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Unit 1 Notes — Intro to Human Anatomy & Physiology (Biol 241)

Unit 1 Part 1: What is Human A&P?

  • Diagram/list of organs and systems includes:
    • Liver, Brain, Thyroid Gland, Gallbladder, Urinary Bladder, Large Intestine, Stomach, Kidneys, Heart, Spleen, Reproductive System, Small Intestine
    • Vein and Artery (as labeled connections)
  • Understanding that these organs participate in multiple organ systems and contribute to homeostasis and function

The Big Picture

  • Humans are among over 66,000 species of vertebrates
  • There must be survival and reproductive benefits to being human

Human A&P: What Does It Mean to Be Human?

  • Structural questions: How are our bodies built? What are the components?
  • Functional questions: How do these structures perform their tasks?
  • Why it matters: personal/family health, future education, future careers

Focus Questions (Course Orientation)

  • How do our organ systems work together to support survival?
  • How do we examine and refer to these systems (terminology) in this class?

Historical Perspective & Foundations

  • The oldest medical science: Egyptian drawings of blood vessels from ~1600 BCE
  • Described structures of the body, locations, compositions, and attachments
  • Historical figures and milestones:
    • 15th Century Egyptian anatomy of a horse
    • Leonardo da Vinci’s heart sketch (~1600 BCE reference in materials)
  • Foundational idea: anatomy (structure) vs physiology (function)

Gross vs Microscopic Anatomy

  • Gross Anatomy (macroscopic): examines large, visible structures
    • Systemic approach: groups of organs working together (used in this class)
  • Microscopic Anatomy: examines molecules/cells/tissues
    • Cytology: study of cells, prefix “cyto-” = cell, -ology = study of
    • Histology: study of tissues, prefix “histo-” = tissue, -ology = study of

Physiology: Function & Levels

  • Physiology investigates the functions of body structures:
    • Individual function (e.g., heart pumps blood)
    • Systemic/cooperative function (e.g., cardiovascular system distributes oxygen-rich blood)
  • Different approaches include:
    • Cell-level processes (cell physiology) – cornerstone of all physiology
    • Organ-specific functions (e.g., brain processes electrical signals)
    • Systemic functions (organ system coordination)
    • Pathological physiology (effects of diseases on the body)
  • Key concept: the relationship between structure and function

Principle of Complementary Structure and Function

  • The way a structure is built determines how it operates
  • Examples: heart valves, joint structure, auditory canal

Levels of Organization

  • Cells → Tissues → Organs → Organ systems → The organism
  • Organization at each level determines structure and functional characteristics of higher levels
  • How cells are organized determines tissue function; how tissues are organized determines organ function

Unit 1 Part 2: Homeostasis in the Human Body

KEY CONCEPTS

  • The body is divided into 11 organ systems
  • All organ systems work together; many organs participate in more than one system
  • Homeostasis: all body systems work together to maintain a stable internal environment
  • Systems respond to external and internal changes to function within a normal range
    • Normal internal range examples: body temperature, fluid balance, metabolism
  • Failure to function within the normal range leads to disease or death

What is Homeostasis?

  • Etymology: Homeo = same; stasis = standing still
  • All body systems work together to maintain a stable internal environment
  • Respond to external/internal changes to keep function within a normal range
  • “Normal” human temperature range: 96^{\circ}\mathrm{F} \le T \le 100^{\circ}\mathrm{F}
  • Each system depends on all others
  • Homeostasis is a state of equilibrium; opposing forces are in balance (e.g., rate of heat loss = rate of heat production)

Mechanisms of Homeostatic Regulation

  • Intrinsic regulation (autoregulation): automatic response to environmental change; occurs directly in cells/tissues/organs
  • Extrinsic regulation: mediated by other organs, primarily nervous & endocrine systems
  • Maintains a dynamic, not static, state of equilibrium
  • All systems of the body are involved

Components of Homeostatic Regulation

  • Receptor (sensor): monitors environment and reports changes (stimuli) – afferent pathway
  • Control center: determines set point, interprets input from receptors, and determines response (usually brain or sometimes spinal cord) – efferent pathway
  • Effector: carries out the response; activity opposes (- feedback) or enhances (+ feedback) the stimulus

Negative Feedback

  • Effector response opposes the original stimulus
  • Output changes the value in the opposite direction of the stimulus, returning toward homeostasis
  • Most common type of feedback mechanism
  • Examples: body temperature regulation, insulin regulation, CO2 levels
  • Schematic flow: Receptors → Control Center → Effectors; effectors enact change to restore normal range

Positive Feedback

  • Effector response enhances the stimulus
  • Used to speed up processes; cascade or waterfall effect
  • Original stimulus is amplified in the same direction; moves away from homeostasis
  • Less common than negative feedback
  • Common examples: blood clotting, uterine contractions during labor

Positive vs Negative Feedback (quick comparison)

  • Positive: increases the stimulus; progress away from homeostasis
  • Negative: decreases the stimulus; progress toward homeostasis
  • Both are necessary in different physiological contexts

Systems Working Together: Table 1-1 (Roles of Organ Systems in Homeostatic Regulation)

  • Internal characteristic: Body temperature
    • Primary organ systems: Integumentary, Muscular, Cardiovascular
    • Functions: heat loss, heat production, heat distribution
  • Internal characteristic: Body fluid composition
    • Primary organ system: Digestive
    • Functions: nutrient absorption, storage, release
  • Internal characteristic: Nutrient concentration
    • Primary organ systems: Cardiovascular
    • Functions: nutrient distribution
  • Internal characteristic: Oxygen and carbon dioxide levels
    • Primary organ system: Cardiovascular
    • Functions: internal transport of gases, exchange and distribution
  • Internal characteristic: Body fluid volume
    • Primary organ system: Urinary
    • Functions: absorption and conservation of water; waste concentration
  • Internal characteristic: Waste product concentration
    • Primary organ system: Digestive; Urinary for excretion
    • Functions: elimination of wastes from blood; transport to excretion sites
  • Internal characteristic: Blood pressure
    • Primary organ systems: Cardiovascular; Nervous & Endocrine
    • Functions: heart force and vessel diameter adjustments to regulate BP
  • Note: This is a compact summary of the roles listed in Table 1-1; the text emphasizes cardiovascular, nervous, endocrine interactions and the integration across systems to maintain homeostasis

