Chapter 9: The Central Nervous System Flashcards
- brain and spinal cord
- Responsible for everything we perceive, do, feel, and think
- coordinating the activities of all our organ systems
- Necessary for the maintenance of homeostasis
central nervous system
-Contains 1011 neurons (100 billion)
Contains 1014 synapses (100 trillion)
central nervous system
the restructuring of the brain networks in response to sensory input and experience
plasticity
- Involved in memory
- Affective behaviors- related to feeling and emotion
- Cognitive behaviors- linked to thinking
plasticity
what is involved in the physical support of the CNS?
-bone
~cranium
~vertebral column
-meninges
~dura mater
~arachnoid mater
~pia mater
-cerebrospinal fluid (CSF)
~cerebroventricles
~clear watery fluid bathing the CNScushion the delicate brain tissue
The meninges and extracellular fluid
-Secreted by ependymal cells of the choroid plexus
~Circulates through ventricles to subarachnoid space
~reabsorbed by arachnoid villi
cerebrospinal fluid
what are the functions of cerebrospinal fluid?
- cushions brain
- Maintains a stable interstitial fluid environment
transports ions and
nutrients from the blood
into the cerebrospinal fluid.
choroid plexus
total volume of CSF
125-150 mL
how much CSF does the choroid plexus produce a day?
400-500 mL
how many times is the CSF recycled?
3 times per day
consist of first and second ventricles
lateral ventricles of the brain
extend through the brain stem
and connect to the central canal
that runs through the spinal cord
third and fourth ventricles of the brain
- accounts for 2% of total body weight (3-4 lbs)
- receives 15% of blood supply
CNS
what is the metabolic rate of the CNS?
- high metabolic rate
- Brain uses 20% of oxygen consumed by body at rest
- Brain uses 50% of glucose consumed by body at rest
what does the CNS depend on for energy?
blood flow
depend on aerobic glycolysis
neurons of CNS
Passes freely across blood–brain barrier carriers
oxygen
move glucose from plasma into the brain interstitial fluid (CNS)
membrane transporters
- Sites of exchange between blood and interstitial fluid
- Thin: single layer of endothelial cells
- Diffusion
capillaries of blood brain barrier
- Special anatomy consisting of CNS capillaries that limit exchange
- Protects brain from toxic water soluble compounds and pathogens
blood brain barrier
cross the blood-brain barrier
small lipid soluble molecules
what two regions lack the blood brain barrier?
- hypothalamic-hypophyseal portal system (getting hormones into circulation)
- vomiting center of medulla oblongata (monitoring for toxins)
secrete
paracrines that
promote tight
junction formation
astrocyte foot processes
prevent solute
movement between
endothelial cells.
tight junctions
- found in CNS
- unmyelinated nerve cell bodies
- dendrites
- axon terminals
- clusters of cell bodies in the CNS are nuclei
gray matter
-found in CNS
-myelinated axons
-axon bundles connecting CNS regions are tracts
~tracts are equivalent to nerves in PNS
white matter
what are the fibers in the white matter in the brain?
- projection fibers
- association fibers
- commissural fibers
Connect cerebral cortex with lower levels of brain or spinal cord
projection fibers
Connect two areas of cerebral cortex on same side of brain
association fibers
Connect same cortical regions on two sides of brain
commissural fibers
primary location of commissural fibers
corpus callosum
- cylinder of nerve tissue (44cm long x 1.4 cm diameter)
- continuous w/ brain
- surrounded by vertebral column
- origin of spinal nerves
spinal cord
what are the functional halves of gray matter?
- dorsal: sensory functions
- ventral: motor functions
what does white matter form?
- ascending tracts
- descending tracts
initiates a response without input from the brain
spinal reflex
consists of sensory and motor nuclei
gray matter
in the spinal cord, it consists of tracts of axons carrying information to and from the brain
white matter
- oldest and most primitive region of the brain
- 11 of 12 cranial nerves originate from here
brain stems
can include sensory fibers, efferent fibers, or both (mixed nerves)
cranial nerves
- is a network that extends throughout the brainstem
- many nuclei are associated with this
reticular formation
controls wakefulness, sleep, muscle tone, pain modulation
reticular formation
- part of the brain stem
- transition from the spinal cord to the brain
- includes somatosensory & corticospinal tracts, pyramids
medulla
carry sensory info to the brain
somatosensory tracts
carry info from cerebrum t spinal cord
corticospinal tracts
crossing of corticospinal tracts so each side of the brain controls the opposite side of the body
pyramids
controls involuntary functions
medulla
what are the involuntary functions that the medulla controls?
- blood pressure
- heart rate
- breathing
- swallowing
- vomiting
- part of the brain stem
- Relay station between cerebrum and cerebellum, also coordinates control of breathing
pons
- part of the brain stem
- Eye movement, also relays signals for hearing and seeing reflexes
midbrain
what are the parts of the brain stem?
- medulla
- pons
- midbrian
- movement coordination
- equilibrium and balance
cerebellum
what does the diencephalon consist of?
- thalamus
- hypothalamus
- pituitary
- pineal gland
relay station and integration of sensory input
thalamus
control of homeostasis, hunger, thirst, endocrine function
hypothalamus
the site of higher brain functions
cerebrum
connects the two hemispheres of the cerebrum
corpus callosum
what does the gray matter consist of in the cerebrum?
- cerebral cortex
- basal ganglia
- limbic system
cognitive functions (sensory perception, thought, reasoning, judgement, memory, imagination, intuition)
cerebral cortex
control of movement
basal ganglia
link between cognitive functions and more primitive emotions such as fear
limbic system
what does the limbic system consist of?
