Introduction to Anatomy & Physiology

Levels of Organization and Homeostasis

Anatomy and Physiology explore the structure and function of the human body, organized from the simplest chemical level to complex organ systems. Understanding these levels is essential for grasping how the body maintains homeostasis.

• Levels of Organization: Chemical, Cellular, Tissue, Organ, Organ System, Organism.

• Homeostasis: The body's ability to maintain stable internal conditions despite external changes.

• Feedback Mechanisms: Negative feedback reduces deviations from a set point; positive feedback amplifies changes.

• Body Cavities: Dorsal (cranial, vertebral), Ventral (thoracic, abdominopelvic).

• Anatomical Terms: Used to describe body positions, regions, and relative locations (e.g., anterior, posterior, medial, lateral).

Histology

Tissues and Epithelium

Histology is the study of tissues, which are groups of similar cells performing specific functions. The four basic tissue types are epithelial, connective, muscle, and nervous tissue.

• Epithelial Tissue: Covers surfaces, lines cavities, forms glands. Classified by cell shape (squamous, cuboidal, columnar) and layers (simple, stratified).

• Connective Tissue: Supports, binds, and protects organs. Types include areolar, adipose, reticular, dense regular/irregular, blood, bone, cartilage.

• Muscle Tissue: Responsible for movement. Types: skeletal, cardiac, smooth.

• Nervous Tissue: Conducts electrical impulses. Main cells: neurons and neuroglia.

Integumentary System

Structure and Function

The integumentary system includes the skin and its derivatives, providing protection, sensation, and temperature regulation.

• Skin Layers: Epidermis (stratum basale, spinosum, granulosum, lucidum, corneum), Dermis (papillary, reticular), Hypodermis.

• Accessory Structures: Hair, nails, sweat glands, sebaceous glands.

• Functions: Protection, sensation, thermoregulation, vitamin D synthesis.

Skeletal System

Bone Structure and Classification

The skeletal system provides support, protection, movement, and mineral storage. Bones are classified by shape: long, short, flat, irregular, sesamoid.

• Long Bone Anatomy: Diaphysis, epiphysis, metaphysis, medullary cavity, periosteum, endosteum.

• Bone Markings: Projections (tuberosity, trochanter), depressions (fossa), openings (foramen).

• Bone Cells: Osteoblasts (build bone), osteoclasts (break down bone), osteocytes (maintain bone).

• Ossification: Intramembranous (flat bones), endochondral (long bones).

• Remodeling Factors: Mechanical stress, hormones, aging, exercise.

Axial and Appendicular Skeleton

The skeleton is divided into axial (skull, vertebral column, thoracic cage) and appendicular (limbs, girdles) components.

• Axial Skeleton: Cranial bones, facial bones, vertebrae, ribs, sternum.

• Appendicular Skeleton: Pectoral girdle (clavicle, scapula), upper limb bones (humerus, radius, ulna, carpals, metacarpals, phalanges), pelvic girdle (ilium, ischium, pubis), lower limb bones (femur, tibia, fibula, tarsals, metatarsals, phalanges).

Articulations (Joints)

Classification and Movements

Joints connect bones and allow movement. They are classified by structure (fibrous, cartilaginous, synovial) and function (immovable, slightly movable, freely movable).

• Synovial Joints: Have a joint cavity, synovial fluid, articular cartilage, ligaments, bursae.

• Movements: Flexion, extension, abduction, adduction, rotation, circumduction, supination, pronation, inversion, eversion, dorsiflexion, plantarflexion, protraction, retraction, elevation, depression, opposition.

• Major Joints: Shoulder, elbow, hip, knee, spine.

Muscle Tissue

Structure and Physiology

Muscle tissue enables movement through contraction. It is classified as skeletal, cardiac, or smooth muscle.

• Muscle Anatomy: Muscle fiber, myofibril, sarcomere, endomysium, perimysium, epimysium.

• Contraction Mechanism: Sliding filament theory, role of actin and myosin, calcium ions, ATP.

• Types of Contractions: Twitch, wave summation, tetany, isotonic (concentric, eccentric), isometric.

• Energy Sources: Aerobic and anaerobic metabolism.

Major Muscles and Actions

Muscles are named by location, action, and attachments. Key muscle groups include those of the head, neck, trunk, upper and lower limbs.

Nervous System

Neural Tissue and Organization

The nervous system controls and coordinates body activities. It is divided into the central (CNS) and peripheral (PNS) nervous systems.

• Neuron Structure: Soma, dendrites, axon, axon hillock, synaptic knobs, myelin sheath, nodes of Ranvier.

• Neuroglia: Support cells (astrocytes, oligodendrocytes, microglia, ependymal cells).

• Action Potential: Electrical impulse generated by ion movement across the membrane.

• Synapse: Junction between neurons; neurotransmitters transmit signals.

Spinal Cord and Reflexes

The spinal cord transmits signals between the brain and body and mediates reflexes.

• Spinal Cord Anatomy: Gray matter, white matter, dorsal/ventral roots, central canal.

• Reflex Arc: Sensory receptor, sensory neuron, integration center, motor neuron, effector.

• Spinal Nerves: 31 pairs, named by region (cervical, thoracic, lumbar, sacral, coccygeal).

Brain and Cranial Nerves

The brain consists of the cerebrum, cerebellum, diencephalon, and brainstem. Cranial nerves control sensory and motor functions of the head and neck.

• Cerebrum: Lobes (frontal, parietal, temporal, occipital), fissures, gyri, sulci, corpus callosum.

• Functional Areas: Motor cortex, sensory cortex, association areas.

• Cranial Nerves: 12 pairs, each with specific sensory/motor functions (e.g., olfactory, optic, trigeminal).

Autonomic Nervous System

The autonomic nervous system regulates involuntary functions. It is divided into sympathetic (fight or flight) and parasympathetic (rest and digest) divisions.

• Sympathetic Division: Increases heart rate, dilates pupils, inhibits digestion.

• Parasympathetic Division: Decreases heart rate, stimulates digestion.

• Neurotransmitters: Acetylcholine, norepinephrine.

Special Senses

Vision, Hearing, Equilibrium

Special senses include vision, hearing, taste, smell, and equilibrium. Each sense has specialized receptors and pathways.

• Vision: Photoreceptors (rods, cones), retina, optic nerve.

• Hearing: Cochlea, auditory ossicles, hair cells.

• Equilibrium: Vestibular apparatus, semicircular canals.

Endocrine System

Hormones and Regulation

The endocrine system uses hormones to regulate body functions. Major glands include the pituitary, thyroid, adrenal, pancreas, and gonads.

• Hormones: Chemical messengers released into the bloodstream.

• Pituitary Gland: Master gland controlling other endocrine glands.

• Hypothalamus: Regulates pituitary function and stress response.

• Stress Response: Alarm, resistance, exhaustion phases.

Key Equations and Concepts

• Osmosis:

• Action Potential:

• Muscle Force:

• Bone Remodeling:

Additional info: This guide expands on the syllabus outline, providing definitions, examples, and context for each major topic in Anatomy & Physiology. It is suitable for exam preparation and review.