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Module 1: Introduction to Anatomy and Physiology

Characteristics of Living Organisms

  • Characteristics and their importance:
    • Responsiveness (irritability): Indicates the organism recognizes changes in its internal or external environment.
    • Adaptability: Changes the organism's behavior, capabilities, or structure; required for adaptability and survival in a constantly changing world.
    • Growth and reproduction: Growth must occur before reproduction; organisms that do not grow or adapt will not reproduce.
    • Movement: Distributes materials throughout large organisms; organisms may change orientation or position (plants or immobile animals); locomotion in mobile animals.
    • Respiration*: Usually refers to the absorption and utilization of oxygen, and the generation and release of carbon dioxide.
    • Circulation*: Movement of fluids within the organism; may involve a pump and a network of vessels.
    • Digestion*: Chemical breakdown of complex materials for absorption and use by the organism.
    • Excretion*: Elimination of chemical waste products generated by the organism.
  • Footnote: The mechanics of respiration, circulation, etc., depend on the size and complexity of the organism.

The Study of Anatomy (form) and Physiology (function)

  • Anatomy (from Greek/Latin roots meaning “cutting open”): the study of structure.
    • Gross (macroscopic) anatomy: Examination of large structures visible without magnification; e.g., structures of the dissected heart.
    • Microscopic anatomy: Structures that cannot be seen without magnification; e.g., cellular structure of the heart wall.
  • Physiology: The study of function; how structures work together to support life.
  • All specific functions are performed by specific structures.

The Heart: Electrical and Pressure Events (Example of Function)

  • The electrical events in the heart during a heartbeat and the related pressure changes occur over time (ms) and pressure (mm Hg).
  • Sequence observed in the figure:
    • Valve between atrium and ventricle closes
    • Valve between atrium and ventricle opens
    • Valve to the aorta opens
    • Valve to the aorta closes
  • Key pressures:
    • Peak left ventricle pressure around
    • Pressure changes in the left atrium during the cycle
  • This illustrates the coupling of electrical activity with mechanical pressure changes to produce the heartbeat.

Form and Function are Interrelated

  • Physiology and anatomy are closely interrelated both theoretically and practically.
  • Anatomical details are significant because each has an effect on function.
  • Physiological mechanisms are understood through the underlying structural relationships.
  • Example: Elbow joint as a hinge:
    • Gross anatomy: Elbow structure
    • Function: Hinge-like movement in one plane; forward and away from the shoulder; no twisting force
    • Internal structure imposes motion limits (interlocking humerus and ulna, ligaments, surrounding muscles).

Levels of Organization

  • The body’s complexity arises from multiple levels of organization; each level is more complex than the previous one; all levels can be broken down to similar components.
  • Six levels of organization:
    • Organism: Whole human (highest level)
    • Organ System: Multiple organs interacting
    • Organ: Two or more tissues working together
    • Tissue: Group of cells working together
    • Cell: Smallest living unit; depends on organelles
    • Chemicals or Molecules: Atoms (smallest stable unit of matter) form molecules
  • Conceptual idea: Animation of levels often used to illustrate progression from atoms to the whole organism.

Cells

  • Free-living cells: Smallest independent organisms.
  • Most plants and animals are multicellular.
  • Human body contains trillions of cells; about 200 different cell types are typical.
  • Cell sizes are usually given in micrometers (
    \mu m).
  • Example scales: 1

    \mu m is one millionth of a meter; ~1/25,000 of an inch.
  • Major cell types (examples):
    • Smooth muscle cells: Long and slender; found in many organs.
    • Skeletal muscle cells: Large; responsible for body movement.
    • Blood cells: Red blood cells (RBCs) are flattened discs; white blood cells (WBCs) are roughly spherical; RBCs transport O2 and CO2; WBCs fight infection.
    • Bone cells: Reside within bone cavities; maintain bone and recycle calcium/phosphate.
    • Fat cells: Roughly spherical; store excess energy as fat.
    • Cells lining the digestive tract: Delicate; absorb nutrients, vitamins, minerals, water.
    • Reproductive cells: Oocytes (female) and sperm (male); sex cells.
    • Neurons: Nerve cells; process information; many shapes/types; e.g., brain neurons controlling balance and movement.
  • Life requires coordinated cell function: Each cell responds to local environment, and cells across the body are coordinated and controlled.

Tissues

  • Tissues: Collections of cells and cell products performing specific functions.

  • Histology: Study of tissues.

