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Chapter 1 The Human Organism – Vocabulary Flashcards

The Human Organism – Chapter 1 (Seeley’s Essentials of A&P)

Basic Concepts: Anatomy vs Physiology

  • Anatomy:
    • Investigates internal and external body structure
    • Includes details of where things are in the body, what structures are made of, and how parts relate
    • Divisions: Gross (Macroscopic) and Microscopic
    • Etymology: the term means “to dissect; a cutting open”
  • Physiology:
    • Investigates processes and functions of anatomical structures
    • Includes human physiology: functions of cells, organs, and systems; effects of diseases on organ/system function
    • Emphasizes interrelationships among parts of the human organism
  • Relationship between anatomy and physiology:
    • Structure (anatomy) and function (physiology) are interdependent; understanding one aids understanding the other
  • Specialties mentioned:
    • Anatomy specialties: systemic, regional, surface, anatomical imaging
    • Physiology specialties: cellular physiology, organ-system physiology, pathophysiology (effects of disease on function)

Levels of Organization in the Human Body

  • Structural & Functional Organization: Six levels from chemical to organism
    • 1) Chemical:
    • Smallest level; atoms, chemical bonds, molecules
    • 2) Cellular:
    • Cells are the basic units of life; compartments and organelles (e.g., mitochondria, nucleus)
    • 3) Tissues:
    • Groups of cells with similar structure/function plus extracellular substances they release
    • Four broad types: Epithelial, Connective, Muscular, Nervous
    • 4) Organs:
    • Two or more tissue types working together to perform specific functions (examples: stomach, heart, liver, ovary, bladder, kidney)
    • 5) Organ-System:
    • Group of organs contributing to a vital life function (examples: Digestive system, Reproductive system)
    • 6) Organism:
    • All organ systems working together to maintain homeostasis; includes associated microorganisms (e.g., intestinal bacteria)
  • Example tracing organization from elements to organism: C, H, O, N → amino acids → proteins → cell structures → epithelial cells → epidermal tissue → skin → integumentary system → protection from invasive bacteria → healthy baby

Major Organs (Representative List)

  • Brain, Spinal cord, Lung, Heart, Liver, Pancreas (behind stomach), Gallbladder, Kidney (behind stomach), Large intestine, Spleen (behind stomach), Stomach, Small intestine, Urinary bladder

The 11 Organ Systems of the Human Body

  • Integumentary, Skeletal, Muscular, Nervous, Endocrine, Cardiovascular, Lymphatic, Respiratory, Digestive, Urinary, Reproductive
  • Figure 1.2 (illustrative of organ locations; review Figure 1-3, pages 14–15 for relationships)

Interrelationships Among Body Systems

  • Organ systems work together to promote well-being by completing necessary life functions
  • Think about the coordination: for example, oxygen intake and CO2 removal involve respiratory and circulatory systems; fluid movement in body cavities enables nutrient exchange and waste removal

Characteristics of Life

  • Organization: interrelationships between parts determine a greater function
  • Metabolism: sum of all chemical and physical reactions; enables energy use from food; supports changes, growth, and waste elimination
  • Responsiveness: ability to sense and respond to environmental changes (stimulus); includes both internal and external environments
  • Growth: increase in size, cell number, and/or cellular complexity
  • Development: changes in form and size of organism or parts; differentiation of cells from generalized to specialized
  • Reproduction: formation of new cells or organisms; generation of new individuals; tissue repair
  • Overall purpose of metabolism and life processes: to sustain responsiveness, growth, reproduction, development, and energy transport/repair

Homeostasis

  • Homeostasis: maintenance of a relatively stable internal environment despite external fluctuations
  • Key idea: results from interdependent organ systems functioning together
  • Variables: measures of body properties that may change (e.g., temperature, heart rate, blood pressure, glucose, blood counts, respiration rate)
  • Set point and normal range concept: a set point defines an optimal value; a normal range allows tolerance around that set point
  • Think: body temperature fluctuates around a set point

