Nervous Physiology Flashcards
major controlling, regulatory, and communicating system in the body
nervous system
Center of all mental activity including thought, learning, and memory
nervous system
Together with the endocrine system, this system is responsible for regulating and maintaining homeostasis
nervous system
aspect of nervous system that keeps us in touch with our environment, both external and internal
receptors
Composed of brain, spinal cord, nerves, and ganglia
nervous system
Various activities of the nervous system can be grouped together as three general overlapping functions:
sensory
integrative
motor
changes which occur inside and outside the body
stimuli
monitor such things as temperature, light, and sound from the external environment
sensory receptors
Inside the body, the internal environment, receptors detect variations in:
pressure
pH
CO2 concentration
level of various electrolytes
gathered information from receptors, converted into electrical signals
sensory input
electrical signals that are transmitted to the brain
nerve impulses
decisions that are made each moment based on sensory input
integration
muscles and glands, cause an effect in response to directions from the nervous system
effectors
Two main types of cells in nerve tissue:
neuron
neuroglia
actual nerve cell, conducting cell that transmits impulses and the structural unit of the nervous system
neurons
“glial” cell which means nerve glue, nonconductive and provide a support system for the neurons
neuroglia
Special type of connective tissue for the nervous system
neuroglia
carry out the functions of the nervous system by conducting nerve impulses
neurons
Highly specialized and amitotic (cannot be replaced through mitosis
neurons
Each neuron has three basic parts
cell body (soma)
one or more dendrites
axon
similar to other type of cells, it has a nucleus with at least one nucleolus and contains many of the typical cytoplasmic organelles
cell body
Lacks centrioles since it functions in cell division
neuron cell body
cytoplasmic extensions or processes that project from the cell body
dendrites/axon
Sometimes referred to as fibers
dendrites/axon
usually, but not always, short and branching which increases their surface area to receive signals from other neurons
dendrites
▪Number varies
▪Called afferent processes because they transmit impulses to the neuron cell body
dendrites
have only one that projects from each cell body, usually elongated because it
carries impulses away from
the cell body
▪Called an efferent process
axon
infrequent branches of axon
axon collaterals
short branches where axon and axon collaterals terminate
telodendria
end of telodendria that are slightly enlarged to form synaptic bulbs
distal end
surrounds axons, segmented white, fatty substance
myelin
myelinated fibers make up what matter in the CNS
white matter
cell bodies and unmyelinated fibers make up what matter in the CNS
gray matter
unmyelinated regions between the myelin segments
nodes of ranvier
produce the myelin in the peripheral nervous system
schwann cells
Its cytoplasm, nucleus, and outer cell membrane form a tight covering around the myelin and around the axon itself at the nodes of Ranvier (neurilemma)
schwann cells
plays an important role in the regeneration of nerve fibers
neurilemma
produce myelin in the CNS, but there is no neurilemma, which is why fibers within the CNS do not regenerat
oligodendrocytes
Types of neurons according to the direction in which they transmit impulses relative to the CNS
afferent
efferent
carry impulses from peripheral sense receptors to the CNS
afferent
transmit impulses from the CNS to effector organs such as muscles and glands
efferent
Usually have short dendrites and long axons
efferent
located entirely within the CNS in which they form the connecting link between the afferent and efferent neurons
interneurons
Short dendrites and may have either a short or long axon
interneurons
do not conduct nerve impulses, but instead support, nourish, and protect the neurons
neuroglia
Far more numerous than neurons and unlike neurons, are capable of mitosis
neuroglia
benign tumors of the peripheral nervous system which commonly occur in their
sporadic, solitary form in otherwise
normal individuals
schwannomas
Rarely, individuals develop numerous tumors arising from one or many elements of the peripheral nervous system
schwannomas
this problem is a fairly common benign nerve growth and begins when the outer coating of a nerve in your foot thickens
Morton’s Neuroma
Caused by irritation of branches of the medial and lateral plantar nerves that results when two bones repeatedly rub together
Morton’s neuroma
Two subdivisions of the nervous system
CNS
PNS
brain and spinal cord are the organs of this subdivision of the nervous system
central nervous system
located in the dorsal body cavity and are encased in bone for protection
brain and spinal cord
brain is located in this
cranial vault
spinal cord is located in this canal of the vertebral column
vertebral canal
location where the brain and spinal cord
are continuous
foramen magnum
organs include nerves and ganglia
peripheral nervous system
bundle of nerve fibers, much like muscles are bundles of muscle fibers
nerves
extend from the CNS to peripheral organs such as muscle and glands
cranial nerves
spinal nerves
collections, or small knots, of nerve bodies outside the CNS
Ganglia
further divided into an afferent (sensory) division and efferent (motor) division
Peripheral Nervous System
transmits impulses from peripheral organs to the CNS
Afferent or sensory divison
transmit impulses from the CNS out to the peripheral organs to cause an effect or action
efferent or motor division
also called the somatomotor or somatic efferent nervous system, supplies motor impulses to the skeletal muscles
