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Amanda Gil Period 3 Nervous System - Coggle Diagram
Amanda Gil Period 3 Nervous System
Major divisions and subdivisions
Central Nervous System (CNS): brain and spinal cord
Peripheral Nervous System(PNS): cranial and spinal nerves that connect CNS to the rest of the body, contains sensory (afferent) and motor (efferent) divisions
somatic nervous system: controls voluntary skeletal muscles
autonomic nervous system: controls involuntary effectors (smooth and cardiac muscles &glands)
integrative function: coordination of sensory information in the CNS, processing of this information is the basis for decision making
sensory function: provided by sensory receptors that detect internal and external changes, information travels from receptors to sensory neurons to CNS
motor function: nerve impulses (CNS) are conducted along motor neurons to effectors(muscles/glands that respond to decisions made in the CNS
Drugs of Abuse
Heroine: heroine mimics natural opiates and binds to opiate receptors and turns off dopamine inhibition
Affects: produces immediate feelings of sedation and well being
Ecstasy: ecstasy mimics serotonin and is taken up by serotonin transporters that become confused and transport serotonin out of the cell
Affects: serotonin pathways, responsible for mood, sleep, perception, and appetite
Marijuana: THC in Marijuana anandamide and binds to cannaboid receptors, THC doesnt break down easy
Affects: slows down movement and makes a person more relaxed / calm
Methamphetamine: meth mimics dopamine and is taken into the cell, enters dopamine vesicles and forces dopamine molecules out, causes transporters to work in reverse
Affects: makes person feel intense pleasure and exhilaration
Alcohol: makes GABA receptors more inhibitory, binds to glutamate receptors and prevents glutamate from exciting the cell
Affects: areas of the brain that are involved with memory formation, desicion making, and impulse control
Cocaine: cocaine blocks dopamine transporters, leaves dopamine trapped in the synaptic cleft, dopamine binds again and again which overstimulates the cell
Affects: the controlling of voluntary movements, person is often fidgety and unable to stay still
LSD: chemically resembles serotonin and binds to serotonin receptors, sometimes inhibits or excites receptors
Affects: feelings of wakefulness and a startle response to unexpected stimulus
Action potential and the nerve impulse
neuron remains at rest until stimulated, stimulus can change action potential in either direction, excitatory stimulus opens chemically gated Na+ channels that then flow into cell due to concentration gradient and causes the inside of the neuron to become less negative
Threshold stimulus: stimulus strong enough to cause so many Na+ ions to enter neuron
reaching an action potential is all or no response
when action potential is reahced the cell responds by returning to resting potential by process of polarization
Impulse conduction: an action potential at the trigger zone causes an electrical current to flow to adjacent regions of the axons membranes
Continuous conduction: occurs in unmyelinated axons, conduct impulses sequentially over entire length of their membrane
Saltatory conduction: occurs in myelinated axons, impulses jump from 1 node of ranvier to another since sodium and potassium channels occur only at the nodes
Major parts and functions of the brain
Diencephalon: processes sensory input and controls many homeostatic processes
between cerebral hemispheres and above midbrain, surround 3rd ventricle
hypothalamus: maintains homeostasis by regulating visceral activities
thalamus: sorting and directing sensory info arriving from another part of nervous system to cerebral cortex , channels all sensory impulses except smell and produces awareness of sensation
Cerebrum: largest portion, associated with higher mental functions and sensory / motor functions
Structure: consists of 2 cerebral hemispheres, corpus callosum (connects hemishperes), gyri( ridges), sulci( grooves), fissures
(deep grooves), 4 lobes ( frontal, occipital, temporal, parietal),
Function: provides higher brain function -- interpretation of sensory input, initiating voluntary muscular movements, stores info for memory, integrates info for reasoning, intelligence, personality
Cerebellum: coordinates muscular activity, posture , integrates sensory info for position of body
cerebellar cortex lies outside arbor vitae: core of white matter
communicates with other parts of CNS through 3 pairs of tracts= cerebellar peduncles
Brainstem: coordinates/ regulates visceral activities, connects different parts of the nervous system
Midbrain: between diencephalon and pons, contains many motor pathways between cerebrum and lower portions of nervous system
Pons: between midbrain and medulla oblongata, contains centers that help regulate the rate and depth of breathing
Medulla oblongata: transmits all ascending/descending impulses between the brain and spinal cord , houses nuclei that controls visceral functions
Reticular formation: network of nerve fibers connecting small masses of gray matter throughout the brainstem , decreased activity: sleep, increased: wakefulness, injury: comatose state
Major parts and functions of the spinal cord
cauda equina: structure formed where spinal cord tapers to a point inferiorly, consists of spinal nerves in lumbar/sacral areas
structure: 31 segments that each connect to a pair of spinal nerves
lumbar enlargement: thickened region near bottom of spinal cord that gives rise to nerves that serve lower limbs
white matter: made up of bundles of myelinated nerve fibers, surrounds a butterfly shaped core of gray matter: housing neurons and neuron cell bodies
cervical enlargement: thickened area near top of spinal cord and provides nerves to upper limbs
central canal: in the middle of gray matter and contains CSF
spinal reflexes controlled by reflex arcs that pass through spinal cord
functions: transmit impulses to/from brain and house spinal reflexes
surrounded by meninges: dura mater, arachnoid mater, and pia mater
ascending tracts: carry sensory info to brain
descending tracts: carry motor info from brain to muscles/glands
Classification of Neurons