  • Four primary tissue types:

    • Epithelial
    • Connective
    • Muscle
    • Neural

  • Epithelial tissue:

    • Forms a barrier with specific properties; covers every exposed body surface.
    • Lines digestive, respiratory, reproductive, and urinary tracts.
    • Surrounds internal cavities; lines inner surfaces of blood vessels and the heart; produces glandular secretions.
    • Visual summary: Covers/protects exposed surfaces; lines internal passageways and chambers; produces glandular secretions.

  • Connective tissue:

    • Diverse in appearance; all contain cells surrounded by extracellular matrix.
    • Matrix composed of: protein fibers and ground substance (fluid).
    • Amount of matrix varies by type.
    • Functions: fills internal spaces; provides structural support; stores energy.
    • Visual: Matrix, fibers, ground substance.

  • Muscle tissue:

    • Ability to contract forcefully.
    • Major functions: skeletal movement, soft tissue support, maintenance of blood flow, movement of materials internally, stabilization of body temperature.
    • Three types:
    • Skeletal: Attached to skeleton; moves or stabilizes the position of bones or internal organs.
    • Cardiac: Found only in the heart; propels blood through vessels.
    • Smooth: Found in walls of blood vessels, glands, and along respiratory, circulatory, digestive, and reproductive tracts.

  • Neural tissue:

    • Specialized to carry information within the body.
    • Two basic cell types: neurons (nerve cells) and neuroglia (supporting cells).
    • Locations: Central nervous system (brain and spinal cord) and Peripheral nervous system (links CNS with other tissues and organs).
    • Neurons conduct electrical impulses and carry information; neuroglia support neuron function.

Levels of Structural Organization (Revisited)

  • Reminder: Six levels of organization are organism, organ system, organ, tissue, cell, and chemicals/molecules (atoms to molecules).

Organs and Organ Systems

  • Organ: Functional unit composed of more than one tissue type; specific arrangement determines function.
    • Example: The Heart includes:
    • Cardiac muscle (contracts to form heartbeat)
    • Epithelia (lines inner/outer surfaces)
    • Connective tissue (attaches tissues)
    • Neural tissue (adjusts and coordinates activities)
  • Organ system: Interacting organs performing a range of functions; typically eleven organ systems in the human body; none function in isolation (interdependent).
  • Animation: Organ systems interact to maintain body function.
  • The major functions of the 11 organ systems (as listed):
    • Integumentary system: Protection from environmental hazards; temperature control
    • Skeletal system: Support and protection of soft tissues; mineral storage; blood formation
    • Muscular system: Locomotion; heat production
    • Nervous system: Directing immediate responses to stimuli; coordination of activities
    • Endocrine system: Directing long-term changes in activities of other systems
    • Cardiovascular system: Internal transport of cells and dissolved materials (nutrients, wastes, gases)
    • Lymphatic system: Defense against infection and disease
    • Respiratory system: Delivery of air for gas exchange in lungs
    • Digestive system: Processing of food and absorption of nutrients, minerals, vitamins, and water
    • Urinary system: Elimination of excess water, salts, and wastes; pH control
    • Reproductive system: Production of sex cells and hormones

Homeostasis

  • Homeostasis: A stable internal environment; maintenance of a relatively constant state.
  • Homeostatic regulation: Physiological adjustments to preserve homeostasis in variable environments.
  • Key components of a homeostatic mechanism:
    • Receptor (sensor): Detects environmental changes
    • Control center (integration center): Processes information from receptor and issues commands
    • Set point: Desired value in the control center
    • Effector: Responds to commands to oppose the stimulus
  • Example: Temperature regulation using a thermostat analogy; normal room temperature around set point (e.g., 22°C or 72°F) with oscillation around the set point.
  • Negative vs positive feedback (overview):
    • Negative feedback: Effector opposes the original stimulus; minimizes change; primary mechanism of homeostatic regulation; set point may vary with environment/activity.
    • Positive feedback: Initial stimulus produces a response that exaggerates the change; typically occurs in emergencies requiring rapid completion of a process (e.g., blood clotting).

Negative Feedback: Homeostatic Regulation (Body Temperature Example)

  • At normal body temperature (set point 37°C or 98.6°F), control center is relatively inactive; basal blood flow and sweat gland activity are normal.
  • When temperature rises, receptors send signals to the control center; effectors (vasodilation of skin vessels and sweating) promote heat loss; cooling occurs and temperature returns toward set point.
  • The mechanism results in oscillation around the set point rather than a fixed value.

