Overview
This lecture covered the histological study, skeletal system, and muscular system of frogs through dissection and microscopy, focusing on identifying tissue types, skeletal components, and muscle group functions.
Histology of Frog Tissues
- Frogs possess four major tissue types: epithelial, connective, muscular, and nervous.
- Epithelial tissue: tightly packed cells form protective linings; observed in frog skin.
- Connective tissue: includes blood, with red and white blood cells and platelets suspended in plasma; provides support and transport.
- Muscular tissue: elongated, striated fibers specialized for contraction; found in limb muscles.
- Nervous tissue coordinates responses via electrical impulses but was not observed in this experiment.
- Tissue structure is closely linked to function, supporting protection, movement, transport, and communication.
Frog Skeletal System
- The axial skeleton includes the skull, vertebral column, and urostyle, providing structural support and organ protection.
- The appendicular skeleton comprises limb bones and girdles, enabling locomotion and movement.
- Hind limbs are longer and stronger than forelimbs, adapted for jumping and swimming.
- The pelvic girdle is fused to the vertebral column for stability.
- Skeletal adaptations differ across vertebrates based on habitat: aquatic (flexible, streamlined), aerial (lightweight, fused), terrestrial (robust, stable).
- The frog’s urostyle absorbs landing impact and assists in jumping.
Frog Muscular System
- Major muscle groups include gastrocnemius (hind limbs) for jumping, and forelimb muscles for support and balance.
- Antagonistic muscle pairs, like biceps (flexion) and triceps (extension), enable coordinated limb movement.
- Skeletal muscle: striated, voluntary, cylindrical fibers; observed via microscope.
- Smooth muscle: non-striated, involuntary, spindle-shaped fibers; not dissected but observed in reference slides.
- Cardiac muscle: striated, involuntary, branched fibers with intercalated discs; observed in references.
- Muscles pull on bones, acting as levers, resulting in movement.
Key Terms & Definitions
- Epithelial tissue — tightly packed cells forming protective linings and barriers.
- Connective tissue — tissue providing support, energy storage, and nutrient transport (includes blood).
- Muscular tissue — tissue composed of fibers responsible for movement through contraction.
- Nervous tissue — tissue specialized for transmitting electrical impulses.
- Axial skeleton — central skeleton including skull, vertebral column, and urostyle.
- Appendicular skeleton — limb bones and girdles attached to the axial skeleton.
- Antagonistic muscle pair — two muscles performing opposite actions at a joint.
Action Items / Next Steps
- Repeat experiments to examine nervous tissue and complete tissue-type observations.
- Use prepared stained slides or digital microscopy for enhanced cellular detail.
- Perform a full dissection to explore all muscle groups and locate smaller skeletal components.
- Study actual smooth and cardiac muscle tissue for direct comparison.
- Prepare labeled diagrams of musculature and skeletal structures for review.