Chapter 12 Packet Review Flashcards
Neurophysiology
The study of the nervous system
Central Nervous System
The brain and spinal chord. Deciphers info and initiates responses. I.E: Intelligence, memory, emotions
Peripheral Nervous System
Cranial and spinal nerves. Relays info to and from the CNS: Cranial and spinal nerves
Afferent Division
A division of the PNS Sensory input: detect changes and feel sensations. Takes FROM stimulus TO the CNS
Receptors
Detect changes, respond to stimuli
Efferent Division
A division of the PNS Motor output: carries motor commands from CNS to an effector
Effector
Target organs which respond by doing something; muscles, glands, adipose tissue
Somatic Nervous System
controls skeletal muscle contractions on a voluntary conscious and a subconscious level (reflex)
Autonomic Nervous System
Controls smooth muscle, cardiac muscle, adipose tissue and glands; a visceral control center. Sub divisions are sympathetic and parasympathetic divisions
Neurons
“Nerve fibers”; regardless of function all neurons have the same physical properties: cell body, 1 axon and dendrites
Cell body
contains nucleus surrounded by perikaryon found in the CNS for protection by the skeleton . Do not divide because they lack centrioles
Perikaryon
Cytoplasm surrounding the nucleus; mitochondria present for ATP production, ribosomes and rough er present for protein synthesis; clusters of rough er and ribosomes stain darkly and are called nissel bodies which make up gray matter in the cerebral cortex
Dendrites
Branched processes increase surface area for cell bodies to receive impulses. Transmit TOWARD the cell body
Axon
process of the cell body that transmit impulses AWAY from the cell body
Axoplasm
cytoplasm of the axon
Axolemma
specialized plasma membrane surrounding the axoplasm
Initial Segment
base of the axon
Axon Hillock
thickened area where the axon joins the cell
Telodendria
extensions on the distal end of the axon; terminal branches
Axoplasmic transport
two-way transport between the cell body and synaptic terminals
Anterograde and Retrograde Flow
Ante=materials carried TOWARD the synaptic terminals
Retro=materials carried toward the CELL BODY
Synaptic Terminal
point of communication with another cell
Synapse
space between the axon of one neuron and dendrites or cell body of the next neuron. The site of one way impulse transmission
Presynaptic Neuron
conducts impulses TOWARD the synapsis; info giver
Postsynaptic Neuron
transmit the impulse AWAY from synapses; info receiver
Synaptic Cleft
space separating the two cells
Neruotransmitter
chemical released into synapse by electrical nerve impulses
Synaptic Vesicles
within the synaptic terminal neurotransmitters are found within small sacs
Neuromuscular Junction
synapses between a neuron and a muscle
Neuroglandular Junction
synapse between a neuron and a gland
FIGURE 12-3 will be on test
Axonic, bipolar, unipolar, multipolar
Anaxonic
in brain and special sense organs; cannot determine the axon from the dendrites; poorly understood
Bipolar
rare sense receptors like smell, sight, hearing; two processes separated by the cell body
Unipolar
Sensory neurons of the PNS; longest extends from toes to spinal chord; dentrites and axon are continuous with cell body off to the side
Multipolar
Most common; all motor neurons in PNS; TWO or MORE dendrites and a single axon
Sensory Neurons
Afferent division; carry impulses from receptor to CNS. They are unipolar, 2 types: Somatic Sensory Neurons=receive info about ouside world via receptors in the skin, skeletal muscles and joints
Visceral Sensory Neurons=monitor internal conditions within the organs
Interoceptors
monitor digestive, respiratory, cardio, urinary and reproductive systems; distention, deep pressure, pain
Exteroceptors
monitor external environment with touch, temp, pressure, taste, smell, sight, equilibrium and hearing
Proprioceptors
monitor the position and movement of skeletal muscles and joints
Motor Neurons
EFFERENT division carry impulses from CNS to the EFFECTORS
Somatic Motor Neurons
voluntary, linked to skeletal muscles
Visceral Motor Neurons
Involuntary, linked to smooth and cardiac muscles, adipose tissue and glands
Effectors
the organ or tissues that respond to info from the CNS; muscles and glands
Interneurons
Found in CNS; Shuttles signals between sensory and motor neurons. “Association Neurons”
Neuroglial Cells of the CNS
provide support and protection to the neural tissues
Ependymal Cells
Line the central canal of the spinal cord and ventricles of the brain forming an epithelium called EPENDYMA: secrete and circulate the Cerebral Spinal Fluid=in spinal chord and brain, feeds brain tissue nutrients and removes waste, also cushions and protects
Astrocyte
Star-shaped supporting cell; largest and most numerous
Blood-Brain Barrier
capillaries in the brain limit the entry of substances to the brain hormones, waste/harmful substances are not allowed to pass; it could cause the brain to fire off impulses unnecessarily. Capillaries not as permeable. The astrocytes send signals to the capillaries to form tight junctions in their endothelium
Oligodendrocytes
neuroglial cells that form the myelin sheath in CNS; processes extend into pad shape and wrap around the axon forming concentric layers of plasma membrane; this insulates the axons from contact w/extracellular fluid
Myelin Sheath
Phospholipid sheath that protects it electrically insulates neurons from one another and increases the speed of impulses along the axon
Internode
A length of axon that is covered in myelin; the lipids give it a glossy white appearance. (white matter)
Nodes of Ranvier
spaces between adjacent internodes
Microglia
Phagocytic cells of the CNS; “garbage collectors”
Neuroglial Cells of the PNS (fig 12-6)
