CNS brain Flashcards
(93 cards)
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Intro
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Brain and spinal cord - evaluating incoming information and formulating responses to changes that threaten our homeostatic balanace
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Protective coverings
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- Bone: cranial bones encase the brain and vertebrae encase the spinal cord 2. Membranes: coverings of nervous tissue known as meninges
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Meninges
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Dura mater > arachnoid mater > pia mater
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Dura mater
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Made of strong, white, fibrous tissue - connected to periosteum of cranium
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Arachnoid mater
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- delicate, cobweb-like layer that lies between the dura mater and the pia mater - pia mater adheres to the outer surface of the brain and spinal cord
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Meningeal spaces
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Between and around the meninges - epidural - subdural - subarachnoid space
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Epidural space
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- located immediately outside the dura mater, but inside the bony coverings - contains a supporting cushion of fat and other connective tissues - because it is continuous with periosteum on the interior surface of the cranial bones, no epidural space is normally present in the brain
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Epidural injections
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Targeted injection to anesthetize a region of the spine - nerve roots around this region will be anesthetize as well
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Meningitis
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Inflammation of the meninges caused by either a virus or bacterial infection - symptoms are the same for either viral or bacterial meningitis - differential diagnosis is through culturing CSF via a spinal tap
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Subdural space
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Located between dura mater and arachnoid mater - contains a small amount of lubricating serous fluid
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Subarachnoid space
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Located between arachnoid mater and pia mater - contains a significant amount of cerebral fluid
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Meninges of the spinal cord
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Continue down the spinal column
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Film termínale
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Formed from pia mater - around S3, the film termínale blends with the dura mater to form a fibrous cord that is continuous with the periosteum of the coccyx
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cerebrospinal fluid
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Provides a supportive and protective cushion around and within the brain and spinal cord - reservoir of circulating fluid that, alon with blood, the brain monitors for changes in the internal environment - found within the subarachnoid space, around the brain and spinal cord, and within the cavities and canals of the brain and spinal cord - fills up the ventricles
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Formation of CSF
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Occurs mainly by separation of fluid from blood in the choroid plexuses - network of capillaries that project from the pia mater into the lateral ventricles and into the 3 and 4 ventricles
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Circulation of CSF
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Blood is filtered by the choroid pexuses and CSF is produced - after circulating through the ventricles of the brain, the central canal, and the subarachnoid spaces, it is then absorbed back into the blood
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Medulla oblongata
- just above the foramen magnum and extends to inferior border of the pons - composed of all ascending and descending tracts (white matter) and gray matter called the regular foramen - pyramids: 2 bulges of white matter on the central surface - olive: oval projection appearing one on each side of the ventral surface lateral to the pyramids
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Reticular foramen
Contains nuclei (clusters of cell bodies) - some are called control centers for cardiac, respiratory, and vasomotor control - contains vital reflex centers (cardiac, respiratory, vasomotor) and non vital reflexes (vomiting, coughing, sneezing, hiccuping, and swallowing)
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Pons
Bridge: fibers run transversely across the pons into the cerebellum - lies superior to the medulla and inferior to the midbrain - composed of white matter and reticular formation - contains centers for reflexes mediated by cranial nerves V, VI, VII, VIII - contains the pneumotaxic centers that help regulate respiration
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Midbrain
Located superior to the pons and inferior to the cerebellum - composed of both white matter and reticular formation - cerebral peduncles (anterior): extend through the midbrain and conduct impulses esteem the midbrain and cerebrum - tectum (posterior): corpora quadrigemina (2 inferior and 2 superior) - red nucleus - substantial negra
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Cerebellum
Little brain - second largest part of the brain (after cerebrum) but contains more neurons that all other parts of the nervous system combined
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Functions of cerebellum
- acts with the cerebral corte to produce skilled movements by coordinating the activities of groups of muscles - helps control posture; operates at a subconscious level to make movements efficient and coordinated - controls skeletal muscles to maintain balanace - coordinates incoming sensory information from skeletal muscles
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Diencephalanon
Between brain - thalamus and hypothalamus - pineal gland: part of the epithalamus (various small nuclei just outside the thalamus and hypothalamus) - optic chiasma
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Thalamus
Dumbbell shaped mass of gray matter made up of many nuclei - each lateral mass forms one lateral wall of the 3rd ventricle - major center for relaying sensory input to cerebral cortex from the spinal cord, brain stem, cerebellum, basal nuclei, and various parts of the cerebrum
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Functions of thalamus
- impulses from receptors produce conscious recognition of crude (non critical) sensations of pain, temperature, and touch - cell bodies in nuclei of the thalamus relay various sensory impulses (except possibly olfactory) to the cerebrum - associates sensory impulses with feelings of pleasantness/un - relays info from cerebellum and basal nuclei to motor area of cerebral cortex - plays a part in arousal or alerting mechanism - plays a part in production of complex reflex movements
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Hypothalamus
Major regulator of the ANS (HR, respiration’s, GI tract, urinary bladder) - major regulator of homeostasis; it receives input that is interpreted to correct for changes in osmotic pressure, hormone concentrations, and blood temperature - it affects emotions of afforestation, pain, and pleasure - regulates thirst and hunger responses - controls body temp via vasoconstriction, dilation, and sweating
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Pineal gland
- pine nut - important part of the body’s biological clock mechanism - sets/regulates the body’s biological clock - secretes hormones, the most noteable is melatonin (sleep inducer)
