CNS brain Flashcards
Intro
Brain and spinal cord - evaluating incoming information and formulating responses to changes that threaten our homeostatic balanace
Protective coverings
- Bone: cranial bones encase the brain and vertebrae encase the spinal cord 2. Membranes: coverings of nervous tissue known as meninges
Meninges
Dura mater > arachnoid mater > pia mater
Dura mater
Made of strong, white, fibrous tissue - connected to periosteum of cranium
Arachnoid mater
- 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
Meningeal spaces
Between and around the meninges - epidural - subdural - subarachnoid space
Epidural space
- 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
Epidural injections
Targeted injection to anesthetize a region of the spine - nerve roots around this region will be anesthetize as well
Meningitis
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
Subdural space
Located between dura mater and arachnoid mater - contains a small amount of lubricating serous fluid
Subarachnoid space
Located between arachnoid mater and pia mater - contains a significant amount of cerebral fluid
Meninges of the spinal cord
Continue down the spinal column
Film termínale
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
cerebrospinal fluid
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
Formation of CSF
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
Circulation of CSF
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
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
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)
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
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
Cerebellum
Little brain - second largest part of the brain (after cerebrum) but contains more neurons that all other parts of the nervous system combined
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
Diencephalanon
Between brain - thalamus and hypothalamus - pineal gland: part of the epithalamus (various small nuclei just outside the thalamus and hypothalamus) - optic chiasma
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
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
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
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)
Cerebrum
Largest and uppermost division of the brain - contains bulk of brain’s mass - right and left hemisphere
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)
Lobes of cerebrum
- 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
Longitudinal fissure
The deepest groove; division of cerebrum into right and left hemis
Central sulcus
Groove between the frontal and parietal lobes
Lateral fissure
Deep groove between the temporal lobe and the frontal and parietal lobes
Parietooccipital fissure
Groove that separates the parietal lobe from the occipital lobe
Cerebral tracts and basal nuclei
Cerebral tracts are under the cerebral cortex - white matter - 3 types: projection, association, commissural
Projection tracts
Extensions of ascending (sensory) spinothalamic tracts and descending (motor) corticospinal tracts
Association tracts
Most numerous - extend from one convolution to another in the same hemisphere
Commissural tracts
Extend from a point in one hemisphere to a point in the other hemisphere ( compose the corpus callosum)
Corpus callosum
Nerve tissue connecting the right and left cerebral hemispheres - much of the inter-hemispheric communication in the brain is conducted across this
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
Inter capsule
White matter connecting nuclei (v close to basal nuclei)
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
Cerebral localization
Many cerebral cortex functions have a typical location
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
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)
Precentral gyrus
Primary somatic motor area - impulses from neurons in this area descend over motor tracts and stimulate skeletal muscles
Transverse gyrus
Primary auditory area (sensory)
Occipital lobe
Primary visual area (sensory)
Broca’s area
Motor speech area, executive (motor)
Wernicke’s area
Sensory speech area (receptive)
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
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
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
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
Emotions
Both the subjective experiencing and objective expression of emotions, involve the cerebrum’s limbic system (emotional brain)
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
Stress
Hippocampus, amígdala, and limbic system are affected by prolonged stress
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
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
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!
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
Left hemisphere
- Language functions - analytic and local thought - pattern sequencing
Right hemisphere
- perception of auditory material - perceiving and visualizing spatial relationships - creativity
