Chapter 8: Nervous System
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kahighsmith on October 3, 2011
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106 terms
Terms | Definitions |
|---|---|
 Function of nervous system | 1) sensory input: sensory receptors respond to stimuli 2) integration: brain and spinal cord process stimuli 3) control of muscles and glands 4) mental activity: brain 5) homeostasis |
| Central Nervous System (CNS) | - brain and spinal cord |
| Peripheral Nervous System (PNS) | - all neurons outside CNS - collects input from different sources, relays input to CNS and performs action |
| Neurons | - nerve cells - require oxygen and glucose - receive inputs, process input, produce a response |
| Dendrite | - receives stimulus from other neurons or sensory receptors |
| Cell body (stoma) | - process stimuli - contains a nucleus |
| Axon | - transmits stimulus to a gland, muscle, organ or other neuron. |
| Myelin sheath | - fatty, protective wrapping around axons - excellent insulator |
| Nodes of Ranvier | - gaps in myelin sheath where action potentials develp |
| Saltatory conduction | - jumping of action potential |
| Multipolar neuron | - many dendrites and a single axon - ex. CNS and most motor neurons |
| Bipolar neuron | - one dendrite and on axon - ex. eye and nasal cavity |
| Unipolar neuron | - one axon and no dendrites - ex. sensory neurons |
| Neuroglia | - supporting cells for neurons - more numerous than neurons - can divide to produce more cells - 5 types |
| Astrocytes | - star shaped - most abundant - form blood-brain barrier (BBB) |
| Ependymal Cells (choroid plexus) | - produce and circulate cerebrospinal fluid (CSF) - CSF in the ventricles of the brain - choroid plexus is specialized ependymal cell |
| Microglia | - help remove bacteria and cell debris from CNS |
| Oligodendrocytes | - produce myelin sheath in CNS |
| Schwann cells | - produce myelin sheath in PNS |
| Gray matter | - collection of dendrites, cell bodies, unmyelinated axon |
| White matter | - collection of axons and their myelin sheath |
| Organization of CNS nervous tissue | - oligodendrocytes: produce myelin sheath - nerve tracts: collection of axons - nuclei: collection of cell bodies |
| Organization of PNS nervous tissue | - schwann cells: produce myelin sheath - nerves: collection of axons - ganglion: collection of cell bodies |
| Resting Membrane Potential | - outside cell is more (Na+) - inside cell is more (K+) - leak ion channels: 1) always open 2) K+ channels -gated ion channels: 1) closed until opened by specific signal 2) Na+ channels |
| Action Potential | - "electricity" that cause depolarization and repolarization - change resting membrane potential by activating gated ion channels - local current: movement of Na+ which causes inside of cell to be more positive (depolarize) - in enough Na+ enters then threshold is reached and more Na+ channels open |
| Action Potential (cont.) | - once threshold is reached all or none law applies - action potentials continue until Na+ channels close, K+ channels open and repolarization occurs - sodium/potassium pump restores |
| Synapse | - where an axon attaches to a muscle, gland, organ, or other neuron. - involved with release of neurotransmitters. - ex. neuromuscular junction (NMJ) |
| Reflexes | - involuntary response to stimuli |
| Path reflex travels | 1) sensory receptors: pick up stimuli. in skin. 2) sensory (afferent) neurons: send stimulus to interneurons in spinal cord. 3) interneurons (association) neuron: located in CNS and connect to motor neurons 4) efferent (motor) neuron: send response to effector 5) effector: muscle, gland or organ |
| Converging neuronal pathway | - two or more neurons synapse same neuron - allow info to be transmitted in more than one neuronal pathway to converge into a single pathway |
| Diverging neuronal pathway | - axon from one neuron divides and synapses with more than one neuron. - allows info to be transmitted in one neuronal pathway to diverge into 2 or more pathways |
| Covering of the brain | 1) outermost layer: dura mater "tough mother" 2) middle layer: arachnoid mater "spider" 3) surface of brain: pia mater "delicate mother" |
| Meningitis | - infection of the meninges |
| Meninges | - protective wrapping around brain and spinal cord |
| Dura Mater | - superficial - thickest layer |
| Arachnoid Mater | - 2nd layer |
