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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