Positive Feedback: Clotting Example

  • Trigger: Break in a blood vessel wall causes bleeding.
  • Response: Chemicals released by damaged cells begin clotting; clotting reactions recruit more elements, accelerating the process until a clot patches the vessel wall.
  • This loop is self-enhancing and ends with hemostasis.

Anatomical Terms: Landmarks, Regions, and Word Roots

  • Landmarks around the body create a map for orientation; terms are largely based on Latin/Greek roots.

  • Eponyms (named after discoverers or famous cases) have often been replaced by more precise terms.

  • Important word roots, prefixes, suffixes, and combining forms in anatomy (selected examples):

    • a-, a-: without — avascular
    • aer-, aeros: air — aerobic metabolism
    • -algia, algos: pain — neuralgia
    • arteri-, arteria, artery: arterial
    • arthro-, arthros: joint — arthroscopy
    • auto-, auto: self — autonomic
    • bio-, bios: life — biology
    • -blast, blastos: germ — osteoblast
    • bronch-, bronchus: windpipe — bronchial
    • cardi-, cardio-, -cardia, kardia: heart — cardiac, cardiopulmonary
    • cerebr-, cerebrum: brain — cerebral
    • hemispheres
    • cervic-, cervicis: neck — cervical vertebrae
    • chondro-, chondros: cartilage — chondrocyte
    • cranio-, cranium: skull — crani osacral
    • cyt-, cyto-, kytos: hollow cell — cytology
    • -ectomy, ektome: excision — appendectomy
    • end-, endo-, endon: within — endergonic, endometrium
    • epi-, epi: on — epimysium
    • ex-, ex, out of: exocytosis
    • hemo-, haima: blood — hemopoiesis
    • hemi-, hemi: one-half — hemisphere
    • histo-, histos: tissue — histology
    • homo-, homos: same — homozygous
    • hyper-, hyper: above — hyperpolarization
    • hypo-, hypo: under — hypothyroid
    • inter-, inter: between — interventricular
    • iso-, isos: equal — isotonic
    • leuk-, leuko-, leukos: white — leukemia, leukocyte
    • lyso-, -lysis, -lyze: lysis — hydrolysis
    • meso-, mesos: middle — mesoderm
    • micr-, mikros: small — microscope
    • morph-, morpho-, morphe: form — morphology, morphotype
    • myo-, mys: muscle — myofilament
    • nephr-, nephros: kidney — nephron
    • neur-, neuri-, neuro-, neuron: nerve — neural, neurilemma, neuromuscular
    • -ology, logos: the study of — physiology
    • -osis: state/condition — neurosis
    • ost-, oste-, osteo-, osteon: bone — osteal, osteocyte
    • oto-, otikos: ear — otolith
    • path-, -pathy, patho-, pathos: disease — pathogenesis
    • peri-, peri: around — perineurium
    • phago-, phago: to eat — phagocyte
    • -phil, -philia, philo: love — neutrophil, hemophilia
    • -phot, -photo, phos: light — photoreceptor
    • physio-, physis: nature — physiology
    • pre-, prae: before — precapillary sphincter
    • pulmo-, pulmo: lung — pulmonary
    • retro-, retro: backward — retroperitoneal
    • sarco-, sarkos: flesh — sarcomere
    • scler-, sclero-, skleros: hard — sclera, sclerosis
    • -scope, skopeo: to view — colonoscope
    • sub-, sub: below — subcutaneous
    • super-, super: above/beyond — superficial
    • -trophy, trophe: nourishment — atrophy
    • vas-, vas: vessel — vascular

  • Regions of the Human Body (selected structures and regional names):

    • Cephalon (head) → Cephalic region
    • Cervicis (neck) → Cervical region
    • Thoracis (thorax) → Thoracic region
    • Brachium (arm) → Brachial region
    • Antebrachium (forearm) → Antebrachial region
    • Carpus (wrist) → Carpal region
    • Manus (hand) → Manual region
    • Abdomen → Abdominal region
    • Lumbus (loin) → Lumbar region
    • Gluteus (buttock) → Gluteal region
    • Pelvis → Pelvic region
    • Pubis → Pubic region (anterior pelvis)
    • Inguen → Inguinal region
    • Femur (thigh) → Femoral region
    • Crus (anterior leg) → Crural region
    • Sura (calf) → Sural region
    • Tarsus (ankle) → Tarsal region
    • Pes (foot) → Pedal region
    • Planta (sole) → Plantar region

Anatomical Position and Regions: Superficial and Regional Anatomy

  • Anatomical position conventions:
    • Standing upright
    • Hands at sides with palms facing forward
    • Feet together
    • Supine: laying face up
    • Prone: laying face down
  • Mapped surface terms for many regions, including head/face, neck, trunk, upper and lower limbs, and regional terms for the back and abdomen.
  • Abdominopelvic quadrants and regions:
    • Quadrants (four): Right Upper Quadrant (RUQ), Right Lower Quadrant (RLQ), Left Lower Quadrant (LLQ), Left Upper Quadrant (LUQ).
    • Regions (nine): Right hypochondriac, Epigastric, Left hypochondriac; Right lumbar, Umbilical, Left lumbar; Right iliac (inguinal), Hypogastric (pubic), Left iliac (inguinal).