- amygdala
- hippocampus
emotion and memory
amygala
learning and memory
hippocampus
plays a role in emotion
cingulate gyrus
what are the 3 specializations of the cerebral cortex, from a functional viewpoint?
- sensory areas
- motor areas
- association areas
- receive sensory input
- Sensory input translated into perception (awareness)
sensory areas of cerebral cortex
direct skeletal muscle movement
motor areas of cerebral cortex
- Integrate information from sensory and motor areas
- Can direct voluntary behaviors
association areas
coordinates vision
occipital lobe
coordinates hearing
temporal lobe
coordinates info from other association areas; controls some behaviors
frontal lobe
sensory information from skin, musculoskeletal system, viscera and taste buds
parietal lobe
coordinates taste
gustatory cortex
coordinates smell
olfactory cortex
- consists of:
- primary motor coretex
- motor association area (premotor cortex)
- prefrontal association area
frontal lobe
- consists of:
- primary somatic sensory cortex
- sensory association area
parietal lobe
- consists of:
- visual association area
- visual cortex
occipital lobe
- consists of:
- auditory cortex
- auditory association area
temporal lobe
cerebral dominance
cerebral lateralization
Movement left side of body, sensory perception left side, spatial orientation, creativity, music, dream imagery, philosophy and intuition
right brain
Movement right side, sensory right side, logic and analytical processing, strong language capabilities and math skills
left brain
how do we study the functional areas of the brain?
- patients who have neurological defects
- suffered from wounds/injury
- in vivo imaging of brain activity
electrical activity measured by electrode on scalp
Electroencephalography (EEG)
radioactive labeled glucose emits positively charged particles
Positive emission tomography (PET)
increased blood flow
Functional magnetic resonance imaging (fMRI)
- can be integrated in the spinal cord
- usually send sensory info to the brain
simple reflexes
where does most sensory info continue to?
cerebral cortex
what is the primary somatic sensory cortex also known as?
parietal lobe
- Termination point of pathways from skin, musculoskeletal system, and viscera
- Somatosensory pathways
Primary somatic sensory cortex (parietal lobe)
what do Somatosensory pathways carry info about?
- touch
- temperature
- pain
- itch
- body position
what are the special senses that have devoted brain regions?
- visual cortex (occipital lobe)
- auditory cortex (temporal lobe)
- olfactory cortex (temporal lobe)
- gustatory cortex (frontal lobe)
extend from sensory areas to association areas, which integrate stimuli into perception
neural pathways
often very different from the actual stimulus
the perceived stimulus
what is the motor system of the brain?
efferent division of the PNS
what are the 3 major types of the efferent division?
- skeletal muscle movement
- neuroendocrine signals
- visceral responses (smooth & cardiac muscle & glands)
in the somatic motor divsion
skeletal muscle movement
located in the hypothalamus and adrenal medulla
neuroendocrine signals
located in the autonomic division
visceral responses
involved in emotions
CNS structures
what are the specific CNS structures involved in emotion?
- limbic system (amygdala & hypothalamus)
- midbrian
- cerebral cortex
associated with fear and anxiety
amygdala
associated with anger and aggression
hypothalamus
the seat of judgment, intent, and control over expressions of emotions.
prefrontal cortex
similar to emotions but longer lasting
mood
- the impulse that drives out actions
- Internal signals that shape voluntary behaviors
- some related to emotions
motivation
when do motivated behaviors stop?
when a person has reached a certain level of satiety
linked to dopamine
pleasure and addictive behaviors
work with autonomic and endocrine responses
motivation
what are the two broad types of learning?
- associative learning
- nonassociative learning
when 2 stimuli are associated with each other (Pavlov’s canine)
associative learning
change in behavior relative to a single stimulus
- habituations
- sensitization
nonassociative learning
decrease response to irrelevant stimuli
habituations
associating a stimuli with significant outcome
sensitization
when do we become sensitized?
when the circumstances are of impending danger
when do we become habituated?
when the circumstances are unimportant
retain and recall information
memory
what are the main two types of memory?
- short term
- long term
working memory (road clear)
short term memory
what are the subdivisions of long term memory?
- consolidation
- reflexive/procedural
- declarative
short term to long term
consolidation memory
- *is the memory of learned motor skills (does not require conscious thought)
- cerebellum, basal nuclei, pons
- memories you use while riding a bike
reflexive or procedural memory (implicit)
- the memory of learned experiences, facts and events
- letters of the alphabet, birthday
- hippocampus
declarative memory (explicit)
what is long term memory stored in?
memory traces in the cerebral cortex
what are the two language areas in the brain?
- wernicke’s area
- broca’s area
- Language comprehension (understanding language in many forms sound, written words , or even hand signals)
- Wernicke’s aphasia
wernicke’s area
- Language expression (ability to speak or write words)
- Broca’s aphasia
broca’s area
A ganglion in the PNS is equivalent to ________ in the CNS.
a nucleus
Neural tissue has minimal extracellular matrix so support and protection come from external sources. Which of the following is/are involved in this support and protection?
- cerebrospinal fluid
- meninges
- glial cells
- outer casing of bone
Except in periods of starvation, the only fuel source for the brain is/are _______ so 15% of blood pumped by the heart goes to the brain to supply enough _______ from which to generate ATP.
glucose; oxygen
Which of the following brain imaging techniques uses radioactive-labeled glucose?
Positive emission tomography (PET)
