Physiology Flashcards
The nervous system includes
- Sensory components
- Motor components
- Integrative components
Functions of Sensory components
detect changes in environmental stimuli
Motor components functions
generate movement, contraction of cardiac and smooth muscle, and glandular secretions
Functions of Integrative components
receive, store, and process sensory information and then orchestrate the appropriate motor responses.
The nervous system is composed of two divisions
The central nervous system (CNS), which includes the brain and the spinal cord.
The peripheral nervous system (PNS), which includes sensory receptors, sensory nerves, and ganglia outside the CNS.
afferent division
sensory
efferent division
motor
Steps and organization of the nervous system
The sensory or afferent division brings information into the nervous system
This afferent information is then transmitted to progressively higher levels of the nervous system up to cerebral cortex
The motor or efferent division carries information out of the nervous system to the periphery.
This efferent information results in reaction.
The afferent information is transmitted to higher levels of the nervous System until it reaches
Cerebral cortex
Examples of sensory receptors of the pns
visual receptors, auditory receptors, chemoreceptors, and somatosensory (touch) receptors
What is the result of the efferent division carrying information out of the nervous system to the periphery?
contraction of skeletal muscle, smooth muscle, and cardiac muscle or secretion by endocrine and exocrine glands.
Most activities of the nervous system are initiated by
sensory experiences that excite sensory receptors.
These sensory experiences can either cause
immediate reactions from the brain
memories of the experiences can be stored in the brain for minutes, weeks, or years and determine bodily reactions at some future date.
Information from the sensory receptors enters the CNS through …… and is conducted immediately to …….
peripheral nerves
multiple sensory areas
Information from the sensory receptors enters the CNS through peripheral nerves and is conducted to multiple sensory areas in
- (1) the spinal cord at all levels;
- (2) the reticular substance of the medulla, pons, and mesencephalon of the brain;
- (3) the cerebellum;
- (4) the thalamus;
- (5) areas of the cerebral cortex.
The most important eventual role of the nervous system is to control the various bodily activities.
This task is achieved by controlling
- (1) contraction of appropriate skeletal muscles throughout the body,
- (2) contraction of smooth muscle in the internal organs, and
- (3) secretion of active chemical substances by both exocrine and endocrine glands in many parts of the body.
muscles and glands are called….. and why?
effectors
because they are the actual anatomical structures that perform the functions dictated by the nerve signals.
skeletal” motor nerve axis of the nervous system function
controlling skeletal muscle contraction
Operating parallel to skeletal” motor nerve axis
autonomic nervous system
autonomic nervous system functions
controlling smooth muscles, glands, and other internal bodily systems.
skeletal muscles can be controlled from many levels of the central nervous system, including
- (1) the spinal cord;
- (2) the reticular substance of the medulla, pons, and mesencephalon;
- (3) the basal ganglia;
- (4) the cerebellum; and
- (5) the motor cortex.
The lower regions of CNS Aare concerned primarily with
automatic, instantaneous muscle responses to sensory stimuli
The higher regions of CNS Aare concerned primarily with
deliberate complex muscle movements controlled by the thought processes of the brain.
What is the INTEGRATIVE (combination of 2) FUNCTION OF THE NERVOUS SYSTEM
PROCESSING OF INFORMATION
Percentage of sensory information discarded by the brain as irrelevant and unimportant
More than 99%
channeling and processing of information is called
the integrative function of the nervous system.
synapse
junction point from one neuron to the next
Synapses determine
the directions that the nervous signals will spread through the nervous system.
……… can control synaptic transmission, sometimes opening the synapses for transmission and at other times closing them.
facilitatory and inhibitory signals from other areas in the nervous system
postsynaptic neurons respond with
Either large numbers of output impulses, or respond with only a few.
the synapses perform a selective action, how
blocking weak signals while allowing strong signals to pass, but at other times selecting and amplifying certain weak signals and often channeling these signals in many directions rather than in only one direction.
much of the sensory information is
stored for future control of motor activities and for use in the thinking processes.
Most storage of information occurs in
the cerebral cortex
but even the basal regions of the brain and the spinal cord can store small amounts of information.
memory,
function of the synapses which is the storage of information
facilitation
Each time certain types of sensory signals pass through sequences of synapses, these synapses become more capable of transmitting the same type of signal the next time.
Once memories have been stored in the nervous system, they become part of
the brain processing mechanism for future “thinking.”
How are memories stored in the brain
the thinking processes of the brain compare new sensory experiences with stored memories; the memories then help to select the important new sensory information and to channel this into appropriate memory storage areas for future use or into motor areas to cause immediate bodily responses.
