PE 3070 Week 1 & 2 Notes
PE 3070 Week 1 & 2 Notes PE 3070
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This 8 page Class Notes was uploaded by Aurora Moberly on Sunday September 4, 2016. The Class Notes belongs to PE 3070 at Southern Utah University taught by Dr. Julie Taylor in Fall 2016. Since its upload, it has received 35 views. For similar materials see Exercise Physiology in Physical Education at Southern Utah University.
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Test 1: 9/9 PE 3070 Chapter Zero: Introduction to Physiology Exercise Physiology: An acute or chronic adaption by the body in response to physical activity that includes anatomical and physiological changes Exercise Physiology: The study of how the body’s functions are altered when we are physically active Exercise Physiology: How the body’s structure and functions are altered when exposed to acute and chronic bouts of exercise Two basic components of exercise physiology are the acute responses of the body to exercise in all its forms and the adaptation of the body’s systems to repeated or chronic exercise System responsibilities while the body is exercising: The skeletal system provides basic framework for the muscles to act The cardiovascular system delivers fuel to all the cells of the body and removes waste products The cardiovascular and respiratory systems work together to provide oxygen and remove carbon dioxide The integumentary system helps maintain body temperature by allowing the body to exchange heat with its surroundings The nervous and endocrine systems coordinate body temp, maintain fluid and electrolyte balance and assist in the regulation of blood pressure Sports Physiology: The aspects of exercise physiology used to enhance sport performance and optimally train athletes First text published was Physiology of Bodily Exercise by LaGrange 1889 marking it as an academic field of study The second text published on exercise physiology that included theories supported by actual research is The Physiology of Muscular Exercise by F.A. Bainbridge in 1919 The Harvard Fatigue Laboratory (HFL) was operational in 1927 and was first designed to conduct research on fatigue and general health It furthered knowledge and recognition of the field Researched methods to help soldiers be better soldiers in WWII A.V. Hill came up with the idea of this lab but wasn’t directly involved D.B. Bill was the first director of research at HFL and helped write the third edition of Bainbridge’s text; Father of exercise physiology research Sid Robinson conducted some of the first studies on aging and exercise and was a student at HFL David Costill collaborated with Sid Robinson, wrote my textbook Joel Stager worked with David Costill, studied exercise and altitude, mentored my professor Acute Responses: Breathing rates, sweat rates, muscle swelling, heart rate, oxygen consumption, blood pressure, rate of fatigue, hydration status, lactate in blood, cardiac output, stroke volume Chronic Responses: Body composition, muscle size, resting blood pressure, resting heart rate, VO 2Max, resting metabolic rate, exercise capacity, force production, fatigue rate, LDL & HDL Factors that affect acute and chronic responses: Temperature, time of day, environment Ergometer: An exercise device that allows the intensity of exercise to be controlled and measured Treadmills are the most common ergometer Research Process Figure 0.9 pg 14 CrossSectional Research Design: A cross section of the population of interest is tested at one time and the differences between subgroups from that sample are compared Longitudinal Research Design: The same research subjects are retested periodically after initial testing to measure changes over time in variables of interest DoseResponse Relation: The higher the dose of exercise training the higher the resulting variable Crossover Design: The two groups of subjects undergo being the control group and the treatment group. This design was made to overcome the placebo effect Chapter 2: Structure and Function of Exercising Muscle Smooth Muscle (Involuntary): Found in the walls of most blood vessels contracting and relaxing to regulate blood flow as well as the walls of most internal organs allowing them to contract and relax for food movement or to expel urine Controlled by the autonomic nervous system Cardiac Muscle (Involuntary): Muscle that makes up the heart’s structure, found only in the heart Test 1: 9/9 PE 3070 Controlled by the autonomic nervous and endocrine systems, striated, intercalated disks Skeletal Muscle (Voluntary): Muscle that attaches to and moves skeleton; Controlled by somatic nervous