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Compare the somatic nervous system and ANS
- Somatic:
- Concious control of movement and posture
- Voluntary
- Affects localized areas
- ANS:
- Controls visceral functions
- Involantary
- Affects multiple systems
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Fill in the blanks:
- Sympathetic preganglionic nerves are (short). Sympathetic postganglionic nerves are (long)
- Sympathetic ganglia located in the (sympathetic trunk)
- Parasympathetic preganglionic nerves are (long)
- Parasympathetic postganglionic nerves are (short)
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Compare sympathetic nerves and parasympathetic nerve fibers
- Sympathetic:
- Long spread out postganglionic fibers
- Many postganglionic fibers for each pre-ganglionic
- Parasympathetic:
- Short localized postganglionic fibers
- Relatively few postganglionic fibers to each pre-ganglionic
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Discuss sympathetic nerves and parasympathetic nervous system
- Parasympathetic:
- Dominates during rest and digest
- Promotes GI secretion and motility, urination, defecation
- Sympathetic:
- Dominates during emergency situations
- Increases cardiac output, pulmonary ventilation, blood to muscles, blood glucose levels
- Slows down digestion, kidney filtration, etc.
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Discuss autonomic neurotransmittors
- Cholinergic neurons release: Ach, VIP
- Noradreneric neurons release: NA, Neuropeptide Y, Adenosine
- State the cotransmitter: VIP, NPY, Adenosine
- State their function: potentiate action of principle NT
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Outline sympathetic stimulation of heart
- Increase heart rate:
- -- B1 receptors on SA nodes
- -- Coupled to excitatory G-proteins
- -- Increase of cAMP
- -- Opening of Na and Ca channels
- -- Speeds up rate of depolarization
- -- Increases heart rate
- Increase force of contraction
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Outline sympathetic control of blood vessels
- Maintain sympathetic tone (basal level of vasoconstriction)
- Gut and cutaneous blood vessels:
- -- Contain a1 receptors
- -- Sensitive to vasoconstriction
- -- Diverts blood to other areas
- Skeletal muscle blood vessels:
- - Contain b2:
- --- stimulated by moderate [adrenaline]
- --- Vasodilate
- --- In response to exercise
- - Also contain a1:
- --- High [adrenaline]
- --- Vasoconstriction
- --- In response to hemorrhage
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Outline the sympathetic control of:
- Eyes:
- -- a1 – contract dilator pulilae muscles (dilate eye)
- -- b2 – relax ciliary muscles (far vision)
- Airways:
- -- B2 – bronchodilate
- Gastrointestinal tract:
- -- a2 on presynaptic cholinergic neurons – indirectly inhibit tone + motility + secretion
- -- a1 – contract sphincters
- Adrenal medulla:
- -- muscurinic receptors – release Adrenaline into blood
- Salivary glands:
- -- B1- amylase secretion
- Metabolism:
- -- B2 – insulin secretion, glycogenolysis, gluconeogenesis
- -- B1 – lipolysis
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Discuss horner’s syndrome
- Damage to superior cervical ganglion
- Symptoms: ptosis, miosis, anhydrosis, flushing of face
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Outline parasympathetic control of the heart
- At rest its under parasympathetic tone by Vagus; which releases Ach
- Decreases heart rate:
- -- M2 receptors activated
- -- Activate inhibitory G-protein
- -- Reduce cAMP
- -- Close Na and Ca channels
- -- Opens K channels
- -- Cell hyperpolarizes; more difficult to initiate AP
- -- Slowing of heart rate
- Decrease atrial force of contraction:
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Outline parasympathetic control of blood vessels
Trick question…there is none. Its under SYMpathetic control
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Describe the micturition reflex
- Bladder fills
- Stretch receptors activate parasympathetic nerves
- Contracts detrusor muscle
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Outline the parasympathetic control of:
- Bronchial smooth muscle:
- -- contraction; muscous secretion
- GIT:
- -- increase muscle tone and motility; stimulates secretions
- Salivary glands:
- -- stimulate secretions
- Bladder:
- -- detrusor muscle contraction (peeing)
- Eye:
- -- contracts constrictor pupillae muscles
- -- contracts ciliary muscles (near vision)
- Male function:
- -- increase No and VIP
- -- activate guanylate cyclase
- -- increases cGMP
- -- vasodilation
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