2. An Introduction to Health and Physical Education Ted Temertzoglou Paul Challen ISBN 1-55077-132-9 Introduction to Kinesiology The Nervous System and the Control of Movement

3. “An organ system of specialized cells (neurons) that coordinate the actions of an animal by transmitting different signals between parts of the body.” It has 3 main roles : Assemble information about conditions external and internal to the body Analyze information Initiate response that may be necessary to satisfy certain needs of the body

4. The Nervous System and Control of Movement: There are two major components to the human nervous system: 1.Central Nervous System (CNS) 1.Brain and spinal cord 2.Accepts and coordinates information from all parts of the body 3.Has nerves going to and from it, which comprise the second major component of the human nervous system- PNS 2.Peripheral Nervous System (PNS) 1.Responsible for the beating of the heart and digestive system, and all other voluntary and involuntary neuromuscular controls 2.Think of it as a massive road network carrying traffic (information) in and out of the CNS 3.Contains the autonomic and somatic divisions

5. Even though there are 2 major components to this system, they are interconnected Central Nervous system Peripheral Nervous System Brain Spinal Cord

6. Central Nervous System (CNS) Brain and spinal cord Main control centre for almost all body’s activities Receives and interprets signals  commands -main information pathway -spinal nerves branch off cord reaching different organs and tissues -named after where exit

7. Even though there are 2 major components to this system, they are interconnected Central Nervous system Peripheral Nervous System Brain Spinal Cord Autonomic Nervous System Somatic Nervous System Sympathetic System Parasympathetic System Afferent Nerves Efferent Nerves

8. Peripheral Nervous System (PNS) “Roadway” carrying all information towards and away from the CNS Contains 12 pairs of cranial and 31 pairs of spinal nerves 2 roots: 1)Motor Pathway (efferent) 2)Sensory Pathway (afferent) Autonomic Nervous System “Automatic” –involuntary contraction of cardiac muscle and the smooth muscles of our internal organs is regulated by the ANS This subsystem is comprised of two branches; sympathetic and parasympathetic systems, which act as opposing systems. Sympathetic Localized bodily adjustments- sweating Prepare for emergencies – this involves the release of adrenaline from the adrenal gland, an increased HR, widening of BV’s, and similar “fight or flight” responses to deal with immediate danger. Parasympathetic Returns body to normal state Decrease HR, rest, digest…

9. Somatic Nervous System Provides us with our awareness of the external environment- and the corresponding motor activity allowing us to cope with it Contains both afferent and efferent nerve fibres 1.Afferent 2.Efferent Afferent nerves send information to the CNS ex. Touch, pain, heat, cold, balance, body position Efferent nerves carry/send information from the CNS to muscles/organs (skeletal muscles) Through this system, the PNS receives and processes information from receptors in the skin, in voluntary muscles, tendons, and joints, and gives us the sensations of touch, pain, heat, cold, balance, body position, and muscle action.

10. Autonomic and Somatic Nervous Systems

11. Reflexes, Proprioception, and Movement: Reflexes are an important part of all physical movement They are automatic and rapid responses to a particular stimulus. Ex. Pain or the threat of pain If the command centre for the reflex is located in the brain= cerebral reflex If the control centre is located in the spinal cord= spinal reflex

12. Cont… Two types of Reflexes Autonomic Reflexes  mediated by the autonomic division of the nervous system and usually involve the activation of smooth muscle, cardiac muscle, and glands These reflexes regulate bodily functions such as; digestion, elimination, sweating, salivation, blood pressure Somatic Reflexes  involve stimulation of skeletal muscles by the somatic division of the nervous system. Include such reflexes as the stretch and withdrawal Reflex contraction of skeletal muscle is not dependent on conscious intervention by higher centres of the brain but are a way in which our bodies respond to unexpected stimulus.

