Nervous system Flashcards
Regulates and coordinates functions of
the body to maintain homeostasis
Nervous system
receives and interprets all sensory information,
stores memory, and controls movement
Brain
contains nerve bundles and cells that carry
messages from your brain to the rest of your body
Spinal cord
excitable cells of the nervous system
Neurons
regulates and coordinates functions of
the body to maintain homeostasis
Nervous system
receives and interprets all sensory information,
stores memory, and controls movement.
Brain
contains nerve bundles and cells that carry
messages from your brain to the rest of your body.
Spinal cord
contains the nucleus
that dictates the cell’s function
Cell body/soma
short, branching extensions
of the cell that usually receive
information from other neurons or from
sensory receptors and transmit the
information toward the neuron cell body
Dendrites
-single long cell process that either
conduct action potentials towards the
CNS (sensory neurons) or away from
the CNS (motor neurons)
Axon
Language of neurons
■ Electrical signals carried along neurons
to the brain
Action potentials
Voltage-gated sodium
(Na+) channel opening in the nerve cell
membrane. Inside is more positive than
the outside of the membrane
Depolarization
Voltage-gated
potassium (K+) channels open in the
membrane. Negatively charged inside,
while being positively charged outside
Repolarization
Membrane potential
becomes more negative than its start
Hyperpolarization
send electrical signals for sensations, movement,
and control of body functions
Nerves
supports the neurons and their activities.
Glial cells
2 major regions of nervous system
Central nervous system and Peripheral nervous system
consists of the
brain and the spinal cord.
Central nervous system
consists of
all the nervous tissue outside the CNS, including
nerves and ganglia
Peripheral nervous system
It extends from the foramen magnum at the base
of the skull to the second lumbar vertebra.
Spinal cord
communicate between the spinal
cord and the body
Spinal nerves
- the inferior end of the spinal cord
and the spinal nerves exiting there that resembles
a horse’s tai
Cauda equina
tissue consists of
myelinated axons.
White matter
3 columns of spinal cord
Dorsal (posterior) column, Ventral (anterior) column, Lateral column
White matter consists of 2 tracts
Ascending and descending matter
carry sensory information up
to the brain
Ascending matter
carry motor commands
from the brain
Descending matter
tissue that is a collection
of neuron cell bodies and dendrites
Gray matter
Shape of grey matter in spinal cord
Letter H
3 horns of gray matter
Posterior horn, anterior horn, lateral horn
Major regions of the brain
the brainstem,
the cerebellum, the diencephalon, and the
cerebrum
connects the brain and the spinal
cord
Brainstem
Components of brainstem
consists of the medulla oblongata, pons,
and the midbrain
located at the
bottom of the brainstem. It is responsible
for autonomic functions (e.g. blood
pressure, breathing)
Medulla oblongata
responsible for relaying signals
from the motor cortex to the cerebellum,
medulla oblongata, and thalamus
Pons
the smallest region of the
brainstem. It helps to control eye
movement and coordination
Midbrain
group of nuclei
scattered throughout the brainstem that
regulates important functions such as
motor control and consciousness
Reticular formation
It is a major component of the
reticular activating system
(RAS)
Reticular formation
plays an important role in arousing and
maintaining consciousness,
and in regulating the
sleep-wake cycle
Reticular activating system
also known as “little brain”. It is
responsible for balance, movement, and
coordination.
Cerebellum
is the connection between the
cerebrum and the rest of the nervous system
except for the system associated with olfaction or
the sense of smell
Diencephalon
the brain’s relay center. It
relays incoming sensory information
through groups of neurons that project to
the appropriate region in the cerebral
cortex
Thalamus
a collection of nuclei
that are largely involved in regulating
homeostasis. It connects the CNS to the
endocrine system
Hypothalamus
consists of a few small
nuclei, which are involved in the
emotional and visceral response to
odors, and the pineal gland
Epithalamus
an endocrine gland that may influence the onset of puberty and may play a role in controlling some long term cycles that are influenced by the light-dark cycle.
