KINE 3680 Exam 1 Study Guide: Nervous System & Skeletal Muscle Physiology

Vocabulary practice flashcards covering homeostasis, cell signaling, nervous system pathways, resting potential, motor control, and skeletal muscle physiology based on the lecture notes.

Homeostasis

Maintenance of a constant and "normal" internal environment under resting conditions (a process).

Steady State

A steady or unchanging level of a physiological variable (can be outside normal range), representing a state of the body where there is a balance between demands placed on the body and the body's response to those demands.

Biological Control System

A system of interconnected components maintaining a parameter near a constant value, consisting of a sensor (receptor), control center, and effector.

Sensor (Receptor)

Component of a biological control system that detects changes in physiological variables.

Control Center

Component of a biological control system that assesses input and initiates a response.

Effector

Component of a biological control system that changes the internal environment back to normal.

Adaptation

A change in structure or function of a cell and/or organ system that results in an improved ability to maintain homeostasis.

Acclimation

A specific type of adaptation to environmental stresses.

Intracrine Signaling

Cell signaling mechanism where a chemical messenger is produced inside the cell and triggers a signaling pathway within the cell leading to a specific response.

Juxtacrine Signaling

Cell signaling mechanism via cell-to-cell contact, where the cytoplasm in one cell is in contact with the cytoplasm of another by small junctions connecting the cell membranes.

Autocrine Signaling

Cell signaling mechanism where a chemical messenger is produced by a cell, released into extracellular fluid, and then acts upon that same cell by binding to a receptor on its membrane.

Paracrine Signaling

Cell signaling mechanism where a messenger produced by a cell acts on nearby cells to lead to a coordinated response.

Endocrine Signaling

Cell signaling mechanism where messengers (hormones) are released into the blood and carried throughout the body.

Stress Proteins

Proteins that cells synthesize when homeostasis is disrupted to help protect and/or repair the cell.

Heat Shock Proteins

A specific group of stress proteins that help repair damaged proteins.

Central Dogma

Concept explaining how cellular information flows from $\text{DNA} \rightarrow \text{RNA} \rightarrow \text{protein}$.

Circadian Rhythm

Internal body clock that coordinates hormones, temperature, and affects exercise performance capabilities like alertness and strength throughout the day.

Central Nervous System (CNS)

Major division of the nervous system consisting of the brain and spinal cord.

Peripheral Nervous System (PNS)

Major division of the nervous system containing everything outside the CNS, divided into sensory and motor divisions.

Sensory Division

Subdivision of the PNS containing afferent nerves that transmit impulses from receptors to the CNS.

Motor Division

Subdivision of the PNS containing efferent nerves that transmit impulses from the CNS to effectors.

Synaptic Transmission

Communication across a synapse where a chemical messenger (neurotransmitter) is released from an axon and binds to dendrites of another neuron.

Irritability

Ability of dendrites and cell body to respond to a stimulus.

Conductivity

Ability to conduct a nerve impulse along an axon.

Resting Membrane Potential (RMP)

The charge of neurons at rest ($\text{approximately } -70\text{ mV}$), keeping neurons negatively charged to remain ready to respond to a stimulus.

Sodium Potassium Pump

Active transport mechanism that uses ATP to maintain concentration gradients and keep RMP stable at $\text{approximately } -70\text{ mV}$ by pumping $3\text{ Na}^+$ out and $2\text{ K}^+$ in.

Action Potential

A nerve impulse formed when $\text{Na}^+$ gates open and $\text{Na}^+$ rushes into the cell to make it more positive.

Excitatory Postsynaptic Potential (EPSP)

Depolarization of a neuron caused by excitatory neurotransmitters.

Inhibitory Postsynaptic Potential (IPSP)

Hyperpolarization of a neuron caused by inhibitory neurotransmitters.

Proprioceptors

Receptors that provide information to the CNS about body position.

Free Nerve Endings

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

Golgi-Type Receptors

Joint proprioceptors found in ligaments around joints.

Pacinian Corpuscles

Joint proprioceptors found in tissues around joints that focus on joint rotation.