somatic nervous system
Sometimes called the voluntary nervous system
somatic nervous system
also called the visceral efferent nervous system, supplies motor impulses to cardiac muscle to smooth muscle, and to glandular epithelium
autonomic nervous system
Further divided into sympathetic and parasympathetic divisions
Regulates involuntary or automatic functions, called the involuntary nervous system
autonomic nervous system
consist of the brain and spinal cord, which are localed at the dorsal body cavity
central nervous system
surrounds the brain
cranium
protects the spinal cord
vertebrae
the brain and spinal cord is continuous with each other in this
foramen magnum
in addition to bone, the CNS is surrounded by this connective tissue membranes
meninges
Three layers of meninges around the brain and spinal cord
dura mater
arachnoid
pia mater
outer layer of the meninges, tough white fibrous connective tissue
dura mater
middle layer of meninges which resembles a cobweb in appearance, thin layer with numerous threadlike strands that attach it to the innermost layer
arachnoid
space under the arachnoid, filled with cerebrospinal fluid and contains blood vessels
subarachnoid space
innermost layer of the meninges, thin delicate membrane tightly bound to the surface of then brain and spinal cord and cannot be dissected away without damaging the surface
pia mater
tumors of the nerve tissue covering the brain and spinal cord
meningiomas
Not likely to spread, but physicians treat them as
though they are malignant to
treat symptoms that may develop when a tumor applies pressure to the brain
meningiomas
divided into the cerebrum, diencephalon, brain stem, and cerebellum
brain
largest and most obvious portion of the brain
cerebrum
Divided by a deep longitudinal fissure into two cerebral hemispheres
cerebrum
arching band of white fibers that connects the two hemispheres
corpus callosum
Provides a communication pathway between the two halves of the cerebral hemispheres
corpus callosum
Each cerebral hemisphere is divided into five lobes, four of which have the same name as the bone over them (5)
frontal lobe
parietal lobe
occipital lobe
temporal lobe
insula
lobe of cerebral hemisphere that lies deep within the lateral sulcus
Insula (Island of Reil)
centrally located and is nearly surrounded by the cerebral hemispheres
diencephalon
Includes the thalamus, hypothalamus, and epithalamus
diencephalon
about 80 percent of the diancephalons, consist of two oval masses of gray matter that serve as relay station for sensory impulses EXCEPT for the sense of smell going to the cerebral cortex
thalamus
small region below the thalamus, which plays a key role in maintaining homeostasis because it regulates many visceral activities
hypothalamus
most dorsal portion of the diencephalons, small gland involved in the onset of puberty and the rhythmic cycles in the body (like a biological clock)
epithalamus
region between the diancephalons and spinal cord
brain stem
Consist of three parts: midbrain, pons, and medulla oblongata
brain stem
superior portion of the brain stem
midbrain
bulging middle ;portion of the brain stem, region that primarily consist of nerve fibers that form conduction tracts between
the higher brain centers and
spinal cord
pons
extends inferiorly from the pons, continuous with the spina cord at the foramen magnum
▪Also called medulla
▪All ascending (sensory) and descending (motor) nerve fibers connecting the brain and spinal cord passes through this
medulla oblongata
second largest portion of the brain, located below the occipital lobes of the cerebrum
cerebellum
three paired bundles of myelinated nerve fibers form communication pathways between the cerebellum and other parts of the CNS
cerebral peduncles
series of interconnected, fluid-filled cavities found within the brain
ventricles
fluid found in the cavities of the ventricles of the brain
cerebrospinal fluid
extends from the foramen magnum at the base of the skull to the level of the first lumbar vertebra
spinal cord
Continuous with the medulla oblongata at the foramen magnum
spinal cord
Like the brain, surrounded by bone, meninges, and cerebrospinal fluid
spinal cord
Appears oval in shape (x-section)
spinal cord
Divided into 31 segments with each segment giving rise to a pair of spinal nerves
spinal cord
which end of the cord that have many spinal nerves extending beyond the conus medullaris to form a collection that resembles a horse’s tail (cauda equina)
distal end
the roots of the lumbar and sacral spinal nerves, which form a bundle within the lowest part of the spinal column
cauda equina
Two main functions of the spinal cord:
➢Serving as conduction pathway for impulses going to and from the brain (sensory impulses travel to the brain on ascending tracts on the cord, motor impulses travel on descending tract)
➢Serving as reflex center
functional unit of the nervous system
reflex arc
responses to stimuli that do not require conscious thought and consequently occur more quickly than reactions that require thought processes
reflexes
reflex action withdrawing the affected part before you are aware of the pain
withdrawal reflex
refers to tumors that arise from the support cells of the brain
glioma
cells that support the brain
glial cells
include astrocytoma, ependymomas, and oligodendrogliomas which are the most common primary tumors
brain tumor
consist of the nerves that branch out from the brain and spinal cor
peripheral nervous system
Form communication between the CNS and the body parts
PNS
Further divided into somatic nervous system and autonomic nervous system
PNS
consist of nerves that go to the skin and muscles and is involved in conscious activities
Somatic Nervous System
