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Learn about the structure and function of the nervous system, its role in movement, and how it responds to exercise. Discover key concepts such as proprioception and neuron function for enhancing performance and preventing injury.
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Objectives • After this presentation, the participant will be able toexplain the basic structure and function of: • The nervous system • The skeletal system • The muscular system • The endocrine system • Describe how these systems respond and adapt to exercise
Introduction • Human Movement System • Movement is accomplished through the functional integration of three systems, the nervous, skeletal, and muscular systems. • These systems work in concert to produce human movement. • All components must work together to produce sound movement if one component is not working well it will affect the others and cause Kinetic Chain impairments.
Kinetic Chain • The Kinetic Chain • Kinetic means force or motion. • Chain refers to a system that is linked together or connected. • All components work together to manipulate human motion. • If one component of the kinetic chain is not working properly, it will affect the others and ultimately affect the movement.
The Nervous System • The Nervous System is one of the main organ systems of the body and contains specialized cells that transmit and coordinate signals, providing a communication network within the body. • The nervous system is comprised of two main components • The Central Nervous System (CNS) is composed of the brain and spinal cord • The Peripheral Nervous System (PNS) is the nerves that communicate with the CNS
The Nervous System • The nervous system is a communication network within the human body. • It allows us to gather information about our internal and external environments, process and interpret the information, and respond. • Three primary functions • Sensory • Integrative • Motor
The Nervous System • Sensory • The ability of the nervous system to sense changes in either the internal or external environment. • Integrative • The ability of the nervous system to analyze and interpret the sensory information to allow for proper decision making, producing the appropriate response. • Motor • The neuromuscular response to the sensory information.
Proprioception • Is the body’s ability to sense the relative position of adjacent parts of the body. On the test they will define proprioception as the cumulative neural input from all sensory afferents to the Central Nervous System. Training the body’s proprioceptive abilities will improve balance, coordination, and posture, and enable the body to adapt to its surroundings without consciously thinking about movement. • It is important to train the nervous system efficiently to ensure proper movement patterns which can enhance performance and decrease the risk of injury.
The Nervous System • Movement is a response to our sensory information and is therefore dictated by the nervous system. • This reflects the importance of training in a multisensory environment using different balance tools, ex. Bosu ball, Balance pad, Dyna Disc • The most effective way to create positive long-term results in a client is to directly affect (properly train) his or her nervous system.
The Neuron • The functional unit of the nervous system is known as the neuron. • Neurons are composed of three main parts: • Cell body • Includes cell structures like (nucleus, mitochondria, lysosomes, and Golgi complex) • Axon • Provides communication from the brain or spinal cord to other parts of the body • Dendrites • Responsible for gathering information from other structures of the body
The Neuron • There are three main functional classifications of neurons determined by the direction of their nerve impulses: • Sensory • Transmits afferent nerve impulses from receptors to the brain or spinal cord • Motor • Transmits efferent nerve impulses from the brain or spinal cord to the effector sites such as muscles or organs • Interneuron • Transmits nerve impulses from one neuron to another
Central Nervous System • Consists of the brain and the spinal cord
Peripheral Nervous System • Contains 12 cranial nerves and 31 pairs of spinal nerves, that branch out from the brain and spinal cord, as well as all sensory receptors. • Function • Provide a connection for the nervous system to activate different bodily organs, such as muscles (motor information). • Relay information from the bodily organs back to the brain, providing a constant update of the relation between the body and the environment (sensory information).
Peripheral Nervous System • Two further subdivisions of the PNS include the somatic and autonomic nervous systems • The somatic nervous system consists of nerves that serve the outer areas of the body and skeletal muscle, and are responsible for the voluntary control of movement. • The autonomic nervous system supplies neural input to the involuntary systems of the body • The autonomic system is further dived into the sympathetic and parasympathetic nervous systems. The sympathetic nervous system initiates the Fight or Flight response while the parasympathetic initiates the Rest and Digest.
Sensory Receptors • Specialized structures located throughout the body are designed to transform environmental stimuli (heat, light, sound, taste, motion) into sensory information that the brain or spinal cord can interpret to produce a response. • Mechanoreceptors respond to mechanical forces (touch and pressure). • Nociceptors respond to pain (pain receptors). • Chemoreceptors respond to chemical interaction (smell and taste). • Photoreceptors respond to light (vision). • For relevance to this course, we will focus attention on the mechanoreceptors.
