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The Nervous System. Drew Grinsteinner Jacob McGoogan. Functions of the System. Movement The control room for all muscle contractions Senses Taste Touch The nervous system allows us to observe and react to changes in our environment. Functions of the System Movement. - PowerPoint PPT Presentation
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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
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
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 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 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
• 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.