Term
| Study Chart on Muscle characteristics (handout) |
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Definition
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Term
| Skeletal muscle is controlled by ___________ pathways and is _____________. |
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Definition
Decending
Conscious
(association tracts in the brain) |
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Term
| Upper Motor Neurons are located in ______ ___________ |
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Definition
The Brain
(an interneuron) |
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Term
| Upper Motor Neurons are ______________ and _______________. |
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Definition
| Inhibitory and Excitatory |
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Term
| A Lower Motor Neuron is only ______________. |
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Definition
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Term
| Briefly describe the pathway from 1 SN to skeletal muscle. |
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Definition
- 1 SN synapses w/ 2 SN in S.C.
- 2 SN synapses w/ 3 SN in Thalamus
- 3 SN synapses w/ Interneuron in Cortex
- Interneuron synapses with Upper MN in 1 Motor Cortex
- Upper MN synapses with Lower MN in S.C.
- Lower MN innervates a skeletal muscle
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Term
| What is a Monosynaptic Reflex? |
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Definition
A reflex with only one synapse.
SN synapses in S.C. with MN and innervates a muscle
RARE |
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Term
| What is a Polysynaptic Reflex? |
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Definition
A reflex that involves 2 or more neurons.
- SN synapse w/ Interneuron in S.C
- Interneuron synapses w/ MN in S.C. (or brain stem)
- MN innervates muscle
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Term
| Autonomic reflexes are always ______synaptic. Why? |
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Definition
Polysynaptic
Because we know that the sympathetic has 2 Motor Neurons (in the pre and post ganglion) and a Sensory Neuron. (that is at least 3!) |
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Term
| Muscle Spindles are activated by muscle __________ which triggers a _____________. They are located in the ___________. |
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Definition
Stretch
Contraction
Muscle |
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Term
| Golgi Tendon Organs respond to muscle _________, which triggers a _____________ and are located where the ____________ meets the ___________. |
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Definition
Stretch
Relaxation (inhibition)
Tendon/Muscle |
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Term
| What are intrafusal fibers inside a muscle spindle? |
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Definition
- Fibers imbedded w/in the muscle that don't have sarcomeres.
- They are innervated by Sensory Neurons.
- They are always active and sense stretch which activates AP
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Term
| What are Extrafusal fibers inside a muscle spindle? |
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Definition
| Fibers outside of the intrafusal fibers that are innervated by alpha motoneurons. |
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Term
| How does a Golgi Tendon Organ work? |
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Definition
- Tension on the golgi tendon organ causes a SN activation
- SN stimulates the inhibitory neuron
- Inhibitory Neuron inhibits MN (which releases Gaba Proteins)
- Muscle relaxes
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Term
| Reciprocal Innervation is activated by both _____________ and ______________ synapses. |
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Definition
| Excitatory and Inhibatory |
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Term
| Briefly describe how Reciprocal Innervation works. |
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Definition
- A SN from the Muscle spindle sends out an AP
- SN branches-
- one branch synapses with an inhibatory SN then to a MN then to a muscle to relax
- other branch synapses with a MN then to a muscle to contract.
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Term
| List some major characteristics of Smooth Muscle |
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Definition
- Aids in Homeostasis (regulates BP and temp)
- Has slow contractions
- Requires little E (compared to skeletal)
- uses less ATP but has the same force
- maintain force, yet resistant to fatigue
- low O2 consumption
- Contractions are signaled by Hormones and NT
- Can be Excited or Inhibited
- Have variable electric properties
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Term
| How does Smooth Muscle have strange anatomy? |
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Definition
- There are no sarcomeres
- They are arranged in sheets
- Actin and myosin are arrranged in criss-cross bundles
- A Dense Body anchors actin filaments to each other
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Term
| Smooth muscle contraction is a result of an ______________ in intracellular ______. |
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Definition
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Term
| Where does the Ca++ come from for smooth muscle contractions? |
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Definition
| Some from the SPR, but most from the Extracellular Fluid. |
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Term
| Briefly describe the steps of smooth muscle contraction. |
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Definition
VERY COMPLICATED! :)
- Know that a variety of steps leads to the phosphoralization of myosin
- This enhances ATPase's activity of myosin and increases muscle contractions.
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Term
| What are the 3 ways in which Ca++ can get into smooth muscle |
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Definition
- Can open by membrane depolarization - voltage gated
- By chemicals (like hormones) - Chemically gated
- Opened by stretch - mechanically gated
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