Module 3 - Neuromechanics Flashcards

Question

Muscle

Answer 1

- Tissue made up of many muscle cells + associated connective tissue - 3 main types: skeletal, cardiac, smooth

Answer 2

- Muscle fibre/myocyte --> individual cell that when activated produced force that can lead to motion

Answer 3

Fundamental unit of skeletal + cardiac muscle. MANY sarcomeres arranged in sequence within single myofibril + many myofibrils make up a muscle cell

Answer 4

Sarcomeres are composed of highly organized arrangement of myofilaments (composed mainly of actin + myosin) that interact w/ each other to generate force (slide across each other)

Answer 5

- Full, highly organized, full of machinery used to generate force (proteins, structures, etc.) - Fascicle: unit of a muscle cell - Muscle fibre: unit of a fascicle - Myofibril: unit of a muscle fibre (long strands of sarcomere) - Sarcomere: unit of myofibril (ends are Z-lines) - Sarcolemma: cell membrane

Answer 6

- Binding of actin to myosin myofilaments + change in confirmation of myosin - Cross bridge cycle: process involving attachment, conformation change + detachment (with ATP) that generates force

Answer 7

Theory explaining mechanism of muscle contraction associated with cross bridge cycling + sliding of myofilaments past each other to generate force

Answer 8

- Sarcomere shortens when myosin heads in thick myofilaments form cross bridges w/ actin in thin filament - Formation of cross bridge --> initiated when Ca2+ released from sarcoplasmic reticulum bind to troponin --> changes shape - Tropomyosin moves away from myosin binding site on actin --> myosin head binds to actin + forms cross bridge (myosin head must also be activated before cycle can begin --> ATP hydrolysis provides energy to activate into cocked position) - Ends when Ca2+ is actively transported back to SR, troponin returns to original shape --> tropomyosin covers myosin binding site on actin

Answer 9

1) Cross bridge formation: myosin head binds to actin, inorganic P released, bond is stronger 2) Power stroke: ADP released + activated myosin head pivots, sliding thing myofilament toward centre of sarcomere 3) Cross bridge detachment: another ATP binds to myosin head --> link b/w myosin head + actin weakens --> myosin head detaches 4) Reactivation of myosin head: ATP hydrolyzed --> energy reactivates myosin head --> cocked position As long as actin binding sites exposed --> cross bridge cycle repeats --> thin myofilaments pulled towards each other --> sarcomere shortens

Answer 10

Neuron that synapses w/ skeletal muscle cells

Answer 11

Motor neuron + ALL muscle cells it innervates (neuron interacts w/ diff. cell type) --> 100s-1,000s-100,000s

Answer 12

Synapse b/w motor neuron + a skeletal muscle cell

Answer 13

Action potential (depolarization --> repolarization on membrane of skeletal muscle cell)

Answer 14

- Electrical: depolarization of motor neuron (neuronal AP) - Chemical: neurotransmitter (acetylcholine (ACH)) release at neuromuscular junction - Electrical: depolarization of muscle fibre - Mechanical: cross-bridge formation + sarcomere shortening

Answer 15

- Muscle fibres activate in an ALL or NONE manner (1 motor neuron --> all muscle cells it innervates/AP arrives at one muscle --> ACH released --> muscle contracts) 1) Motor unit recruitment 2) AP frequency In general: increase in AP frequency --> increase in force

Answer 16

- Bigger muscle --> more sarcomere --> more force - Cross-sectional area of a muscle --> more muscle cells --> more sarcomeres --> more cross bridges --> more force

Answer 17

Technique to measure electrical activity produced by muscles (muscle APs) that occurs when muscle is stimulated

Answer 18

- Skin prep + electrode placement --> very important - Need to know direction of muscle fibres - Pro: relatively easy technique, less risk of damage/infection - Con: limited to superficial muscle, unsure of which muscle is producing electrical activity (risk of interference)

Answer 19

- Small needle is inserted into a muscle + electrical activity is recorded directly - Pro: specific choice of muscle - Con: invasive (skilled technician needed)

Answer 20

- y-axis: mV, V - x-axis: time

Answer 21

- Positive relationship b/w RAW (unfiltered, no mathematical manipulation) EMG + muscle force - As EMG increases, force increases - CANNOT compare RAW EMG b/w diff. muscles (e.g. diff. size) OR b/w people - Slight delay/lag time w/ force production compared to EMG

Answer 22

- Series of events that req. afferent info + involve some sort of efferent response/effect - Stimulus presented --> SENSORY: info going to CNS through afferent neurons --> CORTICAL: neural info is processed (combined with prior behavioural instructions) --> MOTOR: an effect is determined + is transported through efferent neurons --> muscles activated to perform task - ALL steps take time (short time)

Answer 23

- Time it takes CNS to sense, process, + initiate response to stimulus (from stimulus to onset of response) - Afferent --> processing --> efferent

Answer 24

- Time it takes person to execute specific movement (does not include reaction time) - Time from onset muscle activation (EMG) to end of response - From muscle activated (start) to end of response

Answer 25

- Reaction time + movement time - Total time from stimulus detection --> end of stimulus response

Answer 26

Stimulus intensity + modality (type) - Cognitive/neural impairment - Age - Presence/absence of neurological disease + inheritence - Medications/drugs - Environment (distractions) - Sex SRT: simple reaction time CRT: choice reaction time