13. The Reflex Arc? There are 3 types of neurons(transmit information to each other through a series of connections that form a circuit) in the human body; 1. Sensory neurons  detect or sense information from the outside world. i.e. light, sound, touch, and heat 2. Motor neurons  send signals away from the CNS and elicit a response i.e. movement of a leg or arm 3. Interneuron's  form interconnections between other neurons in the CNS One example of this simple circuit is the REFLEX ARC: allows a pathway long which the stimulus and response messages travel Basic arrangement of the reflex arc involves a; 1. receptor 2. adjustor 3. effector

14. The Reflex Arc Five parts to a reflex arc: Receptor Sensory (or afferent) nerve Intermediate nerve fibre/adjustor Motor (or efferent) nerve Effector organ

15. 5 Components of a Reflex Arc (Exercise Workbook 6.3) ReceptorArea of body that receive initial stimulus (often skin) Sensory (afferent) nerve Carries sensory impulse to spinal column or brain Interneuron (intermediate nerve fibre)/adjustor Adjustor  interprets signal and issues response Motor (efferent) nerve Carries response impulse from spinal cord to muscle or organ Effector Organ-Area of body that carries out response (often muscle) Key to a reflex  it is not the brain that sends the motor signal to the effector.

16. We already discussed how a sensory impulse can cause a muscle to contract.... NOW consider; what determines the extent to which a muscle contracts? The moment when a muscle relaxes? How muscles coordinate with other muscles and with other muscle groups? Answer lies in specialized receptors located within tendons, muscles, and joints. Proprioceptors: “Provide constant sensory information about the state of muscle contraction, the position of body limbs, and body posture and balance” This all-important feedback, along with control over muscles, is provided primarily by the afferent (sensory) input from TWO SENSORY RECEPTORS: 1. Tendon Organs 2. Muscle Spindles Tendon organs and muscle spindles continuously monitor muscle actions and are essential components of the neuromuscular system.  They “TELL” the nervous system about the state of muscle contraction, act as a kind of safely device, and allow the nervous system to respond accordingly

17. 1. Muscle Spindles- sensory receptors- proprioceptors play an essential role in all physical movement, they are the means by which muscles constantly and automatically adjust to the demands placed on them Lie parallel to the main muscle fibre and send constant signals to the SPINAL CORD Consists of specialized muscle fibres, intrafusal muscle fibres, that run the length of the muscle Help maintain muscle tension and are sensitive to changes in muscle LENGTH Contains TWO AFFERENT and ONE EFFERENT nerve fibre Spindle detects changes in the muscle fibre length and responds to it by sending a message to the spinal cord, leading to the appropriate motor responses The resulting contraction allows the muscle to maintain proper muscle tension or tone i.e. an erect posture. -video

18. The Muscle Spindle Motor neuron Sensory neuron (two branches within) Muscle spindle within muscle fibre (magnified) Muscle fibres

20. Muscle spindles are responsible for one of the most recognizable reflexes... The Stretch Reflex (Knee –Jerk) Monosynaptic reflex  depends only on the single connection between sensory and motor neurons of the same muscle- extremely quick and automatic Knee-Jerk is used to demonstrate this type of reflex and is the simplest spinal reflex A tap below the kneecap stretches the patellar tendon and acts as a stimulus, initiating a reflex arc that causes the exterior muscle on top of the thigh to contract As the tendon and muscle fibre are stretched, information is sent to the spinal cord These nerve signals act directly on motor neurons that then quickly proceed to contract the quadriceps femoris, the extensor muscle that serves to extend the lower leg.

