content Consumed and Paraphrased by Danniel Iskandar
Paraphrase Proofread by
Paraphrase Reviewed by