Unit 4 Lecture 32 Flashcards
Autonomic Nervous System: Sympathetic Division
What are the 3 parts to the Peripheral Nervous System?
Somatic, autonomic and enteric nervous system
Describe the somatic nervous system
- somatic sensory (voluntary) ascend to CNS
- somatic motor (voluntary) descend to SKELETAL MUSCLE in PNS
Describe the autonomic nervous system
- autonomic sensory (involuntary) ascend to CNS
- autonomic motor (involuntary) descend into ENTERIC NS or SMOOTH MUSCLE, CARDIAC MUSCLE and GLANDS
Why do we need the autonomic ns?
maintains breathing and cardiovascular function w/out consciousness (sleeping etc)
How does the autonomic ns opperate?
- uses reflex arcs
- its controlled by centers in the hypothalamus and brain stem
What is the difference between the somatic and autonomic ns?
Autonomic:
- Effectors - cardiac muscle, smooth muscle, and glands
- involuntary
- 2 efferent neurons exit CNS
Somatic:
- Effectors- skeletal
- Voluntary
- 1 efferent neuron exits CNS
What are the 2 parts of the autonomic nervous system?
Sympathetic and parasympathetic
Define the sympathetic ns
fight or flight
Define the parasympathetic ns
rest or digest
Where do efferent neurons leave the SC in the somatic ns?
anterior horn (somatic motor)
Where do efferent neurons leave the SC in the autonomic ns?
lateral horn (visceral motor)
Name the first efferent neuron from the autonomic ns
Preganglionic neuron
What happens after the first efferent neuron leaves the CS
It synapses with another efferent neuron in a ganglion -> 2nd efferent neuron
name of the 2nd efferent neuron in autonomic ns
postganglionic neruon
Define ganglion
sensory cell bodies in the PNS
Where are most ganglia found?
near the spinal cord
Define thoracolumbar
preganglionic neurons begin in T1 and L2 regions
What are 3 types of sympathetic ns ganglia
- sympathetic trunk (chain)
- Prevertebral ganglia (collateral)
- Adrenal medulla
Describe the sympathetic trunk (chain)
paired ganglia near spinal cord
What does the postganglionic neuron of the sympathetic trunk innervate?
Visceral organs in thoracic cavity
Describe the prevertebral ganglia (collateral)
Anterior to vertebral bodies
What does the postganglionic neuron of the prevertebral ganglia innervate?
abdominopelvic organs
Describe the adrenal medulla
acts as a modified sympathetic ganglion
What do postganglionic neurons in the adrenal medulla do?
- they are short
- release NOREPINEPHRINE (20%) and EPINEPHRINE (80%) into blood stream
What are norepinephrine and epinephrine called
catecholamines
What makes up the sympathetic trunk?
3 cervical, 11 thoracic, 4 lumbar, and 4 sacral
What makes up the prevertebral ganglia?
celiac ganglion, superior mesenteric ganglion, and inferior mesenteric ganglion
Define neurotransmitter
A chemical transmitter released by neurons to stimulate neighboring neurons/cells
Describe the neurotransmitter process of the sympathetic ns
- preganglionic neurons release ACETYLCHOLINE (ACh)
- Binds to nicotinic cholinergic receptors on postganglionic cell body
- Postganglionic neurons release NOREPINEPHRINE (NE)
- Binds to adrenergic receptor on effector cell
What are the two special cases of neurotransmitters?
Sweat glands and adrenal medulla
Describe sweat glands as a neurotransmitter
- Preganglionic neurons release ACh -> binds ** SAME
- postganglonic neurons release ACh (NOT NE) at the effector -> binds to muscarinic cholinergic receptors at sweat gland
Describe adrenal medulla as a neurotransmitter
- Pregang. releases ACh
- Chromaffin cells act as postgang. neurons & adrenal medulla acts as a modified ganglion
- Chromaffin cells release Epinephrine and NE into blood
When is NE a neurotransmitter?
When it is released from sympathetic nerve endings directly at target tissues (short lived)
When is NE is a hormone
When it is released from the adrenal gland into the blood stream (longer lasting effects)
What is epinephrine?
Hormone - bc it is released from the adrenal gland into the blood
Adrenaline
Define adrenergic receptors
Things that bind epinephrine (adrenaline) and norepinephrine (noradrenaline) at effector tissues
What are the 2 types of adrenergic receptors?
- Alpha adrenergic receptors
2. Beta adrenergic receptors
Define Alpha adrenergic receptors
- found in smooth muscle of arterioles, bladder
- results in CONSTRICTION
Define beta adrenergic receptors
- found in heart, bronchioles, liver
- causes INCREASED METABOLISM
What is the goal of fight or flight
to increase mental alertness, energy availability (glucose) and ability to handle stress
What are specific responses to the sympathetic ns?
- mobilize fuels
- redistribution of blood flow
- decrease urinary output and digestive functions
- Increase heart rate and blood pressure
- Increase activity of sweat gland
- increase diameter of bronchioles
- dilation of pupils
