2 Major cell types
Neurons: functional unit (generates AP's)
Glial cells: non-neuronal cells that support neurons (doesn't generate AP's)
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| Term | Definition |
|---|---|
| 2 Major cell types | Neurons: functional unit (generates AP's) Glial cells: non-neuronal cells that support neurons (doesn't generate AP's) |
| Afferent/sensory division's components - PNS | Somatic sensory, Visceral, Special - All detection of stimuli |
| Efferent/motor division's components - PNS | Somatic motor (voluntary skeletal muscle), Autonomic motor (smooth/cardiac muscle/glands)(sympathetic, parasympathetic, enteric) |
| Astrocytes (glial cell) function | - physically support neurons - form BBB - form scar tissue (inhibits regen of severed axons) - recycle neuroT's - maintain electrolyte balance |
| Gray matter components | unmyelinated cell bodies, dendrites, axon terminals |
| White matter components | myelinated axons and few cell bodies |
| Tracts - white matter | bundle of axons connecting different regions of CNS |
| Protective elements of CNS | - Bone: skull, vertabrae - Meninges: dura, arachnoid, pia mater - CSF - Blood brain barrier |
| The Meninges + meningitis | dura: tough outer arachnoid: spidery intermediate pia: delicate inner meningitis: infection of meninges |
| Cerebrospinal Fluid (made by what and how does it travel) + hydrocephalus | 1. produced by choroid plexus 2. reabsorbed into venous blood 3. mechanical protection 4. electrolyte balance Hydrocephalus: reabsorption is blocked = accumulation of CSF |
| Blood Brain Barrier | - provides oxygen and glucose (brain has no glycogen stores) - transports molecules needed for brain |
| 3 main regions of the brain | cerebrum, cerebellum, brainstem |
| Cerebrum components | Corpus Callosum: nerves that connect R & L hemispheres Cerebral Cortex: outer layer folded into gyri and grooves called sulci |
| 4 major divisions of the diencephalon + functions | Thalamus: integrating center for sensory and motor info Epithalamus: pineal gland (melatonin) Hypothalamus: homeostasis, posterior pituitary (hormones) Subthalamus: movement |
| Components of the brainstem + functions | midbrain: eye movements, auditory/visual, substantia nigra pons: relay between cerebellum and cerebrum, breathing medulla oblongata: involuntary functions |
| Cerebellum + functions | - sensory inputs from spinal cord - motor commands from cerebral cortex - motor timing/scaling/coordination/learning - balance/gait - eye movements |
| Functions of the Limbic System + consists of ____ | learning, emotion, appetite (visceral function), sex, endocrine integration Consists of .... - thalamus, hypothalamus, basal ganglia, cingulate gyrus, hippocampus, amygdala |
| Spinal Cord Functions | - send sensory info from body to brain (dorsal) - send motor commands from brain to body (ventral) - coordinate reflexes (acts w/o signals from brain) - rhythmic movements (walking) |
| Section of the spinal cord | Dorsal roots: axons of aff neurons enter spinal cord Dorsal root ganglia: cell bodies of aff neurons ventral roots: axons of eff neurons leave spinal cord |
| Spinal cord gray matter | Horn: gray matter towards outside of spinal cord |
| Each half of gray matter is divided into....ABC | - dorsal (posterior) horn: cell bodies of interneurons - ventral (anterior) horn: cell bodies of efferent motorneurons supplying skeletal muscle - Lateral horn: cell bodies of autonomic neurons supplying smooth/cardiac muscle and glands |
| Spinal cord white matter | columns/funiculi: posterior/dorsal, lateral, anterior/ventral columns on each side tracts/fasciculi: subdivisions of each column |
| Difference between somatic and special senses | somatic: receptors for skin, muscles, joints, fascia, viscera - somatosensory: perception of touch, pressure, pain, temp, position, movement, vibration special: 5 senses, equilibrium (both), sight |
| Sensation vs. Perception + where is it processed | Sensation: awareness of stimulus Perception: sensation + understanding of meaning both processed in cerebral cortex |
| T/F: olfactory sensory info passes through thalamus on its way to cerebral cortex | F: goes to cerebrum instead |
| 5 major types of receptors | chemo, mechano, thermo, photo, noic(pain) |
| 2 types of sensory receptors | specialized: endings of diff axons Seperate: respond to stim and transmit via synapses |
| 4 fundamentals of sensory info | 1. Modality (stim type) 2. intensity 3. location 4. duration |
| Neural encoding: modality | - structure of receptor determines modality (labelled line codes = receptor projects along pathway to specific region) types of receptors: - tactile (meissners) corpuscle: light - tactile (merkels): touch - free nerve ending: pain - lamellated (pacinian): vibration and deep pressure - ruffini: warmth and mechano |
| Neural encoding: intensity | - increased intensity = membrane potential of aff axon increases - increases cause increased AP's (frequency coding) and uses more receptors (population coding) - changes in firing rate encodes stimulus properties (temporal pattern code) |
| Neural Encoding: Duration | - duration of action potentials in the sensory neuron - slowly adapting (tonic) receptors respond to stimulus the entire time - rapidly adapting (phasic) receptors fire when stimulus first received but stop if strength remains constant (steady state) - ex. cannot smell perfume after a bit The only way to create a new signal is to change intensity of stimulus |
| Neural encoding: Location | - different modalities travel along specific tracts in spinal cord towards brain - locating a stimulus depends on size/density of receptive field - lateral inhibition (CNS) focuses ascending sensory signals = enhances spatial acuity (can tell apart two different stimulus') Smaller receptive field = greater spatial acuity |
| Two-point discrimination | better on hands and face and worse on abdomen/proximal parts - density of receptors is higher in places with better 2-point discrimination - SA of sensory cortex is higher |
