Nervous System Flashcards
nervous system
controls/ regulates all systems of the body receives stimuli via receptors and transmits information via effectors
types of effectors
mechanical effectors (muscles)
chemical effectors (glands)
CNS
brain and spinal cord
PNS
all nervous tissue outside of CNS
neurons
specialized cells for long-distance transmission of electrical stimuli throughout the body
neuroglia
accessory cells that nourish, support, and insulate neurons
perikaryon (soma)
main body of neuron
nerve fiber
extends from perikaryon on each neuron
dendrites and axons
d: transmit incoming signals to perikaryon, the number varies
a: carry impulses away from perikaryon, usually one per neuron
types of neurons
unipolar: single axon that splits into 2 dendrites at the end
bipolar: 2 processes (1 axon and dendrite)
multipolar: many processes in wide variety of structures
types of neuroglia
ependymal, astrocyte, microglia, and oligodendroglia
ependymal
line the central canal of the brain and spinal cord, play role in development and control flow of cerebrospinal fluid
astrocyte and microglia
a: pass nutrients between neurons and blood capillaries
m: engulf foreign materials
oligodendrogilia
create material that insulates the axons, speeds up electrical signal
Schwann cells and (un) myelinated cells
insulate the fibers, in myelinated nerves deposit myelin
nodes of Ranvier
junction between neighboring neuroglia cells in myelin sheaths
graded potential vs action potential
graded potential: signal is proportional to stimulus that triggers it, declines in magnitude as it moves along neuron
action potential: all or nothing, once stimulus hits level the signal in sent and never declines along the neuron
synapses
gaps between adjacent neurons that are used to pass information allow for control of information flow
electrical impulse in axon
release neurotransmitters into space between neurons
convergence and divergence
c: multiple neurons required to pass signal on leads to summation
d: when one neuron passes information to multiple others, the distribution of the signal
afferent vs efferent nerves
afferent carry information to CNS
efferent carry information from CNS
somatic vs visceral nerves
somatic carry info to and from somatic tissue
visceral nerves carry information to and from viscera
somatic sensory and somatic motor nerves
somatic sensory nerves transmit info about pain or temperature from skin (body to CNS)
somatic motor nerves carry impulses from CNS to cause muscle contractions (CNS to body)
visceral sensory and visceral motor nerves
visceral sensory transmit info about condition of internal organs
visceral motor carry impuses from CNS to involuntary muscles and glands
roots of nerve in spinal cord
dorsal: sensory fibers enter the spinal cord
ventral: motor fibers leave the spinal cord
sympathetic chain and Ramus communicans
as fibers leave the spinal cord they connect to chain of ganglia (sympathetic chain)
connect between spinal nerve and sympathetic chain (Ramus communicans)
spinal nerves (ganglia)
sympathetic ganglia: form chain parallel to spinal cord
collateral ganglia: peripheral outside of chain
visceral ganglia: found within walls of visceral organs
Cranial nerves of senses (sensory)
olfactory (I): visceral sensory nerve that controls smell
optic (II): extension of the brain, takes visual info
octaval (auditory) nerve (VIII): takes in info from inner ear (hearing and balance)
cranial nerves of eye muscles (motor)
oculomotor nerve (III): nerve supplying extrinsic eye, supplies fibers to iris
trochlear nerve (IV): supplying extrinsic eye muscles
abducens nerve (VI): suppling extrinsic eye muscles
trigeminal nerve
V, formed from 3 major branches of nerve fibers- ophthalmic, maxillary, mandibular
facial nerve
VII, includes sensory fibers from taste buds and motor fibers associated with hyoid arch and derivatives
in fish opercular complex, Bell’s palsy involves damage of facial nerve leaving face paralyzed
cranial nerves of the mouth
glossopharyngeal nerve (IX): mixed nerve feeding parts of mouth and throat
hypoglossal nerve (XII): motor nerve controls movement of hyoid arch and tongue
left over cranial nerves
nervous terminalis (0): not entirely clear, found in jawed vertebrates
vagus nerve (X): mixed nerve that influences variety of structures (larynx and major visceral organs (heart))
the spinal accessory nerve (XI): the motor nerve that serves the shoulder and neck muscles
lateral line cranial nerves
fish have 6 unnumbered, they are a series of crinal nerves rooted in the medulla and supply lateral line system
water to land cranial nerve transitions
spinal accessory (IX): is modified, innervates the shoulder and neck muscles that are more prevalent on land
hypoglossal (XII): innervates the tongue that is adapted to feeding in non aquatic environment
spinal reflexes
the simplest level of control in the body, a circuit with neurons from the receptors that enter the spinal cord and leave it via neurons connected to an effector