# The Brain 🧠 --- The **brain** is an [[organ]] that makes up part of the [[central nervous system]] that lives in the [[skull]]. It is responsible for [[intelligence|complex thought]], [[limbic system|emotional regulation]], and all sorts of things. Without exaggeration, it's the single most important organ in the body. ![[brain.png]] ## Anatomy There are four main parts of the brain: - The big spongy [[cerebrum]] on the outside, that is where our **higher brain functions** such as intellectual though take place. - The cauliflower looking [[cerebellum]] which does things like coordinate our **balance** and handle **proprioception**. - The inside-parts of the [[diencephalon]], which has a variety of important "administrative" functions. - The spinal-column-attaching [[brainstem]], which controls our most basic life-sustaining functions such as breathing and regulating our heartbeat. The negative space between different parts of the brain are called [[brain ventricles|ventricles]]. that are filled with [[cerebrospinal fluid]], which cushions and protects the brain from jostles and friction. The brain is our most important organ, and also a (concerningly) delicate one. As such it has *many* layers of protection, physical as well as chemical. - The brain is protected from mechanical harm by the [[skull]] on the outside, and the three layered [[meninges]] inside the skull. - The brain also floats in [[cerebrospinal fluid]], without which the 3 pounds of brain would crush itself under it's own weight. - The brain is also protected from *chemical* harm by the [[blood-brain barrier]], which only allows certain particular molecules from the bloodstream into the brain itself. cerebral circulation The brain does not store nutrients and requires a constant supply of oxygen. These needs are met through cerebral circulation; the brain receives approximately 15% of the cardiac output, or 750 mL per minute of blood flow. Brain circulation is unique in several aspects. First, arterial and venous vessels are not parallel as in other organs in the body; this is due in part to the role the venous system plays in CSF absorption. Second, the brain has collateral circulation through the circle of Willis (see later discussion), allowing blood flow to be redirected on demand. Third, blood vessels in the brain have two rather than three layers, which may make them more prone to rupture when weakened or under pressure. ![[parts of the brain.png]] ## Functional Systems The brain can be divided into functional systems that span multiple anatomical divisions. The first of which is the [[reticular formation]], which acts as a sort of constant, low level charge that keeps everything ticking. The second is the [[limbic system]], which is made up of many structures that regulate and helps us control our emotions. There are also **association areas** which make it so you can make sense of certain, technically unrelated things and *associate* them with something. There is the **anterior association area** that takes care of judgment, intellect and assessing consequences of your actions. There is also the **posterior association area** which handles a lot of visual stuff, like facial expressions. The [[basal ganglia]] are a group of structures found in different parts of the brain that are largely responsible for coordinating movements. ## Problems with the Brain - [[neurocognitive disorders|neurocognitive disorders]] - [[cerebral edema]] - [[traumatic brain injury]] - [[hydrocephalus]] - [[brain cancer]] - [[brain tumors]] ___