1. Functions of Muscles:
• Movement: Muscles contract to produce movement in the body, such as walking, running, or even facial expressions.
• Posture and Stability: Muscles help maintain posture and stabilize joints, preventing falls or loss of balance.
• Heat Production: Muscle contractions generate heat, which is vital for maintaining body temperature.
• Protection of Internal Organs: Muscles, particularly in the abdominal region, protect internal organs from injury.
• Circulation of Blood and Lymph: Cardiac and smooth muscles play roles in circulating blood and lymph throughout the body.
2. Characteristics of Muscles:
• Excitability (Responsiveness): Muscles can respond to stimuli (like nerve signals).
• Contractility: Muscles can contract or shorten when stimulated.
• Extensibility: Muscles can be stretched without damage.
• Elasticity: Muscles can return to their original shape after being stretched or contracted.
3. Locations of Smooth, Cardiac, and Skeletal Muscle:
• Smooth Muscle: Found in walls of internal organs (e.g., stomach, intestines, blood vessels).
• Cardiac Muscle: Found only in the heart.
• Skeletal Muscle: Attached to bones and responsible for voluntary movements.
4. Events of Skeletal Muscle Contraction:
1. Nerve Impulse: A signal is sent from a motor neuron to the muscle.
2. Release of Acetylcholine: The neurotransmitter acetylcholine is released into the neuromuscular junction.
3. Muscle Fiber Activation: Acetylcholine stimulates muscle fibers, causing an action potential.
4. Calcium Release: The action potential triggers the release of calcium ions from the sarcoplasmic reticulum.
5. Cross-Bridge Formation: Calcium binds to troponin, moving tropomyosin, which allows myosin heads to attach to actin.
6. Power Stroke: Myosin heads pull actin filaments inward, causing the muscle to contract.
7. Relaxation: ATP breaks the cross-bridge, and the muscle relaxes when calcium is pumped back into the sarcoplasmic reticulum.
5. Isometric vs. Isotonic Contractions:
• Isometric Contraction: The muscle generates tension without changing its length (e.g., holding a weight in a fixed position).
• Isotonic Contraction: The muscle changes length while generating tension (e.g., lifting a weight).
6. Primary Functions of the Skeletal System:
• Support: Provides structural support for the body.
• Protection: Shields vital organs (e.g., brain, heart, lungs).
• Movement: Works with muscles to allow movement.
• Mineral Storage: Stores minerals like calcium and phosphorus.
• Blood Cell Production: Bone marrow produces blood cells.
• Energy Storage: Fat is stored in bone cavities.
7. Parts of a Long Bone:
• Diaphysis: The shaft of the bone.
• Epiphysis: The ends of the bone.
• Metaphysis: Region between the diaphysis and epiphysis.
• Medullary Cavity: Hollow cavity inside the diaphysis, containing bone marrow.
• Periosteum: Outer membrane covering the bone.
• Endosteum: Inner lining of the medullary cavity.
8. Inner and Outer Connective Tissue Linings of a Bone:
• Outer: Periosteum.
• Inner: Endosteum.
9. Structure of a Flat Bone:
• Compact Bone: Dense bone found on the outside.
• Spongy Bone: Lighter, less dense bone found inside, filled with red or yellow marrow.
• No medullary cavity (unlike long bones).
10. Parts of the Osteon:
• Central Canal (Haversian Canal): Contains blood vessels and nerves.
• Lamellae: Concentric layers of bone matrix surrounding the central canal.
• Lacunae: Small spaces containing osteocytes (bone cells).
• Canaliculi: Small channels that connect lacunae and allow for nutrient exchange.
11. How Calcitonin, Calcitriol, and PTH Affect Blood Calcium:
• Calcitonin: Lowers blood calcium levels by inhibiting osteoclast activity (bone resorption).
• Calcitriol: Increases blood calcium by promoting calcium absorption in the intestines and bone resorption.
• PTH (Parathyroid Hormone): Raises blood calcium by stimulating osteoclasts to break down bone and release calcium.
12. Two Forms of Ossification:
• Intramembranous Ossification: Bone develops directly from mesenchymal tissue (e.g., flat bones of the skull).
• Endochondral Ossification: Bone replaces a cartilage model (e.g., long bones).
13. Difference Between Appositional and Interstitial Growth:
• Appositional Growth: Increase in bone diameter (growth at the surface).
• Interstitial Growth: Increase in bone length (growth from within).
14. Different Joint Types:
• Fibrous Joints: Connected by fibrous tissue (e.g., sutures of the skull).
• Cartilaginous Joints: Connected by cartilage (e.g., intervertebral discs).
• Synovial Joints: Have a fluid-filled joint cavity (e.g., knee, elbow).
15. Components of a Synovial Joint:
• Articular Cartilage: Covers the ends of bones.
• Synovial Membrane: Lines the joint capsule and produces synovial fluid.
• Joint Capsule: Surrounds the joint, providing stability.
• Ligaments: Connect bones to other bones.
• Synovial Fluid: Lubricates the joint.
16. Hinge Joint Location:
• Found in the elbow and knee.
17. Pivot Joint Location:
• Found between the first and second cervical vertebrae (atlantoaxial joint).
18. Difference Between a Tendon and a Ligament:
• Tendon: Connects muscle to bone.
• Ligament: Connects bone to bone.
19. What is a Bursa?
• A fluid-filled sac that reduces friction and cushions pressure points between the skin and bones or muscles and bones.
20. Three Types of Arthritis:
• Osteoarthritis: Degeneration of joint cartilage and underlying bone, often due to wear and tear.
• Rheumatoid Arthritis: Autoimmune disease causing inflammation in joints.
• Gout: Caused by the accumulation of uric acid crystals in the joints.
21. Strain vs. Sprain:
• A strain is damage to a muscle or tendon, whereas a sprain is damage to a ligament
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