Negative vs Positive Feedback in Homeostasis

  • Negative feedback (main mechanism for homeostatic regulation):
    • Detects deviation from the set point and initiates a response to reverse the deviation toward the set point/normal range
    • Example: body temperature regulation via sweating and vasodilation when hot
  • Positive feedback:
    • Initial stimulus further stimulates the response, causing progressive deviation away from the set point
    • Not generally used for maintaining homeostasis; occurs in specific normal processes or in response to injury/disease
    • Examples: blood clotting, labor & delivery
  • Comparison (negative vs positive): see Figure 1.7 (conceptual)

Homeostatic Mechanism Components (Feedback Loop)

  • Receptor: detects changes in the variable; receives stimulus
  • Control center: receives receptor signal; sets the optimal value (set point); sends signal to effector
  • Effector: directly causes change in the variable to restore homeostasis
  • Example flow (temperature regulation):
    • Receptors monitor body temperature
    • Information is sent to the brain (control center)
    • If present, the brain triggers effectors (sweat glands, skin blood vessels) to adjust temperature
    • Result: body temperature returns to the normal range
  • Visual sequence (from slide): Receptor → Control center → Effector → Response → Restored homeostasis

Negative Feedback: Control of Body Temperature (Illustrative)

  • Stimulus: body temperature increases
  • Receptors and control centers: brain increases sweat gland activity and vasodilation
  • Effectors: sweat production and skin blood vessel dilation
  • Homeostasis restored: body temperature decreases toward normal range
  • Receptive mechanism also describes the opposite: when temperature decreases, sweat production ceases, vessels constrict, and shivering may occur to raise temperature

Positive Feedback Examples (Further Detail)

  • Uterine stretch during pregnancy stimulates sensory neurons → more oxytocin release → stronger contractions → continued stretch leads to further contractions until fetus is delivered
  • Mammary gland stimulation continues until the original stimulus (fetus removal) ends

Quick Think Question

  • If you are thirsty and drink water, is thirst a negative or positive feedback signal? Why?
    • Negative feedback: thirst sensation diminishes as you drink water, returning toward homeostasis

Anatomical Terminology and Positioning

  • Anatomical Position: standing erect, face forward, palms forward; left/right refer to the subject, not the observer
  • Relative positions depend on this standard orientation

Directional Terms (Human Oriented)

  • Superior (cephalic/cranial) vs Inferior (caudal)
  • Anterior (ventral) vs Posterior (dorsal)
  • Note: In four-legged animals, ventral corresponds to anterior and dorsal to posterior
  • Medial vs Lateral: near vs away from midline
  • Proximal vs Distal: near vs far from point of attachment
  • Superficial vs Deep: toward the surface vs toward the interior

Body Planes and Sections

  • Sagittal plane: divides body into right and left parts
  • Median plane: a mid-sagittal plane that divides body into equal left and right halves
  • Transverse (horizontal) plane: divides body into superior and inferior parts; cross sections are cuts along this plane
  • Frontal (coronal) plane: vertical plane that divides body into anterior and posterior parts
  • Visual references: Figure 1.11 shows sagittal sections and anatomical relationships

Body Regions and Major Areas

  • Body Regions: upper limbs (arm, forearm, wrist, hand), lower limbs (thigh, leg, ankle, foot), central region (head, neck, trunk)
  • Trunk includes head/neck and thorax, abdomen, pelvis, and related regions
  • Major regional terms displayed in Figure 1.9 and Figure 1.9 (textual excerpts):
    • Head: Frontal, Orbital, Nasal, Oral, Otic, Buccal, Mental, Cranial
    • Neck: Cervical; Chest/Thorax: Pectoral, Sternal; Back: Occipital, Nuchal, Dorsal, Scapular, Vertebral
    • Upper limb: Brachial, Antebrachial, Carpal, Manus, Digits, etc.
    • Lower limb: Coxal, Femoral, Patellar, Crural, Tarsal/Dorsum of foot, Pedal, Digital
    • Trunk subdivisions include Abdominal, Umbilical, Pelvic, Inguinal, Pubic, etc.

