answers for Chapters 5, 6, and 7 based on your study guide: ⸻ ✅ 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) ⸻ 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 ⸻ 3. Bone Components • Compact (cortical) bone • Spongy (trabecular) bone • Periosteum • Endosteum • Bone marrow (red & yellow) • Articular cartilage ⸻ 4. Cortical vs Trabecular Bone • Cortical (compact): Dense, outer layer, strength • Trabecular (spongy): Porous, inside bone, reduces weight, houses marrow ⸻ 5. Bone Classification by Shape • Long (femur) • Short (carpals) • Flat (sternum) • Irregular (vertebrae) • Sesamoid (patella) ⸻ 6. Structure of a Long Bone • Diaphysis (shaft) • Epiphysis (ends) • Medullary cavity • Periosteum • Compact bone • Spongy bone ⸻ 7. Microscopic Bone Structure • Osteon (Haversian system) • Central canal • Lacunae (contain osteocytes) • Canaliculi (nutrient pathways) ⸻ 8. Osteoblast vs Osteoclast • Osteoblast: Builds bone • Osteoclast: Breaks down bone ⸻ 9. Three Types of Joints • Fibrous: Immovable (skull sutures) • Cartilaginous: Slight movement (intervertebral discs) • Synovial: Freely movable (knee) ⸻ 10. Osteoporosis & Arthritis • Osteoporosis: Bone thinning • Arthritis: Joint inflammation ⸻ ✅ Chapter 6 – Muscular System 1. Three Muscle Types • Skeletal: Voluntary, striated, attached to bones • Cardiac: Involuntary, heart only • Smooth: Involuntary, organs ⸻ 2. Connective Tissue Coverings • Endomysium → around muscle fiber • Perimysium → around fascicle • Epimysium → around whole muscle ⸻ 3. Fascicle Bundle of muscle fibers (covered by perimysium) ⸻ 4. Sarcomere Functional unit of muscle Boundaries: Z discs ⸻ 5. Bands • I band → thin only • A band → thick (and overlap) ⸻ 6. Filaments • Thick → Myosin • Thin → Actin, Troponin, Tropomyosin ⸻ 7. During Contraction • Sarcomere shortens • Z discs move closer • I band shortens • A band stays same ⸻ 8. Role of Calcium & ATP • Calcium: Exposes binding sites • ATP: Powers contraction & releases myosin ⸻ 9. Cross Bridge Myosin head binding to actin ⸻ 10. Neuromuscular Junction • Nerve releases acetylcholine (ACh) • ACh binds receptors • Muscle action potential starts ⸻ 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 ⸻ 12. Three Ways Muscles Produce ATP • Direct phosphorylation (creatine phosphate) • Anaerobic glycolysis • Aerobic respiration ⸻ 13. Oxygen & Lactic Acid • Aerobic: Requires oxygen • Anaerobic glycolysis: Produces lactic acid ⸻ 14. Fastest Energy System Direct phosphorylation ⸻ 15. Isotonic vs Isometric • Isotonic: Muscle shortens (lifting weight) • Isometric: Tension, no movement (holding weight) ⸻ ✅ Chapter 7 – Nervous System 1. CNS Brain + spinal cord Function: control center ⸻ 2. PNS Cranial nerves + spinal nerves ⸻ 3. Afferent vs Efferent • Afferent: Sensory → to CNS • Efferent: Motor → from CNS ⸻ 4. Three Parts of Neuron • Dendrites (receive) • Cell body • Axon (send signal) ⸻ 5. Synapse Junction between neurons Synaptic cleft = gap between them ⸻ 6. Neurotransmitters Chemical messengers between neurons ⸻ 7. Three Neuron Types • Sensory • Motor • Interneurons ⸻ 8. CNS Neuroglia • Astrocytes • Oligodendrocytes • Microglia • Ependymal cells ⸻ 9. Action Potential Phases • Resting (-70mV) • Depolarization (Na⁺ in) • Repolarization (K⁺ out) • Hyperpolarization ⸻ 10. Myelinated Axons Faster Because Saltatory conduction (jumps between nodes) ⸻ 11. Reflex & Components Automatic response 5 parts: 1. Receptor 2. Sensory neuron 3. Integration center 4. Motor neuron 5. Effector ⸻ 12. Four Lobes of Cerebrum • Frontal → movement • Parietal → sensation • Temporal → hearing • Occipital → vision ⸻ 13. Thalamus, Hypothalamus, Epithalamus • Thalamus → sensory relay • Hypothalamus → homeostasis • Epithalamus → melatonin ⸻ 14. Brainstem Parts • Midbrain → reflexes • Pons → breathing control • Medulla → heart rate ⸻ 15. Cerebellum Balance & coordination ⸻ 16. Meninges • Dura mater • Arachnoid mater • Pia mater Protect CNS ⸻ 17. CSF Cerebrospinal fluid Found in ventricles & around brain/spinal cord ⸻ 18. Spinal Cord Structure: gray center, white outside Function: reflexes & signal pathway ⸻ 19. Sympathetic vs Parasympathetic • Sympathetic → fight or flight • Parasympathetic → rest and digest ⸻ 20. Effects on Organs Sympathetic: • ↑ heart rate • Dilates pupils • Stops digestion Parasympathetic: • ↓ heart rate • Constricts pupils • Stimulates digestion ⸻ 21