Muscle Spindles

Muscle proprioceptors sensitive to muscle length; more spindles allow fine control, whereas fewer spindles yield gross movement.

Golgi Tendon Organs (GTO)

Muscle proprioceptors that monitor tension and serve as safety devices to prevent excessive force by exciting IPSPs.

Chemoreceptors

Receptors sensitive to changes in the chemical environment surrounding muscle.

Somatic Motor Division

Division of the nervous system that carries neural messages from the spinal cord to skeletal muscle (voluntary system).

Cerebrum

Brain structure involved in storage of past experiences, reception of sensory information, and control of voluntary movement.

Cerebellum

Brain structure that coordinates complex movement.

Brainstem

Brain structure responsible for metabolic function, cardiorespiratory control, complex reflexes, and postural reflexes.

Peripheral Factors (Fatigue)

Factors contributing to exercise-induced fatigue that originate within the muscle fibers.

Central Factors (Fatigue)

Factors contributing to exercise-induced fatigue that originate in higher brain centers.

Central Governor Theory

Theory stating that the brain controls how hard your body works during exercise, explaining fatigue as being partly caused by the brain reducing motor output.

Autonomic Nervous System (ANS)

Nervous system division that innervates effector organs not usually under voluntary control.

Sympathetic Division

Subdivision of the autonomic nervous system known for "fight or flight" responses that excites the body.

Parasympathetic Division

Subdivision of the autonomic nervous system known for "rest & digest" functions that inhibits organs.

Epimysium

Fascial layer of skeletal muscle that surrounds the whole muscle.

Perimysium

Fascial layer of skeletal muscle that surrounds fascicles (groups of muscle fibers).

Endomysium

Fascial layer of skeletal muscle that surrounds individual muscle fibers.

Basal Lamina

Layer located below the endomysium directly outside the muscle fiber.

Sarcolemma

Cell membrane of a skeletal muscle cell.

Sarcoplasm

Cytoplasm of a skeletal muscle cell containing cellular and structural proteins, organelles, and myofibrils.

Myofibrils

Contractile protein structures in muscle cells, comprised of actin (thin filaments) and myosin (thick filaments).

Sarcomere

The functional unit of a muscle fiber.

Sarcoplasmic Reticulum (SR)

Network of calcium channels surrounding each myofibril that is essential for storing and releasing $\text{Ca}^{2+}$ to trigger muscle contraction.

Transverse Tubules (T-tubules)

Channels extending from the sarcoplasmic reticulum across the muscle fiber that propagate action potentials and contain dihydropyridine (DHP) receptors.

Terminal Cisternae

Enlarged portions of the sarcoplasmic reticulum that play a role in the release of $\text{Ca}^{2+}$ and contain ryanodine receptors.

Neuromuscular Junction (NMJ)

Site where a motor neuron meets the sarcolemma of a muscle fiber.

Troponin

Protein that binds $\text{Ca}^{2+}$, causing a positional shift in tropomyosin to uncover myosin binding sites on actin.

Tropomyosin

A long, rope-like protein that coils around actin and covers myosin binding sites when $\text{Ca}^{2+}$ is absent.

Sliding Filament Theory

Term describing the step-by-step mechanism of muscle contraction.

Myosin ATPase

Enzyme that breaks down ATP to energize the myosin head for cross-bridge activity.

Type I Fibers

Slow-twitch, slow-oxidative muscle fibers characterized by low fatigability.

Type IIa Fibers

Intermediate fast-twitch, fast-oxidative/glycolytic muscle fibers characterized by high fatigability.

Type IIx Fibers

Fast-twitch, fast-glycolytic muscle fibers characterized by high fatigability.

Size Principle

Orderly recruitment of motor units dependent on the force needed for an action, progressing from smallest to largest ($\text{Type I} \rightarrow \text{Type IIa} \rightarrow \text{Type IIx}$).

Muscle Fatigue

Decline in muscle power output, which is distinct from muscle damage.

DOMS (Delayed Onset Muscle Soreness)

Soreness appearing $24\text{--}48\text{ hours}$ after exercise due to microscopic tears in muscle or connective tissue, resulting in cellular degradation and an inflammatory response.