Abdomen Subdivisions (9 Regions)

  • Epigastric, Right and Left Hypochondriac, Right and Left Lumbar, Right and Left Iliac, Hypogastric (pubic), Umbilical
  • Visual mapping shown in Figure 1.10

Body Cavities and Serous Membranes

  • Body Cavities:
    • Thoracic cavity: within chest wall and diaphragm; contains heart, lungs, thymus, esophagus, trachea
    • Mediastinum: space between the lungs, contains heart, thymus, esophagus, trachea
    • Abdominal cavity: space between diaphragm and pelvis; contains stomach, intestines, liver, spleen, pancreas, kidneys
    • Pelvic cavity: space within pelvis; contains urinary bladder, reproductive organs, part of large intestine
    • Abdominopelvic (abdominal + pelvic) cavity
  • Serous membranes: line trunk cavities and cover organs; have visceral and parietal layers; a serous cavity contains serous fluid to reduce friction
    • Pericardium around the heart (heart cavity: pericardial cavity)
    • Pleura around the lungs (pleural cavities)
    • Peritoneum around abdominal and pelvic organs (peritoneal cavity)

Specific Serous Membranes and Cavities (Key Points)

  • Pericardium:
    • Visceral pericardium covers the heart
    • Parietal pericardium is the outer layer; pericardial cavity contains serous fluid to reduce friction
  • Pleura:
    • Visceral pleura covers the lungs
    • Parietal pleura lines the inner thoracic wall
    • Pleural cavity contains serous fluid; creates friction-free movement; adheres lungs to thoracic wall
  • Peritoneum:
    • Visceral peritoneum covers and anchors organs
    • Parietal peritoneum lines the inner wall of the abdominopelvic cavity
    • Peritoneal cavity contains serous fluid to reduce friction; mesenteries are double layers that hold organs together

Quick Reference: Think about Real-World Relevance

  • Homeostasis underpins virtually every clinical scenario: fever, dehydration, electrolyte imbalances, and hormonal regulation are all homeostatic challenges
  • Understanding planes, regions, and cavities helps in clinical assessment, imaging interpretation, and surgical planning
  • Serous membranes and their fluid-filled cavities reduce friction during organ movement and protect organs during motion

Connections to Foundational Principles and Real-World Relevance

  • Foundational link: structure (anatomy) enables function (physiology)
  • Medical applications: imaging modalities (X-ray, ultrasound, MRI) align with anatomical imaging; anatomical planes guide surgical approaches
  • Ethical and practical implications: accurate terminology and orientation are essential for safe patient care and clear scientific communication

Equations and Quantitative References (LaTeX)

  • Deviation from set point (negative feedback model):
    ext{Let } x ext{ be a variable with set point } x{set}. \Delta x = x - x{set}
  • If \Delta x \neq 0, the control system produces a corrective change to reduce |\Delta x| toward 0:
    ext{response} = -k\,\Delta x,\quad k>0.
  • Broad description of metabolism (qualitative):
    \text{Metabolism} = \sum_{i} (\text{all chemical and physical reactions in the body})

Note for Exam Prep

  • Be able to distinguish between systemic, regional, and surface anatomy approaches
  • Memorize the 11 organ systems and their primary functions
  • Understand the hierarchy from chemical to organism and be able to trace an example through the levels (e.g., amino acids → proteins → cells → tissues → organs → organ system → organism)
  • Be able to explain the components of a homeostatic negative feedback loop and give examples (e.g., temperature, blood pressure, glucose regulation)
  • Distinguish between the visceral and parietal layers of serous membranes and name the associated cavities
  • Recognize body cavities and their major organs, including the mediastinum’s contents and the abdominal/pelvic regions
  • Practice using anatomical directional terms, planes, and regions to describe locations and relationships