system, striated The bones of the skeleton and the skeletal muscle make up what is called the musculoskeletal system More than 600 different skeletal muscles located throughout the body Anatomy of Skeletal Muscle Epimysium: Outermost layer of connective tissue surrounding the entire muscle; Functions to hold the muscle together and give it shape Fascicles: Bundles of fibers wrapped in a connective tissue sheath called the perimysium Muscle Fibers: Located inside the fascicles and are made up of one muscle cell that is multinucleated; Covered by a sheath of connective tissue called the endomysium Tendon: Fibrous cords of connective tissue that transmit the force generated by muscle fibers to bone thereby creating motion Structure of Individual Muscle Fibers: Plasmalemma: Plasma membrane that surrounds the muscle fiber; Apart of a larger unit called the sarcolemma At the end of each fiber the plasmalemma fuses with the tendon Folds up when rested so when the muscle fiber stretches it has room to do so Contains functional folds in the innervations zone that assist in the transmission of the action potential from the motor neuron to the muscle fiber Helps maintain acidbase balance and transport of metabolites from the capillary blood into the muscle fiber Sarcolemma: Composed of plasmalemma and the basement membrane Satellite Cells: Located between the plasmalemma an the basement membrane, involved in the growth and development of skeletal muscle Sarcoplasm: Cytoplasm that surrounds myofibrils, contains transverse tubules (Ttubules) and the sarcoplasmic reticulum (SR) TTubules: Extensions of the plasmalemma that pass laterally through the muscle fiber; Allow transport of substances through the muscle fibers as well as nerve impulses SR: Longitudinal network of tubules that store calcium Myofibrils: Small fibers that make up the basic contractile element of skeletal muscle Sacromere: Basic functional unit of a myofibril and the basic contractile unit of muscle Sacromere: Extends from zdisk to zdisk IBand: Light band, actin ABand: Dark band, actin and myosin HZone: Halfway zone, myosin, may disappear during contraction MLine: Middle, mprotein, holds myosin in place Titin: Wraps around myosin to help stabilize myosin ZDisk: Sarcomere end plates, stabilizes actin Nebulin: Stabilizes actin Myosin Filament: Myosin molecule is composed of two protein strands twisted together and one end of each strand is folded into a globular head; Thick filament; Myosin tails point towards the center of the sacromere and the globular heads point to the sides so they have access to the actin filament Titin: Fine filament proteins that stabilize the myosin filaments Stiffness of titin changes when bound to calcium and may allow you to produce more force Actin Filament: Thin filament composed of three protein molecules actin, tropomyosin and troponin Actin: Forms the backbone of the filament Tropomyosin: Tubeshaped protein that twists around actin strands blocking myosin binding sites when at rest Test 1: 9/9 PE 3070 Troponin: Attached to both actin and tropomyosin and has a binding site for calcium When calcium binds with troponin is causes tropomyosin to change its shape and open up the myosin binding sites Nebulin: Anchoring protein for actin Muscle Fiber Contraction Initiation of muscle contraction occurs in response to a signal from the nervous system Alpha Motor Neuron: Nerve cell that connects with and innervates many muscle fibers; Determines which myosin ATPase the muscle fibers will have Motor Unit: A single αmotor neuron and all the muscle fibers it innervates Neuromuscular Junction: The synapse between the αmotor neuron and a muscle fiber; This is where the communication between the nervous and muscular system occurs ExcitationContraction Coupling: Muscle contraction begins with excitation of a motor neuron and that results in a contraction of the muscle fibers Action Potential: Nerve impulse Acetylcholinesterase: Breaks down acetocholine (ACh) constantly during muscle contraction When a muscle contracts the filaments do not change length, they slide past each other appearing shorter Steps of Muscle Fiber Contraction: 1. Stimulus of the αmotor neuron from an action potential 2. When the action potential arrives at the axon terminal the nerve endings release a neurotransmitter, ACh 3. ACh then crosses the synaptic cleft and binds to receptors on the plasmalemma + 4. If enough ACh binds then the action potential will be spread across the muscle fiber membrane and open up Na ion gates 5. Sodium will enter the muscle cell and start the process of depolarization 6. The action potential travels to