The Nervous System Broken Down

Are you ready to understand the centre of our being; what makes us function; the centre of our movement and being!?

Well here it is!

A neuron is a highly specialised cell that transmits signals to other neurons, muscles and glands.

We have three types of neurons.

Neuron Types

-  Bipolar:  Interneurons
-  Unipolar:  Sensory neurons
-  Multipolar:  Motor neurons

Sensory neurons:  These are receptors that transmit neurons to the central nervous system (CNS).
Motor neurons:  These send out going signals.
Inter neurons:  These receive signals from sensory neurons and send messages to other inter neurons and motor neurons.

Got that?

Well it's about to get a little more confusing...

I'm sure you have heard of our central nervous system...

Well this system regulates our body functions and is the command post of our body.  It senses, processes, and stores information and in effect chemistry of the brain changes when learning something new.

We also have a spinal cord and this occupies the vertebral canal.  The spinal cord contains neural circuits which control different reflexive functions.

The brainstem is located at the top of the spinal column and travels up into the cranial cavity.

We have three parts, these are the medulla, pons and midbrain.  These contain a number of neural centres critical to behaviour and mood.  It controls functions necessary for sustaining life such as our blood pressure (BP) and respiration.

I hope you are keeping up...

We also have a peripheral nervous system (PNS)...

These nervous system extends from the spinal cord carrying messages to and from various muscles, glands and sense organs located through the body.  These are all the neurons outside of the (CNS). We have two more nervous systems that branch off our (PNS), these are the somatic nervous system and the autonomic nervous system.

The somatic nervous system regulates movement of the body's skeletal muscles.  This nervous system contains two types of fibres:

-  Afferent signals
-  Efferent signals (motor neurons)

Afferent signals send information about the internal organs, muscles, body position and peripheral sensations.

Efferent signals form the motor portion of spinal nerves.

These two types of fibres are a network of nerves.

The autonomic nervous system controls muscles we have no control over and regulates our breathing, heart rate (HR), (BP), some glands, and our heart.  There are three branches to this nervous system. We have our sympathetic, parasympathetic and enteric divisions.

The sympathetic division controls arousal and activities that require energy expenditure that prepares the body for action.  It also alerts the brain for 'fight or flight' situations.  It does this by increasing (BP), (HR), blood sugar levels and adrenaline.  It converts stored energy into useable energy by increasing the flow of blood to areas that will need it.

The parasympathetic division calms the body's state, conserves energy and eliminates waste products. It also slows the (HR) and stimulation of digestion.

HOPE THIS HELPS!

Understanding The Brain

WARNING!!!

THIS IS ABOUT TO GET EXTREMELY COMPLEX!

The brain weighs three and a half pounds and has over ten billion cells.  Pretty crazy right!

We have three layers to our brain, these are:

The Central Core:  Structures deep within our brain and is involved in the processes of breathing, digestion and heart rate.

The Limbic System:  This is located within the central core and plays a role in the emotional & sexual behaviour.

AND

The Cerebral Cortex:  This is the outer layer of the brain which allows us to plan, reason and make decisions.

Within the central core are five structures:

THE MEDULLA

This is located just above the spinal cord and is responsible for our reflexes, heart rate, respiration and digestion.  It is considered to be the cross over point allowing the transition from the spinal cord to the brain stem.  

This is why the left side controls the right side!

THE PONS

This is situated just above the Medulla and acts like a bridge for nerve fibres to connect to the cerebellum.  This controls our motor control and sensory analysis nuclei found in the pons which wrap around the base of the cerebellum.  Our Medulla and Pons contain our reticular activating system (RAS).  This is a network of neurons involved in arousal, attention and regulated sleep.  

THALAMUS

This is found deep within the brain.  It is our relay station and what I mean by that is it receives sensory information from our nervous system and is responsible for transmitting information to other parts of the brain.  All our sensory information apart from smell passes through here before entering our cerebral cortex.

CEREBELLUM

This large structure is known as our 'little brain'.  It is situated behind the Medulla and Pons and damage to this structure can have a significant affect on our motor responses, balance and coordination.  It integrates sensory information with information about muscle movement.

The Limbic System

The consists of three structures; our amygdala, hippocampus and hypothalamus.  The limbic system allows our body to keep a thermostat, scientifically known as homeostasis.  It also regulates our blood sugar level, body temperature and blood pressure.

AMYGDALA

This is located deep within our temporal lobe and controls our rage.  This structure receives important sensory information such as smell, sight and sound.  

HIPPOCAMPUS

This is the largest structure in the limbic system and helps with our memory skills, specifically our long term memory.

HYPOTHALAMUS

This is located below the thalamus and is approximately the size of a pea.  It is the most IMPORTANT part of the limbic system.  It regulates our hormonal system by controlling the pituitary gland which is attached to the base of the hypothalamus.

The Cerebral Cortex

This is one eight of an inch thick and contains billions of neurons.  This is responsible for the opposite sides of the body.  The hemispheres are connected by a band of nerves called the corpus collosum.  This transfers the information from one side of the brain to the other.  Our cerebral hemispheres occupy our general sensory input, visual input, and interpretation

FISSURES

We have three fissures that help divide the brain into four regions.

-  Longitudinal - separates the two hemispheres.
-  Central - runs along the top of the brain and separates into front and back.
-  Lateral - runs along the side of the brain and divides the hemispheres into top and bottom.

REGIONS OF THE BRAIN

Frontal Lobe - located at the front of the brain directly in front of the central fissure (our emotions, personality & problem solving skills operate here).

Parietal Lobe - located behind the central fissure & above the lateral fissure at the top of the brain (controls our sensory information).

Temporal Lobe - side of each hemisphere below below lateral fissure (controls our speech).

Occipital Lobe - located at the back of the brain (controls our vision).