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BMS 250 Lecture
Chapter 13
Term | Definition |
---|---|
4 regions of brain | cerebrum, diencephalon, brainstem, cerebellum |
Gyri | "mountains", elevations in brain |
Sulci | "valleys", depressions in brain |
Anterior | rostral |
posterior | caudal |
superior | dorsal |
Inferior | ventral |
Gray matter | neuronal cell bodies, dendrites, unmyelinated axons, internal clusters of gray matter= cerebral nuclei |
White matter | myelinated axons |
Protection and support of the brain | cranial meninges, cerebrospinal fluid within ventricles, blood-brain barrier |
Cranial meninges | 3 layers of connective tissue: pia mater, arachnoid mater, dura mater |
Pia mater | innermost layer of cranial meninges, thin, areolar connective tissue, adheres very closely to the brain, covers small blood vessels |
Arachnoid mater | external to pia mater, delicate web (Collagen and elastic fibers), support cerebral arteries and veins; contains arachnoid space with collagen fibers that contains cerebrospinal fluid |
Dura mater | strongest, most superficial cranial meninges composed of irregular connective tissue with two parts: periosteal layer and meningeal layer; sometimes contains subdural space |
Traumatic brain injury | brain bleed in either epidural hematoma or subdural hematoma |
Brain ventricles | four ventricles in the brain lined with ependymal cells and contains cerebrospinal fluid, connected to each other and the central canal of the spinal cord |
Lateral ventricles | 2 ventricles spanning cerebrum with a channel connecting to a third ventricle by interventricular foramen |
Fourth ventricle | located between brainstem and cerebellum, connects to central canal of spinal cord, connects to third ventricle by cerebral aqueduct |
Third ventricle | found between corpus callosum and lateral ventricles |
Cerebrospinal fluid (CSF) | clear, colorless fluid that circulates within ventricles and subarachnoid space, functions: buoyancy, protection, extracellular chemical stability |
What is the cerebrospinal fluid formed by? | choroid plexus |
Choroid plexus | specialized tissue within each ventricles, ependymal cells in contact with blood capillaries, blood plasma is filtered from capillaries and modified by ependymal cells |
CSF circulation and removal | flowsfrom lateralventricle into 3rdventricle&through cerebralaqueduct into 4thventricle, passes into subarachnoidspace&sacral canalofSC, flows through subarachnoidspace for buoyancy, excessCSF flowsinto arachnoidvilli &drains into duralvenoussinuses |
Blood-brain barrier | regulates entry of substances into brain from general circulation, formed by specialized capillaries and astrocytes: endothelial cells have tight junctions, capillary walls are thicker than normal, perivascular feet of astrocytes wrap around capillaries |
What can enter through the blood-brain barrier? | respiratory gases, small lipophilic molecules, small polar molecules |
What cannot enter through blood-brain barrier? | most pathogens, charged, large, hydrophilic molecules |
Cerebrum | composed of 2 halves: left and right cerebral hemispheres separated by longitudinal fissure |
5 lobes of the brain | frontal, parietal, temporal, occipital, insula |
Parts of cerebrum | corpus callosum, cerebral cortex |
Corpus callosum | primary method of communication between hemispheres |
Cerebral cortex | "bark" forming outer layer of cerebrum; composed of 3 areas- primary motor cortex, motor association areas, sensory areas |
Primary motor cortex (precentral gyrus) | found in frontal lobe; function and initiate voluntary movement |
Motor homunculus | topographic map with distorted portions that reflect the amount of cortex devoted to motor activity of each body part |
Contralateral projections | motor neurons project to opposite side of body (in brain stem or spinal cord) |
Motor association areas | premotor cortex, frontal eyefield, motor speech area (Broca's area) |
Premotor cortex | coordinates learned skilled motor tasks |
Broca's aphasia | speech is understood, but difficulty in articulating due to muscles |
Wernicke's aphasia | fluent articulation, lack of understanding of what is being said |
Sensory areas | primary somatosensory cortex, somatosensory association area, primary visual cortex, visual association area, primary auditory cortex, auditory association area, primary olfactory cortex, primary gustatory cortex |
