Anatomy and Physiology I: Comprehensive Study Notes

Chapter 1 – The Human Body: An Overview

Anatomy vs. Physiology

Anatomy is the study of the structure of body parts and their relationships to one another, while physiology is the study of the function of the body’s structural machinery.

• Anatomy: Focuses on body structures, such as organs, tissues, and cells.

• Physiology: Explains how those structures work and interact.

• Principle of Complementarity: Structure and function are closely related; function always reflects structure.

Structural Organization of the Body

The human body is organized in a hierarchical manner:

• Chemical level: Atoms and molecules

• Cellular level: Cells and their organelles

• Tissue level: Groups of similar cells

• Organ level: Contains two or more types of tissues

• Organ system level: Organs that work closely together

• Organismal level: All organ systems combined

Homeostasis and Feedback Loops

Homeostasis is the maintenance of a stable internal environment despite external changes.

• Negative feedback: The response reduces or shuts off the original stimulus (e.g., regulation of body temperature).

• Positive feedback: The response enhances or exaggerates the original stimulus (e.g., blood clotting).

Anatomical Position, Membranes, and Cavities

• Anatomical position: Body erect, feet slightly apart, palms facing forward, thumbs pointing away from the body.

• Body cavities: Dorsal (cranial and vertebral) and ventral (thoracic and abdominopelvic).

• Membranes: Serous membranes line body cavities and cover organs.

Chapter 3 – Cells: The Living Units

General Structure of a Cell and Organelles

• Nucleus: Contains genetic material (DNA); controls cell activities.

• Mitochondria: Site of ATP production; known as the "powerhouse" of the cell.

• Ribosomes: Sites of protein synthesis; can be free or attached to rough ER.

The Plasma Membrane

• Structure: Phospholipid bilayer with embedded proteins.

• Function: Regulates entry and exit of substances; provides protection and support.

• Membrane Transport: Includes passive (diffusion, osmosis, facilitated diffusion) and active (active transport, endocytosis, exocytosis) processes.

Chapter 4 – Tissue: The Living Fabric

Four Basic Tissue Types

• Epithelial Tissue: Covers body surfaces and lines cavities; functions in protection, absorption, filtration, and secretion.

• Connective Tissue: Supports, protects, and binds other tissues. Four types: connective tissue proper, cartilage, bone, and blood.

• Muscle Tissue: Responsible for movement. Three types: skeletal, cardiac, and smooth.

• Nervous Tissue: Initiates and transmits electrical impulses; found in the brain, spinal cord, and nerves.

Chapter 5 – The Integumentary System

Epidermis

• Cell Types: Keratinocytes (produce keratin), melanocytes (produce melanin), dendritic cells (immune function), Merkel cells (sensory function).

Dermis

• Layers: Papillary (areolar connective tissue) and reticular (dense irregular connective tissue).

• Function: Provides strength, flexibility, and houses blood vessels and nerves.

Skin Color

• Influenced by: Melanin, carotene, and hemoglobin.

• Diseases: Jaundice (yellowing), cyanosis (bluish), erythema (redness).

Chapter 6 – Bones and Skeletal Tissue

Cartilage

• Types: Hyaline, elastic, and fibrocartilage.

• Growth: Appositional (growth from outside) and interstitial (growth from within).

Bone

• Functions: Support, protection, movement, mineral storage, blood cell formation, triglyceride storage, hormone production.

• Gross Structure: Compact and spongy bone; diaphysis and epiphyses.

• Microscopic Structure: Osteocytes, osteoblasts, osteoclasts, osteon (Haversian system).

• Epiphyseal Plate: Site of bone growth in length during childhood.

• Bone Remodeling: Continuous process regulated by negative feedback (e.g., parathyroid hormone and calcitonin).

Chapter 8 – Joints

Structural and Functional Classifications

• Structural: Fibrous, cartilaginous, synovial.

• Functional: Synarthroses (immovable), amphiarthroses (slightly movable), diarthroses (freely movable).

Synovial Joints

• Features: Articular cartilage, joint cavity, articular capsule, synovial fluid, reinforcing ligaments, nerves and blood vessels.

• Bursae and Tendon Sheaths: Reduce friction.

• Stability Factors: Shape of articular surfaces, ligament number and location, muscle tone.

• Examples: Shoulder, knee, hip joints.

Chapter 9 – Muscles

Types of Muscle Tissue

• Skeletal: Voluntary, striated.

• Cardiac: Involuntary, striated, found in heart.

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

Microscopic Structure of Muscle Fibers

• Myofibrils: Contain sarcomeres, the contractile units.

• Sarcomere: Composed of actin (thin) and myosin (thick) filaments.

Sliding Filament Model

• Muscle contraction occurs as myosin heads bind to actin, pulling thin filaments toward the center of the sarcomere.

Action Potential and Muscle Contraction

• Basic Steps: Depolarization, propagation, repolarization.

