Chapter 11 Flashcards
consists of: brain and spinal cord
function: process and coordinate sensory data from inside and outside the body, motor commands to control skeletal muscles, higher functions of the brain
central nervous system
includes: all nervous tissue outside CNS, excluding ENS
functions: deliver sensory information to the CNS and carry motor commands to peripheral tissues and systems
peripheral nervous system
detect changes or respond to stimuli. Neurons and specialized cells. Complex sensory organs
receptor
repsond to efferent signals. cells and organs
effectors
Afferent division:
carries _______ info from PNS sensory receptors to CNS
sensory
Efferent division:
carries _______ commands from CNS to PNS muscles and glands
motor
Controls voluntary and involuntary (reflexes) skeletal muscles contractions
somatic nervous system
Controls subconscious actions, contractions of smooth muscle and glandular secretions; has 2 more divisions
autonomic nervous system
What are the two other divisions of the autonomic nervous system?
- sympathetic nervous system
2. parasympathetic nervous system
stimulating effect: “fight or flight”
sympathetic nervous system
relaxing effect: “rest or digest”
parasympathetic nervous system
detect changes in internal or external environment
receptors
information is sent to the CNS by sensory division of the PNS. Affront
Sensory division of the PNS
Information is processed occurs in the
CNS
motor commands are carried by the motor division of the PNS. efferent
Motor division of the PNS
respond to those commands and change their activities
effectors
the basic functional units of the nervous system
neurons
the most common type of neuron in the CNS
multipolar neuron
receive stimuli from environment/other neurons. Highly branched. CNS neurons receive most information here. Receive info from other neurons
dendrites
The cell body contains the
nucleus and nucleolus
The cytoplasm of a neuron is given the name:
perikaryon
Mitochondrias are present to produce ________
energy
RER and ribosomes produce proteins known as
neurotransmitter
dense areas of RER and ribosomes. Male neural tissue appear gray
Nissl bodies
carries information toward other cells
Axon
Axon carries the electrical signal to ________
target
cytoplasm of axon. Contains neurofibrils, neurotubules, enzymes, organelles
axoplasm
specialized cell membrane. covers the axoplasm
axolemma
orgin of axon from cell body
axon hillock
where action potential is intimated
initial segment
fire extensions, end at axon terminals
telodendria
communicate with other cells
axon terminals
area where neuron communicates with another cell
synapse
neuron that sends message
presynaptic cell
cell that receives that message
postsynaptic cell
small gap that separates presynaptic cell and postsynaptic membrane
the synaptic cleft
is expanded are on axon of presynaptic neuron. Contains synaptic vessels of neurotransmitters
the synaptic terminal
the synaptic terminal contains synaptic vesiscles of ____________
neurotransmitters
Neurotransmitters are ________ _________.
chemical messengers
Neurotransmitters are released at the
presynaptic membrane
Neurotransmitters are affect receptors of
postsynaptic membrane
Neurotransmitters are broken down by
enzymes
synapse between neuron and muscle
neuromuscular junction
synapse between neurons and gland
neuroglandular junction
allow a single neuron to communicate with more than one other cell
collateral branches
Most CNS neurons lack _________
centrioles
If lost to injury or disease, they are ________ replaced by cell division
seldom
Some neural stem cells exist, but most are inactive except
olfactory epithelium, retina of the eye, and hippocampus
located in brain and special sense organs. Small. All cell processes look alike. Functions are poorly understood
anaxonic
two distinct process. 1) Dendritic process that branches 2) Axon, rare, but occur in a special sense organ. small
bipolar
found in sensory neurons of PNS. Very long axon. Axon may extend a meter or more-longest carry sensations from toes to spinal cord . Dendrites and axons continous (fused) cell body off to one side
unipolar
Most common neurons in CNS. Include all skeletal muscle motor neurons. Very long axons. Can be as long as unipolar neurons-longest carry motor signals from spinal cord to muscles that move toes. Multiple dendrites, one axon
Multipolar
Afferent neurons of PNS
sensory neurons
Sensory neurons cell bodies are grouped in
sensory ganglia
Sensory neurons are ________ .
unipolar
Sensory neurons monitor the _________ environment
internal
3 types of sensory receptors:
- Interoceptors
- Proprioceptors
- Exteroceptors
Type of sensory receptor:
monitor internal systems such as detect dissension (stretch), deep pressure, pain
Interoceptors
Type of sensory receptor:
monitor position and movement
proprioceptors
Type of sensory receptor:
Monitor external senses such as touch, temperature, pressure, input or special senses
exteroceptors
efferent neurons of PNS
motor neurons
Motor neurons carry instructions from CNS to peripheral _________ via _________ fibers (axons).
effectors, efferent
2 major efferent systems:
- Somatic nervous system
2. Autonomic nervous system
Type of efferent system:
includes all somatic motor neurons that innervate skeletal muscles. Cell body lies in CNS; axon extends within a peripheral nerve
Somatic nervous system
Type of efferent system:
includes all other peripheral effectors (smooth muscle, cardiac muscle, glands, adipose tissue)
autonomic nervous system
association neurons
interneurons
Interneurons:
Most are located in brain, spinal cord, and autonomic ganglia in between ________ and motor neurons
sensory
Interneurons:
Responsible for distributing sensory information and coordinating _______ activity
motor
interneurons are involved in _______ functions such as memory, planning, and learning
higher
Neuroglia are found in the ______ and ______.
CNS and PNS
4 types of Central Nervous System Neuroglia
- Ependymal cells
- Astrocytes
- Oligodendrocytes
- Microglia
What type of CNS neuroglia:
form epithelium called ependyma. Lines central canal (spinal cord) and ventricles (brain). Secrete cerebrospinal fluid
ependymal cells
What type of CNS neuroglia:
maintain the blood-brain barrier (isolates CNS from chemicals/hormones in the blood)
astrocytes
What type of CNS neuroglia:
Myelinaiation of CNS. Increases speed of action potentials. Myelin insulates myelinated axon. Makes nerds appear white.
