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 2

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 16

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 22

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. 23

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) 24 • 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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