answers for Chapters 5, 6, and 7 based on your study guide:
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✅ Chapter 5 – Skeletal System
1. Functions of the Skeletal System
• Support
• Protection
• Movement (with muscles)
• Mineral storage (calcium, phosphorus)
• Blood cell production (hematopoiesis)
• Fat storage (yellow marrow)
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2. Axial vs Appendicular Skeleton
Axial (80 bones)
• Skull
• Vertebral column
• Ribs
• Sternum
• Hyoid
Appendicular (126 bones)
• Pectoral girdle (clavicle, scapula)
• Upper limbs
• Pelvic girdle
• Lower limbs
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3. Bone Components
• Compact (cortical) bone
• Spongy (trabecular) bone
• Periosteum
• Endosteum
• Bone marrow (red & yellow)
• Articular cartilage
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4. Cortical vs Trabecular Bone
• Cortical (compact): Dense, outer layer, strength
• Trabecular (spongy): Porous, inside bone, reduces weight, houses marrow
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5. Bone Classification by Shape
• Long (femur)
• Short (carpals)
• Flat (sternum)
• Irregular (vertebrae)
• Sesamoid (patella)
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6. Structure of a Long Bone
• Diaphysis (shaft)
• Epiphysis (ends)
• Medullary cavity
• Periosteum
• Compact bone
• Spongy bone
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7. Microscopic Bone Structure
• Osteon (Haversian system)
• Central canal
• Lacunae (contain osteocytes)
• Canaliculi (nutrient pathways)
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8. Osteoblast vs Osteoclast
• Osteoblast: Builds bone
• Osteoclast: Breaks down bone
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9. Three Types of Joints
• Fibrous: Immovable (skull sutures)
• Cartilaginous: Slight movement (intervertebral discs)
• Synovial: Freely movable (knee)
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10. Osteoporosis & Arthritis
• Osteoporosis: Bone thinning
• Arthritis: Joint inflammation
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✅ Chapter 6 – Muscular System
1. Three Muscle Types
• Skeletal: Voluntary, striated, attached to bones
• Cardiac: Involuntary, heart only
• Smooth: Involuntary, organs
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2. Connective Tissue Coverings
• Endomysium → around muscle fiber
• Perimysium → around fascicle
• Epimysium → around whole muscle
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3. Fascicle
Bundle of muscle fibers (covered by perimysium)
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4. Sarcomere
Functional unit of muscle
Boundaries: Z discs
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5. Bands
• I band → thin only
• A band → thick (and overlap)
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6. Filaments
• Thick → Myosin
• Thin → Actin, Troponin, Tropomyosin
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7. During Contraction
• Sarcomere shortens
• Z discs move closer
• I band shortens
• A band stays same
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8. Role of Calcium & ATP
• Calcium: Exposes binding sites
• ATP: Powers contraction & releases myosin
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9. Cross Bridge
Myosin head binding to actin
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10. Neuromuscular Junction
• Nerve releases acetylcholine (ACh)
• ACh binds receptors
• Muscle action potential starts
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11. Steps of Skeletal Muscle Contraction
1. Nerve impulse
2. ACh release
3. Muscle action potential
4. Ca²⁺ released from SR
5. Cross bridge formation
6. Power stroke
7. ATP binds & detaches
8. Relaxation when Ca²⁺ removed
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12. Three Ways Muscles Produce ATP
• Direct phosphorylation (creatine phosphate)
• Anaerobic glycolysis
• Aerobic respiration
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13. Oxygen & Lactic Acid
• Aerobic: Requires oxygen
• Anaerobic glycolysis: Produces lactic acid
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14. Fastest Energy System
Direct phosphorylation
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15. Isotonic vs Isometric
• Isotonic: Muscle shortens (lifting weight)
• Isometric: Tension, no movement (holding weight)
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✅ Chapter 7 – Nervous System
1. CNS
Brain + spinal cord
Function: control center
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2. PNS
Cranial nerves + spinal nerves
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3. Afferent vs Efferent
• Afferent: Sensory → to CNS
• Efferent: Motor → from CNS
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4. Three Parts of Neuron
• Dendrites (receive)
• Cell body
• Axon (send signal)
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5. Synapse
Junction between neurons
Synaptic cleft = gap between them
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6. Neurotransmitters
Chemical messengers between neurons
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7. Three Neuron Types
• Sensory
• Motor
• Interneurons
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8. CNS Neuroglia
• Astrocytes
• Oligodendrocytes
• Microglia
• Ependymal cells
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9. Action Potential Phases
• Resting (-70mV)
• Depolarization (Na⁺ in)
• Repolarization (K⁺ out)
• Hyperpolarization
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10. Myelinated Axons Faster Because
Saltatory conduction (jumps between nodes)
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11. Reflex & Components
Automatic response
5 parts:
1. Receptor
2. Sensory neuron
3. Integration center
4. Motor neuron
5. Effector
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12. Four Lobes of Cerebrum
• Frontal → movement
• Parietal → sensation
• Temporal → hearing
• Occipital → vision
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13. Thalamus, Hypothalamus, Epithalamus
• Thalamus → sensory relay
• Hypothalamus → homeostasis
• Epithalamus → melatonin
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14. Brainstem Parts
• Midbrain → reflexes
• Pons → breathing control
• Medulla → heart rate
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15. Cerebellum
Balance & coordination
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16. Meninges
• Dura mater
• Arachnoid mater
• Pia mater
Protect CNS
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17. CSF
Cerebrospinal fluid
Found in ventricles & around brain/spinal cord
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18. Spinal Cord
Structure: gray center, white outside
Function: reflexes & signal pathway
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19. Sympathetic vs Parasympathetic
• Sympathetic → fight or flight
• Parasympathetic → rest and digest
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20. Effects on Organs
Sympathetic:
• ↑ heart rate
• Dilates pupils
• Stops digestion
Parasympathetic:
• ↓ heart rate
• Constricts pupils
• Stimulates digestion
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