Mechanoreceptors • Muscle Spindle • Sensitive to change in length and rate of length change in muscle. • Golgi Tendon Organ • Sensitive to changes in muscular tension and rate of tension change. • Joint Receptors • Respond to pressure, acceleration, and deceleration of the joint.
The Skeletal System • Framework for our structure and movement • Resting ground for the muscles of our body • Bones form junctions that are connected by muscles and connective tissue known as joints
Divisions of the Skeletal System • Axial Skeleton • Skull • Rib cage • Vertebral column • Appendicular Skeleton • Upper and lower extremities • Shoulder and pelvic girdles
Bone Growth • Bones under go remodeling throughout life cycle • Osteoclasts break down old bone tissue • Osteoblasts build up new bone tissue • Remodeling is the constant process of these cells • As children Osteoblasts are more active, as we age Osteoclasts become more active
Types of Bones • Long • Long cylindrical shaft and irregular or widened ends • Epiphysis ends of long bones • Diaphysis shaft of long bones main production of red blood cells (RBC’s) • Epiphyseal plate is where bone growth (length) occurs
Types of Bones • Short • Similar in length and width and appear somewhat cubical in shape
Types of Bones • Flat • Thin, protective
Types of Bones • Irregular • Unique shape and function
Vertebral Column • Vertebral column: A series of irregularly shaped bones called vertebrae that houses the spinal cord. • Cervical has 7 (concave curve) • Thoracic has 12 (convex curve) • Lumbar has 5 (concave curve) • Sacrum is fused triangle attached to pelvis • Coccyx is tail bone
Joints • One bone that articulates with another bone • Joint motion is referred to as arthrokinematics • Typical joint motions seen in the human articular system • Roll: Rolling on joint surface on another • Femoral condyles rolling over the tibial condyles during a squat • Slide: Sliding of a joint surface across another • Tibial condyles moving (sliding) across the femoral condyles during a knee extension • Spin: Rotation of one joint surface on another • Head of the radius rotating on the end of the humerus during pronation and supination of the forearm
Function of Joints • Provide the bones a means to be manipulated, allowing for movement throughout segments of the body • Provide stability, allowing for movement to take place without unwanted movement • All joints in the human body are linked together • Movement of one joint will directly affect the motion of others
Joint Connective Tissue • Ligaments connect bone to bone and provide static and dynamic stability as well as proprioception. • Characterized by poor vascularity and do not repair or adapt as easily as other tissues in the body
Weight Bearing Exercise • Weight bearing exercise-exercise that forces the body to work against gravity • Running, lifting weights, calisthenics are weight bearing • Swimming and cycling are not • Help build and maintain bones, muscles, and connective tissues, burns lots of calories
The Muscular System • Muscles generate internal tension that, under the control of the nervous system, manipulates the bones of our body to produce movement. • The Muscular System also is needed to stabilize and complete the cycle of movement production.*
Structure of Skeletal Muscle • Muscle is the compilation of many individual muscle fibers neatly wrapped together with connective tissue to form bundles. • The first bundle is the actual muscle itself, wrapped by an outer layer of connective tissue called fascia. The layer immediately surrounding the muscle is called epimysium. • The next bundle of muscle fiber is a fascicle that is wrapped by connective tissue called perimysium. • Each fascicle is made up of many individual muscle fibers that are wrapped by connective tissue called endomysium. • Each layer of connective tissue extends the length of the muscle, helping to form the tendon.
Connective Tissue • Tendons are the structures that attach muscles to bone and provide the anchor from which the muscle can exert force and control the bone and joint. • They have poor vascularity (blood supply), which leaves them susceptible to slower repair and adaptation.
Muscle Fibers (Cells) • Contain typical cell components • Cellular plasma called sarcoplasm (contains glycogen, fats, minerals, and oxygen-binding myoglobin) • Nuclei • Mitochondria (transform energy from food into energy for the cell) • Unlike typical cells, they also have structures called myofibrils.
Contractile Elements • Myofibrils contain myofilaments that are the actual contractile components of muscle tissue. • Actin • Myosin • Actin (thin) and myosin (thick) filaments form sections known as a sarcomere. • A sarcomere is the functional unit of the muscle, much like the neuron is for the nervous system. • It lies in the space between two Z lines. Each Z line denotes another sarcomere along the myofibril
Contractile Elements • Two protein structures that are also important to muscle contraction are tropomyosin and troponin. • Tropomyosin is located on the actin filament and blocks myosin binding sites located on the actin filament, keeping myosin from attaching to actin while the muscle is in a relaxed state. • Troponin, also located on the actin filament, plays a role in muscle contraction by providing binding sites for both calcium and tropomyosin when a muscle needs to contract. Troponin
Generating Force in a Muscle • Neural Activation • Essential for a muscle to manipulate force for either movement or stabilization. • Generated by the communication between the nervous system and the muscular system or the motor unit. • Motor unit = motor neuron and the muscle fibers with which it connects.
