Nervous System

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Nervous System

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Nervous system function
Adaptation, maintains homiostatis in the body. Receives external and internal information and processes it.
Somatci Nervous System
Glands or muscles carries out command
Central Nervous System
Brain and Spinal Cord
Visceral Nervous System
Controls smooth muscle and soft body parts, cardiac muscle and viscera
Automomic Nervous System
Involuntary division automatic activity
Peripheral Nervous System
Cranial Nerves:large nerves of the brain carry impulses to and from the brain. Spinal Nerves: large nerves off spinal cord that carry messages to and from spinal cord. Peripheral Nerves: Smaller nerves that go to all parts of the body. All spinal nerves that carry messages to and from the spinal canal.
Spinal Nerve
Large nerves off the spinal cord
Myelin Sheath
Covering of inulation of some axons
Myelinated Axons
Called white fibers found in white matter of brain and spinal cors & nerve trunks
Grey Matter
Fibers & cell bodies of grey matter are NOT covered with myelin
Cells of the brain and spinal cord
Are myelinated by other nueroglia they have NO neurilemmia
Parasympathetic Nervous System
Body in relxation, body functions return to normal
Sympathetic Nervous System
Times of stress and emotion, fight or flight
Cranial Nerves
Large Nerves from the brain
Voluntary all effectors are skeletal muscles
Sensor Neuron
Carries impulses to CNS receiptors
Motor Neuron
Carries Impulses AWAY from the CNS sends message to recieptors
Neuron fibors carry impulses to the cell body, RECIEPTOR Receives the stimulus begins neuron pathway
Neuron fibers conduct impules AWAY from the cell body to another neuron or muscle or gland, single fiber, may be quite long branches at end
Conducting tissue serve for support and protection.AKA glial Protects: Nervous tissue Supports: Nervous tissue Aids in repair Acts: as Phagocytes to remove pathogens Regulates: Composition of fluids around and between cells
Fatty substance neuron fibers, that insulate & protects the fiber
Schwann Cells
In PNS is prduced by special neuroglia wrap around axon like jelly roll dipositiong layers of myelin when sheath is complete small spaces remain between individual cells. These spaces are called Nodes important in speeding conduction of nerve impulses.
Outermost membranes of schwann cells. Thin coating mechanism by which some peripheral nerves repair themselves
Conducting cell of the nervous system
Cell body
Contains the nucleus and other organelles found in 2 places. CNS and Ganglion
Groups of nerve cell bodies outside the CNS,close to the spine
Fatty material tha covers and insulates axons, found in 2 places. Peripheral Nervous System White matter- myelinated fibers in CNS Grey matter cell bodies and fibers in CNS NOT covered with myelin.
Nodes of Ranvier
Empty spaces between sections of myelin on the axon
Motor End Plate/Neuromuscular juntion
The point at which a nerve fiber contact a muscle cell
Bundle of neuron fibers in the peripheral nervous system
Bundle of neuron fibers within the CNS that act as a unit (form a pathway) Sensory tract takes info to the brain, motor tracts take info AWAY from the brain.
A collection of cell bodies in the brain that regulates one function Ex/ Respiratory, cardiac, temperature centers.
Chemical Changes
Occur in spaces between neuron and between neurons and muscles called Synapses. 1.At end of axon, in vesicles are chemical call neurotransmitter, these chemicals are released into the synapse.Example Acetylcholine stimulus Adrenoline 2. This neurotransmitter combines with receptors on the dendrite of the next neuron. 3. This generates an electrical impulse down the next neuron. 4. To prevent a prolonged nerve impulse, a chemical inactivator in the second neruon breaks down some of the neurotransmitter. Example:Cholinesterase The rest of the neurtransmitter is taken back into the vesicles of the axon of the first neruon.
Electrical Changes
Occur along the lenght of the neuron.Dendrites and Axions. These changes involve ions, which are positive and negative charged particles. The electical impulse is caused by movement of ions through the neuron membrane. 1.In the resting state, the inside of the neuron has negative ions electrical charge and the ouside has a positive charge 2. A signal from the brain causes cells in the membrane to pump positive ions into the neuron, and negative ions ouside the membranes. This change in electrical charges works its way down the lenght of the entire neuron. 3. To prevent a prolonged nerve impulse cells in the neuron membrane rapidly pumps ions back to their original location resulting in a single message being sent. NOTE: Neuron wth myelin transmit impulses hundres of time faster than neuron without myelin. This is because the impulse jumps form one node to the next node rather than traveling through the fiber.
Spinal Cord
Location: Vertebral canal
Cauda Equnia
The nerves that hang below off the end of the spinal cord, seperates into seperate nerves.
Grey matter
H shapes in the brain and continues down the spinal column on each side up and down dorsally, these 2 pairs of columns called Dorsla and Ventral Horns. Cell bodies that are unmyelinated tissue.
Dorsal Horns
Sensory fibers, Stimulus into the spinal cord
Ventral Horns
Motor fibers stimulus out of the spinal cord,
Asending: Sensory to brain and from brain Desending: Motor out of brain to the body. Central Canal: Small canal containing cerbialspinal fluid.
Functions of Spinal Cord
Primary: Transmit sensory impulses to the brain. Motor impulses from the brain to the body Center for spinal cord reflexes.
Reflex Arch
Patellar reflex (no brain involment) Knee jerk reflex
Connective tissue membraes cover brain and spinal cord
4 layers of Menniges
Dura matter: thick tough very proctive Archnoind matter: middle layer contain spider like villa (web) Subarchnoid: cerberal spinal fluid Pia matter: inner most layer lyes on brain and spinal cord Note: Covers whole CNS
Crebro spinal fluid
Formed from blood plasma in the cells of 4 ventricles of the brain.
Name 4 Ventricles
1st 2nd 3rd 4th
Structure of Neuron
Cell body Cell fibers: Dendrite: carries impulses to cell body Axon: carries impulses away from cell body
Types of neurons
Sensory(afferent)carries impulses toward CNS Motor(efferent)carries impulses away from CNS
Cerebral spinal fluid flow
through all ventricles of brain to central canal of spinal cord, subarchnoid reabsorbs CSF back to blood replensishment
Characteristics of CSF
Clear colorless,alkiline PH sterile no bacteria A few WBC H20 glucos and protein.
Peripheral Nervous System
Branch of Brain and spinal cord arises underside of brain. 12 prs of cranial nerves. Supply sensory and motor Nerves to head and neck. Enters all body parts and glands Sciatic nerve is largest
Spinal Nerves
31 prs.
Function of spinal nerves
supply sensory & motor blelow shoulders Roots are spinal column
Name cranial nerves and their function
Olfactory:sense of smell Optic:sense of sight Oculomotor:movement of the eye ball Acoustic(Vestibulocchlear) sense of hearing and equilibrium Vagus:sensory in cardia respiratory and blood pressure refexes: sensory and motor to larynx(speaking) heart rate contraction of alimentary tube(peristalsis) increases didgestive secretions
Sciatic nerve location
Bottom of spine through butt, legs and heels** Major nerve
Central and perepherial
nerves are by location
are by action