Homeostasis Recap

  • System integration: body systems work together to maintain homeostasis
  • Homeostasis is a dynamic equilibrium; opposing forces balance to maintain stable conditions
  • Physiological systems support survival by continuously adjusting to conditions
  • Malfunction can lead to illness or death

Break-Out Session (Study Activity)

  • Discussion prompts to review: components, flow, negative feedback goals, example of negative feedback, positive feedback goals, example

Unit 1 Part 3: Body Cavities

  • Dorsal body cavity consists of two subdivisions:
    • Cranial cavity (encases brain)
    • Vertebral (spinal) cavity (encases spinal cord)
  • Ventral body cavity (coelom) houses viscera and is divided into two subdivisions:
    • Thoracic cavity
    • Abdominopelvic cavity
  • Thoracic cavity subdivisions:
    • Pleural cavities (each houses a lung)
    • Mediastinum (contains pericardial cavity; surrounding thoracic organs)
    • Pericardial cavity (encloses the heart)
  • Abdominopelvic cavity subdivisions:
    • Abdominal cavity (stomach, intestines, spleen, liver, etc.)
    • Peritoneal cavity (serous membrane cavity within the abdominal cavity that extends into the pelvic cavity)
    • Pelvic cavity (within the pelvic bones; contains bladder, reproductive organs, rectum)
  • Visual cue: diaphragms separate thoracic and abdominal compartments

Body Cavities: Summary of Key Divisions

  • Dorsal cavity protects the nervous system; subdivided into Cranial and Vertebral cavities
  • Ventral cavity houses internal organs; subdivided into Thoracic and Abdominopelvic cavities
  • Within the Thoracic cavity: Pleural and Pericardial cavities (via the mediastinum)
  • Within the Abdominopelvic cavity: Abdominal cavity, Peritoneal cavity, Pelvic cavity

Body Cavity Membranes

  • Parietal serosa lines internal body walls; Visceral serosa covers internal organs
  • Serous fluid separates the parietal and visceral serosae
  • Serosa = serous membrane; analogy used in the material: it’s like the “oil” lining around rising dough (to illustrate lubrication between layers)

Unit 1 Part 4: Clinical and Directional Terminology

Learning the Language of Anatomy

  • Word structure is often Greek or Latin-based:
    • Prefix: attached to the beginning of words (e.g., peri- = around; pericardial)
    • Word root: foundation of the word (e.g., bronch = airway → bronchitis)
    • Combining form: word root with a final vowel (e.g., mening/o = membrane → meningitis)
    • Suffix: ending elements added to the word (e.g., -itis = inflammation of; appendicitis)
  • Eponyms (non-Greek/Latin names): anatomical structures named after discoverers; diseases named after famous cases (e.g., Lou Gehrig's Disease)

Anatomical Positioning

  • Anatomical Position: standing, arms at sides, palms forward, feet together
  • Supine Position: lying face up in anatomical position
  • Prone Position: lying face down in anatomical position

Anatomical Landmarks

  • Examples used in class: Femur (thigh bone), Femoral artery (artery supplying thigh)

Body Regions & Abdominopelvic Quadrants/Regions

  • Body regions: head, thorax, abdomen, pelvis, etc.
  • Abdominopelvic quadrants (clinical): RUQ, LUQ, RLQ, LLQ
  • Abdominopelvic regions (anatomical): 9 regions (Right Hypochondriac, Epigastric, Left Hypochondriac; Right Lumbar, Umbilical, Left Lumbar; Right Inguinal, Hypogastric, Left Inguinal)
  • Visual map shows liver, gallbladder, stomach, spleen, kidneys, large/small intestines, bladder, etc. arranged within the regions/quadrants

Anatomical Direction Terminology

  • Relative positions and directions:
    • Cranial (superior) / Caudal (inferior)
    • Anterior (ventral) / Posterior (dorsal)
    • Right / Left
    • Medial (toward the midline) / Lateral (away from midline)
    • Proximal / Distal (closer to or farther from the point of attachment)
  • These terms help locate structures consistently across body planes and sections

Body Planes

  • Sagittal: divides body into right and left portions
    • Midsagittal: plane that lies exactly on the midline
  • Frontal (Coronal): divides body into anterior (distinct) and posterior sections
  • Transverse (Horizontal): divides body into superior and inferior portions
  • Oblique: cuts made diagonally through a plane

Exit Questions (Practice)

  • What is the ultimate (unifying) function of body systems?
  • What type of section is this (through what plane; be specific)?
  • Which body cavity holds the liver? Be very specific.
  • In your own words, define positive feedback and negative feedback.

Quick References & Notation Summary

  • Normal body temperature range: 96^{\circ}\mathrm{F} \le T \le 100^{\circ}\mathrm{F}
  • Major feedback types: Negative Feedback, Positive Feedback (examples: insulin regulation; blood clotting)
  • Major cavities: Dorsal (Cranial, Vertebral); Ventral (Thoracic, Abdominopelvic); within Thoracic: Pleural, Mediastinum, Pericardial; within Abdominopelvic: Abdominal, Peritoneal, Pelvic
  • Fundamental concept: structure and function are complementary; organization across levels influences function; homeostasis is dynamic