provide support and protection to the ganglia - clusters of cell bodies outside the CNS
Satellite Cells (amphicytes)
surround neuron cell bodies in ganglia, regulation surrounding environment
Schwann Cells (neurilemma cells)
Provides the myelin of the PNS. They coil their plasma membrane around the axon of nerves to protect them from surrounding fluids and other axons
Neurilemma
Nucleus and cytoplasm of the schwann cell wrapped around the outside of the myelin sheath
Response to Injury (fig 12-7)
Wallerian Degeneration=repairing of damaged nerves
- fragmentation of axon and myelin occurs in distal stump
- shwann cells form a chord, unites the stumps. macrophages engulf degeneration axon and myelin
- Axon sends buds into network of schwann cells, then starts growing along cord
- Axon continues to grow into distal stump and is enclosed by schwann cells
Resting Potential
transmembrane potential of a resting cell; a change in this potential starts neural activity
Graded Potential
stimulus produces a temporary, localized change in transmembrane potential; decreases with distance from the stimulus
Action Potential
Graded potential can trigger an electrical impulse that spreads along the surface of the axon and maintains the potential despite distance from the stimulus; travels to a synapse
Synaptic Activity
arrival of the action potential to a synapse causes the release of neurotransmitters from the presynaptic membrane which bind to receptors on the postsynaptic membrane allowing permeability and graded potential
Information Processing
response of the post synaptic cell
Chemical Gradient (fig 12-9) and Electrical Gradient (fig 12-9)
see book and packet
Current
movement of charges to eliminate a potential difference
Resistance
how much a barrier restricts movement of those charges
resistance high=low current
resistance low=high current
Electro Chemical Gradient
Potassium Ion Gradient
Sodium Ion Gradient
see fig. 12-10 and packet (copy and paste to watch)
http://www.youtube.com/watch?v=Z9tPTDRjCYU
The electrochemical gradient is a form of potential energy. Any stimulus that increases the permeability of the plasma membrane to Na+ or K+ ions causes sudden and dramatic ion movement. If a sodium channel opens, sodium will flow in fegardless of what the stimulus was.
Na+ K+ exchange pump
(see youtube video above and fig 3-19) ATPase pump out 3 Na+ molecules from the cell and carries 2 K+ molecules into the cell to per 1 ATP molecule, maintaining homeostasis
Changes in the transmembrane potential
cells respond to stimuli which brings them out of a resting potential in order to modify their activities
Passive or Leak Channels
Always open but permeability can vary
Active Channels
gated channels that open or close in response to a stimuli
chemically gated channel (fig 12-11a)
open or close when they bind specific chemicals; receptors that bind ACh are chemically gated channels; most common on dendrites and cell bodies
Voltage-gated Channel (fig 12-11b)
opens or closes based on changes in the transmembrane potential; an excitable membrane, or one capable of generating and conduction an action potential is commonly found in an axon of unipolar and multipolar neurons and the sarcolemma
Mechanically gated Channels (fig 12-11c)
opens or closes based on a distortion in the plasma membrane; found in sensory receptors responding to touch, pressure, or vibration
Graded Potentials (fig 12-12)
Resting state…stimulation…graded potential
Action Potentials
A nerve impulse that is propagated along an axon like dominoes reaching the synaptic terminals; dependent on voltage-gated channels
All or Nothing Principle
Graded potentials like putting pressure on the trigger of a gun. Action potentials are like shooting the gun. If the pressure is strong enough the gun will fire
Generation of an Action Potential
fig 12-14
http://www.youtube.com/watch?v=ifD1YG07fB8
Propagation
Flow or charge with the message repeated over and over as it flows sown the pathway of an axon
Continuous Propagation (fig 12-15)
Occurs in an unmyelinated axon; an action potential at the initial segment spreads the infer one segment of membrane at a time; flows in one direction because the previous section is in a refractory period and cannot be depolarized yet
Saltatory Propagation (fig 12-16)
unmyelinated nodes respond to depolarization because myelin insulates and creates resistance to ion flow; action potetial jumps from node to node allowing the impulse to move more rapidly and uses less energy than continuous propagation
Electrical Synapses
pre and post synaptic membranes are locked together at gap junctions allowing flow of ions between cells. Allows currents to flow from one cell to another; rare (found in eye)
Chemical Synapses
Uses a neurotransmitter to send info between pre and postsynaptic membranes
Excitatory Neurotransmitter
promotes action potentials
Acetylcholine, ACH
common neurotransmitter found at neuromuscular junction in the CNS and PNS. typically excitatory
Inhibitory Neurotransmitter
causes hyperpolarization to suppress an action potential
Acetylcholinesterase, AChE
inactivator of ACH
7 Steps of Choinergenic Synapses
Synapses that release acetylcholine (fig 12-17, table 12-4)
Neuromodulators
alter the rate of neurotransmitter release by the presynaptic neuron or change the postsynaptic cells response to neurotransmitters
Opioids
Pain relieving neuromodulators: endorphins, enkephalins, endomorphins, dynorphins
Synaptic Fatigue
occurs if the presynaptic membrane cannot keep up with neurotransmitter resynthesis demands
Norepinephrine
NE; neurotransmitter=excitatory, depolarizing effect on the postsynaptic membrane
Dopamine
a CNS neurotransmitter. Inhibitory or excitatory
Serotonin
CNS neurotransmitter. Inadequate seotonin production can effect attention span and emotional states