Pineal gland
the largest part of the brain
Cerebrum
Cerebrum is divided into left and right
hemispheres
Longitudinal fissure
provides the major
pathway for communication between the
two hemispheres of the cerebral cortex
Corpus callosum
thin, extensive region of wrinkled gray matter that is responsible for the higher functions of the nervous system such as thinking and other mental processes
Cerebral cortex
Numerous folds or ridges of the brain
Gyrus (plural: gyri)
the groove between two gyri.
Sulcus (plural: sulci)
4 lobe of Cerebrum
Frontal, temporal, parietal, occipital
important in the control of voluntary motor functions, motivation, aggression, mood, and olfactory (smell) reception
Frontal lobe
the
principal center for
receiving and
consciously perceiving
most sensory
information (ex. touch)
Parietal lobe
is involved in olfactory (smell) and auditory
(hearing) sensations and plays an important role
in memory
Temporal lobe
functions in receiving
and perceiving visual
input.
Occipital lobe
separates the
frontal and parietal lobe
Central sulcus
- separates the
temporal lobe from the rest of
the cerebrum
Lateral fissure
these are three connective tissue
membranes that surround and protect the brain
and spinal cord.
Meninges
the most superficial and
thickest of the meninges
Dura mater (tough mother)
the middle layer of
the meninges
Arachnoid mater (named for its spider web like trabeculae)
tissues between the arachnoid
and the pia mater
Trabeculae
thin fibrous membrane that
covers the outer surface of the CNS
Pia mater (tender mother)
- bathes the brain and
spinal cord, providing a protective cushion around
the CNS.
Cerebrospinal fluid
produces the CSF
Choroid plexus
open spaces within the brain where
CSF circulates
Ventricles
group of neuron cell bodies.
○ It forms connections with the different parts of the brain, allowing them to send signals back and
forth
Ganglia
2 types of ganglia
sensory ganglia and autonomic ganglia
2 groups of nerves in PNS
12 pairs of cranial nerves and 31 pairs
of spinal nerves
nerves attached to the brain,
which are primarily responsible for the sensory
and motor functions of the head and neck
Cranial nerves
All the spinal nerves contain axons of
both sensory and somatic motor
neurons
Mixed nerves
the area of skin supplied
with sensory innervation by a pair of
spinal nerves
Dermatome
3 major plexuses of spinal nerves
Cervical, brachial, lumbosacral plexus
originates from spinal
nerves C1 to C4
Cervical plexus
originates from spinal
nerves C5 to T1
Brachial plexus
originates from spinal
nerves L1 to S4
Lumbosacral plexus
Controls voluntary movements and transmits action potentials from CNS to skeletal muscles
Somatic nervous system
2 motor neurons of SNS
Upper and lower motor neurons
■ Cell bodies are in the cerebral
cortex
■ Axons form descending tracts
that connect to lower motor
neurons
Upper motor neurons
■ Cell bodies are in the anterior
horn of spinal cord gray matter or
cranial nerve nuclei
■ Axons leave the CNS and extend
through spinal or cranial nerves
to skeletal muscles.
Lower motor neuron
Motor areas of the cerebral cortex
Primary motor cortex, premotor area, prefrontal area
Action potentials in this region
control voluntary movement of skeletal muscles
Primary motor area
Motor functions are org
Premotor area
Motivation and foresight to initiate
movements as well as regulation of emotional behavior
and mood
Prefrontal area
2 types of descending tracts
Direct & Indirect
Muscle tone and skilled
movements especially of hands
Lateral corticospinal
Muscle tone and movement
trunk muscles
Anterior corticospinal
Movement coordination
Rubrospinal
Posture adjustment, especially during
movement
Retuculuspinal
- Posture and balance
Vestibulospinal
Movement in response to visual reflexes
Tectospinal
Group of functionally related nuclei
- Responsible for planning, organizing, and coordinating
motor movements and posture
- Disorders here cause difficulty in rising and walking and
causes increased muscle tone and exaggerated
uncontrolled movements at rest
Basal nuclei
2 primary nuclei
Corpus striatum, Substantia Nigra
found deep within cerebrum
Corpus striatum
- dark pigmented cells in the midbrain
Substantia nigra
Feedback loops
Stimulatory & Inhibitory
- facilitates muscle activity especially at the
beginning of a voluntary movement
Stimulatory
- facilitates the actions of the stimulatory
circuits by inhibiting muscle activity in antagonist
muscles
Inhibitory
- Attached by cerebellar peduncles to the brainstem
- Consists of gray nuclei and white nerve tracts
- Involved in maintaining balance, muscle tone, and in
coordinating fine motor movement - Compares motor cortex and sensory information from
the moving structures
Cerebellum
● Involved in involuntary movements
● Comprises of motor neurons that carry action potentials from
CNS to the periphery.
