Kines 350 Exam 1

Comprehensive vocabulary flashcards generated from lecture notes covering Exercise Physiology concepts, neuroanatomy, action potential dynamics, proprioceptors, and motor control.

Exercise Physiology

The study of the function of cells, tissues, organs, and systems, and the branch of physiology that studies acute and chronic exercise influences.

Acute Exercise

A single bout of exercise, encompassing rest, submaximal exercise, and maximal exercise.

Chronic Exercise

Exercise training that results in adaptations at rest, submaximal exercise, and maximal exercise.

Mode

The specific type of exercise performed.

Duration

The length of time spent exercising, measured in minutes.

Frequency

The number of exercise sessions performed per week.

Intensity

The physical work performed during exercise.

Ergometry

The measurement of work output using devices such as a treadmill or cycle ergometer.

Central Nervous System (CNS)

The anatomical division consisting of the brain and spinal cord that actively helps control the internal environment to maintain internal homeostasis.

Peripheral Nervous System (PNS)

The anatomical division containing neurons outside the CNS, divided into sensory (afferent) and motor (efferent) divisions.

Afferent Fibers

Sensory nerve fibers that transmit impulses from receptors to the central nervous system.

Efferent Fibers

Motor nerve fibers that transmit impulses from the central nervous system to effector organs.

Cerebral Cortex

The outermost layer of nonmyelinated gray matter in the cerebrum responsible for conscious mind, intellect, and awareness.

Frontal Lobe

A superficial lobe of the cerebrum responsible for general intellect and motor control.

Insular Lobe

A deep central lobe of the cerebrum involved in emotion and self-perception.

Primary Motor Cortex

A region in the frontal lobe responsible for conscious control of skeletal muscle movement via pyramidal cells.

Basal Ganglia

Clusters of cell bodies deep within the cerebral white matter that initiate sustained or repetitive movements such as walking, running, posture, and muscle tone.

Thalamus

A component of the diencephalon serving as a major sensory relay center that determines conscious awareness.

Hypothalamus

A component of the diencephalon that maintains homeostasis and regulates appetite, fluid balance, sleep, blood pressure, heart rate, breathing, and temperature.

Cerebellum

A brain structure that controls rapid, complex movements, coordinates timing and sequence, and compares movements with intentions to execute corrections.

Brain Stem

An information relay between the brain and spinal cord comprising the midbrain, pons, medulla oblongata, and reticular formation.

Neuron

The functional unit of the nervous system.

Dendrites

Neuron structures that conduct electrical impulses toward the cell body.

Axon

Neuron structure that carries electrical impulses away from the cell body.

Schwann Cells

Cells that produce the discontinuous myelin sheath along axons in the peripheral nervous system.

Synapse

The contact point between the axon of one neuron and the dendrite of another neuron.

Multiple Sclerosis

An autoimmune CNS disease where immune cells attack cells that produce the myelin sheath, slowing nerve conduction. Resulting in a loss motor control

How can MS patients help prevent the progression of the disease?

Exercise training upregulates BDNF which increases neuroplasticity in the brain to keep connections working longer.

Irritability

The ability of dendrites and the nerve cell body to respond to a stimulus and trigger a neural impulse.

Conductivity

The transmission of a nerve impulse along the axon.

Resting Membrane Potential

The negative electrical charge inside cells at rest, ranging from $-40\,\text{mV}$ to $-75\,\text{mV}$ in neurons.

Sodium-Potassium Pump

An active transport pump requiring ATP that moves $2\,\text{K}^+$ into the cell and $3\,\text{Na}^+$ out of the cell to maintain resting membrane potential.

All-or-None Law

The rule stating that once a nerve impulse is initiated, it will travel the full length of the neuron.

Neurotransmitter

A chemical messenger released from the presynaptic membrane that binds to receptors on the postsynaptic membrane to cause depolarization.

Temporal Summation

The summation of several excitatory postsynaptic potentials (EPSPs) from a single presynaptic neuron over time.

Spatial Summation

The summation of excitatory postsynaptic potentials (EPSPs) from several different presynaptic neurons simultaneously.

Inhibitory Postsynaptic Potentials (IPSP)

Postsynaptic potentials that cause hyperpolarization (making resting membrane potential more negative) so neurons resist depolarization.

Proprioceptors

Receptors located in joints and muscles that provide the CNS with information regarding body position.

Kinesthesia

The conscious recognition of body position and the speed of limb movement.

Free Nerve Endings

The most abundant type of joint proprioceptors, sensitive to touch and pressure.

Pacinian Corpuscles

Mechanoreceptors located in skin, internal organs, and joint capsules sensitive to deep pressure, stretch, vibration, and rate of joint rotation.

Muscle Spindle

A muscle proprioceptor consisting of intrafusal fibers that provides information about muscle length/stretch and rate of shortening.

Golgi Tendon Organ (GTO)

A muscle proprioceptor that monitors muscle force production and induces reflex relaxation to prevent injury during excessive force generation.

Intrafusal Fibers

Specialized muscle fibers inside muscle spindles that run parallel to extrafusal fibers.

Gamma Motor Neurons

Motor neurons that stimulate intrafusal fibers to contract in concert with extrafusal fibers.

Motor Unit

A motor neuron and all the specific muscle fibers it innervates.

What does the muscle ratio determine?

The number of motor neurons that innervate the muscle fibers determines the type. Higher ratio of motor unit /muscle fibers results in type S fibers, 1/1 ratio results in type FR, and more muscle fibers/motor unit results in type FF.