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Cerebrum
Largest and uppermost division of the brain - contains bulk of brain’s mass - right and left hemisphere
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Info about cerebrum
Cerebral cortex is outer rim and composed of gray matter. Contains more than 1 billion neurons - surface of the cerebral cortex is irregular, each ridge is called a gyrus - between adjeacent Geri lie either shallow grooves called Sullivan, or deeper grooves called fissures (divide hemispheres into lobes)
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Lobes of cerebrum
1. Frontal lobe: control of emotion 2. Parietal lobe: processes senses other than hearing and vision 3. Temporal lobe: processes hearing 4. Occipital lobe: processes vision 5. Ínsula: riel island, hidden from view buried in lateral fissure
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Longitudinal fissure
The deepest groove; division of cerebrum into right and left hemis
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Central sulcus
Groove between the frontal and parietal lobes
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Lateral fissure
Deep groove between the temporal lobe and the frontal and parietal lobes
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Parietooccipital fissure
Groove that separates the parietal lobe from the occipital lobe
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Cerebral tracts and basal nuclei
Cerebral tracts are under the cerebral cortex - white matter - 3 types: projection, association, commissural
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Projection tracts
Extensions of ascending (sensory) spinothalamic tracts and descending (motor) corticospinal tracts
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Association tracts
Most numerous - extend from one convolution to another in the same hemisphere
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Commissural tracts
Extend from a point in one hemisphere to a point in the other hemisphere ( compose the corpus callosum)
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Corpus callosum
Nerve tissue connecting the right and left cerebral hemispheres - much of the inter-hemispheric communication in the brain is conducted across this
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Basal nuclei
Islands of gray matter that lie deep in white matter in each hemisphere - play a role in regulating initiation and termination of movement - helps regulate muscle tone required for body movement - control subconscious contraction of skeletal muscles (arm swing) - help initiate and terminate attention, memory, planning - help regulate emotional behaviors
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Inter capsule
White matter connecting nuclei (v close to basal nuclei)
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Functions of cerebral cortex
Certain areas of the cerebral cortex engage predominantly in one particular funciton - function of each region depends on structures with which it communicates
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Cerebral localization
Many cerebral cortex functions have a typical location
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Cerebral plasticity
Localization of funciton varies from person to person and even at different times in an individual’s life when the brain has sustained damage
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Postcentral gyrus
Primary somatic sensory area - receives impulses from receptors activated by hear, cold, and touch stimuli - cortex contains a somatic sensory may of the body (sensory homunculus)
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Precentral gyrus
Primary somatic motor area - impulses from neurons in this area descend over motor tracts and stimulate skeletal muscles
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Transverse gyrus
Primary auditory area (sensory)
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Occipital lobe
Primary visual area (sensory)
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Broca’s area
Motor speech area, executive (motor)
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Wernicke’s area
Sensory speech area (receptive)
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Integrative functions of cerebral cortex
Consist of all events that take place in the cerebrum between its reception of sensory impulses and its sending out of motor impulses - conscious - language - emotions -memory
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Consciousness
Sácate of awareness fo one’s self, one’s environment, and other humans - very little is known about the neural mechanisms that produce consciousness - depends on excitation of cortical neurons by impulses conducted by the reticular activating system
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Reticular activating system
Centers in the brainstem’s reticulat formation that receive impulses from the spinal cord anda relay to the thalamus. From the thalamus to all parts of cerebral cortex - sensory or ascending - functions: arousal or alerting system, crucial for maintaining consciousness, alertness and attentiveness
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Language
The ability to speak and write workds, the ability to understand spoken and written words - speech centers are located in the frontal, parietal, and temporal lobes - the left cerebral hemisphere contains language areas in about 97% of the population - lesions in the speech centers give rise to language defects: aphasia or dysphasia
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Emotions
Both the subjective experiencing and objective expression of emotions, involve the cerebrum’s limbic system (emotional brain)
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Limbic system
To bring about normal expression of emotions parts of the cerebral cortex other than the limbic system must also function - cingulate gyrus - hippocampus - and primary connections with thalamus, amígdala and more
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Stress
Hippocampus, amígdala, and limbic system are affected by prolonged stress
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Hippocampus
Primary role in converting short-term to long-term memory - regulates activity of the hypothalamus-pituitary-adrenal axis (HPA) by shutting down the stress response when it is no longer needed - prolonged stress interferes with memory, spatial navigation, and the ability to regulate the HPA axis - prolonged stress can cause atrophy of the hippocampus
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Amygdala
Associated with emotions, survival instincts, and memory - plays a significant role in fear response - prolonged stress seems to cause hypersensitivity in the amygdala (increases anxiety and reaction to fear) - prolonged stress results in enlargement of the amygdala
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Prefrontal cortex (stress)
Responsible for planning, logic, self-regulation, and higher mental functioning - stress results in shrinkage and loss of dendrites in this area - results in impaired decision making, self regulation, and higher mental function, and decreases the ability to cognitively adapt - allows the amygdala to go un key and creates a viscous loop!
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Memory
- the cortex is capabel of stoking and retrieving both short-term memory and long-term memory - the temporal, parietal, and occipital lobes are amount the areas responsible for short and long term memory - research findings indicate that the cerebrum’s limbic system pays a key role in memory - the hippocampus pays a primary role in converting short-term to long-term memory
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Left hemisphere
- Language functions - analytic and local thought - pattern sequencing
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Right hemisphere
- perception of auditory material - perceiving and visualizing spatial relationships - creativity
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