Neuron: contains a cell body, tubular cytoplasm filled dendrites and a tubular cytoplasm filled axon
sensory (afferent) neurons: conduct impulses from peripheral receptors to CNS, usually unipolar although some bipolar
interneurons (association/internuncial) neurons: multipolar neurons lying within CNS that form lines between other neurons; the cell bodies of some interneurons aggregate in specialized masses: nuclei
Motor (efferent) neurons: multipolar neurons that conduct impulses from CNS to peripheral effectors (muscles/ glands)
Multipolar neurons: many dendrites & 1 axon arising from their cell bodies, most neurons with cell bodies in CNS are multipolar
unipolar neurons: only 1 process extending from the cell body-- outside cell body: soon splits into 2 parts that function as 1 axon, peripheral process has dendrites near a peripheral body part and the central process runs into CNS-- cell bodies are found in ganglia outside CNS-- sensory neurons
bipolar neurons: 2 processes extending from from the cell body to a dendrite and axon found in some of the special senses (eyes, nose, ears)
Major Functions
functions: thinking, movement, internal process of physiology
neurons: communicate via electrical impulses with other neurons or other tissues
major aspects: sensory input, integration, processing, decision making, and motor output
neuroglia: cells that support, nourish, protect, and insulate neurons
neurotransmitters: chemical messengers in a synapse that convey an electrical impulse from a neuron to another cell
flow of information: sensory receptor(sensory input)--integration(brain and spinal cord)--effector(motor output
Neurotransmitters
Acetycholine: controls skeletal muscle actions in the CNS and stimulates skeletal muscle contraction at the neuromuscular junction in PNS
norepinephrine: creates a sense of feeling good in CNS and may excite or inhibit autonomic nervous system actions in PNS
there are more than 100 neurotransmitters and their action depends on the type of receptors in a specific synapse
Releas of neurotransmitter: action potential passes along axon and over surface of its synaptic knob, synaptic knob membrane becomes more permeable to calcium ions and diffuse inward, in the presence of Ca ions, synaptic vesicles fuse to synaptic knob membrane, synaptic vesicles release their neurotransmitter into synaptic cleft
Compare and Contrast Autonomic Nervous System
portion of PNS that functions constantly and independently without conscious effort
Sympathetic divisions: active in conditions of stress or emergency (fight or flight)
Parasympathetic: active under normal, restful conditions (rest and digest)
Postganglionic neuron: fiber (axon) leaves an aoutonomic ganglion and innervates a visceral effector
Preganglionic neuron: leaves cns and synapse with 1 or more neurons which have cell bodies in an autonomic ganglion in the pns
Disorders & Diseases
Cerebrovascular Accident / stroke (occurs when blood flow to a portion of the brain is halted)
Causes: blood vessels burst, diabetes, high cholesterol
Symptoms: severe headache, change in alertness, confusion or memory loss
Treatment: hospitalization, blood thinners, surgery
Autism (brain disorder that makes it difficult to communicate)
Symptoms: hereditary, mostly males
Symptoms: anxiety, depression, repeated behaviors
Treatment: medication, coping skills, specialized therapy
Alzheimer's Disease (a form of dementia associated w/ age) Causes: hereditary, over 60, high insulin levels
Symptoms: memory loss, confusion, disorientation, unfounded suspicions
Treatment: uncurable, medication, herbal therapies
Spinal Cord Injury (damage to spinal cord)
Causes: direct injury or disease, assault, fall, accident, fluid build up around spinal cord
Symptoms: weakness, spastic muscles, paralysis
Treatment: uncurable, medication, herbal therapies
Meningitis (infection in the meninges surrounding the brain) Causes: drug allergies, tumors, fungi or parasites Symptoms: stiff neck, severe headache, fever and chills Treatment: antibiotics, medication, vaccination to prevent
Multiple Sclerosis ( autoimmune disease that damages the myelin sheath)
Causes: hereditary, ages 20-40 diagnosed, possibly viral infection
Symptoms: constipation, stool leakage, vision & hearing loss, inconsistent urination
Treatment: no known cure, assistive devices, steroid treatment
Connective Tissue Coverings
endoneurium: covering around individual fibers (axons)
perineurum: covering around fasicles
epineurium: outer covering of nerve
Reflex Arc
provide basis for involuntary actions (reflexes)
interneuron: in CNS (reflex center)
sensory receptor: detects change
motor neuron: carries a command to effectors
effector: muscle/gland that carries out the reflex
sensory neuron: carries info from receptor to CNS
Cranial Nerves
12 pairs arise from the underside of the brain, most are mixed nerves with sensory and motor nerve fibers
olfactory: smell
optic: vision
Accessory: soft palate, pharynx, larynx, neck and back
oculomotor: raise eyelids, move eyes, adjust amount of light entering eyes, and focus lenses
trochlear: move eyes
Trigeminal: surface of eyes, tear glands, scalp, forehead, upper eyelids, upper teeth, upper gum, upper lip, lining of palate, skin of face, skin of jaw, lower teeth, gum, lip, and mastication
abducens: move eyes
facial: taste receptors for anterior tongue, facial expressions, tear glands, salivary
vestibulocochlear: equilibrum, and hearing
Glossopharyngeal: pharynx, tonsils, posterior tongue, swallowing, salivary
Vagus: speech, swallowing, heart, smooth muscle, glands in thorax and abdomen
Hypoglossal: tongue
Spinal Nerves
31 pairs arise from spinal cord, all except 1st pair are mixed nerves
each arise from 2 roots: sensory dorsal roots and motor ventral roots
branches of spinal nerves form networks called plexuses
Cervical Plexus: lie on either side of neck, supply muscles and skin of the neck, include phrenic nerves that control diaphragm
Brachial Plexus: arise from lower cervical and upper thoracic nerves, supply muscles and skin of arms, forearms, hands, lead into upper limbs, include musculocutaneuos, ulanr median, radial, and axillary nerves
Lumbrosacral plexus: arise from lower spinal cord, supply muscles and skin of lower abdomen, external genitalia, buttocks, legs, and include obturator, femorl and sciatic nerves