the Ttubules to the interior of the cell causing the SR to release its stored calcium 7. Calcium binds to troponin causing tropomyosin to move off the myosin binding sites of actin 8. Myosin heads are able to bind to actin creating crossbridges and muscle contraction begins Sliding Filament Theory: When myosin crossbridges are activated, they bind with actin, resulting in a conformational change in the crossbridge which causes the myosin head to tilt and drag the thin filament toward the center of the sarcomere Power Stroke: The tilting of the myosin head The pulling of the thin filament past the thick shortens the sarcomere and generates force 1. The myosin head binds to ATP 2. ATPase located on the head splits ATP into ADP and P causing the power stroke; ATPase is activated by magnesium 3. Myosin head remains on the actin until more ATP binds to the head 4. When ATP binds again to the head it recocks are prepares for the next power stroke father down the actin filament 5. This action causes the filaments to slide over each other and the sacromere “shortens” 6. This continues until the Zdisks are reached or calcium pumped back into the SR Muscle Relaxation At the end of muscle contraction calcium is pumped back into the SR through an active calciumpumping system The calciumpumping system requires ATP to actively pump calcium back into the SR When calcium leaves the troponin and tropomyosin return to their resting places causing the thick and thin filaments to return to their original relaxed state Muscle Fiber Types Type I Fibers: Slowtwitch Slow oxidative system, high oxidative capacity, low glycolytic capacity, sow contractile speed, high fatigue resistance, low motor unit strength High level of aerobic endurance, recruited during lowintensity events Type II Fibers: Fasttwitch, anaerobic exercise, shorthigh intensity exercise Type IIa: Most frequently recruited; Fast oxidative/glycolytic system, moderately high oxidative capacity, high glycolytic capacity, fast contractile speed, moderate fatigue resistance, high motor unit strength Type IIx: Fast glycolytic system, low oxidative capacity, highest glycolytic capacity, fast contractile speed, low fatigue resistance, high motor unit strength Test 1: 9/9 PE 3070 Type IIc: Least used, not a lot is known about them Type I and Type II fibers differ in their speeds of contraction due to their form of myosin ATPase (Type I has a slow ATPase and Type II has a fast ATPase) Type II fibers have a better developed SR than Type I making them more adapt at delivering calcium to the muscle cell The αmotor neuron in Type I has a smaller cell body and innervates less than 300 muscle fibers The αmotor neuron in Type II has a larger cell body and innervates more than 300 muscle fibers meaning more fibers contract when a Type II muscle cell is stimulated creating that large contractile force Type II muscle fibers tend to be larger in size than Type I muscle fibers Muscle Fiber Recruitment If a muscle wants more force it recruits more motor units Principle of Orderly Recruitment: Motor units are activated on the basis of a fixed order of fiber recruitment in which motor units within a given muscle appear to be ranked Size Principle: The order of recruitment of motor units is directly related to the size of their motor neuron Motor units with smaller motor neurons will be recruited first Muscle Movement occurs in three types of contractions concentric, static and eccentric Concentric Contraction: Shortening of a muscle, dynamic contraction Slow concentric contractions produce the maximal force Dynamic Contraction occurs when there is joint movement Static (Isometric) Contraction: The muscle is producing force but the length of the muscle is not changing Cross bridges are formed but the external force is too great for the thin filaments to be moved Eccentric Contraction: Muscle exerts force while lengthening, dynamic contraction Fast eccentric contractions produce the maximal force Muscle force production is dependent on number and type of motor units activated, the frequency of stimulation of each motor unit, the size of the muscle, the muscle fiber and sarcomere length and the muscles speed of contraction Twitch: The smallest contractile response of a muscle fiber or a motor unit to a single electrical stimulus Summation: A series of stimuli that fire in rapid sequence before complete relaxation of the muscle from the first stimulus that results in increased force or tension Tetanus: Continued stimulation at higher frequencies result in the peak force of the muscle fiber Rate Coding: The process by which the tension of a given motor unit can vary