Primary somatosensory cortex | receives sensations of touch and temperature |
Somatosensory association area | interprets texture, shape, or pressure of current sensation and integrates current sensation with previous experiences |
Primary visual cortex | receives and processes incoming visual information |
Visual association area | analyzes color, movement, and form to identify what we are seeing |
Primary auditory cortex | receives and processes incoming sounds and auditory information |
Auditory association area | interprets characteristics of sound, saves memories of past sounds |
Primary olfactory cortex | processes information related to smell |
Primary gustatory cortex | processes information related to taste |
Function of frontal lobe | movement |
Function of parietal lobe | touch and temperature |
Function of temporal lobe | audition and olfaction |
Function of occipital lobe | vision |
Function of insula | gustation |
Diencephalon | found "in between brain", consists of epithalamus, thalamus, and hypothalamus |
Epithalamus | contains pineal gland (secretes melatonin) which helps regulate circadian rhythms |
Thalamus | relay center for incoming sensory information, filters and forwards a small portion of incoming sensory information to the cerebrum; contains 12 thalamic nuclei with axons that project to a particular area of cerebral cortex |
Hypothalamus | control of autonomic nervous system (influences heart rate, blood pressure, digestive activities, &respiration, control of endocrine system, regulates body temp, control of emotional behavior, food intake, and water intake, regulation of circadian rhythms |
Brain stem | consists of midbrain, pons, and medulla oblongata, bidirectional passageway for tracts extending between the brain and spinal cord, contains autonomic and reflex centers necessary for survival and many cranial nuclei |
Midbrain | contains cerebral peduncles, substantia nigra, tectum, and tegmentum |
Cerebral peduncles | descending axons of motor neurons (corticospinal tracts) |
Substantia nigra | dopaminergic neurons involved in movement and reward |
Tectum | contains superior and inferior colliculi, 2 pairs of sensory nuclei, relay stations in auditory and visual processing, and relays voluntary and involuntary eye movement (cranial nerve III and IV) |
Superior colliculi | part of tectum that is the visual reflex center that usually tracks moving objects and controls visual reflexes |
Inferior collilculi | part of tectum that is the auditory reflex center that deals with sound localization and controls auditory reflexes |
Pons | pontine respiratory center that regulates skeletal muscles of breathing along with medullary respiratory center, has superior olivary nuclei that deals with sound localization, contains CN V, VI, VII, VIII |
Tegmentum | red nuclei and reticular formation, integrates information from cerebrum and cerebellum, issues involuntary motor commands to the erector spinae muscles of the back (maintain posture) |
Medulla oblongata | sensory&motor tracts between brain&SC, contains autonomic centers: cardiac (regulate heart rate&contractile strength), vasomotor (regulates blood vessel diameter&blood pressure), & respiratory (regulate respiratory rate), contains CN VIII, IX, X, XI, XII |
Cerebellum | "little brain", function: fine-tune and coordinate movements, maintains equilibrium and posture |
What does cerebral dysfunction result in ? | ataxia and can be due to degeneration of drugs |
What do higher-order brain functions involve? | complicated networks of multiple structures working together for a common purpose; ex. emotion, personality, learning and memory, sleep, language, reasoning and judgement, intelligence |
Limbic system | processes and experiences emotions, consists of cingulate gyrus, formix, certain nuclei of the diencephalon, olfactory bulb and tract, amygdala, hippocampus, and parahippocampal gyrus |
Amygdala | responsible for fear response, aggression, emotion memory |
Hippocampus | responsible for storing memory and forming long-term memory |
Prefrontal cortex (PFC) | controls emotion expression, other roles include personality, planning, problem solving, complex thought, judgement, and decision making |