Chapter 9 – Skeletal Muscles
1. Connective Tissue Surrounding a Skeletal Muscle:
• Epimysium: Surrounds the entire muscle.
• Perimysium: Surrounds bundles of muscle fibers (fascicles).
• Endomysium: Surrounds individual muscle fibers.
2. Histology and Function of Sarcomeres:
• Histology: Sarcomeres are the structural and functional units of skeletal muscles, composed of repeating units between two Z-lines.
• Function: They enable muscle contraction through the sliding filament mechanism.
3. Main Components:
• Thin Filaments: Actin, tropomyosin, and troponin.
• Thick Filaments: Myosin.
4. Function of Transverse Tubules and Sarcoplasmic Reticulum:
• Transverse Tubules (T-tubules): Transmit action potentials deep into the muscle fiber.
• Sarcoplasmic Reticulum: Stores and releases calcium ions for muscle contraction.
5. Motor Unit: A motor neuron and all the muscle fibers it innervates.
6. Neuromuscular Junction: The synapse where a motor neuron meets a muscle fiber, allowing for signal transmission.
7. Synapse: A junction between two neurons or a neuron and a muscle cell where communication occurs.
8. Actions of Acetylcholine (ACh):
• Initiates muscle contraction by binding to receptors on the sarcolemma.
• Degraded by: Acetylcholinesterase.
9. Neurotransmitter Released at Motor Axon Terminals: Acetylcholine.
10. Steps in Excitation-Contraction Coupling:
• Action potential travels along sarcolemma.
• Calcium is released from the sarcoplasmic reticulum.
• Calcium binds to troponin, causing tropomyosin to move, exposing binding sites on actin.
• Myosin heads form cross-bridges and initiate contraction.
11. Order of Muscle Fiber Contraction:
• Action potential → Calcium release → Cross-bridge formation → Power stroke → ATP binding → Cross-bridge detachment.
12. Mechanism of Muscle Contraction:
• Sliding filament theory: Actin and myosin filaments slide past each other.
13. Interaction of Actin, Myosin, and Calcium:
• Calcium binds to troponin, shifting tropomyosin to expose myosin-binding sites on actin, enabling cross-bridge cycling.
14. Cross-Bridges: Myosin heads that bind to actin during contraction.
15. Contraction Types:
• Isotonic: Muscle length changes.
• Eccentric: Muscle lengthens under tension.
• Isometric: Muscle tension without length change.
• Concentric: Muscle shortens under tension.
16. Force of Muscle Contraction:
• Controlled by motor unit recruitment.
• Partial Tetany: Incomplete relaxation.
• Fused Tetany: Sustained contraction without relaxation.
17. Bones and Muscles as Levers:
• Fulcrum: Pivot point of the lever.
18. Synergist and Antagonist:
• Synergist: Assists the primary mover.
• Antagonist: Opposes the primary mover.
19. Muscle Atrophy: Wasting of muscle due to disuse or disease.
20. Myasthenia Gravis: Autoimmune disorder causing muscle weakness by targeting ACh receptors.
21. Linea Alba: A fibrous structure running down the midline of the abdomen.
22. Origin, Insertion, and Actions of Specific Muscles:
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Chapter 17 – Digestive System
1. Alimentary Canal: A continuous muscular tube extending from the mouth to the anus.
2. Functions of the Digestive System:
• Ingestion, digestion, absorption, and elimination.
3. Breakdown and Absorption:
• Carbohydrates: Begin in the mouth (amylase).
• Proteins: Start in the stomach (pepsin).
• Fats: Start in the small intestine (lipase, bile).
4. Layers of Alimentary Canal Walls:
• Mucosa, submucosa, muscularis, serosa.
5. Accessory Organs:
• Liver, pancreas, gallbladder.
6. Sympathetic vs. Parasympathetic Effects:
• Sympathetic: Decreases digestion.
• Parasympathetic: Enhances digestion.
7. Hormones:
• Gastrin: Stimulates gastric juice secretion.
• Cholecystokinin (CCK): Stimulates bile and pancreatic juice.
• Secretin: Stimulates bicarbonate secretion.
8. Peristalsis vs. Segmentation:
• Peristalsis: Wave-like contractions.
• Segmentation: Mixing movements.
9. Epiglottis Function: Prevents food from entering the trachea.
10. Heartburn: Caused by stomach acid reflux into the esophagus.
11. Stomach Parts: Fundus, body, pylorus.
12. Secretions:
• Parietal Cells: Hydrochloric acid, intrinsic factor.
• Chief Cells: Pepsinogen.
13. Digestive Enzymes and Substances:
• Amylase: Breaks down starch.
• Pepsin: Digests proteins.
• Trypsin: Protein digestion.
• Lipase: Fat digestion.
• Bile Salts: Emulsify fats.
14. Liver, Gallbladder, Pancreas Functions:
• Liver: Produces bile.
• Gallbladder: Stores bile.
• Pancreas: Produces enzymes and bicarbonate.
15. Anatomy of Bile Ducts:
• Common hepatic, cystic, and pancreatic ducts form the common bile duct.
16. Functions of Large Intestine:
• Absorption of water, vitamin production, and feces formation.
17. Defecation Reflex: Triggered by rectal wall distension.
Chapter 18 – Nutrition
1. Excess Glucose Storage: As glycogen in the liver and muscles.
2. Tissue Requiring Glucose: Nervous tissue (brain).
3. Triglyceride Components: Glycerol and three fatty acids.
4. Essential Amino Acids: Cannot be synthesized by the body
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