Parts of CNS
- the spinal cord
- brain stem
- cerebellum
- diencephalon
- Cerebral hemispheres
Parts of brain stem
medulla, pons, and midbrain
Parts of diencephalon
thalamus and hypothalamus
Parts of Cerebral hemispheres
cerebral cortex, white matter, basal ganglia, hippocampal formation, and amygdala
most caudal portion of the CNS
spinal cord
Spinal Cord extends from
the base of the skull to the first lumbar vertebra.
The spinal cord is segmented, with…. pairs of spinal nerves that contain …
31
both sensory (afferent) nerves and motor (efferent) nerves.
Sensory nerves carry information to the spinal cord from
The skin, joints, muscles, and visceral organs in the periphery via dorsal root and cranial nerve ganglia.
Motor nerves carry information
from the spinal cord to the periphery
Types of motor nerves
somatic motor nerves
autonomic motor nerves
Functions of somatic motor nerves
innervate skeletal muscle
Functions of automatic motor nerves
innervate cardiac muscle, smooth muscle, glands, and secretory cells
Ascending pathways in the spinal cord carry
sensory information from the periphery to higher levels of the CNS.
Descending pathways in the spinal cord carry
motor information from higher levels of the CNS to the motor nerves that innervate the periphery.
Even after the spinal cord has been cut in the high neck region
many highly organized spinal cord functions still occur.
neuronal circuits in the cord can cause
- (1) walking movements,
- (2) reflexes that withdraw portions of the body from painful objects,
- (3) reflexes that stiffen the legs to support the body against gravity, and
- (4) reflexes that control local blood vessels, gastrointestinal movements, or urinary excretion.
the upper levels of the nervous system often operate by sending signals to
the control centers of the cord, simply “commanding” the cord centers to perform their functions.
Many, if not most, of what we call subconscious activities of the body are controlled in …….
in the lower areas of the brain
medulla, pons, mesencephalon, hypothalamus, thalamus, cerebellum, and basal ganglia
Examples of subconscious activities controlled by lower areas
- subconscious control of arterial pressure and respiration
- Control of equilibrium
- Feeding reflexes , such as salivation and licking of the lips in response to the taste of food,
- many emotional patterns such as anger, excitement, sexual response, reaction to pain, and reaction to pleasure
Where is subconscious control of arterial pressure and respiration achieved
medulla and pons.
subconscious control of arterial pressure and respiration is achieved mainly in
the medulla and pons.
Control of equilibrium is a combined function of
the older portions of the cerebellum and the reticular substance of the medulla, pons, and mesencephalon.
Feeding reflexes, such as salivation and licking of the lips in response to the taste of food, are controlled by areas in
the medulla, pons, mesencephalon, amygdala, and hypothalamus.
Ten of the 12 cranial nerves (CN III–XII) arise in
brain stem.
What are the cranial nerves that arise in the brain stem
CN III–XII
These cranial nerves CN III–XII carry
sensory information to the brain stem and motor information away from it.
What is the rostral extension of the spinal cord
Medulla
Medulla contains
autonomic centers that regulate breathing and blood pressure.
centers that coordinate swallowing, coughing, and vomiting reflexes.
Vomiting coughing and swallowing is coordinated by
Medulla
Pons is ….to the medulla
Rostal
Pons working with centers in the medulla, participates in
balance and maintenance of posture and in regulation of breathing.
Pons functions
participates in balance and maintenance of posture and in regulation of breathing.
relays information from the cerebral hemispheres to the cerebellum.
The midbrain is … to the pons
rostral
Midbrain participats in …. and contains……
control of eye movements.
relay nuclei of the auditory and visual systems.
cerebellum
foliated (“leafy”) structure that is attached to the brain stem and lies dorsal to the pons and medulla.
The functions of the cerebellum are
coordination of movement, planning and execution of movement, maintenance of posture, and coordination of head and eye movements.
integrates (combines) sensory information about position from the spinal cord, motor information from the cerebral cortex, and information about balance from the vestibular organs of the inner ear.
cerebellum is conveniently positioned between
the cerebral cortex and the spinal cord,
Together, ….. form the diencephalon
the thalamus and hypothalamus
Diencephalon means
between brain.”
location of the thalamus and hypothalamus
between the cerebral hemispheres and the brain stem.
The thalamus function
processes almost all sensory information going to the cerebral cortex and almost all motor information coming from the cerebral cortex to the brain stem and spinal cord.
Hypothalamus lies …. to the thalamus
Ventral
Hypothalamus functions
contains centers that regulate body temperature, food intake, and water balance.
controls the hormone secretions of the pituitary gland.
The hypothalamus is
an endocrine gland that controls the hormone secretions of the pituitary gland.
How does the hypothalamus act as a gland
The hypothalamus secretes releasing hormones and release-inhibiting hormones into hypophysial portal blood that cause release (or inhibition of release) of the anterior pituitary hormones.
