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
association neuron
connect to receptor and effector neurons, completing the circuit (sensory in, effector, motor out)
how are spinal reflexes devoted to maintaining posture simpler?
sensory neuron synapses directly with the motor neuron, cutting out the association as the middleman
visceral reflex arc, postganglionic motor neuron
has three ganglia: sympathetic, collateral, and visceral
autonomic sensory fibers
monitor internal environment of the animals (bp, temp, O2 and CO2 tension)
autonomic motor fibers
control involuntary muscles and glands
autonomic nervous system and its 2 antagonistic systems
independent elements of the nervous system
sympathetic: controls viscera during strenuous activity or frightened
parasympathetic: takes control to restore the body to resting state
neurotransmitter released during the two systems of the autonomic nervous system
sympathetic: norepinephrine and epinephrine (adrenaline or no adrenaline)
parasympathetic acetylcholine
structural differences between sympathetic and parasympathetic nervous system
preganglionic motor nerves ins sympathetic are short while they are long in parasympathetic
s: the synapse in sympathetic or collateral ganglia will long postganglionic nerves
p: they reach all the way to the visceral organ they are innervating before synapsing with the postganglionic nerve
location of sympathetic system
flows from the spinal cord in thoracic and lumbar region- thoracolumbar outflow
motor neurons move through the sympathetic chain ganglia
inferior cervical ganglion: controls lungs and heart
celiac: controls digestive system
inferior mesenteric: controls intestine and urogenital systems
location of parasympathetic system
sends data from cranial and sacral region of spinal cord- craniosacral outflow
facial (VII): salivary glands
glossopharyngeal (IX): glands
vagus (X): lungs, heart, and digestive systems
anatomical division of the autonomous system
cranial autonomic system: autonomic nerves originating from cranial nerves
spinal autonomic system: autonomic nerves originating from spinal column
enteric autonomic system: independent stem found in lining of digestive tract
anatomy of enteric system
neurons are woven together in patches of nerves called plexuses
myenteric plexuses: outer wall of smooth muscle
submucosal plexuses: deep within smooth muscle near lumen
neurons sense food in stomach and stimulates smooth muscle to create peristaltic waves moving food
Interoceptors
gives info to CNS
proprioceptors: supply info about body posture
exteroceptors: supply info about the external environment
embryology of CNS
formed by folding ectoderm into the neural fold, brain hollow canals open in fluid-filled spaces called ventricles
walls of CNS
meninges wrap brain and spinal cord
composed of dura mater (outer), arachnoid (middle) and pia mater (innermost with blood vessels)
cerebrospinal fluid (CSF) fills the arachnoid
CSF cerebrospinal fluid
derived from blood via choroid plexus
flows through the canal of the spinal cord and the ventricles in the brain
spinal tap
done after serious brain damage, sampling the CSF from the spinal cord, if RBCs present in CFS, it indicates potential damage to CNS
multilayer meninges
CNS in fish is surround by single primitive meninx
the layer is doubled in amphibians, reptiles, and birds, creating secondary meninx
spinal cord regions
grey matter: interior that is involved in spinal reflexes
dorsal horn: extension of grey matter that receives sensory signals
ventral horn: extension of grey matter that sends out motor neurons
white matter: outside the grey matter and is involved in spinal tracts
associaion neurons and spinal reflexes
sensory neurons entering dorsal horn synapse with the association neurons
association neurons can direct this info to different places (ventral horn, ventral horn on the other side, and the spinal cord)
spinal tract
collections of nerve fibers that pass info up and down cord
spinothalamic tract begins in spinal cord and ends at thalamus
ascending tracts
fasciculus gracilis and fasciculus cuneatus carry posture info to medulla
spinocerebellar tract carry unconscious posture info to the cerebellum
lateroventral spinothalamic carries info about pain and temp to thalamus
descending tracts
carry impulses from brain back to spinal cord
corticospinal tracts runs from cerebral cortex to neurins that controls limb muscles
tectospinal tract is assoicates with optic and auditory stimuli
rubrospies the midbrain aids in coordination of movements
parts of hindbrain
cerebellum (divided into corpus and auricles/flocculus (tetrapods), medulla oblongata, and pons (crossroads between cerebellum and cerebrum)
cerebellum
involved in processing sensory information to keep balance and equilibrium
refinement of motor action
human with damage to cerebellum have:
ataxia: loss of coordination of limbs body and speech
dysmetria: under or overshooting when reacginf for something
midbrain
