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The Nervous System
Control Center for Maintaining Homeostasis
Nervous System
The nervous system coordinates the activities of all of the body’s organ systems so that they work in concert with one another
What systems must cooperate during exercise?
What do we use to respond to changes in the external environment?
Do the senses operate individually?
Components of the Nervous System
Two main sectionsThe Central Nervous System
Brain and spinal cordcoordinating center for incoming and outgoing
informationPeripheral Nervous system
Nerves that extend to the rest of the bodyCarries information between organs and the CNS.
Two basic types of Nerves
sensory or afferent nervesCarry signals to CNS
motor or efferent nervesCarry signals from CNS
Peripheral Nervous System (PNS)
Somatic nervesconnect skin, skeletal muscles and bones to CNS
Autonomic nervesConnect visceral organs
Somatic nerves
control skeletal muscles, bones and skinVoluntarySensory to CNSCNS to Motor
Reflexes
Autonomic nerves
Special motor nerves that control the internal organsComprised of two divisions that work in opposition
Sympathetic nerves• Fight or flight response (survival)
Parasympathetic nerves• Active when body is at rest • “resting and digesting”
Autonomic
Broken into two different divisions (systems) the Parasympathetic and Sympathetic
Parasympathetic House keeper division Uses acetylcholine (neurotransmitter)
Sympathetic Excitatory division Uses norephinephrine (neurotransmitter)
What is a Nerve
A Collection of nerve fibers in the peripheral nervous system
Cells of the Nervous System
Two type of cells that make up nerve fibers
NeuronsSupportive cellsNeurogliaSchwann cells
Nerve Cells
Neurons transmit electrochemical signals along their length
cell bodydendritesAxonaxon terminals
Cell Body
The Cell body contains all of the cell organelles. Such as the:
NucleusMitochondria…
Important in the manufacturing of Neural transmitters.
Dendrites
The Branching structure that receives signals from other Nerves or if they are sensory Neurons receive signals externally.Conducts the nerve impulse to towards the cell body.
Axon
the long extension of a neuron that carries nerve impulses away from the body of the cell.
Link the Nerve to either the next nerve (sensory or interneuron) or to a muscle (motor neuron)
Axon
Usually much longer than a Dendrite and usually covered with a insulating layer called the myelin sheath.axon terminals - the the hair-like ends of axon
Release chemicals (neurotransmitters) to transmit signal to next neuron in junction Junctions between neurons and another cell called a synapse
Supportive Nerve Cells
Glial Cells supporting cells that usually form a type of protection and insulation for electical conduction
Proper names for CNS and PNSNeuroglia in CNS
Schwann cells in PNS
Glial Cells in PNS
Myelin Sheath
Myelin is the fatty substance that wraps around axons and protects/insulates themFormed by Schwann Cells in the PNS,
gaps called Nodes of Ranvier are left between the myelinMyelination and the Nodes of Ranvier increase the speed that the electrical signal moves down the axon.
Myelin Sheath
New research suggest that the electrical wave that travels down the axon actually jumps from one node to another. Thereby increasing the speed of transmission.Multiple sclerosis is caused by the destruction of the myelin sheath
Neurilemma
All nerves in the peripheral nervous system contain a thin membrane called the neurilemma.It surrounds the axon and promotes regeneration of damaged axons.
Neurilemma
Nerves in the brain that contain myelin sheath and neurilemma are called white matter and those that aren’t is the gray matter. Damage to the gray matter is permanent.
Different Types of Neurons
They all carry electro-chemical nerve signals, but differ in structure
(the number of processes, or axons, emanating from the cell body) and are found in different parts of the body.
Sensory neurons Motor-neurons Interneurons
Interneurons
form all the neural wiring within the CNS. have two axons (instead of an axon and a dendrite). one axon communicates with the spinal cordOther one with either the skin or muscle.