Anatomy & Physiology
Let’s dig into structure and function of our brain.
Structure (anatomy) is what it is made up of and function (physiology) is what it does.
The first curious question to answer is who has brains? 😜
Look around. Any living organism that moves has a brain (which is typically animals). Plants do not move and hence they don’t have a brain 🤔.
Movement and Symmetry
If you watch closely there is a certain symmetry to animal bodies.
In a jelly fish, the symmetry is radial. We (humans) are bilaterally symmetrical. In a human body, the symmetry is bilateral. You can draw a big line head to toe and divide the body into left and right.
The body can move in left and right. To coordinate this movement our brains are structured in a certain way. To move, we need information about the environment. So we use our sense organs to get that information. Then the information is passed to our brains through sensory nerves aka neurons.
Inside our brain we make sense of the information and that is what we call as perception (aka making meaning). Once you made some meaning, you make decision on how to act on that information. When you put things in action, you move. Now you use your motor nerves.
High Level Structure
There is a structure to our brain (all animal brains for that matter) as shown below as humps.
Hind Brain
Mid Brain
Fore Brain
Some animals retain this primitive structure (like a shark). The closer the brain is to the spinal chord - hindbrain, the more basic our functions will be. Functions of survival like heart beat, circulation, respiration etc. The higher and advanced the functions are (like emotions and thinking), the processing moves to the forebrain.
Detailed Structure
Our human brain is divided into brainstem (back of the brain), cerebellum, thalamus and cerebrum (upper larger portion of the brain).
Brainstem has three individual structure: Medulla Oblongata, Pons and Midbrain. The brainstem takes care of basic functions like breathing, circulation and respiration.
If you notice, when someone is hurt in the brainstem (say an accident), they pass away immediately (fatal and catastrophic) because it controls the life functions. If you are injured in other parts of the brain, you will still survive but that is not the case with brainstem. The other important function of the brainstem is to route the sensory information (in) and motor information (out).
Cerebellum is behind the brain stem and it control motion (motor control). Coordination, motor memory.
Thalamus sits right above the brain stem and it is more like a router to our body. It sorts and sends data to the right places. Just below that is hypothalamus (hypo means below) and it control homeostasis (balance) in our body.
Below Hypothalamus is the pituitary gland. It technically belongs to the brain. It takes care of all the hormones (water balance, oxytocin etc)
Cerebrum is the larger and upper part of the brain. The main function is integration. It makes sense of information that comes in. To do this it has billions of neurons. Each neuron talks to another neuron through synapses so we have billions of synapses as well. If you do an fMRI, you can understand what goes on into your brain in action. We can see where the blood flows as you process different things. Something cute, something ugly and something neutral. Today, we know what is going on in your head :)
If you take a top shot of cerebrum, you can see that there are two hemisphere and these are connected by a tissue called as corpus collosum. There is lateralisation in our brain. We tend to use our left side for reasoning, logic and the other side for facial recognition etc. We can move these functions back and forth (plasticity). You can survive without one hemisphere (hemispherectomy is the name of the surgery).
Below the corpus collosum we have this structure called Basal Ganglia (made up of nuclei - similar type of neurons). It controls a lot of our motor control. BG is responsible for motor learning (voluntary movement), executive functions, emotional behaviours. It also plays an important role in reward and reinforcement, addictive behaviours and habit formation. If someone has Parkinson’s disease, they will have problems with BG and hence their movement is affected. Don’t worry about the other anatomical details below for now.
That should do for today. Tomorrow we will dig into 80 percent of our brain and understand more details. This is a foundation for understanding aspects of our behavior, emotions and learning.
🥂 to structure and functions!
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