Anatomy and Physiology Laboratory: Frog Pithing, Muscle-Nerve Preparation, and Stimuli

Comprehensive vocabulary flashcards covering laboratory procedures, reflexes, muscle-nerve preparations, forms of stimuli, muscle twitch phases, and skeletal muscle fiber types.

Pithing

A procedure performed on laboratory animals to render them free of pain prior to physiological experiments requiring the observation of living tissues.

Genus Rana

The amphibian genus belonging to the family Ranidae, serving as the frog of choice for comparative anatomy dissections and teaching musculoskeletal, cardiac, and neurophysiology.

Fejervarya limnocharis

The scientific name of the rice field frog (formerly Rana limnocharis), chosen for laboratory studies due to being non-toxic, presenting low biological hazard, and carrying a low risk of severe pathological transmission.

Corneal Reflex

A sensory perception test in which touching the frog's eyelid elicits a blink response in normal frogs, but yields no response once the neural tissues of the brain are destroyed.

Reflex Withdrawal Response

A spinal cord reflex check performed by pinching the frog's leg; an intact spinal cord will cause the limb to retract or withdraw.

Gastrocnemius Muscle

A large muscle located in the postero-inferior region of the frog leg opposite the peroneus muscle, commonly dissected for muscle-nerve preparations.

Muscle-Nerve Preparation

An in-vitro experimental setup comprising four key anatomical structures from a live frog model: the sciatic nerve, gastrocnemius muscle, femur, and Achilles tendon.

Mechanical Stimulus (Nerve Response)

Nerve stimulation applied via tying with thread or pinching with forceps; initial compression induces a twitch or spasm, but progressively causes twitching to decrease or cease altogether as damage increases.

Thermal Stimulus (Hot vs. Cold)

Stimulation applied to a nerve via a heated or chilled glass rod; hot stimuli produce an immediate, strong contraction of the muscle, whereas cold stimuli produce an initial reflex contraction followed by relaxation.

Chemical Stimulus (NaCl)

Application of sodium chloride crystals directly onto the nerve, causing chemical irritation via salt ions that triggers abnormal electrical activity and muscle contractions.

Muscle Twitch

A complete cycle of contraction and relaxation observed across all muscle fibers in a single motor unit in response to a single action potential from a motor neuron.

Lag Phase

The latent period between stimulus application to the motor neuron and the onset of muscle contraction, during which acetylcholine binds ligand-gated $\text{Na}^+$ channels and an action potential propagates down T tubules to trigger voltage-gated $\text{Ca}^{2+}$ channel opening.

Contraction Phase

The phase of a muscle twitch that begins when $\text{Ca}^{2+}$ diffuses from the sarcoplasmic reticulum to bind troponin, exposing active sites on actin and initiating cross-bridge cycling.

Relaxation Phase

The phase of a muscle twitch where $\text{Ca}^{2+}$ is actively pumped back into the sarcoplasmic reticulum, reducing sarcoplasmic $\text{Ca}^{2+}$ levels and causing cross-bridge cycling to halt.

Slow-Twitch Oxidative (Type I) Muscle Fibers

Skeletal muscle fibers with slow ATP breakdown, slow myosin ATPase activity, high myoglobin content, many mitochondria and capillaries, high fatigue resistance, and low glycogen concentration; primarily maintain posture and support endurance activities.

Fast-Twitch Oxidative Glycolytic (Type IIa) Muscle Fibers

Skeletal muscle fibers with rapid ATP breakdown, fast myosin ATPase activity, high myoglobin content, many mitochondria and capillaries, intermediate fatigue resistance, and high glycogen concentration; utilized for endurance activities in endurance-trained muscles.

Fast-Twitch Glycolytic (Type IIb) Muscle Fibers

Skeletal muscle fibers characterized by fast myosin ATPase activity, low myoglobin content, few mitochondria and capillaries, low fatigue resistance, and the highest anaerobic capacity; utilized for rapid, intense movements of short duration.