The Nervous System

Drew Grinsteinner Jacob McGoogan

Functions of the SystemMovementThe control room for all muscle contractions

SensesTasteTouch

The nervous system allows us to observe and react to changes in our environment

Functions of the SystemMovement

Central Nervous System (CNS)

All intentional movements, feelings, thoughts and processes

Peripheral Nervous System (PNS)

All actions of the body that do not deal with the CNS. These are all essentially reactions.

Sounds Familiar….. Reactions are a feedback mechanism!

Functions of the SystemIntentional movement (CNS)

These movements originate as nerve impulses from the brain

The impulses travel down the spinal chord and reach a particular muscle fiber

The neurons that transmit this impulse are called motor neurons

Functions of the SystemReactions (PNS)

Reactions are movements that do not deal with the CNS, but instead, the Peripheral Nervous System

Sensory Neurons transmit an impulse to interneurons located in the spinal chord

These impulses are then transferred to motor neurons connected to the muscle fiber it stimulates

Functions of the SystemThe Feedback MechanismStimulus- A sudden force put onto the body that a sensory

neuron picks up

Receptor- The sensory neuron that transmits a nerve impulse to the spinal chord. The impulse hits an interneuron and is sent back through a motor neuron pathway

Effector- The nerve impulse hits the motor neuron which then stimulates the muscle to contract briefly, causing a twitch

Structure of the NeuronNerve cells= Neurons

These cells are structural and functional units of the nervous system that are specialized to react to physical and chemical changes in the surrounding environment

These cells send nerve impulses which are in the form of electrochemical changes

Structure of the NeuronNeurons have…The main rounded area which is the cell body

Off of the cell body are 2 types of attachments, dendrites and an axon

Dendrites are the attachment that receive impulsesAxons are the attachment that send impulses

Structure of the Neuron Cont.All along the axon, Schwann Cells or

Neurolemmocytes envelope the axonThe purpose of a Schwann Cell is to produce myelin

Myelinated Nerve cells appear white and whole groups of cells are referred to as white matter

Unmyelinated cells do not appear white and are viewed in a group as grey matter

Structure of the Neuron

http://www.enchantedlearning.com/subjects/anatomy/brain/Neuron.shtml

Synapses The junction between any two communicating

neurons is called a synapses.

The impulses that are sent travel between many neurons in a series of complex nerve pathways.

The neuron carrying the impulse into the synapse is the sender or the pre-synaptic neuron

The Neuron receiving the impulse in a synapse is the receiver or the post-synaptic neuron

Axon end of synapses (Pre-Synaptic) The distal end of the axon have either 1 or more

extensions called synaptic knobs, which are absent in dendrites

When a nerve impulse reaches a synaptic knob, the synaptic vesicles in the knob release neurotransmitters

Neurotransmitters diffuse across the axon’s membrane and bind with specific receptors in the post-synaptic neuron

Dendrite end of the synapse (post-synaptic) The post-synaptic neurotransmitter receptors

receive the electro-chemical signals

The unused portion of the neurotransmitters get recycled by diffusing back in to the vesicles located in the axon

This process is then repeated until the nerve impulse reaches its destination. Ex: Muscle Fibers, Interneurons, or the Brain

Synaptic Transmission

http://mycozynook.com/28_06aNeuronCommunicat-L.jpg

Central Nervous System(CNS)The Central nervous system is composed

primarily of the Brain and Spinal cord

Disruptions of the central nervous system can cause side effects ranging from paralysis to death.

So be careful

The Brain

The Brain There are 5 lobes of the brain which

include: Frontal lobe Occipital lobe Parietal lobe Temporal lobe Insula lobe (inside the brain)

The Brain The cerebellum is used to send signals

to voluntary muscle control

The brain stem is used to send those signals outside the brain.

The Spinal Cord

The Spinal Cord The spinal cord is made up of 31

segments each with a pair of spinal nerves

Also part of the CNS

The Spinal Cord The spinal cord unlike the peripheral

neurons can send messages to the nerves itself causing reflexes.

The peripheral nervous system is the nerves and nervous tissue outside of the central nervous system

Damage to these nerves are not as fatal and life changing unlike the central nervous system

The system is split in two categories the Autonomic and Somatic nerves.

Peripheral Nervous System(PNS)

Autonomic Vs. Somatic

Autonomic Nervous System

Somatic Nervous System

0 The part of the PNS that functions independently

0 Runs in two parts Sympathetic and Parasympathetic

0 The part of the PNS that functions dependently

0 Responsible for Senses and Cranial Nerves

HUMAN SENSES AND CRANIAL NERVES

• Primarily Motor

• Transmit impulses that raise eyelids, move eyes, focus lenses, and adjust light entering eye

• Sensory

• Transmits the senses of vision

HUMAN SENSES AND CRANIAL NERVES

Optic Oculomotor

• Mixed

• Transmit messages to the mouth and tear glands

• Primarily Motor

• Transmit messages to move the eyes

HUMAN SENSES AND CRANIAL NERVES

Trochlear Trigeminal

• Sensory

• Transmit impulses to aid hearing and equilibrium

• Primarily Motor

• Transmit messages to move the eyes

HUMAN SENSES AND CRANIAL NERVES

Abducens Vestibulocochlear

• Mixed

• Transmit impulses to assist speech and swallowing

• Mixed

• Transmit impulses to throat and saliva glands as well as swallowing

HUMAN SENSES AND CRANIAL NERVES

Glossopharyngeal Vagus

• Primarily Motor

• Transmit impulses to the tongue

• Primarily Motor

• Cranial Branch

Transmit impulses to the soft plate, pharynx, and larynx.

• Spinal Branch

Transmit impulses to the neck and back

HUMAN SENSES AND CRANIAL NERVES

Accessory Hypoglossal

HUMAN SENSES AND CRANIAL NERVES

Taste Vs. SmellOlfactory cells (sense of smell) Facial (sense of taste)

The to senses are connected via limbic system which is responsible for emotions and memories

Which means when you eat something you like it does not really taste good it is your body remembering it tasting good and displaying emotion accordingly.

AUTONOMIC NERVOUS SYSTEM(SYMPATHETIC) Preganglionic Fibers originate in the gray matter of the

spinal cord

The axons leave through ventral roots traveling a short distance

They leave the spinal nerves and enter a member of the paravertebral ganglia

After this the postganglionic fiber returns to the spinal cord

The preganglionic fibers of the parasympathetic division arise from the brain stem and the spinal cord

From there they go to various viscera the relatively short postganglionic fibers go to specific muscles or glands

Autonomic Nervous System(Parasympathetic)

DISEASES AND DISORDERS

HeadachesBrain Tissue has no pain sensitive nerve cell therefore when somebody has a headache it is actually caused by blood vessels in the brain where other nerves in the brain transmit as pain.

Migraines are just a more extreme case of the same concept.

DISEASES AND DISORDERS

Multiple Sclerosis The immune system in this genetic disorder attacks the myelin in the nerve cell as a alien disease and starts to eat away at the myelin. As the myelin breaks down nerve impulses are disrupted causing many people with the disorder to lose balance and coordination.

DISEASES AND DISORDERS

Epilepsy1 in every 100 to 200 people have this condition where the brain temporally lose all control to process incoming and control skeletal muscle. The visible symptoms of this is seizures and loss of consciousness for the time the episode begins the symptoms can be treated through medication.

Thank you! Now lets play telephone to help learn these concepts