Week 8 Bone Features, Order Anura

Welcome & Introduction

• Instructor: Nirosha Murugan, PhD

  • Assistant Professor of Biology at Algoma University.

  • Focus areas: regenerative medicine, cancer biology, neuroscience.

  • Notable work: Regrowing a functional limb in frogs using a five-drug cocktail.

  • Key insight: Potential for dormant regenerative capabilities in frogs and other animals.

Lab Exam 2 Overview

Point Breakdown

• Total Points: 43

• Graded out of: 40 points

• Bones Section: 33-36 points

  • 1 point for proper names (no colloquial terms like collarbone, cheekbone).

  • 0.5 points for Anterior vs. Posterior, Right vs. Left, and Bone features.

  • Possible definitions per checklist.

• Frog Section: 7-10 points

  • External/internal anatomy and muscles (1-2 points).

  • Background info from PowerPoint (PPT).

  • Prepared microscope slides are important; major tissue types for Cephalochordata/amphioxus.

• Questions based strictly on checklists and PowerPoints.

Lab Exam 2 Details

• Location: IO306 (lab)

• Date: Tuesday, March 11th

• Schedule:

  • Last Names A-K: 11:20 AM (Doors open), 11:30 AM (Exam starts)

  • Last Names L-W: 12:20 PM (Doors open), 12:30 PM (Exam starts)

• Exam Duration: 30 minutes (approx. 30 seconds per question).

• Policy: Do not knock on the door once closed; wait for it to reopen.

• What to Bring: Pencil or Pen (blue/black ink only).

Lab Safety Guidelines

• Eye Protection: Mandatory.

• Attire: Closed-toe shoes, long pants.

• Hygiene: Sanitize work areas and dissection kits upon entering/leaving.

• Allergens: Be aware of latex.

Biological Classification Overview

Basic Concepts

• Organization Levels:

  • Parazoa, Eumetazoa

  • Symmetry types: Radial, Bilateral

• Key Terms:

  • Choanoflagellates, Radiata, Gastrulation

  • Body Cavity: Acoelomates, Pseudocoelomates, Coelomates.

  • Development types: Protostomia, Deuterostomia.

Characteristics of Chordates

• General Features:

  • Found in aquatic and terrestrial environments.

  • Distinct head and trunk supported by cartilage or vertebrate structures in adults.

  • Features: Notochord, well-developed brain, sensory organs, dorsal nerve cord, closed circulatory system.

• Examples: Reptiles, amphibians, birds, mammals.

Bone Anatomy

Types of Bone Markings

• Non-articulation Markings (for muscle attachment):

  • Trochanter: Large, blunt projection (femur).

  • Tuberosity: Large rounded projection (tibia, ulna).

  • Tubercle: Small rounded projection (humerus, radius).

  • Crest: Narrow projection forming a ridge (ilium, tibia).

  • Spine: Slender bone extension (vertebrae).

  • Process: Sharp, slender extension (radius).

• Joint Formation Markings:

  • Head: Rounded region at the proximal end of a bone (femur).

  • Facet: Shallow, smooth surface (ribs, vertebrae).

  • Condyle: Round knob (mandible, femur).

Depressions/Openings

• Meatus: Canal-like passage (temporal).

• Sinus: Air-filled cavity within a bone (frontal, sphenoid).

• Fossa: Shallow bone depression (temporal, scapula).

• Sulcus: Furrow along a bone (humerus).

• Fissure: Narrow opening for blood vessels or nerves (orbital).

• Foramen: Round opening for vessels/nerves (occipital).

Amphibia Class Overview

Characteristics of Amphibians

• Aquatic and terrestrial organisms.

• Distinct features:

  • Protruding eyes, cleft tongue.

  • Maxillary and vomerine teeth, semi-permeable skin.

  • Undergo metamorphosis; exhibit sexual dimorphism with males having vocal sacs.

Internal Anatomy of Frogs

Circulatory and Digestive Systems

• Heart: 3-chambered.

• Lungs and Digestive System:

  • Function: Processes food for absorption into the bloodstream.

  • Organs included: Stomach, intestines, gall bladder, spleen.

Urogenital System

• Function: Waste extraction/processing from blood & reproduction.

• Organs included: Kidneys, adrenal glands, testes (males), ovaries (females), cloaca.

Muscle Tissue

Functions

• Produces body movements.

• Stabilizes body positions.

• Stores/moves substances within the body, contributes to metabolism.

• Generates heat through muscle activity.

Properties

• Electrical Excitability: Action potentials.

• Contractility: Ability to shorten forcefully.

• Extensibility: Ability to stretch.

• Elasticity: Ability to return to original shape.

Types of Muscle Tissue

1. Skeletal Muscle:

   • Striated, tubular, voluntary, multi-nucleated, usually attached to skeleton.

2. Cardiac Muscle:

   • Striated, branched, involuntary, present only in heart walls.

3. Smooth Muscle:

   • Non-striated, spindle-shaped, involuntary, found in internal organs.

Histology of Skeletal Muscle

• Components:

  • Nuclei, striations, endomysium.

• Structures:

  • Longitudinal section (l.s.), cross-section (c.s.).

Skeletal Muscle Hierarchy

• Muscle fiber (cell) → Endomysium → Fascicle → Perimysium → Epimysium → Tendon → Motor neuron → Blood vessels.

Sarcomeres

Key Points

• Basic contractile unit of myocyte.

• Composed of thick filaments (myosin) and thin filaments (actin, tropomyosin, troponin).

Frog Muscle Identification

• Ventral Muscles: Rectus abdominis, Pectoralis, Sartorius, Adductor magnus, Triceps femoris, Gastrocnemius.

• Dorsal Muscles: Adductor magnus (cut), Gracilis major, Triceps femoris, Semimembranosus, Latisimus dorsi.

To Do List for Students

• Dissect preserved Frog specimen.

• Review external and internal anatomy, bone identification, and muscle features.

• Study prepared slides of skeletal muscle.

• Familiarize with striated muscle structures.