tectum: roof of midbrain that receives sensory info from optic, auditory and later line (divided into superior and inferior colliculi in mammals)
tegmentum: floor of midbrain that initiates motor input
parts of forebrain
telencephalon: cerebrum and corpus callosum
diencephalon: thalamus and hypothalamus
epithalamus
pineal gland: effect skin pigment in fish/ amphibians and biological rhythm in amniotes
habenular: may be involved in variety of activites (reproductive behavior, pain proccessing, sleep wake cycles and stress respoe)
hypothalamus
regulates homeostasis via stimulating pituitary gland
mammillary bodies involved in reproductive behavior and short term memory
telencephalon cerebrum
includes cerebral hemispheres and olfactory bulbs
outer walls of hemispheres form cerebral cortex
subcortical regions comprises rest of cerebral tissue
mammalian cerebrum
heavily folded to accommodate more volume, rounded folds are gyri, gooves are sulci, fissure is deep sulci
commissures are bonds of neurons that connect left and right halves
corpus callosum is most prominenet commissure within eutherian mammals (connects hemispheres)
naming of cerebral hemispheres
hippocampus after sea horse
amygdala after almond shape
pallium (cerebral hemispheres)
divided into three region
medial pallium: receives auditory, visual, somatosensory, and lateral line input and little olfactory input
dorsal and lateral pallidum: receives ascending input from thalamus and spinal cord
dorsal ventricular ridge (DVR) cerebral hemisphere in reptiles and birds
expansion of lateral pallium
pallium in mammals
dorsal pallium is greatly expanded and differentiated called the cerebral cortex
medial pallium/hippocampus related to inquisitiveness and short term memory
subpallium
divided into septum and striatum
septum: recieves info from medial pallium
forms key part of limbic system
basal ganglia
formed by striatum and palladium
Parkinson’s involves involuntary tremors and movement due to degeneration of nuclei in basal ganglia
pallium function
indirectly contrails locomotion via receiving positional info from thalamus and transmits responses to basal ganglia, hypothalamus, and brain stem
expanded in vertebrates with locomotory innovation (DVR in birds, dorsal pallium in mammals)
limbic system structure
midbrain and forebrain interconnected
thalamus, hypothalamus, and mammillary bodies
basal ganglia (amygdala)
septum (subpallium)
medial pallium
cingulated gyrus (subcortical tissue)
circuit called papez circiuit
limbic function
damaging cingulate gyrus disrupts ordering of complex behaviors
reticular formation
consists of neurons and fibers in medulla and midbrain
maintain alertness in cerebral cortex
filter that decides which signals to relay to higher brain function
acts as an association neuron between sensory neurons and brain and motor neurons
Varicella Voster Virus (VZV)
high infectious human virus, primary infection causes acute varicella
acute varicella
known as chicken pox, causes an itchy rash with small fluid-filled blisters, highly contagious
encephalitis
inflammation of the brain tissue; viral infection, bacterial infection, and parasitic infestation are causes; causes headache, fever and stiff muscles
LOC
loss of consciousness
sports-related concussions (SRC)
not often associated with LOC, generally related to low velocity impacts resulting in disorientation and confusion instead
Traumatic brain injury (TBI)
physical injury to the head/ brain
umbrella term for physical trauma, chemical/ toxic effects, hypoxia, tumors, infections, and stroke
define physical trauma, chemical/ toxic effects, hypoxia, tumors, infections, and stroke
physical trauma: falling, car accidents, blunf force trauma, gun shot wounds
chemical/ toxic effects: metabolic disorders, carbon monoxide poisoning
hypoxia: heart attacks, respiratory failure, drops in blood pressure
tumors: cancer overgrowing brain tissue, surgeries to remove tumors
infections: meningitis, encephalitis
stroke: blood blockage or tearing in an artery or vein
official definition of concussion
caused by direct blow to head, neck or another part of body in a way that transmits force to the head
results in rapid onset of short lived impairment of neurological function
symptoms reflect function disturbance not structural one
graded symptoms that do not include loss of consciousness
pathology of concussion
caused by rotational acceleration/ deceleration of the brain, parts of the brain shear past each other, causing disruption of synapses and stretching of axons, and massive flux of neurotransmitters crossing gap at once
reticular activation system
filters signal to and from the brain, loss of consciousness can arise from disruption of system
malignant oedema
build up of fluid in brain causing excess pressure which can be fatal, second impact syndrome results in this
Chronic traumatic encephalopathy (CTE)
degenerative brain disease found in athletes, military vets and others with a history of repeated brain trauma
taupathy
degenerative disease associated with build up of Tau proteins in brain tissue
Alzheimer’s is a secondary tauopathy
