Autonomic Nervous System Flashcards
Autonomic Nervous System
- Consist of motor neurons
- Also called involuntary nervous system
Somatic vs. ANS
-
Both:
- have motor fibers
-
Differ:
- Origin
- Effectors
- Ganglia
- Target organ responses to neurotransmitters
Somatic NS (Origin)
-
Origin:
- cell body is in the ventral horn
Somatic NS (effector)
-
Effector:
- Voluntary skeletal muscles
ANS (Origin)
-
Origin:
- Lateral horn
ANS (effector)
-
Effectors:
-
involuntary:
- cardiac muscles
- smooth muscles
- glands
-
involuntary:
Divisions of Autonomic Nervous System
-
Sympathetic (fight or flight)
- Thoracolumbar Division
-
Parasympathetic (Rest and Digest)
- Craniosacral Division
Somatic NS uses a _____ motor neuron
Single
All somatic motor neurons release _____
Acetylcholine (ACh)
Effects always stimulatory
Autonomic nervous system uses ____ motor neuron chain
two
- Preganglionic Neuron
- Postganglionic Neuron
Postganglionic fibers release _____ or _____ at effectors
- norepinephrine
- acetlycholine (ACh)
- Effects are either stimulatory or inhibitory, depending on type of receptor
Comparison (Picture)
Localized vs. Widespread
-
Parasympathetic:
- short-lived, highly localized control over effectors (localized)
-
Sympathetic:
- longer lasting, bodywide effects (widespread)
Role of the Parasympathetic NS
- Maintenance activities and conserves body energy
- S.L.U.D.D
- Blood pressure, heart rate, resp. rate are low
- G.I Tract activity high
- Pupils constricted
- Immune system active
- Growth and repair (healing)
SLUDD
- Salivation
- Lacrimation
- Urination
- Digestion
- Defecation
Parasympathetic Nervous Systems does not affect ____ and ______ glands
adrenal and sweat glands
Role of Sympathetic NS
- “fight or flight system”
-
4 e’s
- increase heart rate and respiration
- dry mouth
- cold, sweaty skin; contract arrector pili muscles
- dilated pupils
- Shunts blood to skeletal muscles and heart
- Liver release glucose
4 e’s
- Exercise
- Excitement
- Emergency
- Embarrassment
Which organs only receive sympathetic fibers?
- Adrenal medulla
- Sweat glands
- Arrector Pili muscles
- kidneys
- most blood vessels
Parasympathetic (Craniosacral) Division…
-
Long preganglionic fibers from brain stem and sacrum
- Extend from CNS almost to target organs
- Synapse with postganglionic neurons in autonomic/terminal ganglia close to/within target organs
- Short postganglionic fibers synapse with effectors- hence effects are localized
Sympathetic (Thoracolumbar) Division…
- Preganglionic neurons are in spinal cord segments T1-L2 in the lateral horns of spinal cord
- 23 sympathetic chain ganglia
- Short preganglionic neurons
- Long postganglionic neurons
Preganglionic fibers pass through _______ and enter ______ _____ ______ (Sympathetic Division)
- Rami communicantes
- sympathetic trunk (chain) ganglia
Preganglionic fibers pass directly to ______ _____ without synapsing
adrenal medulla
Cranial Nerves of Parasympathetic division
- Oculomotor nerves III - smooth muscle of eye
- Facial Nerves VII - stimulate lacrimal glands in head
- Glossopharyngeal Nerves IX - parotid salivary glands
- Vagus Nerve X - neck and nerves plexuses for ~ all thoracic and abdominal viscera
________ ____ release neurotransmitter ACh
Cholinergic Fibers
- all ANS preganglionic axons
- All Parasympathetic postganglionic axons at effector synapse
________ ____ release neurotransmitter NE
Adrenergic Fibers
- Most sympathetic postganglionic axons
- Exception: sympathetic postganglionic fibers secrete ACh at sweat glands
Most visceral organs have ____ _______
Dual Innervation (both para and sym. nerves)
- Sym. Division increases heart and resp. rates, and inhibits digestion and elimination
- Para. Division decreases heart and resp. rates, and allows for digestion and discarding of wastes
_______ - main integrative center of ANS activity
Hypothalamus
- other controls come from cerebral cortex, reticular formation, and spinal cord
Centers of hypothalamus control include:
- Heart activity and blood pressure
- Body temp, water balance, and endocrine activity
- Emotional stages and biological drives
- Reactions to fear and “fight or flight” system
Homeostatic Imbalances of the ANS
-
Hypertension
- overactive sym. vasoconstrictor response to stress
- treated with adrenergic receptor - blocking drugs
Effects of Age on ANS
- Constipation
- Dry Eyes
- Frequent eye infections
- Orthostatic hypotension
- low blood pressure after position change
- pressure receptors less responsive to blood pressure changes
- cardiovascular center fails to maintain healthy blood pressure