Size Principle

The orderly recruitment of motor units during exercise, where the smallest motor units are activated first, followed by larger motor units as force demands increase.

Type S Motor Unit

Slow, highly oxidative motor units (Type I fibers) representing the smallest motor units.

Type FR Motor Unit

Fast, fatigue-resistant motor units (Type IIa fibers) representing intermediate motor units.

Type FF Motor Unit

Fast, fatigable motor units (Type IIx fibers) representing the largest motor units.

Central Fatigue

Fatigue resulting from neuronal dysfunction within higher brain centers and/or motor neurons during exercise.

Central Governor Theory

Theory stating that a central control center regulates exercise performance by reducing motor output to exercising muscle to protect against catastrophic homeostasis disruptions.

List the structures from biggest to smallest unit

1. Epimysium

2. Muscle

3. Perimysium

4. Muscle fascicles

5. Endomysium

6. Muscle fiber

7. Basement membrane

8. Myofibrils

9. Sarcolemma

10. Myofilaments

What is the unit of contraction for muscle fibers?

A sarcomere

What two myofilaments are used for muscle contraction?

1. Myson (thick filament)

2. Acting (thin filament)

What other structures help with the conduction of muscle contraction?

• Sarcoplasmic Reticulum- once acetylcholine is transmitted into the t-tubules and depolarizes the SR, SR then sen s Ca+ to actin site to allow myosin head to attach

• Transverse tubules-opening to allow acetylcholine to move to the SR

What are the steps of Neuromuscular Junction that lead to Action potential in the muscle fiber sarcolemma

1. Motor neuron action potential

2. AP triggers Ca+2 to enter voltage gated channels via Ca+2 pump

3. Acetylcholine release

4. Acetylcholine binding to receptors on motor end plate of sarcolemma sarcolemma

5. Binding ACh to receptors causes Na+ channels to open

6. Na+ into muscle fiber results in depolarization called End Plate Potential (EPP)

7. EPP is always sufficient enough to trigger AP (no threshold required)

8. AP enters t-tubules

How do muscles contract?

Sliding filament theory

• sarcomere shortens due to power stroke by myosin head and actin moving

• cross-bridge form when myosin head is attached to actin

  • #of cross-bridges= muscle force

Label the following

1. Relaxed sarcomere

2. H-zone

3. Actin

4. Myosin

5. Z-line

6. A band

7. I band

8. M-line

What is the importance of troponin and tropomyosin?

In Sarcoplasmic Reticulum Ca+2 binds to troponin and causes position change in tropomyosin allowing for actin site to be exposed

Is it true that ATP is used during muscle contraction?

Yes, ATP hydrolysis provides energy required for the “power stroke”

What are the steps of the Sliding Myofilament Theory?

1. resting fiber; myosin head is not attached to actin

2. myosin head binds to actin and forms cross bridge

3. Pi is released from myosin head from ATPase breakdown, causing conformational change in myosin

4. Power stroke causes filaments to slide; ADP is released

5. A new ATP binds to myosin head, allowing it to release from actin

6. ATP is hydrolyzed and phosphate binds to myosin, causing myosin head to return to normal orientation

What is muscle fatigue? What causes muscle fatigue?

defined as a decline in muscle power output

Causes:

1. decreases in muscle force production at cross-bridge level

2. decrease in muscle shortening velocity (muscle does not contract quickly enough)

• neurotransmitters in the brain stop signaling other neurons in the brain to eventually signal the muscles

• intensity of muscle power output differs fatigue

True or false does muscle fatigue depend on the exercise intensity?

True, higher intensive exercise causes more muscle fatigue than low-moderate exercise

What mechanism are responsible for muscle fatigue during intensive exercise?

During heavy, very heavy, and severe exercise

• a decrease of Ca+ release from SR to accumulate of metabolites that inhibit myofilament sensitivity

  • Ca+2 cannot bind to troponin which can’t move tropomyosin, therefore myosin head cannot bind to form cross-bridge

• H+ bind to Ca+2 binding sites on troponin-preventing binding and contraction

• Both Pi and radicals modify cross-bridges head and reduces number of cross-bridges bound to actin

What mechanism responsible for muscle fatigue during moderate intensive exercise?

• An increase of free radical production and glycogen depletion

• Accumulation of Pi and H+ in muscle DO NOT contribute to muscle fatigue for moderate exercise

• Depletion of muscle glycogen produces ATP production

What are muscle cramps? What are the causes of them?

spasmic, involuntary muscle contractions due to high intensive, moderate exercise from hyperactive motor neurons in spinal cord

• The increase of excitatory activity of muscle spindles and decrease inhibitory effect from Golgi Tendon organ

What two theories are out there to explain exercise-related skeletal muscle cramps

1. Dehydration and electrolyte imbalance theory

• exercise induces dehydration and loss of electrolytes, this causes in imbalance and results in a discharge of ACh

2. Altered neuromuscular control theory

• exercise-induced muscle fatigue and/or injury causing increased muscle spindle activity and/or inhibition of Golgi tendon organ function

What are the 3 muscle fiber types and what do they do?

1. Slow muscle fiber type I (slow twitch)- endurance, long duration tasks

2. Fast muscle fiber type II (fast twitch)- high force, produce high power output

• Type IIa and Type IIx

True or false people only have 1 certain type of muscle fiber type and that determines if they are more sprinters or marathon runners

False, people usually have a mix of all 3 different types of muscle fibers. This allows for both power inducing exercise and long duration exercise.

• It is determined by genetics and exercise habits