Unit 1: Introduction to Anatomy & Physiology

Levels of Organization

The human body is organized in a hierarchical manner, from the smallest chemical units to the complete organism.

• Atom: The smallest unit of matter (e.g., carbon, hydrogen).

• Molecule: Combination of atoms (e.g., water, proteins).

• Organelle: Specialized structures within cells (e.g., mitochondria).

• Cell: Basic unit of life (e.g., muscle cell, neuron).

• Tissue: Group of similar cells performing a function (e.g., epithelial tissue).

• Organ: Structure composed of multiple tissues (e.g., heart).

• Organ System: Group of organs working together (e.g., digestive system).

• Organism: The complete living being.

Major Body Systems and Their Functions

The body consists of several systems, each with specific functions.

• Integumentary: Protection, temperature regulation.

• Skeletal: Support, movement, protection.

• Muscular: Movement, heat production.

• Nervous: Control, communication.

• Endocrine: Hormone production, regulation.

• Cardiovascular: Transport of nutrients and waste.

• Lymphatic: Immunity, fluid balance.

• Respiratory: Gas exchange.

• Digestive: Breakdown and absorption of food.

• Urinary: Waste elimination, fluid balance.

• Reproductive: Production of offspring.

Cell Transport Mechanisms

Cells use various methods to move substances across membranes.

• Active Transport: Movement against concentration gradient using energy (ATP).

• Selectively (Semi) Permeable: Membranes allow some substances to pass, restrict others.

• Facilitated Diffusion: Passive movement via protein channels.

• Diffusion: Movement from high to low concentration.

• Osmosis: Diffusion of water across a membrane.

• Endocytosis: Uptake of materials into cell (includes phagocytosis and pinocytosis).

• Filtration: Movement due to pressure differences.

• Exocytosis: Release of substances from cell.

Anatomical Position and Directional Terms

Standardized terms describe locations and positions in the body.

• Superior: Above.

• Inferior: Below.

• Anterior (Ventral): Front.

• Posterior (Dorsal): Back.

• Medial: Toward midline.

• Lateral: Away from midline.

• Deep: Further from surface.

• Superficial: Near surface.

• Proximal: Closer to point of attachment.

• Distal: Farther from point of attachment.

• Cephalic: Toward head.

• Caudal: Toward tail.

Planes of Reference

Planes are used to describe anatomical sections.

• Coronal (Frontal): Divides body into anterior and posterior.

• Sagittal: Divides body into left and right.

• Midsagittal: Divides body into equal left and right halves.

• Transverse: Divides body into superior and inferior.

• Longitudinal: Along the length of a structure.

• Cross-section: Perpendicular to the length.

Body Regions and Cavities

The body is divided into regions and cavities for descriptive purposes.

• Major Regions: Head, neck, trunk, upper limbs, lower limbs.

• Major Cavities: Cranial, thoracic, abdominal, pelvic, vertebral.

Homeostasis

Homeostasis is the maintenance of a stable internal environment.

• Variable: The factor being regulated (e.g., temperature).

• Set Point: Ideal value for the variable.

• Normal Range: Acceptable range around the set point.

Tissues & Histology

There are four major tissue types, each with unique structure and function.

• Epithelial: Covers surfaces, lines cavities, forms glands.

• Connective: Supports, binds, protects (e.g., bone, blood).

• Muscle: Movement (skeletal, cardiac, smooth).

• Nervous: Communication, control (neurons, glia).

Integumentary System

The integumentary system protects the body and regulates temperature.

• Functions: Protection, sensation, temperature regulation, vitamin D synthesis.

Structure of Skin

Skin consists of layers with specialized functions.

• Epidermis: Multiple strata (layers), including stratum corneum, lucidum, granulosum, spinosum, basale.

• Dermis: Papillary and reticular layers.

• Thin vs. Thick Skin: Thick skin (palms, soles) has more strata and lacks hair.

Unit 2: Skeletal System

Functions and Components

The skeletal system provides support, protection, and movement.

• Axial Skeleton: Skull, vertebral column, rib cage.

• Appendicular Skeleton: Limbs, girdles.

Structure of Osteon

The osteon is the functional unit of compact bone.

• Central Canal: Contains blood vessels and nerves.

• Lamellae: Rings of bone matrix.

• Lacunae: Spaces housing osteocytes.

• Canaliculi: Channels for nutrient/waste exchange.

Bone Cells

Bone cells maintain, build, and break down bone tissue.

• Osteocytes: Mature bone cells.

• Osteoblasts: Build bone matrix.

• Osteoclasts: Break down bone matrix.

• Osteoprogenitor Cells: Stem cells for bone.

Anatomy of a Long Bone

Long bones have distinct structural features.

• Diaphysis: Shaft.

• Epiphysis: Ends.

• Metaphysis: Between shaft and ends.

• Medullary Cavity: Contains marrow.

• Periosteum: Outer covering.

• Endosteum: Inner lining.

Endochondral Bone Formation

Most bones form from cartilage models.

• Cartilage model develops.

• Bone replaces cartilage in diaphysis, then epiphyses.

• Growth continues at epiphyseal plates.

Bone Remodeling

Bone is continuously renewed and repaired.

• Calcitonin: Lowers blood calcium, stimulates osteoblasts.

• Parathyroid Hormone: Raises blood calcium, stimulates osteoclasts.

Synovial Joints

Synovial joints allow movement and are stabilized by various structures.

• Components: Articular cartilage, joint cavity, synovial membrane, ligaments.

• Mobility vs. Stability: More mobility often means less stability.

Joint Movements

Major joints allow specific movements.

• Neck: Flexion, extension, rotation.

• Shoulder: Abduction, adduction, rotation.

