The purpose of this blog is to work as a reflective tool for a group of three individuals on the course NBE-E4210 – Structure and operation of the human brain D. We will present here what we have learned on the lectures, exercises, and excursions and the observations we made during the learning process and if any questions arose while exploring the weekly topic. After each chapter we aim to reflect what we already knew about the topic in question and if there were any challenges when it came to understanding the concepts of the week in question. We use the coursebook Bear, Connors, Paradiso: Neuroscience: Exploring the Brain, 4th edition, Lippincott, Williams & Wilkins (2015) as a source for information and sometimes external sources which are mentioned at the end of the post.
Neuroscience and nervous system
Neuroscience is a field of science which researches the functions and structure of the nervous systems in general and it aims to understand the fundamental properties of these systems. When it comes to humans and their nervous system, the nervous system is defined as a perplexing system that controls and coordinates our actions by transmitting signals to and from different parts of our bodies. There are two main components of this system:
- The Central Nervous System (CNS) which consists of the central organ brain where all signals are processed and spinal cord that helps body and brain communicate.
- The Peripheral Nervous System which has all the other neural elements collectively known as neurons that conducts the transfer of signals to and from the central nervous system.
Some fun facts:
- Brain is one of the largest organs of the human body and the most complex one.
- On average an adult brain weighs around 1.4kgs. Up to 60% of it is fat  cells while 73-75% of the brain is water [1, 2]
- It is a myth that humans use only 10% of their brain, (we apparently use more than 10% even when we are asleep).
- There are approximately 86 billion neurons in the brain.
When it comes to the presented facts about the brain, it was surprising to discover that we use more than 1/10 of our brain. Perhaps this is because the equipment and the technology we use nowadays have been improved enough so the scientists are able to detect more brain activity than before using modern technology.
The lectures inspired us to search more information about the composition of the brain and it was fascinating to find out that around 73-75% of the brain consists purely of water, or perhaps better said, a water solution since we have e.g. different kinds of molecules in the fluid from which the brain consists of. So, based on this it can be stated that for example, dehydration will have an adverse effect not only on the human body in general but also on the proper functioning of the brain.
Structure of the brain
- The cerebrum is the uppermost section of the brain. It consists of two hemispheres, which are further classified into four lobes:
- the frontal lobe (lobus frontalis),
- the parietal lobe (lobus parietalis),
- the occipital lobe (lobus occipitalis),
- the temporal lobe (lobus temporalis).
The cerebrum is responsible for the initiation of the movement, coordination of the movement, temperature, touch, vision, hearing, judgment, reasoning, problem-solving, emotions, and learning
2. The cerebellum (little brain) is found near the brain stems (Figure 1(a)). This part handles the coordination of the voluntary movements. The functions also include motor skills such as balance, coordination and posture.
3. Brain Stems located in the hind position of the brain is made up of midbrain, pons and medulla oblongata. These parts have individual functions but together they help regulate breathing, heart rate, blood pressure and several other essential functions.
There are two types of cells in the human nervous system: neurons and glia. Neurons are responsible for receiving sensory data and transmitting it to other neurons. They also transfer messages to muscle cells and enable movement. Neurons can be classified by the number of connections they have to other cells. Multipolar neurons are the most common type of brain cell.
Glia support neurons by filling the empty space, insulating and sustaining them. There are different types of glia which have different functions. Astrocytes regulate chemical content and remove waste. Microglia are part of the immune system and they remove waste, viruses and weak synapses from the brain. Oligodendrial and Schwann cells build the myelin layers which insulate axons and ependymal cells guide neuron migration during brain development. Neurons and their composition were familiar to most of the group at least when it came to the multipolar neurons, as they are the most common type of the neurons of the brain. The further classification of the neurons and different types of glia were new information for the group as a whole, except Schwann and Oligodendrial cells which construct the myelin layers of the axons. The myelin layer composition applies to multipolar neurons as well so at least most of the group had some information about them as a basis.
- Santos-Longhurst, A. What Is the Physical Composition of the Human Brain? Available at: https://www.healthline.com/health/is-the-brain-a-muscle
- USGS. The Water in You: The Water in Human Body. Available at: https://www.usgs.gov/special-topic/water-science-school/science/water-you-water-and-human-body?qt-science_center_objects=0#qt-science_center_objects
- University of Queensland, Queensland Brain Institute. Types of Neurons. 2018. Available at: https://qbi.uq.edu.au/brain/brain-anatomy/types-neurons
- Glial Cells. Available at: https://biologydictionary.net/glial-cells/
- NBIA. Structure and Function of the Human Brain. Available at: https://www.nbia.ca/brain-structure-function/