| Pia Mater | - 3rd layer - surface of brain |
| Subarachnoid space | - where cerebrospinal fluid sits |
| Epidural space | - in vertebral column between dura and vertebra - injection site for epidural anesthesia |
| Spinal block and spinal tap | - in subarachnoid space where cerebrospinal fluid can be removed or anesthetic inject - numbs spinal nerves |
| Ventricles | - cavities (4) in CNS that contain fluid - fourth ventricle : 1) base of cerebellum 2) continuous with central canal of spinal cord. |
| Cerebrospinal Fluid (CSF) | - fluid that bathes the brain and spinal cord - provides a protective cushion around the CNS - produced in choroid plexus of brain - reabsorb by arachnoid villi - increase production of CFS = hydrocephalus |
| Brainstem | - components: 1) medulla oblongata 2) pons 3) midbrain |
| Midbrain | - location: above pons - function: coordinate eye movement, pupil diameter, turning head toward noise |
| Medulla Oblongata | - location: continuous with spinal cord - function: regulates heart rate, blood vessel diameter, breathing, swallowing, vomiting, hiccuping, coughing, sneezing, balance. - other: pyramids: involved in conscious control of skeletal muscles |
| Pons | - location: above medulla, bridge between cerebrum and cerebellum - function: breathing, chewing, salivation, swallowing |
| Reticular Formation | - location: scattered throughout brainstem - function: regulates cyclical motor function, respiration, walking, chewing, arousing and maintaining consciousness, regulates sleep-wake cycle |
| Diencephalon | - location: between the brainstem and cerebrum - components: thalamus, hypothalamus, epithalamus |
| Thalamus | - characteristics: largest portion of diencephalon - function: influences mood and detects pain |
| Epithalamus | - location: above thalamus - function: emotional and visceral response to odors |
| Hypothalamus | - location: below thalamus - characteristics: control pituitary gland and is connected to it by infundibulum. - function: controls homeostasis, body temp, thirst, hunger, fear, rage, sexual emotion |
| Cerebrum characteristics | - largest portion of brain - divisions: left and right hemispheres divided by longitudinal fissure. - lobes: frontal, parietal, occipital, temporal |
| Cerebral Cortex | - location: surface of the cerebrum, composed of gray matter - function: controls thinking, communication, remembering, understanding, and initiates involuntary movements. |
| Gyri | - folds on cerebral cortex that increase surface area |
| Sulci | - shallow indentations |
| Fissure | - deep indentations |
| Left hemisphere | - controls right side of body - responsible for math, analytic, and speech |
| Right hemisphere | - controls left side of body - responsible for music, art, abstract ideas |
| Corpus Callosum | - connection between 2 hemispheres |
| Frontal lobe | - loc: front - func: controls voluntary motor functions, aggression, moods, smell |
| Parietal lobe | - loc: top - func: evaluates sensory input such as touch, pain, pressure, temp, taste |
| Occipital lobe | - loc: back - func: vision |
| Temporal lobe | - loc: sides - func: hearing, smelling, memory |
| Primary sensory areas of the Cerebral Cortex | - in Cerebral Cortex - where ascending tracts project - where sensations are perceived |
| Primary somatic sensory cortex | - in Cerebral Cortex - general sensory area - in parietal lobe - sensory input such as pain, pressure, temp. |
| Primary motor cortex | - in Cerebral Cortex - frontal lobe - controls voluntary motor movement |
| Premotor area | - in Cerebral Cortex - frontal lobe - where motor functions are organized before initiation. |
| Prefrontal area | - in Cerebral Cortex - motivation and foresight to plan and initiate movement |
| Speech | - maintained in left hemisphere |
| Sensory speech (Wernicke's area) | - parietal lobe - where words are heard and comprehended |
| Motor speech (Bronca's area) | - frontal lobe - where words are formulated |
| Basal Nuclei | - group of functionally related nuclei - plan, organize, coordinate motor movement and posture - corpus striatum: deep in cerebrum - substantia nigra: in midbrain |
| Encoding | - brief retention of sensory input received by brain while something is scanned, evaluated and acted up - also called sensory memory - in temporal lobe - lasts less than a second |
