Chapter 11 Functional Organization of Nervous Tissue
9 Characteristics Responsible for Resting membrane Potential - -1.
concentration of K+ = higher inside cell, concentration of Na+ =higher
outside cell
2. plasma membrane 50-100 times more permeable to K+ because of leak
channels
3. Plasma membrane is impermeable to large, intracellular, negatively
charged molecules like proteins. anions trapped inside the cell
4. potassium ions diffuse from inside to outside of cell
5. small negative charge develops on inside of plasma membrane
6. negative attracts positive and when negative is great enough to
prevent additional positive, equilibrium is established
7. charge difference across plasma membrane at equilibrium is reflected
as difference in potential: milivolts
8. resting membrane potential is proportional to potential for K+ to diffuse
out of cell but not out to atual rate of flow for K+
9. at equilibrium, very little movement of K+ or other ions takes place
across the plasma membrane
- absolute refractory period - --complete insensitivity exists to another
stimulus;
-from beginning of action potential until near end of repolarization;
-no matter how large the stimulus; second action potentials cannot be
produced;
-has consequences for function of muscle; particularly how often a.p.s.
can be produced
- Action Potential frequency - -Number of potentials produced per unit of
time to a stimulus;
threshold stimulus;
subthreshold stimulus;
maximal stimulus;
submaximal stimulus;
supramaximal stimulus;
, - Action Potentials - -depolarization phase followed by repolarization
phase
depolarization: more positive
repolarization: more negative (may get afterpotential [slight
hyperpolarization])
series of permeability changes when a graded potential causes
depolarization of membrane
large enough graded potential can cause membrane to reach threshold
then get action potential
all-or-none principle
no matter how strong the stimulus, as long as its greater than threshold,
then action potential will occur
- Astrocytes - -Neuroglia of the CNS
cover surfaces of neurons and blood vessels via pia mater
-regulate substances reaching CNS from blood (blood/brain barrier)
-lots of microfilaments for support
-produce chemicals promoting tight junctions to form blood/brain barrier
-regulate extracellular brain fluid composition
- AUTONOMIC NERVOUS SYSTEM - -From CNS to:
smooth muscle,
cardiac muscle,
certain glands;
involves subconscious or involuntary control;
two neuron system; CNS to ganglion; ganglion to effector;
- Autonomic Nervous System Divisions - -Parasympathetic;
Sympathetic;
Enteric;
- axoaxonic synapses - -axon of one neuron synapses with the
presynaptic terminal (axon) of another
many of the synapses of CNS
- Axonic Transport mechanism: into the body - -Into the Cell Body,;
-damaged organelles, recycled
plasma membrane, and substances
taken in by endocytosis can be
transported up axon to cell body;
, -the rabies and herpes virus can enter
axons in damaged skin and be taken
to CNS
- Axonic Transport mechanisms - -Axoplasm moved from cell body
toward terminals;
-supply for growth, repair, and
renewal;
- it can also move cytoskeletal proteins and
organelles away from cell body
toward axon terminals
- axons - -Axons can branch to form collaterals;
- Axons contain - -the axon hillock; an initial segment: beginning of
axon;
the trigger zone: which is site where action potentials are generated; the
trigger zone includes the axon hillock and part of axon nearest to the cell
body;
the axoplasm; the axolemma;
presynaptic terminals (terminal boutons);
and synaptic vesicles;
- Bipolar Neurons - -are located in the sensory in the retina of the eye
and nose;
bipolar neurons have only one dendrite and one axon
- Blood/Brain Barrier - -protects neurons from toxic substances;
allows exchange of nutrients and waste products between neurons and
blood;
prevents changes in make up of blood from affecting functions of the
brain;
- Cells of the Nervous System - -Neuroglia:
these support and protect neurons;
Neurons:
otherwise known as nerve cells, receive stimuli and transmit action
potentials
organization of Nerve Cells;
cell body: soma;
dendrites: receive input;
