Transcript 11.3 Spinal Cord and Reflexes

Sponge: Set up Cornell
Notes on pg. 19
11.3:
2.1 Atoms, Ions,
The Spinal Cord
and Molecules
Topic:
11.3: The Spinal Cord
Essential Question:
1. What is the main
function of the spinal
nerves?
2. What are the 2 main
functions of the spinal
cord?
1. What is the main function
of the spinal nerves?
2. What are the 2 main
functions of the spinal cord?
Spinal Cord:
• Slender column of nervous
tissue
• Extends downward
through vertebral canal
• Consists of 31 segments,
each of which gives rise
to a pair of spinal nerves
which connect body parts
with CNS
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BODIES Exhibit
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CNS: Spinal Cord Video 2m57s
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• Cervical enlargement:
supplies nerves to upper
limbs
• Lumbar enlargement:
supplies nerves to lower
limbs
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Cross Section of Spinal Cord
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Functions of the Spinal Cord:
1. Center for spinal reflexes
2. Pathway for nerve impulses to and from the
brain
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Clinical Application 11.3 :Spinal Cord Injuries
1. When vertebrae are compressed and break, a
chain reaction occurs. List the 4 things will likely
happen next.
2. The severity of a spinal cord injury depends
on…?
3. What is the most COMMON cause of injury to
the spinal cord?
4. What is regeneration?
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Eyes of Nye: Cloning
• Neural “Regeneration” clip (13m8s)
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Clinical Application 11.3 :Spinal Cord Injuries
1.
•
•
•
•
When vertebrae are compressed and break, a chain reaction occurs. List the 4
things will likely happen next.
Action potentials set off in neurons, killing many of them
Dying neurons release calcium ions, which activate tissue-degrading enzymes
White blood cells arrive and produces inflammation that destroy
healthy/damaged neurons
Axons tear/myelin coating stripped off/vital connections between nerves and
muscles are cut
2. The severity of a spinal cord injury depends on…?
• The extent and location of damage
3. What is the most COMMON cause of injury to the spinal cord?
• Vehicular accidents (car crashes)
4. What is regeneration?
• Rats given implants of neural stem cells regain some ability to walk- used as a
“patch”
Sponge: Set up Cornell
Notes on pg. 21
Topic:
11.3: Reflexes
Essential Question:
1. On pg. 20 please draw a
picture of a reflex arc.
The neurons MUST be
color coded and
labeled.
11.3: Reflexes
2.1 Atoms, Ions,
and Molecules
Reflex arc- A simple pathway, including only a few neurons, that
carry out the simplest responses…reflexes.
Reflexes – automatic, subconscious responses to stimuli
within or outside the body.
• Maintain homeostasis by controlling: heart rate, breathing
rate, blood pressure, digestion, swallowing, sneezing,
coughing, and vomiting
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Reflex Arcs
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Reflexes 55s
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Label the parts of this reflex arc:
1
5
3
Spinal Cord
4
2
Key: Effector Motor Neuron
Sensory Neuron
Receptor Interneuron
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1 Receptor
5 Effector
3 Interneuron
Spinal cord
4 motor
neuron
2 Sensory neuron
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Spinal Cord Reflexes Video
3m15s
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Reflex Arc EQ:
ReceptorSensory neuron Interneuron  Motor neuronEffector
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Reflex Behavior
1. Knee-jerk reflex:
•Involves 2 neurons- a sensory neuron and a motor neuron
• Helps maintain an upright posture
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Reflex Behavior
2. Withdrawal reflex:
• Involves a sensory/interneuron/and motor neuron
• Prevents or limits tissue damage
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Reflex Arc
3. Crossed extensor reflex:
• While a muscle is contracting due to a withdrawal reflex
on one side, the muscles on the opposite side also contract
to maintain balance
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Reflex Arc
• On pg. 20 please draw an example of a
reflex arc. MUST BE A STORY!!!
• 3 Colors
(for each type
of neuron)
• Labels
Key: Effector Motor Neuron
Receptor Interneuron
Sensory Neuron Spinal cord
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Clinical Application 11.2 Questions:
Use of Reflexes
1. Why do doctors test your reflexes?
2. How can observing reflexes determine damage to the
nervous system?
3.How can we tell if the nervous system is damaged?
4. Describe the healthy response to each of the 5 reflexes
listed.
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Clinical Application 11.2 Questions:
Use of Reflexes
1. Why do doctors test your reflexes?
• Reflexes are commonly used to obtain information on the condition of the
nervous system
2. How can observing reflexes determine damage to the nervous system?
• Observing reflexes may reveal the location and extent of damage to some
part of the nervous system.
3. How can we tell if the nervous system is damaged?
• Injury to any component of a reflex arc alters its function (the reflex will not
show normal results)
4. Describe the healthy response to each of the 5 reflexes listed.
• Biceps-jerk reflex: biceps contract, forearm flexes at elbow
• Triceps-jerk reflex: triceps contracts, forearm extends slightly
• Abdominal reflex: abdominal muscles contract
• Ankle-jerk reflex: plantar flexion (foot flexes)
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• Cremasteric reflex: contracting muscles elevate the testis
Laboratory Report 26:
Meninges and Spinal Cord
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Laboratory Report 27: Reflex Arc and Reflexes
Most reflexes demonstrated in this lab are stretch reflexes
1. A sensory neuron conducts an impulse and synapses with a
motor neuron
2. The motor neuron conducts an impulse to the effector muscle
3. The stretched muscle responds by contracting to resist or
reverse further stretching
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• These stretch reflexes are important to maintain proper posture,
balance, and movements
• Observations of these reflexes in clinical tests on patients may
indicate damage to a level of the spinal cord or peripheral
nerves of the particular reflex arc
Ankle-jerk reflex
Biceps-jerk reflex
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