There is a break down of what after a muscle contraction?
Ach using acetylcholinesterase enzyme to relax muscle
a neuron conducting impulses outwards from the brain or spinal cord
a neuron conducting impulses inwards to the brain or spinal cord
Carries messages from the Sensory Neuron to the Motor Neuron
Most common Type of Neuron
Over all Purpose of Nevous System
-Response to internal and external stimuli
-Overall body homeostasis
-Voluntarily controlled motions and locomotions
-involuntary control of viseral actions (organs)
-protection through use of reflex arcs
-thought processes, reasoning , interpretation of nervous system stimuli impulses and motor reactions
-close association with endocrine glands fr impulse passage and homeostatsis.
Individual neurons carry what in one direction from dendrites receiving to axon terminal release using fraded andaction potentials, Na+ and K+ ion pumps?
Carry information from central cervous system to periphery with the intent of carrying out a response. Motor neurons.
Pathway leaving the sensor and going to the control center; Sensory Neurons
Are neurons connected?
Neurons are NOT connected; they are close and neurotransmitters such as ACH or Norepinephrine are sent within the synapsis
cell body with single process that divides into two branches and functions as an axon. (L) found in ganglia outside the brain and spinal cord
Two Processes; A neuron with a single axon and a single dendrite, often projecting from opposite sides of the cell body. Bipolar neurons are typically associated with sensory organs; an example is the bipolar neuron in the retina of the eye. - note that one axon may innervate many different muscles, or other things.
Three or more processes; cell body with many processes one of which is an axon, the rest dendrites. (L) brain and spinal cord.
Purpose of Myelination
Speed of impulse passage and difference to unmyelinated; Increases the speed of transmission of nerve impulses
Myelination is an insulator as plastic around electrical wire
Regions of the brain and spinal cord containing dense collections of myelinated fiber
Contains mostly nerve cell bodies and unmyelinated fibers
Conduct umpulses quite slowly; Dendrites are always unmyelinated
Neurons/ Nerve Cells
Highly spcialized cells that conduct messages in the form of nerve impulses from one part of the body to another
type of neuroglial cell that produces myelin in the CNS
Supporting cells of the peripheral nervous system responsible for the formation of myelin.
Central Nervous System CNS
consists of the brain and spinal cord; the dorsal body cavity; it inteprets sensory input and dictates motor responses based on reflexes, current conditions and past experience
Peripheral Nervous System PNS
The part of the nervous system outside the CNS; consists mainly of the nerves(bundles of axons) that extend from the brain and spinal cord.
The ____ the nerve- the faster the impulse
The all or none phenomena means what?
It either happens completly or it doesn't happen at all; If the number of Na+ ions entering the cell is too low to achieve threshold, no AP will occur.
Concentrations of cell bodes of several neurons in one place to amplify impulse as apssed-outside CNS
What is the single longest nerve
Sciatic nerve down past hip inot leg- of sacral plexus
Divisions of CNS
Voluntary and Involuntary systems
Divisions of PNS
Somatic and Autonomic (called enteric) they further separate into Sympathetic and Parasympathetic
Includes nervous 31 pairs of body nerves and 12 pair of crainial nerves
Autonomic NS and glands of somatic cells, glial cells, associative neruons, interneurons
What is a Reflex?
an automatic instinctive unlearned reaction to a stimulus
Microglia and its role
smallest neuroglial cells; phagocytic cells that enculf cellular debris, waste products and pathogens. increase in number as a result of infection or injury