● Innervate smooth and cardiac muscles, as well as glands
Autonomic nervous system
2 main neurons in ANS
Preganglionic neuron, Postganglionic neuron
All preganglionic neurons of both sympathetic
and parasympathetic division secrete the
neurotransmitter acetylochine
Preganglionic neuron
- Most postganglionic neurons of the
sympathetic division secrete the
neurotransmitter norepinephrine
Postganglionic neuron
2 divisions of ANS
Para/sympathetic division
- “Fight or Flight”
- prepares the body for physical activity
Sympathetic division
- “Rest and Digest”
- Stimulates involuntary activities of the body at
rest
Parasympathetic division
- Organs that receive autonomic neurons
innervated by both the sympathetic and
parasympathetic division
Dual innervation
Consists of plexuses within the wall of the digestive tract
Enteric nervous system
- capable of monitoring and controlling the digestive tract
independently of the CNS through local reflexes
Enteric neuorn
stimulate enteric motor
neurons, which stimulate glands to secrete
Enteric interneurons
connect the digestive tract to the
CNS
Sensory neuron
connect the CNS to the digestive tract
Para/sympathetic neurons
located entirely within the enteric
plexuses.
Enteric neurons
is an independent subdivision of the
PNS that is integrated with the ANS
ENS
have receptors distributed
throughout the body and are divided into somatic
senses (providing information about the body and
environment) and visceral senses (providing
information about internal organs, mainly pain and
pressure).
General senses
are more localized and include
smell, taste, sight, hearing, and balance
Special senses
Respond to mechanical
stimuli like bending/stretching
Mechanoreceptors
Respond to chemicals, e.g.,
odor molecules for smell.
Chemoreceptors
Respond to light (vision).
Phtoreceptors
Respond to temperature
changes.
Thermoreceptors
Respond to pain stimuli.
Nocireceptors
Respond to painful stimuli,
temperature, and movement
Free nerve endings
Detect light touch and superficial
pressure
Merkel disks
Detect light touch
associated with hair movement
Hair follicle receptors
: Provide fine, discriminative
touch.
Meissner corpuscles
Detect continuous pressure
Ruffini corpuscles
Detect deep pressure,
vibration, and proprioception.
Pacinian corpuscles
Sharp, pricking pain (fast
transmission)
Localized pain
Burning, aching pain (slow
transmission)
Diffuse pain
Pain perceived in a different
location than the stimulus, e.g., pain from a heart
attack felt in the left shoulder.
Referred pain
Located in the olfactory epithelium,
have specialized cilia that interact with odorants
Olfactory neuron
Action potentials travel from
olfactory neurons to the olfactory cortex for perception.
Pathways for olfaction
Located on the tongue and other parts of the
mouth, consisting of epithelial cells and taste cells
Taste buds
Sour, salty, bitter, sweet, and umami (savory).
Taste types
Sensory information is
carried by the facial, glossopharyngeal, and vagus nerves to the brain
Neural pathways for taste
○ Eyebrows
○ Eyelids
○ Conjunctiva
○ Lacrimal Apparatus
○ Extrinsic Eye Muscles
Accessory structures of the eye
Includes the sclera and cornea
Fibrous tunic
: Includes the choroid, ciliary body,
and iris
Vascular tunic
The retina, which includes rods
and cones for light perception
Nervous tunic
Auricle and external auditory canal.
External ear
Tympanic membrane, auditory
ossicles (malleus, incus, stapes).
Middle ear
Cochlea (for hearing) and vestibular
system (for balance).
Inner ear
Sound waves travel through the auditory canal to
the tympanic membrane, causing vibrations that
are transferred to the cochlea for sound
perception
Hearing mechanism
Detected by the vestibule
Static equilibrium
Detected by the semicircular canals
Dynamic equilibrium
