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Questions and Answers
Which of these is NOT a functional division of the Peripheral Nervous System (PNS)?
What are the two main divisions of the Autonomic Nervous System?
Parasympathetic Nervous System and Sympathetic Nervous System
The sympathetic nervous system is responsible for the 'rest and digest' response.
False
What type of receptors bind norepinephrine and epinephrine?
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What is the primary function of the primary motor cortex?
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The withdrawal reflex is activated by ______.
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Match the following neurotransmitters with their division in the autonomic nervous system:
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Study Notes
Peripheral Nervous System (PNS) Divisions
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Functional Divisions:
- Somatic Sensory: Senses from skeletal muscles, skin, joints
- Visceral Sensory: Senses from internal organs
- Special Sensory: Smell, taste, vision, hearing, balance
- Somatic Motor: Controls skeletal muscle movement
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Autonomic Motor: Controls internal organs
- Parasympathetic: "Rest and Digest" functions
- Sympathetic: "Fight or Flight" functions
- Enteric: Controls gastrointestinal system
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Anatomical Divisions:
- Cranial Nerves: 12 pairs, named with Roman numerals
- Spinal Nerves: 31 pairs, named based on vertebral region
Brain White and Gray Matter
- Gray Matter: Outer layers (cerebral and cerebellar cortex) and inner regions (basal nuclei, thalamus)
- White Matter: Myelinated axons organized into tracts (association, projection, commissures)
- Primary Motor Cortex: Controls body movement, located in the frontal lobe
- Somatosensory Cortex: Receives sensory input, located posterior to the motor cortex
- Both cortices have body maps (homunculi) for sensory and motor functions
Spinal Cord White and Gray Matter
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Gray Matter:
- Dorsal horns: Contain sensory nuclei
- Ventral horns: Contain motor nuclei
- Lateral horns: Contain visceral motor nuclei (only in thoracic and lumbar regions)
- White Matter: Axon columns (anterior, posterior, lateral) that form tracts for sensory and motor communication
Spinal Reflexes
- Patellar Reflex: Triggered by stretch receptors in muscle spindles, involves afferent neuron activation and motor neuron response
- Withdrawal Reflex: Activated by pain, causes ipsilateral contraction of flexor muscles and inhibition of extensor muscles.
- Crossed-Extensor Reflex: Response on the opposite side of the body to maintain balance during a withdrawal reflex
Autonomic Nervous System (ANS)
- Controls smooth muscle, cardiac muscle, and glands
- Two main divisions:
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Parasympathetic Nervous System (PNS): "Rest and Digest"
- Decreases cardiac output
- Stores energy
-
Sympathetic Nervous System (SNS): "Fight or Flight"
- Increases cardiac output
- Mobilizes energy
-
Parasympathetic Nervous System (PNS): "Rest and Digest"
- Both divisions are always active to maintain homeostasis
Neural Pathways of ANS
- Uses a two-neuron chain:
- Preganglionic neuron: Cell body located in the CNS
- Postganglionic neuron: Cell body located in peripheral ganglia
- PNS has long preganglionic neurons and short postganglionic neurons
- SNS has short preganglionic neurons and long postganglionic neurons
Adrenergic and Cholinergic Receptors
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Adrenergic Receptors:
- Bind norepinephrine/epinephrine
- Alpha and Beta subtypes
-
Cholinergic Receptors:
- Bind acetylcholine
- Nicotinic and Muscarinic subtypes
- Nicotinic receptors are ionotropic (ion channels)
- Muscarinic and Adrenergic receptors are metabotropic (use second messenger systems and are G protein-coupled receptors, GPCRs)
Sympathetic vs. Parasympathetic Neurotransmitters
- Sympathetic: Uses norepinephrine and epinephrine as neurotransmitters
- Parasympathetic: Uses acetylcholine as the neurotransmitter
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