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.

• Physiology is the study of the function of the body’s structural machinery—how the body parts work and carry out their life-sustaining activities.

• Principle of Complementarity: Structure and function are closely related; what a structure can do depends on its specific form.

• Example: Bones can support and protect body organs because they contain hard mineral deposits.

Structural Organization of the Body

• Levels of organization (from simplest to most complex):

  1. Chemical level (atoms, molecules)

  2. Cellular level (cells and their organelles)

  3. Tissue level (groups of similar cells)

  4. Organ level (contains two or more types of tissues)

  5. Organ system level (organs that work closely together)

  6. Organismal level (all organ systems combined)

Homeostasis and Feedback Loops

• Homeostasis is the maintenance of a stable internal environment despite continuous outside changes.

• Maintained by feedback mechanisms:

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

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

Anatomical Position, Membranes, and Cavities

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

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

• Membranes: Serous membranes line body cavities and cover organs (parietal and visceral layers).

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 endoplasmic reticulum.

The Plasma Membrane

• Structure: Phospholipid bilayer with embedded proteins, cholesterol, and carbohydrates.

• Function: Selectively permeable barrier; regulates movement of substances in and out of the cell.

• Membrane Transport:

  • Passive transport: Does not require energy (e.g., diffusion, osmosis, facilitated diffusion).

  • Active transport: Requires energy (ATP) to move substances against their concentration gradient.

Chapter 4: Tissue – The Living Fabric

Four Basic Tissue Types

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

• Connective Tissue: Supports, protects, and binds other tissues; four main types:

  1. Connective tissue proper

  2. Cartilage

  3. Bone

  4. Blood

• Muscle Tissue: Responsible for movement; three types:

  1. Skeletal muscle (voluntary, striated)

  2. Cardiac muscle (involuntary, striated, heart only)

  3. Smooth muscle (involuntary, non-striated)

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

Chapter 5: The Integumentary System

Epidermis

• Composed of keratinized stratified squamous epithelium.

• Cell types: keratinocytes (produce keratin), melanocytes (produce melanin), Langerhans cells (immune function), Merkel cells (sensory receptors).

Dermis

• Two layers: papillary (areolar connective tissue) and reticular (dense irregular connective tissue).

• Functions: provides strength, elasticity, and houses blood vessels, nerves, and accessory structures.

Skin Color and Disorders

• Influenced by melanin, carotene, and hemoglobin.

• Disorders: cyanosis (bluish color), jaundice (yellowish), erythema (redness), pallor (paleness).

Chapter 6: Bones and Skeletal Tissue

Cartilage

• Types: hyaline, elastic, fibrocartilage.

• Growth: appositional (new layers added to surface), interstitial (expansion from within).

Bone

• Functions: support, protection, movement, mineral storage, blood cell formation, fat storage, hormone production.

• Gross structure: compact and spongy bone, diaphysis, epiphyses, membranes (periosteum, endosteum).

• Microscopic structure: osteocytes, osteoblasts, osteoclasts, osteon (Haversian system).

• Epiphyseal plate: site of bone growth in length during childhood.

• Bone remodeling: regulated by negative feedback involving hormones (e.g., parathyroid hormone).

Chapter 8: Joints

Classifications

• Structural: fibrous, cartilaginous, synovial.

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

Synovial Joints

• Six general features: articular cartilage, joint (synovial) cavity, articular capsule, synovial fluid, reinforcing ligaments, nerves and blood vessels.

• Bursae and tendon sheaths reduce friction.

• Stability depends on articular surfaces, ligaments, and muscle tone.

• Examples: knee, shoulder, hip joints.

Chapter 9: Muscles

Types of Muscle Tissue

• Skeletal, cardiac, and smooth muscle (see above for details).

Microscopic Structure of Muscle Fibers

• Muscle fibers contain myofibrils, which are composed of sarcomeres (contractile units).

• Sarcomeres contain 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

• Action potential: electrical signal that triggers muscle contraction.

• Calcium ions bind to troponin, allowing myosin-actin interaction.