from that of a twitch to tetanus by increasing the frequency of stimulation of that motor unit Each muscle fiber has an optimal length for generating force in which there is an optimal amount of overlap of thick and thin filaments or optimal amount of cross bridges formed Rigor Mortis: The body can no longer generate ATP so the myosin heads are stuck on the actin filaments and can’t be released because there is no more ATP. This is why when we die we get muscle stiffness Muscle Biopsy: Hollow needle is inserted into the muscle of the belly and a part of the muscle is taken out, the sample is frozen and stored then sliced and looked at under a microscope Chapter 3: Neural Control of Exercising Muscle Central Nervous System: Composed of the brain and spinal cord Peripheral Nervous System: All the nerves that go to and from the brain and spinal cord Sensory (Afferent) Nerves: Responsible for telling the CNS what is going on inside and outside of the body Effector Nerves: Responsible for sending information from the CNS to the various parts of the body in response to signals coming in from the sensory division Somatic Nervous System: Voluntary control Autonomic Nervous System: Involuntary control Sympathetic: Fight or flight response Parasympathetic: Rest and digest response Neuron: Basic structural unit of the nervous system Anatomy of Neuron: Cell Body: Contains a nucleus; Axon and dendrites are connected to the cell body Test 1: 9/9 PE 3070 Axon Hillock: The cell body tapers into a coneshaped region known as the axon hillock Dendrites: Branches that come out of the cell body from everywhere and receive all of the neurons action potentials and stimuli Axon: The neuron’s transmitter that conducts impulses away from the cell body Axon Terminal: At the end of the axon it branches out into axon terminals that have little knobs at the end of their branches, these knobs house vesicles containing neurotransmitters Nerve Impulse: Occurs when a stimulus is strong enough to change the electrical charge of a neuron Resting Membrane Potential (RMP): The electrical potential difference between the inside and the outside of a neuron; RMP of a neuron is 70mV causing the membrane to be polarized Polarized: The charges across the membrane differ + + Neurons have a high concentration of K on the inside of the membrane and a high concentration of Na on the outside of the membrane Causes of the negative RMP inside of the neurons: The cell membrane is more permeable to K than Na so the K moves out of the cell to balance out the high concentrations of the K in the cell and the low concentration of K outside of the cell SodiumPotassium Pump: Maintains the imbalance of K /Na but actively pumping K in the cell and Na out of + the cell Contains Na K adenosine triphosphataste (ATPase) + + Moves three Na while moving two K in resulting in more positively charged ions outside of the cell causing a negative RMP inside of the cell Depolarization: Occurs any time the charge difference becomes more positive than the RMP of 70mV (moves closer to zero) Typically the result of a change in the membranes Na permeability Hyperpolarization: The RMP becomes more negative Graded Potentials: Localized changes in the membrane potential triggered by a change in the neuron’s local environment Not strong enough to travel the length of the neuron Action Potentials: A rapid and substantial depolarization of the neuron’s membrane All action potentials begin as a graded potential that have a large enough stimulation to result in an action potential Threshold: The membrane voltage that must be reached for a graded potential to become an action potential AllorNone Principle: If the threshold is reached or exceeded there will be an action potential if threshold isn’t reached then there will not be an action potential Absolute Refractory Period: When an axon’s sodium gates are open and it’s in the process of generating an action potential is it unable to respond to any other stimulus Relative Refractory Period: When sodium gates are closed and potassium gates are open and repolarization is occurring that segment of the axon could respond to another stimulus but it must be of a substantially greater magnitude to generate a new action potential Two characteristics of a neuron determine how quickly an impulse can travel down an axon: myelination and diameter Myelination: An axon containing a myelin sheath Myelin Sheath: A sheath formed by myelin, a fatty substance, which wraps around sections of the axon with gaps of unmyelinated axon; Formed by specialized cells called Schwann cells Nodes of Ranvier: Gaps between the sections of the