Central nervous system -Consists of the spinal cord and brain. It also contains neural tissue, connective tissue, and Blood vessels. The functions of  CNS are to process and coordinate using either our sensory data -where touch signals to the brain are sent from inside the body out, Motor commands- where peripheral organs activities are controlled, and Higher functions of the brain such as our intelligence, memory, emotion and learning all take place in the brain.

Peripheral nervous system -  Is made up of all the neural tissue outside of the CNS and takes place outside of the brain's spinal cord and the nerves of the body.

The Functions of the PNS is to carry information in, deliver sensory information out, and carry motor commands to peripheral tissues and systems. The peripheral nerves are nerves with bundles of axon with connective tissues and blood vessels which carry out motor command and sensory information in and out of the PNS.

Meninges

The meninges isolates the spinal cord to keep it separate and protected from surroundings and the rest of the body, protect spinal cord and carry blood supply. Around the brain they’re called cranial meninges.

Spinal cord

Grey matter is unmyelinated neurons that processes spinal reflexes. White matter is myelinated neurons that are superficial compared to gray matter. Ascending tracts go up and carry sensory information to the brain, descending tracts go down and carry motor commands to effectors. 

Spinal nerves

All Spinal nerves are mixed nerves, they carry sensory and motor info. A nerve plexus contains fibers from many spinal nerves and they get carried together to a target location. Major plexuses include the cervical, brachial, lumbar and sacral plexuses. The optic nerve transmits visual info to the brain, olfactory nerve transmits smell info to the brain, the phrenic nerve controls the diaphragm, thoracic nerves control muscles and the skin of thoracic walls.

A spinal reflex is a rapid and automatic nerve response triggered by a specific stimulus, this is controlled by the spinal cord gray matter, not the brain. A stimulus arrives and activates a receptor, a sensory neuron is activated, the CNS processes the info, a motor neuron is activated, response by the effector.

Overview of the brain

 97% of the body’s neural tissue found in the brain, is composed of three main regions: the cerebrum, cerebellum and brain stem. 

It is surrounded by the cranium, meninges and

Cerebrospinal fluid, it functions as a cushion and it protects the brain from physical injuries. It also helps to control the chemical environment of the brain, like the nutrients and waste. The cerebrum is the largest part of the brain and it controls all conscious thoughts. 

The cerebellum is like a small brain below the occipital lobe, it adjusts postural muscles, helps with balance and equilibrium and fine movement coordination. The brainstem processes info between the spinal cord and cerebrum or cerebellum.

Overview of cerebrum

The cerebrum is the largest part of the brain and it controls all conscious thoughts and intellectual functions such as touching, smelling, and imagination. The cerebrum processes somatic sensory and motor info. The corpus callosum stretches across the midline of the brain and it connects the left and right hemispheres. Each hemisphere receives info from and sends commands to the opposite side of the body, this is called contralateral. 

The left hemisphere controls reading, writing and math. The right hemisphere is responsible for senses and recognition. Its surface is composed of gray matter called the cerebral cortex and it is heavily folded, that makes the surface area larger and it is important because the gray matter does all the processing. Each hemisphere is divided into five lobes, frontal lobe found in the forward part of the brain, parietal lobe found behind the frontal lobe, occipital lobe found on the very back, and temporal lobe located on the side of the head.

Motor areas initiate movement and are found in the frontal lobe, they include the primary motor cortex which controls all voluntary movements. The premotor cortex coordinates motor responses. And the motor writing center which coordinates fine movements of the hands. 

Sensory areas receive information related to sensation. The primary sensory cortex receives somatic sensory information such as touch, pain and temperature. The visual cortex receives info from photoreceptors. And the auditory cortex receives info from sounds receptors. Processing areas process information. The insula interprets sensory info from internal organs. The auditory association area interprets info from the auditory cortex. And the visual association area interprets activity in the visual cortex.