Directional and Sectional Terms

  • Common directional terms (relative to anatomical position):

    • Anterior (ventral): toward the front of the body; navel is on the anterior surface. Also called ventral for humans.
    • Posterior (dorsal): toward the back of the body; shoulder blade is posterior to the rib cage.
    • Superior (cranial/cephalic): toward the head; the pelvis border is superior to the thigh.
    • Inferior (caudal): toward the tail; hips are inferior to the waist.
    • Proximal: nearer to the attachment of a limb to the trunk.
    • Distal: farther from the attachment of a limb to the trunk.
    • Lateral: farther from the midline.
    • Medial: nearer to the midline.
    • Superficial: at or near the surface.
    • Deep: farther from the surface.

  • Planes of section:

    • Frontal (coronal) plane: separates anterior and posterior portions.
    • Transverse (horizontal) plane: separates superior and inferior portions; cross section.
    • Sagittal plane: separates right and left portions; midsagittal (median) plane passes through the midline; parasagittal is parallel to the midline but unequal halves.

  • Orientation/terminology for planes:

    • Transverse/horizontal: perpendicular to long axis; sectioned transversely.
    • Sagittal: parallel to long axis; sagittally.
    • Midsagittal: divides body into right and left halves.
    • Parasagittal: parallel to midsagittal but unequal portions.
    • Frontal (coronal): separates anterior and posterior portions; usually used for sections through the skull.

  • Visual reference: Major sectional planes summary (Frontal, Transverse, Sagittal).

Planes and Sectional Terms (Additional Details)

  • Terminology for describing sections:
    • Horizontal/Transverse: cross section separating superior and inferior portions.
    • Sagittal: separates left and right portions.
    • Midsagittal/Median: divides right and left halves at the midline.
    • Parasagittal: unequal left/right portions.
    • Frontal/Coronal: separates anterior and posterior portions; often applied to skull sections.

Quick Reference: Notation and Common Terms

  • For quick recall, you can think of the body as organized from simple to complex: atoms → molecules → cells → tissues → organs → organ systems → organism.
  • Key conversion facts:
    • 200 cell types in the human body (typical number commonly cited).
    • Cell size often in the micrometer range: 1 ext{ µm} = 10^{-6} ext{ m}.
    • Human body contains trillions of cells.

Summary of Key Points for Exam Preparation

  • Understand how structure (anatomy) and function (physiology) are interconnected; landmarks at the tissue and organ level determine how a function works.
  • Be able to identify and describe the four tissue types and give an example of each:
    • Epithelial (barrier, lining surfaces)
    • Connective (matrix, support, energy storage)
    • Muscle (contractility: skeletal, cardiac, smooth)
    • Neural (neurons and neuroglia; signaling)
  • Memorize the 11 organ systems and their primary functions; know how they contribute to homeostasis and how they interact.
  • Explain homeostasis using the components: receptor, control center, set point, and effector; understand the negative feedback mechanism that maintains stability and the situations where positive feedback occurs (e.g., clot formation).
  • Be familiar with directional and sectional terminology, including anterior/posterior, superior/inferior, proximal/distal, medial/lateral, superficial/deep, and the three major planes: frontal, sagittal, transverse.
  • Recognize and use anatomy terminology for regions and landmarks, including the major regional terms (cephalic, cervical, thoracic, abdominal, pelvic, lumbar, inguinal, etc.), and know how to reference abdominopelvic quadrants and nine-region divisions.
  • Understand the common roots and prefixes used to form anatomical terms (e.g., cardio-, neuro-, cyt-, -ology, -lysis) to decipher new terms quickly.
  • Basic numerical references to remember:
    • Set points and typical values:
    • Body temperature set point: 37^ op o C (≈ 98.6^ op o F)
    • Room temperature example: 22^ op o C (≈ 72^ op o F)
    • Size reference: cells and tissues are typically on the order of micrometers: 1 ext{ µm}.