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Autonomic nervous system
- innervate cardiac muscle
- smooth muscle
- most exocrine glands and some endocrine glands
- 2 neuron chian
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postganglionic neurons in the sympathetic division
- an axon may synapse with post ganglionic neurons in the ganglion t first reaches for
- an axon may continue, without, synapsing, through the synaptic trunk ganglion
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cranial flow
- preganglionic fibers run via:
- Oculomotor nerve (3)
- facial nerve (7)
- glassopharyngeal nerve (9)
- vagus nerve (10)
- cell bodies located in cranial nerve nuclei in the brain stem
-
outflow in the vagus nerve
- fibers innervate visceral organs of the thorax and most of the abdomen
- stimulates - digestion reduction in heart rate and blood pressure
- Preganglionic neutrons cell bodies
- located in dorsal motor nucleus in the medulla
-
sympathetic vs parasympathetic
- SNS = promote fight or flight response
- PNS = dominates in quiet, relaxed situations
- 75% of all impulse travel along the vagus nerve ( cranial nerve 10)
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anatomical differences in SNS and PNS
- 1. Length of postgangliotic fibres
- SNS = long fibres
- PNS = short fibers
- 2. Branching of axons
- SNS = highly branched
- influences many organs
- PNS = few branches
- localized effect
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Neurotransmitters of ANS
- Neurotransmitter released by the pregangliotic axons
- Ach = for both branches (cholinergic)
- Neurotransmitter released by postgangliotic axons
- SNS = most release noreepinepherine (adrenergic)
- PNS = release Ach
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receptors
- For Ach, nicotinic receptors exist on all autonomic ganglia
- Muscarinic receptors = exist on all effector cells membranes
- For NE and EPI = alpha and beta receptors
-
adrenergic receptors
- Alpha receptors
- A1= contraction of genitouitary smooth muscle
- Ga= activates phospholipase C
- IP3 and DAG
- <Ca++> = ↑ contractions
- A2 = contraction of vascular smooth muscle
- Gi = ↓ cAMP
- Beta receptorsB1= effects the heart
- B2=smooth muscle
- B3= lipolysis in adipose tissue
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