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Chapter 17&18: Pathways and ANS
Pathways and ANS
33
Anatomy
Undergraduate 1
11/13/2011

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Term
What is a pathway
Definition
Consists of a tract and nucleus
CNS communicates with peripheral body structures
Conducts sensory or motor information
Term
What is a tract
Definition
Groups or bundles of axons that travel together in the CNS
Term
What is a nucleus
Definition
Collection of neuron cell bodies located in the CNS
Term
What is a sensory pathway
Definition
Ascending pathway, sensory information is gathered by sensory receptors and ascends through the spinal cord to brain
1) discriminative touch permits textures and shapes of unseen objects
2)temperature and pain
3)Proprioception
Term
What is a motor pathway
Definition
descending pathways, transmit motor information from the brain through the spinal cord to muscles and glands.
Term
What is Decussate (Decussation)
Definition
to cross over from one side of the body to the other. Left side of brain processes info from right side of body.
Term
What 3 neurons does the sensory pathway use to transmit info from peripheral body to the brain?
Definition
Primary neuron, secondary and tertiary neurons
Term
What is the primary neuron
Definition
dendrite part of receptor that detects stimulus
cell body resides in root ganglia
axon projects to secondary neuron
Term
What is a secondary neuron
Definition
interneuron
cell body in posterior horn of the spinal cord or brainstem
axon projects to thalamus for conscious sensation, or celbellum for unconscious proprioception.
Term
What is the tertiary neuron
Definition
cell body resides in thalamus
Term
What is the lemniscal pathway
Definition
information about limb position and discriminative touch (exactly where your being touched), precise pressue, and vibration sensations.
Term
what is the anterolateral pathway
Definition
part of sensory pathways.
Anterior - Transmits crude touch (cant tell what's touching you)and pressure
Lateral - pain and temperature.
Term
what is the spinocerebellum
Definition
Sensory pathway
Critical for regulating posture and coordinating skilled movements. Integrated and acted upon at a subconscious level.
Does not use tertiary neurons
Term
What is a motor pathway
Definition
descending pathways of the brain and spinal cord that control the activities of the skeletal muscle.
Formed from cerebral nuclei, the cerebellum, descending projection tracts, and motor neurons.
Two pathways, direct and indirect
Term
What is a direct pathway
Definition
Motor pathway
also called pyramidal or corticospinal pathway
Originates in the pyramidal cells of the primary motor cortex.
Term
What is a Corticobulbar tract
Definition
A direct pathway
Axons of these lower motor neurons help form cranial nerves.
Transmit motor information to control eye movement, cranial, facial, pharyngeal and laryngeal muscles.
Term
What is the corticospinal tract
Definition
cerebral cortex to the brainstem, medulla oblongata, continue into spinal cord. composed of lateral and anterior tracts.
Term
What is the lateral corticospinal tract?
Definition
innervate skeletal muscles that control skilled movements in limbs including guitar playing, piano, dribbling
Term
What is the anterior corticospinal tract?
Definition
Voluntary activities.
Represent 15% of the axons of the upper motor neurons that extend through the medulla oblongata.
Term
What is an indirect pathway
Definition
Motor pathway
Motor input, issue motor commands for activities that occur unconsciously. knowing how fast to walk, how far to go, and when to stop.
Includes Rubrospinal, Tactospinal, Vestibulospinal, and Reticularspinal
Term
What is reticular formation
Definition
functional brain has motor and sensory components.
motor component assist in automatic motor functions like respiration, blood pressure and heart rate.
Sensory component processes visual, auditory and touch stimuli a keeps you in a state of mental awareness.Also arouses you from sleep by sending sound of alarm clock to cerebellum.
Term
What are the divisions of the automatic nervous system
Definition
Parasympathetic and Sympathetic.
Term
What is the Parasympathetic
Definition
Origin of fibers - brain and spinal cord
Length of fibers - long preganglionic and short postganglionic
Location of gangion - in the visceral effector organs.
Involves D activities, Digestion, defecation and diuresis.
Term
What is the sympathetic
Definition
Origin of fibers - Thoracolumbar region of spinal cord
Length of fibers -short preganglionic and long postganglionic
Location of ganglia - close to spinal cord
Involves E activities, exercise, excitement, emergency, and embarrassment.
Term
Name the two neurotransmitters involved in the ANS
Definition
Acetycholine (ACh) and Norephinephrine (NE)
Term
Which fibers release ACh?
Definition
released by all preganglionic axons and by all parasympathetic postganglionic fibers.
Released by some sympathetic postganglionc fibers.
Term
Which fibers release NE?
Definition
Released only by the sympathetic post ganglionic fibers
Term
Fibers that release ACh are called?
Definition
Cholinergic
Term
Name the receptors that ACh binds to
Definition
Nicotinic and Muscarinic
Term
How do neurotransmitters affect the heart?
Definition
Parasympathetic stimulation by ACh slows the heart while sympathetic stimultion NE speeds up the heart rate.
Term
Name two receptors Epinephrine and NE bind to
Definition
Alpha
Beta (Beta only on heart)
Term
Name the sympathetic ganglionic or post ganglionic fibers?
Definition
Adrenergic
-Releases Epinephrine or NE.
Term
What do Cholinergic fibers release
Definition
ACh
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