myelin sheath Saltatory Conduction: The action potential jumps from one node to the next as it travels down a myelinated axon; This type of conduction is why myelinated axons send action potentials faster than unmyelinated axons Neurons of a larger diameter conduct nerve impulses faster than neurons of a smaller diameter because they have less resistance to local current flow Synapse: The site of action potential transmission from the axon terminals of one neuron to the dendrites of another The signal that is transmitted from one neuron to another goes from being electrical to chemical back to electrical Synapse consists of the axon terminal of the neuron sending the action potential, receptors of the receiving neuron and the space inbetween Presynaptic Neuron: The neuron sending the action potential Postsynaptic Neuron: The neuron receiving the action potential Test 1: 9/9 PE 3070 Synaptic Cleft: Space between the presynaptic and postsynaptic neurons When the impulse reaches the presynaptic terminal synaptic vesicles containing neurotransmitters are released into the synaptic cleft and bind to the postsynaptic receptors When sufficient binding occurs a serious of graded depolarizations occur and if threshold is reached an action potential occurs Once the neurotransmitter binds to the postsynaptic receptor the neurotransmitter is then degraded by enzymes, actively transported back into the presynaptic terminal, diffuse away from the synapse Neuromuscular Junction: The site at which a motor neuron communicates with a muscle fiber Works like a synapse except the axon terminals protrude into motor end plates which are invaginated (folded to form cavities) segments on the plasmalemma of the muscle fiber ACh released from the αneuron bind to receptors on the muscle fibers plasmalemma causing depolarization Once threshold is reached an action potential is spread across the Ttubules initiating muscle fiber contraction Acetylcholine and norepinephrine are the two major neurotransmitters involved in regulating physiological responses to exercise; Categorized as smallmolecule, rapidacting neurotransmitters Acetylcholine: Primary neurotransmitter for motor neurons that innervate skeletal muscle as well as for most parasympathetic autonomic neurons Excitatory in the somatic nervous sytem Inhibitory in parasympathetic nerve endings like the heart Cholinergic: Nerves that release acetylcholine Norepinephrine: Neurotransmitter for most sympathetic autonomic neurons Excitatory or inhibitory Adrenergic: Nerves that release norepinephrine Excitatory Postsynaptic Potential (EPSP): An excitatory impulse that causes depolarization Inhibitory Postsynaptic Potential (IPSP): An inhibitory impulse that causes hyperpolarization For summation the postsynaptic neuron must keep a running total of the neurons responses both EPSP and IPSP, this process is done at the axon hillock Tracts: Bundles of individual neurons located in the CNS Nerves: Bundles of individual neurons located in the PNS Cerebrum: Composed of the right and left hemispheres Corpus Callosum: Tracts that connect the two hemispheres allowing them to communicate Cerebral cortex (Grey Matter) forms the outer portion of the hemispheres and is the site of the mind and intellect, the conscious brain Nonmyelinated Frontal Lobe: General intellect and motor control Temporal Lobe: Auditory input and interpretation Parietal Lobe: General sensory input and interpretation Occipital Lobe: Visual input and interpretation Insular Lobe: Diverse functions usually linked to emotion and selfperception Primary Motor Cortex: Located in the precentral gyrus of the frontal lobe of the cerebrum Responsible for control of fine and discrete muscle movements Neurons located here are called pyramidal cells and they let us consciously control skeletal muscle movement Areas that require the finest motor control have a greater representation in the motor cortex thus allowing for more neural control Pyramidal cells axons form extrapyramidal tracts that extend from the cerebral cortex to the spinal cord Preomotor Cortex: Just anterior to the precentral gyrus of the frontal lobe Learned motor skills of a patterned nature are stored here (muscle memory) Basal Ganglia: Located in the cerebral white matter, deep in the cortex Ganglia: Cluster of nerve cell bodies Control movements of a sustained and repetitive nature, like walking or running Test 1: 9/9 PE 3070 Involved in maintaining posture and muscle tone Diencephalon: Contains the thalamus and the hypothalamus Thalamus: All sensory input except for smell is integrated at the thalamus and then sent to the appropriate region of