Skeletal System

Types and Functions of Cartilage

Cartilage is a specialized connective tissue that provides support, flexibility, and strength to various structures in the body. There are three main types: hyaline cartilage, elastic cartilage, and fibrocartilage.

• Hyaline cartilage: Maintains the shape of a structure while allowing great flexibility.

• Fibrocartilage: Resists compression and provides great tensile strength.

• Elastic cartilage: Provides support with flexibility and resilience.

Locations of Cartilage Types in the Body

Functions of Skeleton and Bone Tissue

The skeleton and bone tissue perform several vital functions:

• Support: Provides a framework for the body and supports soft tissues.

• Protection: Protects vital organs (e.g., skull protects the brain, rib cage protects the heart and lungs).

• Movement: Acts as levers for muscles to produce movement.

• Mineral storage: Stores minerals such as calcium and phosphorus.

• Blood cell formation: Houses bone marrow, which produces blood cells (hematopoiesis).

• Triglyceride storage: Stores fat in yellow bone marrow.

• Hormone production: Produces osteocalcin, which helps regulate bone formation and protects against obesity and diabetes.

Bone Structure and Cells

Bones are composed of compact and spongy bone, each with distinct structures and functions.

• Osteons: Structural units of compact bone.

• Trabeculae: Lattice-like structures in spongy bone.

• Osteocytes: Mature bone cells that monitor and maintain bone matrix.

• Canaliculi: Tiny canals filled with tissue fluid and extensions of bone cells.

• Central canals: Canals that run through the core of each osteon.

• Lacunae: Chambers that contain mature bone cells.

• Osteoblasts: Bone-forming cells that secrete the bone matrix.

• Osteoclasts: Cells that resorb (break down) bone.

Bone Disorders

Types of Bone Fractures

Muscular System

Functions of Skeletal Muscle Tissue

Skeletal muscle tissue is essential for movement and other physiological functions.

• Movement: Responsible for voluntary movements of the body.

• Posture: Maintains posture and body position.

• Stabilization: Stabilizes joints.

• Heat production: Generates heat as a byproduct of muscle activity.

Muscle Proteins and Their Functions

• Myosin: Makes up most of the thick filament; binds calcium ions.

• Actin: Makes up most of the thin filament.

• Troponin: Binds calcium ions.

• Tropomyosin: Blocks binding sites on the thin filament.

Muscle Contraction Cycle

The cross bridge cycle is the process by which muscles contract:

1. Myosin head attaches to actin forming a cross bridge.

2. Power stroke: Myosin head pivots, pulling actin filament toward the center of the sarcomere.

3. ATP binds to myosin, causing it to detach from actin.

4. ATP is hydrolyzed, re-cocking the myosin head for another cycle.

Types of Muscle Contractions

• Isometric contraction: Muscle does not change in length; load is not moved.

• Isotonic contraction: Muscle changes in length; load is moved.

Effects of Aerobic vs. Resistance Exercise

Types of Muscle Tissue

• Skeletal muscle: Voluntary, striated, attached to bones for movement.

• Cardiac muscle: Involuntary, striated, found only in the heart.

• Smooth muscle: Involuntary, non-striated, found in walls of hollow organs.

Nervous System

Major Functions of the Nervous System

The nervous system is responsible for communication, control, and integration throughout the body.

• Sensory input: Detects changes inside and outside the body.

• Integration: Processes and interprets sensory input and decides what should be done.

• Motor output: Activates effector organs (muscles and glands) to respond.

Central and Peripheral Nervous Systems

• CNS (Central Nervous System): Consists of the brain and spinal cord; responsible for integration and control.

• PNS (Peripheral Nervous System): Consists of nerves outside the CNS; transmits signals between the CNS and the rest of the body.

Neuroglia (Glial Cells) and Their Functions

• Ependymal cells: Line cerebrospinal fluid-filled CNS cavities.

• Schwann cells: Form myelin sheaths around PNS nerve fibers.

• Microglia: Defensive cells in the CNS; engulf microorganisms and debris.

• Satellite cells: Surround and support neuron cell bodies in the PNS.

Neuron Structure and Function

• Cell body (soma): Contains the nucleus and major biosynthetic center.

• Dendrites: Most responsible for receiving information from other neurons.

• Axon: Generates nerve impulses and transmits them; contains neurofibrils and a spherical nucleus.

Classification of Neurons

• Motor neurons: Transmit impulses from the CNS to muscles or glands.

• Sensory neurons: Transmit impulses from receptors in the skin or internal organs toward the CNS.

• Interneurons: Also called association neurons; connect sensory and motor neurons within the CNS.

Membrane Channels and Action Potentials

• Chemically gated channels: Open when a neurotransmitter binds to them.

• Voltage-gated channels: Open and close in response to changes in membrane potential.

• Mechanically gated channels: Open in response to physical deformation of the receptor.

The transition from local graded potential to long-distance action potential occurs at the axon hillock.

Nodes of Ranvier

Nodes of Ranvier are gaps in the myelin sheath along axons that facilitate rapid conduction of action potentials by allowing saltatory conduction.

Equations and Key Concepts

• Resting membrane potential:

• Action potential threshold:

• Calcium's role in neurotransmitter release: influx triggers exocytosis of neurotransmitter vesicles.

Additional info:

• Some tables and questions reference figures and sections from a textbook; students should consult their course text for diagrams and further details.

• Some content inferred from context and standard Anatomy & Physiology curriculum.