Isotonic and Isometric Contractions

Pyruvate Dehydrogenase Complex & TCA Cycle

Pyruvate Dehydrogenase Complex (10)

Intro to Concept Sketches and Isometric Sketching

Physical Chemistry Isochoric Conditions Equations

Chapter 1: Structure and Function of the Muscular, Nervous, and Skeletal Systems I. The Muscular System. A. Gross Anatomy (Macrostructure) of Skeletal Muscle Connective Tissue Coverings: Epimysium: Outer layer of connective tissue surrounding the entire muscle belly.  Perimysium: Connective tissue surrounding bundles of muscle fibers (fascicles).  Endomysium: Connective tissue surrounding individual muscle fibers.  Tendon: Extension of connective tissues that connects muscle to bone to transmit force.  B. Microscopic Anatomy of Skeletal Muscle Muscle Fiber (Cell): Sarcolemma: The muscle cell membrane that encloses cell contents and conducts electrical impulses.  Sarcoplasm: Cytoplasm of the muscle cell containing ATP, glycogen, enzymes, and organelles.  Multinucleated: Muscle cells contain multiple nuclei located along the cell membrane.  Mitochondria: Organelles responsible for aerobic ATP production.  Sarcoplasmic Reticulum (SR): Internal network storing calcium ions (\bm{\text{Ca}^{2+}}) necessary for muscle action.  Transverse Tubules (T-Tubules): Channels running perpendicular to the myofibrils that carry action potentials deep into the cell.  C. Myofibrils & Sarcomere Structure Myofibril: Columnar protein structures containing contractile filaments.  Myofilaments: Myosin (Thick Filament): Consists of a head, neck, and tail; forms cross-bridges with actin.  Actin (Thin Filament): Globular protein structures containing binding sites for myosin heads. Associated with troponin and tropomyosin (regulatory proteins).  Sarcomere: The basic contractile unit of a muscle fiber bounded by Z-lines.  Z-line: Anchors actin filaments; marks the boundary of a sarcomere.  A-band: Alignment of myosin filaments (dark area).  I-band: Region containing only thin (actin) filaments (light area).  H-zone: Center of the A-band containing only thick (myosin) filaments.  M-line: Center anchor line for adjacent myosin filaments.  II. Neuromuscular Junction & Sliding Filament Theory A. Neuromuscular Junction (NMJ) Point of communication between a motor neuron and a skeletal muscle fiber.  Acetylcholine (ACh): Neurotransmitter released from the axon terminal into the synaptic cleft upon arrival of an action potential.  B. Steps in the Sliding Filament Theory 1. Action Potential: An impulse travels down the motor neuron to the axon terminal.  2. ACh Release: ACh is released into the synaptic cleft and binds to receptors on the sarcolemma.  3. Depolarization & \bm{\text{Ca}^{2+}} Release: The action potential travels along the T-tubules, triggering the release of calcium (\bm{\text{Ca}^{2+}}) from the sarcoplasmic reticulum into the sarcoplasm.  4. Troponin-Tropomyosin Shift: Calcium binds to troponin, causing a conformational change that moves tropomyosin away from myosin-binding sites on actin.  5. Cross-Bridge Formation: Energized myosin heads bind to open active sites on actin.  6. Power Stroke: Hydrolysis of ATP drives the power stroke; myosin pulls actin filaments toward the center of the sarcomere (H-zone shortens).  7. Detachment & Reset: A fresh ATP molecule binds to the myosin head, causing detachment from actin. ATP is hydrolyzed by myosin ATPase, re-energizing the head for subsequent cycles as long as calcium and ATP remain present.  III. Muscle Fiber Types & Actions A. Types of Muscle Actions Concentric: Muscle force exceeds external resistance; muscle shortens.  Eccentric: External force exceeds muscle force; muscle lengthens while developing tension.  Isometric: Muscle force equals external resistance; muscle length does not change.  B. Classification of Muscle Fibers Type I (Slow-Twitch / Slow Oxidative): High fatigue resistance, high aerobic capacity, high myoglobin content, lower force output, and slower contraction speed.  Dominant during endurance activities (e.g., walking, marathon running).  Type IIa (Fast-Twitch / Fast Oxidative-Glycolytic): Moderate fatigue resistance, hybrid aerobic/anaerobic capacity, moderate force production, fast contraction speed.  Type IIx (Fast-Twitch / Fast Glycolytic): Low fatigue resistance, high power/force output, high glycolytic capacity, very fast contraction speed.  Dominant during short-duration explosive movements (e.g., sprinting, heavy resistance training).  IV. The Nervous System A. Organization Central Nervous System (CNS): Brain and spinal cord.  Peripheral Nervous System (PNS): Nerve fibers outside the CNS.  Motor (Efferent) Neurons: Carry impulses from the CNS to peripheral effectors (muscles).  Sensory (Afferent) Neurons: Relay sensory inputs from sensory receptors (muscle, skin) back to the CNS.  Autonomic vs. Somatic: Somatic: Controls voluntary functions (e.g., skeletal muscle activation).  Autonomic: Controls involuntary functions (heart rate, digestion) via Sympathetic ("fight-or-flight") and Parasympathetic ("rest-and-digest") branches.  B. Proprioceptors Muscle Spindle: Sensory organs aligned in parallel with extrafusal muscle fibers.  Sensitive to changes in muscle length and rate of length change.  Triggers the myotatic (stretch) reflex, causing rapid concentric contraction of the stretched muscle to prevent overstretching.  Golgi Tendon Organ (GTO): Sensory receptors located in series within tendons near the neuromuscular junction.  Activated by excessive tension produced within the muscle. Causes reflex inhibition (relaxation) of the active muscle to protect against tendon damage or injury.

RP8: Investigation into the effect of a named factor on the rate of dehydrogenase activity in extracts of chloroplasts

Isometric, Isotonic & Isokinetic

L10 - The Pyruvate Dehydrogenase Complex

Pyruvate Dehydrogenase Complex

Glycolysis & Pyruvate Dehydrogenase

Glycolysis & Pyruvate Dehydrogenase

Glycolysis & Pyruvate Dehydrogenase

Pyruvate Dehydrogenase (PDH) Complex

Pyruvate Dehydrogenase Complex

Pyruvate Dehydrogenase Complex (PDC)

Chapter 18: Pyruvate Dehydrogenase Complex

RP8 Dehydrogenase activity in chloroplasts

RP8 Investigation into the effect of a named factor on the rate of dehydrogenase activity in extracts of chloroplasts

Inner Products, Orthogonality, and Isometrics