• The hypothalamus also contains the cell bodies of neurons of the posterior pituitary gland that secrete antidiuretic hormone (ADH) and oxytocin.
The hypothalamus also contains the cell bodies of neurons of …. that secretes ………..
posterior pituitary gland antidiuretic hormone (ADH) and oxytocin.
……. joins the pituitary gland and hypothalamus
Infundibular gland
The cerebral cortex is considered
an extremely large memory storehouse.
The cortex never functions alone but always in association with
lower centers of the nervous system.
the cerebral cortex is essential for most of
our thought processes
The cerebral cortex converts functions of the lower regions to
determinative and precise operations.
What initiates wakefulness in the cerebral cortex
lower brain centers
What happens when lower brain centers initiate wakefulness in the cerebral cortex
opening its bank of memories to the thinking machinery of the brain.
cerebral hemispheres consist of
the cerebral cortex, an underlying white matter, and three deep nuclei
What are the three deep nuclei-of cerebral hemispheres
basal ganglia, hippocampus, and amygdala
The functions of the cerebral hemispheres are
perception, higher motor functions, cognition, memory, and emotion.
Cerebral corte
convoluted (coiled) surface of the cerebral hemispheres
Four lobes of cerebral cortex
frontal, parietal, temporal, and occipital.
Cerebral cortex lobes are separated by
Sulci or grooves
Cerebral cortex functions
receives and processes sensory information and integrates motor functions.
These sensory and motor areas of the cortex are further designated as …….. depending on ……..
“primary,” “secondary,” and “tertiary,”
how directly they deal with sensory or motor processing.
The primary areas of cerebral cortex are the most …… and involve the ……. number of synapses
direct and involve the fewest number of synapses
tertiary areas of cerebral hemispheres require
most complex processing and involve the greatest number of synapses.
Association areas function
integrate diverse information for purposeful actions.
the limbic association area is involved in
motivation, memory, and emotions.
1) The primary motor cortex contains….
Which projects …..
the upper motoneurons, which project directly to the spinal cord and activate lower motoneurons that innervate skeletal muscle
The primary sensory cortex consist of
the primary visual cortex, primary auditory cortex, and primary somatosensory cortex
The primary sensory cortex receives information from
from sensory receptors in the periphery, with only a few intervening synapses.
Secondary and tertiary sensory and motor areas surround
the primary areas
Secondary and tertiary sensory and motor areas functions
are involved with more complex processing by connecting to association areas.
There are ….. deep nuclei of the cerebral hemispheres
three
There are three deep nuclei of the cerebral hemispheres they are
Basal ganglia, hippocampus, and amygdala.
The basal ganglia consist of
the caudate nucleus, the putamen, and the globus pallidus.
The basal ganglia function
receive input from all lobes of the cerebral cortex and have projections, via the thalamus, to the frontal cortex to assist in regulating movement.
The hippocampus and amygdala are part of the …. system.
limbic
The hippocampus function
Involved in memory
amygdala function
involved with the emotions and communicates with the autonomic nervous system via the hypothalamus (e.g., effect of the emotions on heart rate, pupil size, and hypothalamic hormone secretion).
The simplest synapses are
one-to-one connections consisting of a presynaptic element (e.g., motoneuron) and a postsynaptic element (e.g., skeletal muscle fiber).
many synapses are more complicated and use synapses in …… to integrate converging information.
relay nuclei
Relay nuclei are found throughout the CNS, but they are especially prominent in
the thalamus.
Relay nuclei contain several different types of neurons including
local interneurons and projection neurons.
Almost all information going to and coming from the cerebral cortex is processed in
thalamic relay nuclei.
The projection neurons function
extend long axons out of the nuclei to synapse in other relay nuclei or in the cerebral cortex.
in the somatosensory system, the topographic information is represented as
sensory homunculus in the cerebral cortex
In the visual system, the topographic representation is called …., in the auditory system it is called ….., and so forth.
retinotopic
tonotopic
Almost all sensory and motor pathways are
bilaterally symmetric
sensory or motor activity on one side of the body is relayed to ……cerebral hemisphere
the contralateral
Pathway crossing of CNS is called
decussations
commissures
Areas of the brain that contain only decussating axons
corpus callosum
the commissure connecting the two cerebral hemispheres
visual system pathways
mixed, having both crossed and uncrossed pathways.
half of the axons from each retina cross to the contralateral side and half remain ipsilateral.
Visual fibers that cross do so in
the optic chiasm.
Nerve fibers are classified according to
their conduction velocity, which depends on the size of the fibers and the presence or absence of myelination.
the larger the fiber, the higher the
conduction velocity.
Conduction velocity also is increased by the presence of
a myelin sheath around the nerve fiber.
Thus, large myelinated nerve fibers have the …. conduction velocities, and small unmyelinated nerve fibers have the …. conduction velocities.
fastest
slowest
