Sponge: Set up Cornell Notes on pg. 21 Topic: 11.3: Spinal Cord and Reflexes Essential Question: 1.What are the 2 main functions of the spinal cord? 2.What is the main function of the spinal nerves? 2.1 Atoms, Ions, and Molecules 11.3: Spinal Cord and Reflexes 1.What is the main function of the spinal nerves? 2.What are the 2 main functions of the spinal cord? GET OUT HOMEWORK FROM FRIDAY *Need your textbook tomorrow

P. 20 Reflexes Reflex Arc “Story”

3 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

4 BODIES Exhibit

CNS: Spinal Cord Video 2m57s 5

6 Divided into same sections as the vertebral column

7 Cervical enlargement: supplies nerves to upper limbs Located in neck Lumbar enlargement: supplies nerves to lower limbs

8 Cross Section of Spinal Cord

9 Major functions of the Spinal Cord: 1.Center for spinal reflexes 2.Pathway for nerve impulses to and from the brain

10 What happens if our spinal cord is damaged or severed?

Eyes of Nye: Cloning Neural “Regeneration” clip (13m8s-15m56s) 11

12 Reflex arc- A simple pathway, including only a few neurons, that carry out the simplest response or 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

13 Spinal reflex- A reflex that involves the spinal cord ONLY, and not the brain

Reflexes 55s 14

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Reflex Arc Animation 27

Spinal Cord 4 5 Label the parts of this reflex arc: Key: Effector Motor Neuron Receptor Interneuron Sensory Neuron

29 1 Receptor 2 Sensory neuron 3 Interneuron 4 motor neuron 5 Effector Spinal cord

30 Receptor Sensory neuron Interneuron Motor Motor neuron Effector Spinal cord Please color-code your reflex arc. 3 Colors (one for each type of neuron) Make a key P. 20 sensory interneuron motor

31 Reflex Arcs

32 Pathway of a Reflex Arc: Stimulus Receptor  Sensory neuron  Interneuron (in spinal cord)  Motor neuron  Effector (muscle or gland)

Spinal Cord Reflexes Video 3m15s 33

34 Reflex Behavior 1. Knee-jerk reflex: Involves 2 neurons- a sensory neuron and a motor neuron Helps maintain an upright posture

35 Reflex Behavior 2. Withdrawal reflex: Involves a sensory/interneuron/and motor neuron Prevents or limits tissue damage

36 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

Pre-lab Meninges and Spinal Cord 37 GET YOUR TEXTBOOK

Study Guide Return Tape on p. 14/15 38

Cane Toad Reflex 4m51s-12m45s 39

Pre-laboratory Report 26-27: Meninges and Spinal Cord Day 1 40 Complete everything except for LAB 27: PART B

Sponge: Set up Cornell Notes on pg. 23 Topic: 11.3: Lab Report 26/27 Essential Question: 1.Which reflex was the easiest to elicit? 2.1 Atoms, Ions, and Molecules 11.3: Lab Report 26/27 1.Which reflex was the easiest to elicit? Get Out Lab Report 26/27

Lab Report 26/27 Check Have lab reports out in two separate piles for signature If they are not complete, you MAY NOT participate in today’s activity until they are done. 42

Explain Cast: The Kneejerk Reflex 5m43s 10 Bullets 43 P. 22

Laboratory Exercise 27: Spinal Cord Reflexes Day 2 44

Laboratory Exercise 27: Reflex Arc and Reflexes 45 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

46 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 Biceps-jerk reflex Ankle-jerk reflex

Knee-jerk reflex 47

Ankle-jerk reflex 48

Biceps-jerk reflex 49

Triceps-jerk reflex 50

Plantar Reflex 9s 51

Laboratory Exercise #27 Lab Manual P READ DIRECTIONS Fill out Part B of Lab 27 52

Classwork/Homework Clinical Application –Read/Highlight/Answer questions 53

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) Cremasteric reflex: contracting muscles elevate the testis 54

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”