| Divergence | each sensory afferent sends branches to many CNS neurons |
| Convergence | a given CNS neuron receives inputs from many sensory afferents |
| Somatosensory cortex | recognizes where ascending sensory tracts originate (in parietal lobe) |
| Cortical association areas | - receives input from primary cortices |
| Presynaptic inhibition | - reduces transmitter release at synapse between 1st and 2nd order sensory neurons - inhibits specific sensations - lasts several milliseconds |
| Postsynaptic inhibition | - hyperpolarizes membrane of 2nd order sensory neuron - reduces effect of ALL synaptic inputs (non-selective) - less than 1 millisecond |
| How does the brain distinguish different types of information? | Labelled Line Codes |
| Why does phantom limb pain occur? | - somatic receptors receive stimuli, if afferent fibers are stimulated when approaching cortex, it travels the same than if somatic receptors were stimulated directly - after amputation, remaining afferent fibers still transmit like there were specialized to despite having no somatic receptors at beginning of afferent pathway |
| 3 classes of movements generated by motor systems | - reflexes: rapid, involuntary controlled by magnitude of stimulus - rhythmic motor behavior: initiation and termination, voluntary, once activated it becomes reflex-like (ex. walking) - voluntary |
| 3 organizational principles to create movement | - continuous flow of sensory info - hierarchy of control levels (cortical areas = lower level) - parallel systems |
| High centers that control bodily movement | - form complex plans via command neurons - structures: involved in memory, emotions, motivation, sensorimotor cortex |
| Middle level that controls bodily movement | - converts higher center plans to many smaller motor programs - transmitted through descending pathways to local control level - Structures: sensorimotor cortex, cerebellum, basal nuclei, brainstem nuclei |
| Local level that controls bodily movement | - specifies activity of muscles and joints - Structures: brainstem or spinal cord interneurons, afferent/motor neurons |
| Basal Nuclei/Ganglia | - paired motor and learning functions - receives input from cortex and provides feedback via thalamus - initiates movement - suppresses activity of muscles that would resist the movement - form some of extrapyramidal system - looping parallel circuits (sensorimotor cortex -> basal nuclei -> thalamus -> sensorimotor cortex) |
| Descending pathways divide into 2 groups | - pyramidal system: voluntary control of muscle, corticospinal (supplies muscles of body)/corticobulbar tracts (supplies muscles of head/neck) - extrapyramidal system: involuntary control, doesn't pass through medullary pyramids |
| Descending pathways | carry motor info from brain/brainstem to muscles via spinal cord |
| 2-neuron chain structure of descending pathways | - Upper motor neurons: initiates signal from brain, synapse with lower motor neurons in spinal cord or brainstem, originates in primary motor cortex or brainstem nuclei - Lower motor neurons: relays signal to muscle, originates in ventral horn of spinal cord or cranial nerve nuclei in brainstem |
| where are medullary pyramids located | - white matter structures in medulla oblongata of brainstem |
| How do signals of extrapyramidal system travel | through the tegmentum of brainstem (contains brainstem nuclei where descending pathways originate) |
| what does the EEG of a sleeping person look like? | - slower frequency, higher amplitude - theta and delta rhythm - slow wave sleep |
| what does the EEG of an increasingly drowsy person look like? | - goes to beTa rhythm (alerT) |
| reticular formation | controls states of consciousness |
| Declarative Memory (explicit) | retention/recall of conscious experiences that can be put into words - memory of an event (knowing where it happened) - involves: hippocampus, amygdala (limbic system) |
| Procedural Memory (implicit) | memory for skilled behaviors aka. how to do things - riding a bike involves: sensorimotor cortex, basal nuclei, cerebellum |
| Consolidation | short term memories become long term memories |
| retrograde amnesia | short term memory stopped from a blow to the head |
| anterograde amnesia | lose the ability to consolidate short term memories |
| Long-term potentiation | synapses undergo increase in effectiveness when heavily used - alters gene expression (new protein synthesis) |
| Plasticity for memory formation | ability of neural tissue to change from activation |
| left vs right hemispheres functions | left: produce/comprehend language, conceptualize, speaking/writing, verbal memory right: understan/express emotional aspects of language males only use left side females use both |
| Broca's area (frontal lobe) | - motor aspects of speech - lesions result in motor aphasia (slurring) but can still understand |
| Wernicke's area (temporal lobe) | - comprehension of language - lesions result in sensory aphasia (handed a pen, what is it? a spoon, use it? writes her name) - sensory to motor is different than sensory to cognitive |
| most consistent risk factor for neurodegenerative diseases | age |
| Dementia | loss of (cognitive function, thinking, reasoning, remembering) - buildup of proteins |
| Alzheimer's: most common cause of dementia | loss of cholinergic neurons |
| senile (amyloid) plaques of alzheimers disease | deposits of beta-amyloid protein (between nerve cells), clump together = toxic |
| neurofibrillary tangles of alzheimers disease | tangles of tau protein inside neuron (cant transport materials) |
| Parkinson's disease | affects substanitia nigra neurons - affects neurons of pars compacta region: control of body movement and muscle tone |
| symptoms of parkinsons disease | - parkinsonian gait (slowness - bradykinesia, shuffling, reduced arm swing) - emotionless face - asymmetric resting tremor - instable posture - impaired balance - rigidity - freezing (akinesia) |