• Role of Calcium: Binds to troponin, exposing binding sites on actin.

• Role of ATP: Provides energy for cross-bridge cycling and detachment.

Chapter 11 – Nervous System and Nervous Tissue

Divisions of the Nervous System

• Central Nervous System (CNS): Brain and spinal cord.

• Peripheral Nervous System (PNS): Cranial and spinal nerves.

Glial Cells

• CNS: Astrocytes, oligodendrocytes, microglia, ependymal cells.

• PNS: Schwann cells, satellite cells.

Structure and Function of a Neuron

• Cell Body: Contains nucleus and organelles.

• Dendrites: Receive signals.

• Axon: Transmits impulses away from cell body.

• Myelination: Increases speed of impulse conduction.

Membrane Potentials

• Resting Membrane Potential: Typically -70 mV; maintained by sodium-potassium pump.

• Graded Potential: Short-distance, localized changes.

• Action Potential: Long-distance, all-or-none electrical signal.

• Saltatory Conduction: Rapid transmission in myelinated axons.

Synapse and Neurotransmitters

• Synapse: Junction between neurons; can be electrical or chemical.

• Neurotransmitters: Chemical messengers (e.g., acetylcholine, dopamine, serotonin).

Chapter 12 – Central Nervous System

Cerebrum

• Structure: Two hemispheres, five lobes (frontal, parietal, temporal, occipital, insula).

• Cerebral Cortex: Responsible for higher functions (conscious thought, memory, reasoning).

• Grey vs. White Matter: Grey matter contains neuron cell bodies; white matter contains myelinated axons.

• Diseases: Parkinson’s (dopamine deficiency), Huntington’s (genetic neurodegeneration).

Diencephalon

• Regions: Thalamus (relay station), hypothalamus (homeostasis, links to pituitary), epithalamus.

• Hypothalamus-Pituitary Interaction: Regulates endocrine system.

Brain Stem

• Regions: Midbrain, pons, medulla oblongata; control vital functions.

Cerebellum

• Coordinates voluntary movements and balance.

Brain Protection

• Meninges: Dura mater, arachnoid mater, pia mater.

• Blood-Brain Barrier: Protects brain from harmful substances.

Spinal Cord

• Functions: Conducts impulses to and from the brain; center for reflexes.

• Cross-section Anatomy: Grey matter (cell bodies), white matter (axons).

• Disorders: Paralysis, spinal cord injuries.

Chapter 13 – Peripheral Nervous System

Sensory Receptors

• Types: Mechanoreceptors, thermoreceptors, photoreceptors, chemoreceptors, nociceptors.

• Location: Exteroceptors (external), interoceptors (internal), proprioceptors (muscles/joints).

Sensation vs. Perception

• Sensation: Awareness of stimulus.

• Perception: Interpretation of stimulus.

Pain Perception

• Detected by nociceptors; can be modulated by endogenous opioids.

Nerves and Reflexes

• Nerves: Bundles of axons in PNS.

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

Chapter 14 – The Autonomic Nervous System

Overview and Comparison

• Autonomic Nervous System (ANS): Controls involuntary functions (smooth muscle, cardiac muscle, glands).

• Somatic vs. Autonomic: Somatic controls skeletal muscle (voluntary); autonomic controls smooth/cardiac muscle and glands (involuntary).

• Effectors: Somatic (skeletal muscle), Autonomic (cardiac, smooth muscle, glands).

• Efferent Pathways: Somatic (one neuron), Autonomic (two-neuron chain: preganglionic and postganglionic).

• Neurotransmitters: Somatic (acetylcholine), Autonomic (acetylcholine, norepinephrine).

Parasympathetic vs. Sympathetic Divisions

• Parasympathetic: "Rest and digest"; craniosacral origin; ganglia near or in effector organs; long preganglionic, short postganglionic fibers.

• Sympathetic: "Fight or flight"; thoracolumbar origin; ganglia close to spinal cord; short preganglionic, long postganglionic fibers.

Chapter 15 – The Special Senses

Hearing

• Sound Conduction Pathway: Sound waves → tympanic membrane → ossicles → oval window → cochlear fluids.

• Cochlea: Spiral-shaped organ; contains organ of Corti (hearing receptor).

• Auditory Pathway: Cochlear nerve → brainstem → thalamus → auditory cortex.

Vision

• Eye Anatomy: Sclera, cornea, lens, retina.

• Rods & Cones: Rods (dim light, black/white), cones (color, sharp vision).

• Colorblindness: Deficiency in one or more types of cones.

• Astigmatism: Irregular curvature of cornea or lens.

• Pathway of Light: Cornea → aqueous humor → lens → vitreous humor → retina.

Taste

• Taste Buds: Contain gustatory cells; located on papillae of tongue.

• Receptors: Detect sweet, sour, salty, bitter, umami.