Presentation 18: Nervous system overview, PNS and ANS Flashcards
Autonomic Nervous System (ANS) Function
visceral motor system (non-voluntary control) ex. controls heart muscles
How does the ANS differ from the PNS and CNS?
Composed of at least 2 neurons in a series that carry signals to visceral effectors (i.e. cardiac and smooth muscles, glands, etc,)
- preganglionic neuron
- postganglionic neuron
Preganglionic neuron
Neuron that’s part of the ANS
- stretches from CNS to autonomic ganglion
- short in sympathetic system
- long in parasympathetic system
Post ganglionic neuron
Neuron that’s part of the ANS
- stretches from autonomic ganglion cell body to effector
- long in sympathetic system
- short in parasympathetic system
How is the ANS categorized in Amniota
The Sympathetic (aka thoracolumbar) and Parasympathetic (craniosacral) systems
Sympathetic system
Part of the ANS in amniota (thoracolumbar)
- exits CNS w/ spinal nerves but diverge @ visceral ramus
- adrenergic system (neurotransmitters = adrenalin + noradrenalin)
- synapse occurs in synaptic trunk (collection of ganglia)
Parasympathetic system
Part of the ANS in amniota (craniosacral)
- fibers exit CNS w/ cranial nerves 3,4,9,10, + 11
- neurotransmitter = acetylcholine
What are the functions of the nervous system?
- allows body to respond to changes in external environment
- regulates internal environment
- store information
What are the components of the Nervous System?
- Central Nervous System (CNS) = brain and spinal cord
- Peripheral Nervous System (PNS) = cranial, spinal, and autonomic nerves
- Neurons = soma and 1 or more processes (an efferent axon and many afferent dendrites)
What are bundles of somas and processes called in the CNS vs the PNS?
Bundles of somas:
- CNS = Nucleus/Center/Olive
- PNS = Ganglion
Bundles of processes:
- CNS = tracts
- PNS = nerves
Neuroglia
Cells that support, nourish, and insulate neurons
- include microglia, astrocytes, oligodendroglia/schwann cells, and ependymal cells
Ependymal cells
Line central canal of CNS (ependymus)
Microglia
Engulf and destroy foreign material/bacterial (phage cells)
Astrocytes
pass nutrients and maintain normal physiology
Oligodendroglia
In the CNS - insulate axons by producing myelin sheath which surround the axon alongside neurolimma which form white (more myelin) and grey (less myelin) fibers
Schwann cells
In the PNS - insulate axons by producing myelin sheath which surround the axon alongside neurolimma which form white (more myelin) and grey (less myelin) fibers
What are the Meninges
Connective tissue that surrounds and protects the brain and spinal cord from rubbing against bone
- Fishes have 1 layer (menix primitiva)
- Non mammalian vertebrates have 2 (dura mater and lepto meninx)
- mammals have 3 (dural mater, arachnoid matter, and pia mater)
What are the different layers of the Meningesd in fish, non-mammalian vertebrates, and mammals?
Fish: Menix primitiva
Non-mammals: 2 layers
- Dura mater (outer layer in contact w/ bone)
- Lepto meninx (inner vascular layer)
Mammals: 3 layers (lepto meninx divides)
- Dura mater (outer layer in contact w/ bone)
- Arachnoid mater (middle layer)
- Pia mater (innermost vascular layer)
Spinal Nerves
Metameric (repeated unit arranged sequentially) w/ dorsal and ventral root that attatch to nerves of spinal cord
- fuse distally and then form ventral, dorsal, and visceral rami
Describe the Rami of the spinal nerves
Ventral Ramus: Hypaxial muscles - coordinates and organizes limb movement through plexus (brachial i.e. anterior limbs and lumbosacral i.e. post limbs)
Dorsal: Epaxial Muscles
Visceral: Goes to organs and autonomous NS
How are PNS nerves categorized?
-Somatic (voluntary) vs Visceral (involuntary)
AND
-Sensory (afferent) vs Motor (efferent)
Cranial nerve diversity
at least 10 pairs in all vertebrates, 12 in amniota along with cranial nerve 0 (detects pheromones)
- nerves 11 and 12 are homologous to non-amniotes, but only present as descrete nerves in amniotes
- 11 = part of 10 and occitospinal series
- 12 = rest of occitospinal series
Describe the main functions of the cranial nerves
Nerves 1, 2, + 8 = sensory nerves
- 2 + 8 = somatic sensory for optic and otic sense organs = optic/auditory nerves
- 1 - visceral sensory nerve epithelium of olfactory tract = olfactory nerve
Nerves 3, 4 + 6 = somatic motor nerves
- innervate eye muscles, similar to spinal nerves but no dorsal (sensory) root
Nerves 5, 7, 9, + 10 = mixed function
- Usually assoc. w/ gill arches
- 5 = mandibular arch, 7 = hyoid arch, 9 = 1st branchial arch, 10 = remaning brachial arches