| Consolidated | - data that has been encoded - temporal lobe - short term memory |
| Storage | - long term memory - few minutes or permanently (depends on retrieval) |
| Retrieval | - how often info is used |
| Short-term memory | - info is retained for a few seconds or minutes - bits of info (usually 7) |
| Long-term memory | - can last for a few minutes or permanently |
| Episodic memory | - places or events |
| Learning | - utilizing past memories |
| Brain waves | - used to diagnose and determine treatment for brain disorders |
| Electroencephalogram (EEG) | - electrodes planted on scalp to record brains' electrical activity. |
| Alpha waves | - person is awake in quiet state |
| Beta waves | - intense mental activity |
| Delta waves | - deep sleep |
| Theta waves | - in children |
| Cerebellum | - loc: below cerebrum - char: means little brain. cortex is composed of gyri, sulci, gray matter - func: controls balance, muscle tone, coordination of fine motor movement. |
| Spinal Cord | - extends from foramen magnum to 2nd lumbar vertebra (between L1 and L2 in adult) - end as conus medullaris - horse's tail = cauda equina - protected by vertebral column - spinal nerves allow movement - if damaged, paralysis can occur |
| Gray Matter in Spinal Cord | - center of spinal cord - looks like letter H or a butterfly - posterior horn: contains axons which synapse with interneurons - anterior horns: contain somatic neurons - lateral horns: contain autonomic neurons - central canal: fluid filled space in center of cord (CFS) |
| White Matter in Spinal Cord | - outside spinal cord - contains myelinated fibers - contains 3 columns dorsal, ventral, lateral columns - ascending tracts: axons that conduct action potential toward brain - descending tracts: axons that conduct action potential away from brain |
| Sensory functions | - CNS constantly receives sensory input - we are unaware of most sensory input - sensory input is vital of our survival and normal function |
| Spinothalamic tract | - general sensation to the thalamus then synapse and continue to somatosensory cortex |
| Dorsal column | - 2 point discrimination, touch, balance |
| Ascending tracts | - pathways in brain and spinal cord - transmit info via action potentials from periphery to brain - each tract has limited sensory input - tracts are named that indicat origin and termination - made of 2-3 neurons in sequence |
| Descending tracts | - project from upper motor neurons in cerebral cortex to lower motor neurons in spinal cord and brainstem - control different types of movement |
| Corticospinal tract | - motor to skeletal muscles |
| Divisions of PNS | 1) afferent (sensory): collects input from periphery and sends it to CNS 2) efferent (motor): carries processed input from CNS to effector |
| Divisions of Efferent (motor) | 1) automatic: - response is automatic (involuntary) - controls smooth and cardiac muscles and glands 2) somatic: - response is voluntary - controls skeletal muscles |
| Cranial Nerves | - 12 pairs - named by roman numerals - 2 categories of function: sensory and motor |
| Spinal Nerves | - arise along spinal cord from union of dorsal roots and ventral roots - contain axons sensory and somatic neurons (afferent and efferent fibers) - located between vertebra (intervertebral foramen) - categorized by region of vertebral column from which it emerges (C for cervical) |
| Spinal Nerves (cont.) | - 31 pairs of spinal nerves (8C, 12T, 5L, 5S, 1C0) - organized in 3 plexuses: - cervical (C1-C4) - brachial (C5-T1) - lumbosacral (L1-S4) |
| Cervical Plexus | - spinal nerves C1-C4 - innervates muscles attached to hyoid bone and neck - contains phrenic nerve (C3, C4, and C5) which innervates diaphragm |
| Brachial Plexus | - originates from spinal nerves C5-T1 - supply nerves to upper limb, shoulder and hand |
| Lumbosacral | - originates from spinal nerves L1 to S4 - supply nerves lower limbs |
| Sympathetic (thoracolumbar region) | - activated during times of stress - part of fight or flight response - prepares for physical activity by raising heart rate, blood pressure and BR - sending more blood to skeletal muslces - inhibiting digestive tract |
| Parasympathetic (craniospinal region) | - "housekeeper" - activated under normal conditions - involved in digestion, urine production, and dilation/constriction of pupils, etc. |
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