Oligodendrocytes
What type of CNS neuroglia:
smallest and least humerus neuroglia. migrate through neural tissue. Devlopmentally related to monocytes and macrophages. Mobile phagocytic cells that remove cellular debris
Microglia
Myelination increases speed of _______ _________.
action potentials
Myelination makes nerves appear ?
white
myelin-wrapped areas of axon
internodes
nodes= _____ between internodes where axons may branch
gaps
a “gang of neuron cell bodies surrounded by neuroglia in the PNS
ganglia
2 types of PNS neuroglia:
- satellite cells
2. Schwann cells
type of PNS neuroglia:
surround ganglia. regulate environment around neurons, similar to astrocyte role in CNS
Satellite cells
Neurons perform all ________ information processing, and control functions of the nervous system
communication
Neuroglia are essential to _______ and ______ of neurons
survival and function
axon and myelin degenerate distal to the injury (PNS)
Wallerian degeneration
Schwann cells proliferate along the original _______ path
axon
The axon grows along path created by
Schwann cells
Schwann cells wrap around the elongating _____
axon
If normal synaptic contacts are reestablished:
normal function may return
If axon stops growing or grows in wrong direction :
normal function will be different
Nerve regeneration is limited in the CNS because many more _____ are involved
axons
Astrocytes produce ____ ________ that can block axon growth in damaged area
scar tissue
Astrocytes release ________ that block axon regrowth
chemicals
the cause of many neurological disorders
Demyelination
Characterized by recurrent incidents of demyelination. Affects axons in optic nerve, brain and spinal cord. Common signs and symptoms: partial loss of vision, problems with speech and balance, cases are progressive
Multiple Sclerosis
Demyelination of peripheral nerves. Usually triggered by a virus. Signs/Symptoms: weakness or tingling of legs, increases in severity and leads to paralysis . Most patients fully recover, but some continue to have residual weakness
Guillain- Barre syndrome
All plasma (cell) e=membrane produce electrical signals by ion movements. Membrane potential is particularly important to neurons
Membrane potentials
4 Main Membrane Processes in Neural Activities:
- Resting Potential
- Graded Potential
- Action Potential
- Synaptic activity
membrane processes:
membrane potential of an undistributed cell; starting point
resting potential
Value of resting membrane potential:
-70 mV
Resting potential: inside is slightly ______ compared to outside
negative
Membrane process:
temporary, localized change in resting potential.
produced by: typical stimulus
Graded potential
Membrane Process:
electrical impulse. produced by a graded potential that large enough. Propagates along surface of axon to the synapse
Action potential
Synaptic activity: releases __________ at presynaptic membrane
neurotransmitter
Synaptic activity: produces graded potentials in ___________ membrane
post synaptic
Synaptic activity:
Information processing is the response (integration of stimuli) of the ________ cell.
postsynaptic
Extracellular environments contain high concentrations of:
sodium ions (Na+) chloride ions (Cl-)
Cell membranes are ________ __________.
selectively permeable
Membrane permeability varies by _____
ion
Resting membrane potential is
-70 mV
Leak channels are always _____
open
concentration gradient =
chemical gradient
postitive and negative charges are ________ to each other
attracted
like charges are ________
repulsed
the sum of chemical and electrical forces that act on the plasma membrane
the electrochemical gradient
The point where there would be no net movement of a particular ion across the cell membrane
equilibrium potential
K+=
-90mV
Na+=
+66mV
3 Classes of Gated Channels
- Chemically gated channels
- Voltage-gated channels
- Mechinally gated channels
Name the gated channel:
open in the presence of specific chemicals at a binding site. Found on neuron cell body and dendrites
Chemically gated channels
Name the gated channel:
Respond to charges in membrane potential. Have activation gates (open) and inactivation gates (close). An excitable membrane is a membrane capable of generating and conducting an action potential. Found in neural axons, skeletal muscle sarcolemma, cardiac muscle
Voltage-gated channels
Name the gated channel:
Respond to physical distortion of membrane surface. Found in sensory receptors such as touch, pressure, vibration
Mechanically gated channels
local potentials =
graded potentials
A change in membrane potential that cannot spread far from site of stimulation. Any stimulus that opens a gated channel produces a graded potential
graded potentials
Depolarization to threshold:
threshold amount:
-60mV to -55mV
4 Steps in the generation of an Action Potential
- Depolarization to threshold
- Activation of Na+ channels
- Inactivation of Na+ channels and activation of K+ channels
- Return to normal permeability
What step in generation of Action Potential?
Rapid depolarization. Na+ ions rush into cytoplasm
Activation of Na+ channels;s
What step in generation of Action Potential?
This happens at 30 mV . Inactivation gates close. K+ channels open. repolarization begins
Inactivation of Na+ channels and activation of K+ channels
What step in generation of Action potential?
K+ channels begin to close when the membrane reaches -70 mV. K+ closes but hyperpolarized at -90mV but returns to normal.
Return to normal permeability
During the refractory period, the membrane will _____ response normally to additional stimuli
not
Time during which the membrane cannot respond to any further stimulation. Na+ channels are open or inactivated
Absolute refractory period
Time during which the membrane can respond, but has to have a really strong stimulus
Relative refractory period
moves the action potentials along the length of the axon
Propagation of action potentials
action potential appears to move step by step through the entire axon. occurs in unmyelinated axons. Slower
continuous propagation
occurs in myelinated axons; depolarizes are the nodes. skips internodes. faster
Saltatory propagation