Neural Activation • Electrical impulses are transported from the central nervous system down the axon of the neuron. • When the impulse reaches the end of the axon (axon terminal), chemicals called neurotransmitters are released. • Neurotransmitters (chemical messengers) cross the synapse between the neuron and muscle fiber, transporting the electrical impulse from the nerve to the muscle. The specific neurotransmitter that initiates muscular contraction is acetylcholine (ACh).* • ACh falls into receptor sites on the muscle fiber, specifically designed for its attachment. • Once attached, ACh stimulates the muscle fibers to go through a series of steps that produce muscle contractions. • Either a summation causes all motor fibers of a unit to fire or none, this is the “all or nothing law”
Sliding Filament Theory • The proposed process of how the contraction of the filaments within the sarcomere takes place. • A sarcomere shortens as a result of the Z lines moving closer together. • The Z lines converge as the result of myosin heads attaching to the actin filament and asynchronously pulling (power strokes) the actin filament across the myosin.
Muscle Fiber Types • Type I: Slow Twitch • Higher in capillaries, mitochondria, and myoglobin • Increased oxygen delivery • Smaller in size • Produce less force • Slow to fatigue • Long-term contractions (stabilization) • Type II: Fast Twitch • Lower in capillaries, mitochondria, and myoglobin • Decreased oxygen delivery • Larger in size • Produce more force • Quick to fatigue • Short-term contractions (force and power)
Muscles as Movers • Agonist muscles act as prime movers • Gluteus maximus is an agonist for hip extension • Synergist muscles assist prime movers during movement • Hamstring and the erector spinae are synergistic with the gluteus maximus during hip extension • Stabilizer muscles support or stabilize the body while the prime movers and the synergists perform the movement patterns • Transversus abdominis, internal oblique, and multifidus stabilize the low back, pelvis, and hips during hip extension
Endocrine System • System of glands that secrete hormones that control bodily function • Consists of host organs, chemical messengers, target cells • Target cells bind specifically to hormones • Regulates body functions (growth, metabolism, response to stress)
Endocrine Glands • Primary glands of the endocrine system include: • Pituitary “master gland” with anterior, posterior and intermediate globes, hypthalamus, thyroid and adrenal glands
Endocrine Glands • Pituitary- Master control gland has three lobes • Anterior- Secretes growth hormone, prolactin, ACTH (adrenal glands) TSH (Thyroid), FSH (sex organs) and LH (sex organs). • Intermediate lobe secretes MSH (skin) • Posterior lobe secretes ADH (fluid retention), oxytocin (childbirth),
Endocrine Glands • Thyroid gland-regulates metabolism • Adrenal glands-fight or flight hormones and inflammation (epinephrine “adrenaline” and norepinephrine • Testosterone is produced in testes and adrenal glands, men produce 10 times more than women
Blood Glucose Control • Control of blood glucose levels regulated by the pancreas to prevent wide swings in blood glucose levels • Insulin- brings glucose into cells from blood stream, results in net drop in blood sugar levels • Glucagon- Signals the liver and muscles to breakdown glycogen stores and release, results in net rise on blood sugar levels • Exercise improves bodies utilization of glucose
Hormones • Both produced by men and women • Testosterone-men produce 10 times more is produced in testes and adrenal glands, major anabolic agent • Estrogen-produced in ovaries and adrenal glands, women produce significantly more • Cortisol produced in adrenal is main catabolic agent • Growth Hormone-produced in pituitary major anabolic agent • Thyroid-Found in in neck, controls metabolism • Exercise can elevate all these hormones
Summary • The three components of the kinetic chain (nervous, muscular, and skeletal systems) all work together to produce movement. • The nervous system is composed of billions of neurons that transfer information throughout the body, through two interdependent systems: the central nervous system and the peripheral nervous system. • The skeletal system is the body’s framework and is made up of bones and joints in two divisions: axial and appendicular. • The muscular system is made up of many individual fibers attached to bones by way of the tendons. Muscles generate force through neural activation, sliding filament theory, and excitation–contraction coupling.
