Introduction
What is the Brain Made of?
The brain is 60% fat, 40% minerals and macromolecules, made up of matter: grey and white. Grey matter makes up the outermost layer of the brain, containing neurons to allow information to be processed, simultaneously releasing new information. This is released through axons found in white matter. White matter makes up 45% of the brain and provides connections between different brain regions to the cortex.
The Shape of the Brain:
The ridges or coiled surface structures of the brain are called the gyri, and the shallow depressions or indentations are called the sulci. The gaps in between the sulcus/gyrus provide space for blood vessels.
Meninges
Meninges are the 3 layers of membrane that cover and protect the central nervous system(brain and spinal cord).
1. Dura mater
This is the very outer layer, closest to the skull. It is thick and tough, with space in between the layer to allow for passage of blood vessels.
2. Arachnoid mater
Named after its web-like appearance, the arachnoid mater is a layer of thin connective tissues that lie under the dura mater, however it does not contain any blood vessels or nerves.
3. Pia mater
The pia mater is the layer closest to the brain, consisting of a thin membrane rich in arteries and veins.
Main Components & Their Functions
The Brain can be divided into the 3 main components, the: cerebrum, cerebellum and brainstem.
Cerebrum
The cerebrum is the largest part of the brain; with an outer layer of grey matter known as the cerebral cortex which oversees high-level processes. The cerebrum is split into 2 hemispheres, the right hemisphere responsible for the left side of the body, and the left hemisphere responsible for the right ride of the body. The two halves are bridged by an area of white matter called the corpus callosum. The Cerebrum itself can be split up into 4 lobes, each having a different function.
Frontal Lobe
The frontal lobe is the largest lobe of the brain, involved in all things action. This includes forming skeletal, muscle, eye, facial movement, decision-making as well as recognising smell. The motor cortex, which generates signals to direct movement, is located in the frontal lobe. Furthermore, what is known as Broca’s Area, responsible for speech production, is also situated in the frontal lobe.
Parietal Lobe
Its function heavily based on sensation, the parietal lobe integrates multiple modes of sensory inputs. Examples of this would be: identifying objects, spatial recognition, and interpreting pain and touch. An area in charge of interpreting speech also sits in the parietal lobe, known as Wernicke’s area.
Occipital Lobe
Found in the back of the brain, the occipital lobe processes visual information. However the process is highly complex and involves numerous separate functions: mapping the visual world, determining colour, distance, size and depth, identifying visual stimuli and transmitting the visual information to other brain regions.
Temporal Lobe
The temporal lobe is involved in memory and hearing, where sound is processed and speech is interpreted. The temporal lobe also aids short-term memory, moreover is where the hippocampus- an area for forming new memories- is lodged.
Cerebellum
Nicknamed “the little brain”, the cerebellum sits at the lower back of the head, resembling a miniature version of the cerebrum- it too is divided into 2 hemispheres. The cerebellum plays a vital role in motor coordination: the muscles and eyes, which allows the body to balance, change posture, walk etc.
Brainstem
This is the trunk of your brain, which connects the brain to the spinal cord, authorising electrical impulses to pass along the central nervous system. The brainstem has 3 parts the: midbrain, pons and medulla. The midbrain plays a role in hearing, movement and responds to changes in the environment and external stimuli(sensitivity). Pons-latin for ”bridge”- connects the midbrain to the medulla. Its job also includes tear production, chewing, blinking, balance, hearing and many more. Lastly, the medulla, at the bottom of the brainstem, institutes reflexive activities(sneezing, coughing, vomiting). The medulla can also regulate heart rhythm, breathing, and O2 and CO2 levels in the blood.
The Limbic System
Hidden from view, in the deeper structures of the brain locates the limbic system, the part of your brain that determines your behavioural and emotional responses. There is no agreed upon list of all the parts that make up the limbic system, however these are the main contributors:
Amygdala
The Amygdala, which means “almond”, refers to its size and shape. The Amygdala regulates an individual’s emotion, learning and memory. It processes reflexive emotions such as fear and anxiety, helping the body prepare for ‘fight or flight’ reactions: fighting, fleeing, feeding or mating.
Hippocampus
Found in the temporal lobe, the hippocampus plays an essential function in memory formation, learning and spatial navigation. Being in close proximity to the amygdala, emotion is associated with an event to reinforce and strengthen memory retention.
Hypothalamus
The Hypothalamus connects with many other brain regions and is responsible for controlling hunger, thirst, emotion, body temperature and circadian rhythm(the body’s personal sleep pattern). In addition, the pituitary gland(secretes hormones) is also controlled by the hypothalamus.
Thalamus
The thalamus is the main relay station in the brain to the cortex. Most of the incoming sensory information makes a stop in the thalamus before reaching the different sensory cortexes, including the: visual, auditory, gustatory(taste) and somatic(touch) cortex, with an exception to the olfactory(smell) cortex.
Basal Ganglia
Found at the top of the midbrain, the basal ganglia regulates voluntary movements, maintains balance and posture. They are also involved in cognitive and emotional behaviour, linked with the formation of habits and addictions.
Cingulate Gyrus
The cingulate gyrus is the outermost region of the limbic system, situated above the corpus callosum. It helps regulate emotion, behaviour, pain and motor functions, processing information with respect to spatial orientation of objects in the environment.
Very informative!! 🙌