the brain; The thalamus regulates what sensory input reaches the conscious brain, very important for motor control Hypothalamus: Maintains homeostasis by regulating all processes that affect the body’s internal environment Blood pressure, heart rate & contractility, respiration, digestion, body temp, thirst & fluid balance, neuroendocrine control, appetite & food intake, sleepwake cycles Cerebellum: Located behind the brain stem Coordinates movement, controls rapid and complex muscular activates, timing of motor activities, rapid progression of one movement to the next, aids the primary motor cortex & basal ganglia, makes corrective adjustments in the motor activities that are elicited by other parts of the brain, smoothens out movement Cerebellum is an integration system that compares the intended activity with the actual activity occurring and makes adjustments for any incorrect movement Brain Stem: Composed of the midbrain, pons, medulla oblongata Connects the brain and the spinal cord Site of origin for 10 of the 12 pairs of cranial nerves Contains the major autonomic centers that control the respiratory and cardiovascular systems Reticular Formation: Specialized collection of neurons that coordinate skeletal muscle function, maintain muscle tone, control cardiovascular and respiratory functions and determine state of consciousness Has a pain control system PNS contains 43 pairs of nerves, 12 cranial and 31 spinal Sensory Division: Carries sensory information toward the CNS Sensory neurons originate in blood vessels, internal organs, muscles and tendons, skin, and sensory organs Mechanoreceptors: Respond to mechanical forces such as pressure, touch, vibrations or stretch Thermoreceptors: Respond to changes in temperature Nociceptors: Respond to painful stimuli Photoreceptors: Respond to electromagnetic radiation to allow vision Chemoreceptors: Respond to chemical stimuli Motor Division: CNS transmits information to various parts of the body through motor neurons Autonomic Nervous System: Sympathetic Nervous system and parasympathetic nervous system Sympathetic Nervous System: Prepares the body to face a crisis and sustains its function during crisis Parasympathetic Nervous System: Body’s housekeeping system, active when the body is at rest SensoryMotor Integration: For the body to respond to sensory stimuli the sensory and motor divisions of the nervous system must function together in the following sequence of events: 1. Sensory stimulus is received by sensory receptors 2. Sensory action potential is transmitted along sensory neurons to the CNS 3. The CNS interprets the sensory information and determines which response is most appropriate or reflexively initiates a motor response 4. Action potentials for the response are transmitted from the CNS along αmotor neurons 5. The motor action potential is transmitted to a muscle and the response occurs Integration Center: The area in which the sensory impulses terminate; Sensory input is interpreted and linked to the motor system Spinal Cord integration centers respond usually in a simple motor reflex Lower brain stem integration results in subconscious motor reactions of a complex nature Cerebellum integration results in subconscious control of movement, center of coordination Thalamus integration results in conscious realization of various sensations Cerebral Cortex integration results in our ability to discretely localize the stimulus and realize there is a stimulus Once a sensory impulse is received it can evoke a motor response from one of these areas 1. Spinal Cord 2. Lower regions of the brain 3. Motor area of the cerebral cortex Test 1: 9/9 PE 3070 Motor Reflex: A preprogrammed response, any time the sensory nerves transmit a certain action potential the body responds instantly and identically Muscle Spindle: Group of specialized muscle fibers found between regular skeletal muscle fibers, extrafusal (outside the spindle) Composed of intrafusal (inside the spindle) fibers and the associated nerve endings Intrafusal fibers are controlled by gamma motor neurons Cannot contract because there is no actin or myosin, this region can only stretch The muscle fibers and muscle spindle stretch if the other stretches The muscle spindles moniter the length of muscles but stopping its stretch Golgi Tendon Organs: Encapsulated sensory receptors through which a small bundle of muscle tendon fibers pass Golgi tendon organs are sensitive to tension in the muscletendon complex Inhibit the tension in the tendon/muscle if it becomes too great to prevent injury The muscle fibers in a specific motor unit are homogeneous with respect to fiber type