axons: output of information
9 Characteristics Responsible for Resting membrane Potential - -1.
concentration of K+ = higher inside cell, concentration of Na+ =higher
outside cell
2. plasma membrane 50-100 times more permeable to K+ because of leak
channels
3. Plasma membrane is impermeable to large, intracellular, negatively
charged molecules like proteins. anions trapped inside the cell
4. potassium ions diffuse from inside to outside of cell
5. small negative charge develops on inside of plasma membrane
6. negative attracts positive and when negative is great enough to
prevent additional positive, equilibrium is established
7. charge difference across plasma membrane at equilibrium is reflected
as difference in potential: milivolts
8. resting membrane potential is proportional to potential for K+ to diffuse
out of cell but not out to atual rate of flow for K+
9. at equilibrium, very little movement of K+ or other ions takes place
across the plasma membrane
- absolute refractory period - --complete insensitivity exists to another
stimulus;
-from beginning of action potential until near end of repolarization;
-no matter how large the stimulus; second action potentials cannot be
produced;
-has consequences for function of muscle; particularly how often a.p.s.
can be produced
- Action Potential frequency - -Number of potentials produced per unit of
time to a stimulus;
threshold stimulus;
subthreshold stimulus;
maximal stimulus;
submaximal stimulus;
supramaximal stimulus;
, - Action Potentials - -depolarization phase followed by repolarization
phase
depolarization: more positive
repolarization: more negative (may get afterpotential [slight
hyperpolarization])
series of permeability changes when a graded potential causes
depolarization of membrane
large enough graded potential can cause membrane to reach threshold
then get action potential
all-or-none principle
no matter how strong the stimulus, as long as its greater than threshold,
then action potential will occur
- Astrocytes - -Neuroglia of the CNS
cover surfaces of neurons and blood vessels via pia mater
-regulate substances reaching CNS from blood (blood/brain barrier)
-lots of microfilaments for support
-produce chemicals promoting tight junctions to form blood/brain barrier
-regulate extracellular brain fluid composition
- AUTONOMIC NERVOUS SYSTEM - -From CNS to:
smooth muscle,
cardiac muscle,
certain glands;
involves subconscious or involuntary control;
two neuron system; CNS to ganglion; ganglion to effector;
- Autonomic Nervous System Divisions - -Parasympathetic;
Sympathetic;
Enteric;
- axoaxonic synapses - -axon of one neuron synapses with the
presynaptic terminal (axon) of another
many of the synapses of CNS
- Axonic Transport mechanism: into the body - -Into the Cell Body,;
-damaged organelles, recycled
plasma membrane, and substances
taken in by endocytosis can be
transported up axon to cell body;
, -the rabies and herpes virus can enter
axons in damaged skin and be taken
to CNS
- Axonic Transport mechanisms - -Axoplasm moved from cell body
toward terminals;
-supply for growth, repair, and
renewal;
- it can also move cytoskeletal proteins and
organelles away from cell body
toward axon terminals
- axons - -Axons can branch to form collaterals;
- Axons contain - -the axon hillock; an initial segment: beginning of
axon;
the trigger zone: which is site where action potentials are generated; the
trigger zone includes the axon hillock and part of axon nearest to the cell
body;
the axoplasm; the axolemma;
presynaptic terminals (terminal boutons);
and synaptic vesicles;
- Bipolar Neurons - -are located in the sensory in the retina of the eye
and nose;
bipolar neurons have only one dendrite and one axon
- Blood/Brain Barrier - -protects neurons from toxic substances;
allows exchange of nutrients and waste products between neurons and
blood;
prevents changes in make up of blood from affecting functions of the
brain;
- Cells of the Nervous System - -Neuroglia:
these support and protect neurons;
Neurons:
otherwise known as nerve cells, receive stimuli and transmit action
potentials
organization of Nerve Cells;
cell body: soma;
dendrites: receive input;
axons: output of information