Answer 27

- Only 1 stimulus + 1 response - e.g. "Hear something --> push a button"

Answer 28

- Number of diff. stimuli presented each required diff. response - Reaction time gets longer w/ more stimuli - e.g. various pitch sounds --> press diff. button for each

Answer 29

- Simultaneous performance of 2 tasks often leads to performance deficits in component tasks - Thought to be proof of capacity limitation in cognition - Can't to Z things at the same time as fast is if they were separate Multi-tasking: - Possible, some people better than others - Aspect of learning + practice

Answer 30

Muscle primarily responsible for a movement (e.g. biceps brachii in bicep curl)

Answer 31

Muscle that opposes the movement of agonist (e.g. triceps brachii in bicep curl)

Answer 32

- Dependent on posture + movement - e.g. Knee flexion + extension while sitting vs lying down - Gravity always affects body --> posture + movement change agonist vs antagonist

Answer 33

- Simultaneous activation of agonist + inactivation (relaxation) of antagonist - Maximizes amount of force it can produce (does not need to overcome agonist)

Answer 34

- Simultaneous activation of agonist + antagonist - Stabilizes joint - e.g. Carrying heavy load --> stability of joint needed to support weight + prevent injury

Answer 35

CANNOT graph without kinematics (EMG only) --> don't know what's going on

Answer 36

Study of effects + control of forces that act on + are produced by living beings

Answer 37

Study of MOTION of objects (w/out reference to the FORCES that caused the motion)

Answer 38

Study of FORCES that cause motion

Answer 39

- Displacement (m) - Velocity (m/s) - Acceleration (m/s^2)

Answer 40

*ROTATIONAL* - Angular displacement (rad) - Angular velocity (rad/s) - Angular acceleration (rad/s^2)

Answer 41

*LINEAR* - Action/influence that moves body or influences movement of the body - UNIT: newtons (N) - Internal forces: created primarily by skeletal muscles - External forces: created by ground (ground reaction force), external loads, other individuals, + from passive sources (e.g. wind resistance)

Answer 42

*ANGULAR* - "Moment of force" - Force that tends to change the rotational motion of an object - UNIT: Nxm - M +ve: counter-clockwise - M -ve: clockwise

Answer 43

- Have magnitude (length) + direction - Tail and head - A non vertical/horizontal vector is a sum of its vertical + horizontal components

Answer 44

- Perpendicular distance from application of force - Distance b/w point of rotation + application of force - Larger moment arm --> larger moment of force (rotational)

Answer 45

Point in centre of object where all of the mass of object is equally distributed in all directions

Answer 46

Force of gravity acts in downward direction (-y) through the centre of mass (COM) of an object

Answer 47

- Mass x acceleration due to gravity (9.8m/s^2) F = m x a F = 5kg x -9.8m/s^2 F = -49N

Answer 48

M = F x d Approach 1: - F = force applied - d (moment arm) = perpendicular distance b/w axis of rotation + line of force - No 90 degree angle --> trig Approach 2: - F = force vector component that is perpendicular to segment - d (moment arm) = distance from axis of rotation to point of application of force - USING THIS ONE

Answer 49

- Must consider all moments acting on a segment --> must consider the sum of the moments - If a segment is stationary --> sum of M = 0

Answer 50

- Visual observation - Goniometer (instrument to measure angles): hand held/electronic - Inertial sensors: measure acceleration - Optical/magnet motion capture: gold standard for measuring kinematics

Answer 51

Hand held: - Pro: can do everywhere on anyone - Con: guess, estimate, not very accurate, stuck with static Electronic: - Pro: mobile - Con: may not be as accurate Potentiometer: - Pro: accurate joint angle - Con: tethered to one spot, immobile

Answer 52

High-end: - Pro: accurate - Con: expensive Personal (e.g. Apple Watch): - Pro: affordable in comparison, easy to use - Con: not as accurate

Answer 53

- Gold standard (one of best techniques, go-to, reliable) of measuring kinematics - Cameras tracking dots: know exactly where each joint is in 3D (inertia + joint angle), can calc. displacement, velocity, acceleration, etc. - Pro: really accurate/gold standard - Con: expensive, software + trained people required

Answer 54

- Manual assessment - Dynamometer: device to measure force, moment, or power (hand held/electronic) - Force plates: instrument to measure ground reaction forces

Answer 55

- Want to understand where deficits in body are through comparison w/ healthy parts - Pro: can do it anywhere - Con: lots of training required, not very accurate (subjective, don't know how many N)

Answer 56

Hand held, hand grip: - Pro: objective (N, kg), measures amount of force - Con: have to be able to brace yourself to oppose the force Isokinetic dynamometer: - Pro: can test most joints, can control many variables (joint angle, speed (fixed/variable), resistance), completely adjustable, 360 degree rotation - Con: Expensive

Answer 57

- Gold standard in measuring kinetics (forces) - Can get a sense of interaction w/ environment while doing things - Need kinematics to go with kinetics for full picture - Pro: can measure force in all 6 directions + moments, really accurate - Con: alone --> no idea of kinematics, really sensitive, some are anchored into ground/others mobile

Answer 58

- EMG (muscle activation) - Kinematics (movement) - Kinetics (forces) Combined = full picture

Answer 59

- Optical motion capture: kinematics - Force plates: kinetics

Module 3 - Neuromechanics Flashcards

(83 cards)