21. 1. The receptor muscle senses the action of the hammer against the patellar ligament through the muscle spindle’s sensory neuron 2. The message is transmitted along the afferent (sensory) nerve axon to the spinal cord 3. The afferent neuron then synapses with the efferent pathway (motor neuron) of the same muscle 4. An impulse is transmitted along the efferent pathway (motor neuron) to the muscle fibre 5. The motor unit contract simultaneously, which in turn brings about a knee-jerk action to accommodate the additional stretch Motor neuron Sensory neuron (two branches within) Muscle fibres Muscle Spindles at Work

22. Polysynaptic Reflex A reflex with one or more interneurons between the primary sensory fibres and motor neurons More = more complex = slower Withdrawal Reflex(Pain –sharp/hot)

23. 1. Stimulus is detected by receptors i.e. skin 2. Receptors initiate nerve impulses in the sensory neurons leading from the receptors 3. Impulses travel into the spinal cord where the sensory nerve terminals synapse with interneurons 4. Some of the interneuron's synapse with motor neurons that travel out from the spinal cord to the effectors organ 5. The arm flexors withdrawal the arm/hand from the danger zone; 6. Other sensory neurons synapse with interneurons that affect motor neurons in the opposing arm/leg and cause these muscles to come into action- see next example

24. Polysynaptic Reflexes – cont’d Crossed-Extensor Reflex: Observed when one leg or arm automatically compensates for a reflex action in opposing leg or arm Involves multiple synapses and muscle groups

25. 2. Golgi Tendon Organs (GTO) Are sensory receptors found at the end of muscle fibres that merge into the tendon itself and that detect changes in muscle tension. Are aligned in series with the muscle, such that any muscle stretching also stretches the GTO receptor Specifically positioned to detect increased tension exerted on the tendon Serve as a tension detection device for the muscle system. Help protect the muscle from excessive tension that would otherwise result in damage to the muscle or the joint or even BOTH. Provide feedback to the CNS regardless of magnitude of the tension- thus play an important role in strength and power, since in order to be able to exert a greater force, you must overcome the obstacles presented by the Golgi tendon organ itself.

26. Golgi Tendon Organs

27. Golgi Tendon Organs (GTO’s) 1)Change in tension  2)impulse sent along sensory (afferent) neuron to spinal cord  3)synapse with interneuron  4)motor (efferent) neuron sends impulse  5)muscle relaxes (preventing injury) (Fill in Workbook Exercise 6.4)

28. Golgi Tendon Organs & Muscle Spindles Golgi Tendon OrgansMuscle Spindles Location Where tendon meets muscle fibre In belly of muscle fibre PositionIn series with muscle fibreParallel to muscle fibre Respond to Changes in muscle/tendon tension Changes in muscle length Sensory neurons 12

29. Workbook: Pg. 118-119

30. Consider: 1.What is the role of sensory receptors found in muscles, tendons, and joints in producing physical movement? MAIN IDEAS: 1.Proprioception is a person’s ability to sense the position, orientation, and movement of the body. This body system plays an indispensable role in physical movement 2.Specialized sensory receptors, called proprioceptors, are located within tendons, muscles, and joints 3.These receptors i.e. muscle spindles and golgi tendon organs – provide sensory information about the state of muscle contraction, the position of body limbs, and body posture and balance.

31. ©Thompson Educational Publishing, Inc. 2003. All material is copyright protected. It is illegal to copy any of this material. This material may be used only in a course of study in which Exercise Science: An Introduction to Health and Physical Education (Temertzoglou/Challen) is the required textbook. Spinal Cord and Head Injuries  Spinal cord injuries:  Damage to the spine can result in an inability to send impulses to body parts  Nerves above injury keep working, nerves below may not  Paraplegia:  Injury prevents use of legs but not arms  Quadriplegia:  Injury prevents movement of both arms and legs © iStockphoto.com/”caracterdesign”

32. ©Thompson Educational Publishing, Inc. 2003. All material is copyright protected. It is illegal to copy any of this material. This material may be used only in a course of study in which Exercise Science: An Introduction to Health and Physical Education (Temertzoglou/Challen) is the required textbook. Spinal Cord and Head Injuries  Head injuries:  Most common head injury is a concussion:  Occurs when brain literally hits the skull; often involves injury to nerve fibres  Ranges from mild to severe  Symptoms can include: headaches, fatigue, memory problems, or slurred speech © iStockphoto.com/”AlexKalina”