INTRO TO ANS PCOL Flashcards
known as nerve cells and has characteristic of excitability
neurons
ability to respond to a stimulus and convert it into an action potential
electrical excitability
3 parts of neuron
cell body (soma)
dendrites and an axon (nerve fibers)
2 types of sensory division
somatic senses
special senses
nerves that come out from the brain are called
cranial nerves
Central Nervous system is composed of
- CNS main function is integration and the source of thoughts, emotions, and memories
brain and spinal cord
involves all nervous tissue outside the CNS
Peripheral Nervous System
PNS has nerves/ bundles of axons
12 pairs of cranial nerves from brain and 31 pairs of spinal nerves from the spinal cord
PNS is divided into 2
sensory (afferent) division
motor (efferent) division
conveys input from sensory receptors to CNS and divided into 2 divisions: somatic and special senses
Sensory (afferent) division
example of somatic senses
touch, temperature, pain
example of special senses
sight, smell, hearing, taste and balance/ equilibrium
It conveys output from the CNS to effectors (muscles and glands)
and had 2 divisions: Somatic Nervous System and Autonomic Nervous System
Motor (efferent) division
ANS is divided into two or three division
Sympathetic NS - fight or flight responses
Parasympathetic NS - rest and digest activities
Enteric NS - regulate the activity of smooth muscles and glands of the GI tract
group of cell bodies or soma is called
ganglion
group of axons in PNS is called
nerve
cell bodies in the brain is called
nucleus/nuclei
2 cell bodies of ANS are found at
- CNS
- autonomic ganglion
cell body of somatic nervous system is found at
CNS (spinal cord)
2 autonomic motor pathways
-preganglionic neuron
- postganglionic neuron
has cell bodies in the CNS (brain or spinal cord)
-axons exit the CNS as cranial nerves or spinal nerves
- small-diameter, myelinated fibers -synapses with postganglionic neuron
preganglionic neuron
cell body in the autonomic ganglion
- small diameter, UNMYELINATED fibers
- synapses with visceral effector (smooth muscle, cardiac muscle, glands)
postganglionic neuron
Preganglionic neurons in SYMPATHETIC divisions have cell bodies in the lateral horns of the —
twelve thoracic and 1st two lumbar segments of the spinal cord (thoracolumbar) (T1 to L2)
Preganglionic in PARASYMPATHETIC division have cell bodies in the nuclei of the four cranial nerves in the brainstem —- and in the lateral gray horns of the —-
4 CNs - 3, 7,9,10
horns of the 2nd to 4th sacral segments of the spinal cords (craniosacral)
in autonomic ganglion of SYMPATHETIC Division is located at:
sympathetic trunk ganglia (lie lateral to the vertebra and the postganglionic axons innervate organs above the diaphragm) and prevertebral ganglia (lie anterior to the vertebra and the postganglionic axons innervate organs below the diaphragm)
in autonomic ganglia of PARASYMPATHETIC Division lies close to or within
the walls of visceral organs
the postganglionic fibers in sympathetic are
long and may be many for each preganglionic neuron
the postganglionic fibers in parasympathetic division are –
short and few for each preganglionic neuron
sweat glands are sympathetic but
cholinergic (neurotransmitter is ACh and the receptor is muscarinic)
fight or flight response
- dominant during physical or emotional stress
- effects are longer lasting and more widespread
sympathetic responses
rest and digest response and dominant during period of rest and discovery
- reduce body functions that supports physical activity
- supports functions that conserve and restore body energy
parasympathetic responses
the sympathetic effect of contraction is also known as
mydriasis
a region where communication occurs between two neurons or neuron and an effector cell
synapse
a nerve cell cell that carries nerve impulse toward a synapse
Presynaptic neuron
cell that receives a signal
post synaptic cells
Sympa PRESS
Para Pre Long
In sympathetic, preganglionic is shorter than postganglionic fiber
In parasympathetic, preganglionic is longer than postganglionic fiber
all preganglionic fibers are
cholinergic
all parasympathetic post ganglionic fibers are
cholinergic
(Sympathetic) all preganglionic receptors are
Nicotinic
2 types of synapse
electrical
chemical
action potentials (impulses) conduct directly between the plasma membranes of adjacent neurons through structures called gap junctions (which contains connexons)
- no neurotransmitter involved
- common in visceral smooth muscle, cardiac muscle and the developing embryo and brain
Electrical synapse
advantages of electrical synapse
faster communication and synchronization
Plasma membranes of synaptic neurons and postsynaptic cells do not touch
chemical synapse
it separates the presynaptic neurons and postsynaptic cells; filled with interstitial fluid’
- presynaptic neuron releases a neurotransmitter that diffuses through the synaptic cleft and binds to receptors the postsynaptic neuron
synaptic cleft
In chemical synapse,
- presynaptic neurons converts an electrical signal (nerve impulse) into a —
chemical signal (released neurotransmitter)
In chemical synapse,
- postsynaptic cell receives the chemical signal and converts it to an —
electrical signal (postsynaptic potential)
the synaptic delay in chemical synapse is about —
0.5 millisecond
steps in neurotransmission
synthesis
storage
release
fate (receptor activation or removal of neurotransmitter)
3 ways of the removal of neurotransmitter
diffusion - out of circulation
reuptake - by presynaptic neuron
enzymatic degradation
proteins that allow the fusion of vesicles and plasma membrane
snare proteins
2 types of snare proteins
v-SNARE and t-SNARE
V-snare proteins found in the vesicles and two examples are
synaptotagmin and synaptobrevin
t-SNARE are found in the target plasma membrane and two examples are:
syntaxin and SNAP-25
cholinoceptors include
nicotinic and muscarinic
catechol group with ethylamine side chain
catecholamines
adrenergic receptor or adrenoceptors
alpha receptor and beta receptor
alpha 1 receptors is dominant for
contraction of vascular smooth muscle and vasoconstriction in aorta and coronaries
alpha 2 receptor are dominant as an —
inhibitory receptor on sympathetic neurons
b 1 receptor is involved in heart, kidneys and dominant mediator of positive —- effects in heart
inotropic and chronotropic
b 2 receptor is involved in lungs and responsible for —
smooth muscle relaxation and skeletal muscle hypertrophy
b 3 receptor is involved in adipose tissue, GI tract and heart and have
—
metabolic effects