• ATP provides energy for contraction and relaxation.

Chapter 11: Nervous System and Nervous Tissue

Divisions of the Nervous System

Division	Main Components	Function
Central Nervous System (CNS)	Brain, Spinal Cord	Integration and command center
Peripheral Nervous System (PNS)	Cranial and Spinal Nerves	Communication lines between CNS and body

Glial Cells

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

• PNS: Schwann cells, satellite cells.

Structure and Function of a Neuron

• Cell body (soma): contains nucleus and organelles.

• Dendrites: receive signals.

• Axon: transmits signals away from cell body.

• Myelination increases speed of impulse conduction (saltatory conduction); non-myelinated fibers conduct more slowly.

Membrane Potentials

• Resting membrane potential: difference in charge across the membrane at rest.

• Graded potential: short-distance signal, varies in strength.

• Action potential: long-distance signal, all-or-none response.

• Saltatory conduction: action potentials jump from node to node in myelinated axons.

Synapse and Neurotransmitters

• Synapse: junction between neurons; allows communication via neurotransmitters.

• Examples of neurotransmitters: acetylcholine, dopamine, serotonin.

• Functions: excitatory or inhibitory effects on postsynaptic neuron.

Chapter 12: Central Nervous System

Cerebrum

• Largest part of the brain; divided into two hemispheres and five lobes (frontal, parietal, temporal, occipital, insula).

• Cerebral cortex: responsible for higher functions (conscious thought, memory, voluntary movement).

• Gray matter: neuron cell bodies; white matter: myelinated axons.

• Disorders: Parkinson’s disease (dopamine deficiency), Huntington’s disease (genetic, affects movement).

Diencephalon

• Includes thalamus (relay station), hypothalamus (homeostasis, links nervous and endocrine systems), epithalamus.

• Hypothalamus controls pituitary gland (master endocrine gland).

Brain Stem and Cerebellum

• Brain stem: midbrain, pons, medulla oblongata; controls vital functions (breathing, heart rate).

• Cerebellum: coordinates movement and balance.

Brain Protection

• Meninges: three protective membranes (dura mater, arachnoid mater, pia mater).

• Blood-brain barrier: protects brain from harmful substances.

Spinal Cord

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

• Cross-section: gray matter (cell bodies), white matter (axons), dorsal and ventral roots.

• Trauma/disorders: paralysis, loss of sensation.

Chapter 13: Peripheral Nervous System

Sensory Receptors and Nerves

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

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

• Sensation: awareness of stimulus; perception: interpretation of stimulus.

• Pain perception: protective mechanism.

• Nerves: bundles of axons in PNS; structure includes endoneurium, perineurium, epineurium.

Reflexes and Reflex Arc

• Reflex: rapid, involuntary response to stimulus.

• 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:

  • Effectors: skeletal muscle (somatic), cardiac/smooth muscle & glands (autonomic)

  • Efferent pathways: one neuron (somatic), two-neuron chain (autonomic)

  • Neurotransmitters: acetylcholine (somatic), acetylcholine/norepinephrine (autonomic)

Parasympathetic vs. Sympathetic Divisions

• Parasympathetic: "Rest and digest"; originates in brainstem and sacral spinal cord; ganglia near target organs; long preganglionic, short postganglionic fibers.

• Sympathetic: "Fight or flight"; originates in thoracic and lumbar spinal cord; ganglia near spinal cord; short preganglionic, long postganglionic fibers.

Chapter 15: The Special Senses

Hearing

• Sound conduction pathway: external ear → tympanic membrane → ossicles → oval window → cochlear fluids.

• Cochlea: spiral-shaped organ; contains hair cells that transduce sound vibrations into nerve impulses.

• Auditory pathway: cochlear nerve → brainstem → auditory cortex.

Vision

• Eye anatomy: cornea, lens, retina, optic nerve.

• Rods: detect dim light; cones: detect color.

• 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: located on papillae of tongue; types include fungiform, foliate, circumvallate.

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