Nervous System Unit Lesson 4: Peripheral Nervous System Flashcards
what is the peripheral nervous system composed of
all the other nerves when you exclude the brain and spinal cord
what is the purpose of the peripheral nervous system
its purpose is to send signals from outlying(far from a center/main body) neurons to the central nervous system for processing
what are sensory pathways
chains of neurons that travel from a receptor to the cerebral cortex
what are motor pathways
chains of neurons that travel from the brain to motor neurons
what are the two components of the PNS
nerves and ganglia
what are nerves
assemblages of axons that are referred to as “nerve fibres”
what are ganglia
swollen regions in the nerves that contain collections of cell bodies
what are cranial nerves(how many pairs, what do they do)
12 pairs of nerves that link regions of the brain to regions in the face, neck, and torso
what are spinal nerves(how many pairs, where are they located)
31 pairs of nerves that emerge from between openings in the vertebral column
the spinal nerves are arranged in a manner where two short branches(dorsal root and ventral root) attach to the spinal cord and join together moving away from it. what does the dorsal root contain and what is it composed of?
the dorsal root contains cell bodies termed dorsal root ganglion and it is composed of sensory fibres conducting impulses toward the spinal cord
the spinal nerves are arranged in a manner where two short branches(dorsal root and ventral root) attach to the spinal cord and join together moving away from it. what does the ventral root contain and what does it do?
it contains motor fibres that conduct impulses away from the spinal cord to the effectors
what is the somatic nervous system(what is it responsible for?)
it is a part of the peripheral nervous system that takes sensory information from receptors to the central nervous system and takes motor commands from the CNS to the skeletal muscles
what nervous system contains reflex arcs
the somatic nervous system
what are reflexes
automatic, involuntary responses to a stimulus
what are reflex arcs
nerve pathways that initially circumvent(go around) sending the signal to the brain
how do reflex arcs work
the stimulus is sent to the spinal cord where it travels through short interneurons and motor neurons that elicit an immediate response from an effector
divide the autonomic nervous system into parts
it can be divided into sympathetic and parasympathetic divisions
what is the sympathetic nervous system(what is it responsible for)
it is a collection of nerves that are concerned with stressful situation
what happens when your sympathetic nervous system is active(also talk about one of its functions)
portions of your body are stimulated to the state best suited for the situation. one of the functions is to activate the adrenal medulla to secrete hormones epinephrine and norepinephrine into the blood
what is the parasympathetic nervous system responsible for
functions that are opposite to the sympathetic nervous system(“rest and digest”, housekeeper)
what is the main neurotransmitter associated with the parasympathetic nervous system and what are its effects like
acetylcholine(ACh). in its interactions with cells, it promotes effects that are opposite to the sympathetic nervous system