• Elbow: Flexion, extension.

• Wrist: Flexion, extension, deviation.

• Hip: Flexion, extension, rotation.

• Knee: Flexion, extension.

• Ankle: Dorsiflexion, plantarflexion.

Unit 3: Muscle Tissue and Muscles

Functions of Muscle Tissue

Muscle tissue enables movement, maintains posture, and produces heat.

• Movement of body parts.

• Stabilization of joints.

• Heat generation.

Gross Anatomy of Muscle

Muscles are organized into bundles and connective tissue layers.

• Whole Muscle: Composed of fascicles.

• Muscle Fascicle: Bundle of fibers.

• Muscle Fiber: Individual cell.

• Epimysium: Surrounds entire muscle.

• Perimysium: Surrounds fascicles.

• Endomysium: Surrounds fibers.

• Tendon: Connects muscle to bone.

• Aponeuroses: Flat tendons.

Microscopic Anatomy of Muscle Fiber

Muscle fibers contain sarcomeres, the functional units of contraction.

• Sarcomere: Contains actin and myosin filaments.

• Z-line: Boundary of sarcomere.

• A-band: Dark region (myosin).

• I-band: Light region (actin).

Sliding Filament Theory

Muscle contraction occurs as filaments slide past each other.

• Myosin heads bind to actin, pull, and release.

• ATP provides energy for the cycle.

Excitation-Contraction Coupling

Muscle contraction is triggered by nerve signals.

• Motor neuron releases acetylcholine (ACh).

• Action potential travels along sarcolemma and T-tubules.

• Sarcoplasmic reticulum releases Ca++.

• Ca++ enables cross-bridge formation.

• ATP powers contraction and recovery stroke.

Muscle Twitch and All-or-None Law

A muscle twitch consists of three phases; muscle fibers obey the all-or-none law.

• Latent: Time between stimulus and contraction.

• Contraction: Muscle shortens.

• Relaxation: Muscle returns to original length.

• Threshold Stimulus: Minimum stimulus needed.

• All-or-None Law: Fibers contract fully or not at all.

Major Muscles and Groups

Muscles are grouped by function and location.

• Hamstrings: Flex knee.

• Quadriceps: Extend knee.

• Rotator Cuff: Stabilize shoulder.

Energy for Muscle Contraction

Muscles use several energy sources for contraction.

• ATP: Immediate energy.

• Creatine Phosphate: Rapid ATP regeneration.

• Glycolysis: Anaerobic ATP production.

• Aerobic Respiration: Sustained ATP production in mitochondria.

Unit 4: Nervous System

Myelin Sheath

The myelin sheath insulates nerve fibers and speeds up signal transmission.

• Formed by Schwann cells (PNS) and oligodendrocytes (CNS).

• Wraps around axons in layers.

Brain Structure and Function

The brain is divided into regions with specialized functions.

• Cerebrum: Higher functions, sensory, motor.

• Cerebellum: Coordination, balance.

• Diencephalon: Thalamus, hypothalamus (relay, homeostasis).

• Brainstem: Vital functions (breathing, heart rate).

• Ventricles: CSF production and circulation.

Hemispheric Lateralization

The left and right hemispheres have specialized functions.

• Left: Language, logic.

• Right: Spatial, creativity.

Spinal Tracts

Spinal tracts carry sensory and motor information.

• Ascending Tracts: Sensory fibers to brain.

• Descending Tracts: Motor fibers from brain.

Cranial Nerves

There are 12 cranial nerves, each with specific functions.

• Examples: Olfactory (smell), Optic (vision), Vagus (autonomic control).

Peripheral Nervous System Divisions

The PNS is divided into somatic and autonomic systems.

• Somatic: Voluntary control of muscles.

• Autonomic: Involuntary control (heart, glands).

Sympathetic vs. Parasympathetic

The ANS has two divisions with opposing actions.

• Sympathetic: "Fight or flight" (increases heart rate, dilates pupils).

• Parasympathetic: "Rest and digest" (decreases heart rate, stimulates digestion).

Unit 5: Special Senses

Receptors for General Senses

Different receptors detect various stimuli.

• Mechanoreceptors: Touch, pressure.

• Thermoreceptors: Temperature.

• Nociceptors: Pain.

• Photoreceptors: Light (in eye).

• Chemoreceptors: Chemicals (taste, smell).

Cells of the Retina

The retina contains specialized cells for vision.

• Rods: Low light, black and white vision.

• Cones: Color vision, high acuity.

• Bipolar Cells: Transmit signals from photoreceptors.

• Ganglion Cells: Form optic nerve.

Structure and Function of the Eye Wall and Fluids

The eye wall consists of three layers and contains fluids for shape and function.

• Sclera: Outer, protective.

• Choroid: Middle, vascular.

• Retina: Inner, sensory.

• Aqueous Humor: Anterior chamber fluid.

• Vitreous Humor: Posterior chamber gel.

Pathway of Light

Light passes through several structures before reaching the retina.

• Cornea → Aqueous humor → Lens → Vitreous humor → Retina.

Structure and Function of the Ear

The ear is divided into three regions, each with specific functions.

• Outer Ear: Collects sound (auricle, external canal).

• Middle Ear: Transmits sound (ossicles).

• Inner Ear: Hearing and balance (cochlea, vestibular apparatus).

Physiology of Sound

Sound is detected and processed through a series of steps.

• Sound waves vibrate tympanic membrane.

• Ossicles transmit vibrations to cochlea.

• Hair cells in cochlea convert vibrations to nerve impulses.

• Impulses travel to brain for interpretation.

Additional info: Academic context and expanded explanations were added to ensure completeness and clarity for exam preparation.