Functions of the Skeletal System

Support, protection, movement, mineral storage, blood cell production, fat storage.

Axial Skeleton

Comprises 80 bones including the skull, vertebral column, ribs, sternum, and hyoid.

Appendicular Skeleton

Comprises 126 bones including the pectoral girdle, upper limbs, pelvic girdle, and lower limbs.

Compact Bone

Dense outer layer of bone providing strength.

Spongy Bone

Porous inner bone structure that reduces weight and houses marrow.

Bone Classification by Shape

Includes long (femur), short (carpals), flat (sternum), irregular (vertebrae), and sesamoid (patella).

Diaphysis

Shaft of a long bone.

Epiphysis

Ends of a long bone.

Osteon

The structural unit of compact bone, also known as Haversian system.

Osteoblast

Cell that builds bone.

Osteoclast

Cell that breaks down bone.

Types of Joints

Fibrous (immovable), cartilaginous (slight movement), and synovial (freely movable).

Osteoporosis

Condition characterized by bone thinning.

Arthritis

Condition characterized by joint inflammation.

Three Muscle Types

Skeletal (voluntary), cardiac (involuntary), and smooth (involuntary).

Connective Tissue Coverings in Muscles

Endomysium (around muscle fiber), perimysium (around fascicle), epimysium (around whole muscle).

Fascicle

Bundle of muscle fibers covered by perimysium.

Sarcomere

Functional unit of muscle bounded by Z discs.

I Band

Region of sarcomere containing only thin filaments (actin).

A Band

Region of sarcomere with thick filaments (myosin) and overlap.

Myosin

Thick filament involved in muscle contraction.

Actin

Thin filament involved in muscle contraction.

Role of Calcium in Muscle Contraction

Calcium exposes binding sites for myosin on actin.

Cross Bridge Formation

Attachment of myosin head to actin during muscle contraction.

Neuromuscular Junction

The site where a motor neuron meets a muscle fiber.

CNS

Central nervous system, comprising the brain and spinal cord.

PNS

Peripheral nervous system, comprising cranial and spinal nerves.

Afferent Neurons

Sensory neurons that carry signals to the CNS.

Efferent Neurons

Motor neurons that carry signals from the CNS.

Neuron

Basic unit of the nervous system, consisting of dendrites, cell body, and axon.

Synapse

Junction between two neurons.

Neurotransmitters

Chemical messengers that transmit signals across synapses.

Sensory Neurons

Neurons that respond to sensory stimuli and transmit information to the CNS.

Motor Neurons

Neurons that carry signals from the CNS to muscles or glands.

Interneurons

Neurons that connect sensory and motor neurons within the CNS.

Astrocytes

Type of neuroglial cell that supports neurons in the CNS.

Action Potential Phases

Includes resting, depolarization, repolarization, and hyperpolarization.

Saltatory Conduction

Fast transmission of action potentials in myelinated axons.

Reflex Arc Components

Includes receptor, sensory neuron, integration center, motor neuron, and effector.

Four Lobes of Cerebrum

Frontal (movement), parietal (sensation), temporal (hearing), occipital (vision).

Thalamus

Sensory relay center of the brain.

Hypothalamus

Regulates homeostasis.

Brainstem

Includes midbrain, pons, and medulla, essential for regulating basic life functions.

Meninges

Three protective layers surrounding the CNS (dura mater, arachnoid mater, pia mater).

CSF

Cerebrospinal fluid; surrounds and protects the brain and spinal cord.

Sympathetic Nervous System

Part of the autonomic nervous system that prepares the body for 'fight or flight'.

Parasympathetic Nervous System

Part of the autonomic nervous system that promotes 'rest and digest' functions.

Fight or Flight Response

Physiological reaction promoting survival in response to perceived threats.

Rest and Digest Response

Physiological reaction promoting maintenance activities of the body.