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The Human Body: Orientation, Organization, Terminology, Planes, Cavities, and Homeostasis

The Human Body: An Orientation — Study Notes (Ch. 1.1, 1.3–1.6) Anatomical Position: This is the standard reference position for the body, standing upright, with feet parallel, arms at the sides, and palms facing forward. This position serves as a starting point for anatomical terminology and provides a clear framework for describing locations and movements of different body parts.

Anatomy vs. Physiology

  • Anatomy focuses on structure: the arrangement and relationships of body parts.

  • Physiology focuses on function: how those parts work and operate.

  • Core idea: form (structure) enables function (role/operation).

Medical Terminology

  • Medical terms are included in lectures and chapter reviews.

  • You are responsible for ALL TERMS included in lecture slides, including the terminology list presented in the slides.

  • Terminology is foundational for accurate description and communication in anatomy and physiology.

1.3 Organization of the Human Body

  • Hierarchical levels (from simple to complex):

    • ext{Chemical}
      ightarrow ext{Cellular}
      ightarrow ext{Tissue}
      ightarrow ext{Organ}
      ightarrow ext{System}
      ightarrow ext{Organismal}

  • These levels describe how matter and structures combine to form living organisms.

  • Example: Atoms combine to form molecules; molecules form organelles; organelles form cells; cells form tissues; tissues form organs; organs form organ systems; organ systems form an entire organism.

Levels of Organization — What You Should Know

  • Order from the lowest/basic to the highest/most complex.

  • Include an example for each level (e.g.,

    • Chemical level: atoms/molecules (e.g., H_2O)

    • Cellular level: cells (e.g., epithelial cells)

    • Tissue level: epithelial tissue

    • Organ level: stomach

    • System level: digestive system

    • Organismal level: human
      )

Sample Question (Review Style)

  • Question: When we talk about the cells that make up epithelial tissue, we are looking at what level of organization?

    • a) Cellular level

    • b) Chemical level

    • c) Tissue level

    • d) Organ level

    • e) System level

  • Correct answer: c) ext{Tissue level}

1.4 Organ Systems

  • The human body comprises 11 organ systems.

  • For each system, know the main components and main functions.

Organ Systems and Their Basic Functions

  • Integumentary System

    • Regulates body temperature

    • Provides protection

    • Eliminates some wastes

    • Helps synthesize Vitamin D

    • Detects sensation

  • Skeletal System

    • Supports and protects

    • Provides attachment sites for muscles

    • Aids in body movement

    • Stores blood-forming cells and minerals/lipids

  • Muscular System

    • Produces movement via skeletal muscles

    • Maintains posture

    • Produces heat

  • Nervous System

    • Regulates body activities

    • Detects, interprets, and responds to perturbations via muscle contractions or glandular secretions

  • Endocrine System

    • Regulates body activities via hormones transported in the blood

  • Cardiovascular System

    • Heart pumps blood

    • Blood transports O₂, CO₂, nutrients

    • Helps regulate acidity, temperature, and water content of body fluids

    • Blood components defend against disease and repair damaged vessels

  • Respiratory System

    • Delivers O₂ to cells; removes CO₂ from cells

    • Helps regulate body fluid acidity

    • Aids in sound production

  • Digestive System

    • Physically and chemically breaks down food

    • Absorbs nutrients

    • Excretes solid wastes

  • Urinary System

    • Produces, stores, and eliminates urine

    • Eliminates wastes; regulates volume and chemical composition of blood

    • Maintains mineral balance; helps regulate RBC production

  • Reproductive System

    • Gonads produce gametes (sperm/oocytes) and release hormones regulating reproduction and other body processes

    • Transport and storage of gametes; mammary glands produce milk

  • Immune and Lymphatic System

    • Returns protein and fluid to blood

    • Carries lipids from GI tract to blood

    • Helps protect the body from harmful agents

1.5 Anatomical Terms

A. Anterior and Posterior Major Regions (selected terms)

  • Anterior terms (examples):

    • Temple (temporal) • Orbital (eye) • Nasal (nose) • Oral (mouth) • Mental (chin)

    • Sternal (breastbone) • Frontal (forehead) • Cephalic (head) • Cranial (skull)

    • Face (facial) • Occipital (base of skull) • Cervical (neck)

    • Thoracic • Acromion (shoulder) • Axillary (armpit) • Mammary (breast) • Umbilical (navel)

    • Coxal (hip) • Pollex (thumb) • Brachial (arm) • Abdomen • Antecubital (front of elbow)

    • Upper limb • Lumbar • Pelvis • Antebrachial (forearm) • Carpal (wrist)

    • Scapular (shoulder blade) • Vertebral (spinal column) • Olecranal (elbow back) • Sacral (between hips)

    • Gluteal (buttock) • Dorsum (back of hand) • Perineal (between anus and external genitals)

    • Palmar (volar; palm) • Manual (hand) • Inguinal (groin) • Phalangeal (fingers)

    • Pubic (pubis) • Femoral (thigh) • Patellar (kneecap) • Crural (leg) • Tarsal (ankle)

    • Fibular/Peroneal • Pedal (foot) • Metatarsal • Hallux (big toe) • Digital/Phalangeal (toes)

    • Popliteal (hollow behind knee) • Sural (calf) • Calcaneal (heel)

  • Posterior terms (examples):

    • Posterior terms include structures like Calcaneal (heel) in the posterior view as well, alongside Occipital (base of skull), Vertebral (spinal column), Scapular (shoulder blade) and Gluteal (buttock)

B. Anatomical Position

  • Anatomical position is the standard reference position for describing anatomy.

  • Prone: face down; Supine: face up.

Major Regions (Basic Major Regions)

  • Cephalic region

  • Cervical region

  • Trunk

  • Upper limb

  • Lower limb

Cephalic and Cervical Regions

  • Cephalic region components: Skull (cranial), Face (facial), Forehead (frontal), Nose (nasal), Mouth (oral)

  • Cervical region: Neck

Regions of the Trunk

  • Chest (thoracic) • Sternum (breastbone) • Mammary (breast)

  • Abdomen (abdominal) • Pelvis (pelvic)

Upper Limb Regions

  • Armpit (axillary) • Arm (brachial) • Forearm (antebrachial) • Wrist (carpal) • Hand (manual)

Lower Limb Regions

  • Thigh (femoral) • Foot (pedal) • Ankle (tarsal) • Toes (digital/phalangeal)

Posterior View — Major Posterior Terms

  • Base of skull (occipital)

  • Shoulder blade (scapular)

  • Spinal column (vertebral)

  • Buttocks (gluteal)

  • Popliteal (hollow behind knee)

  • Sural (calf)

  • Calcaneal (heel)

1.5 Anatomical Terms – Directional Terms

  • Superior: above, over, toward the head

  • Inferior: below, under, farther from the head

  • Anterior: in front, toward the front of the body

  • Posterior: behind, toward the back of the body

  • Proximal: closer to the attachment point of a limb to the trunk

  • Distal: farther from the attachment point of a limb to the trunk

  • Medial: toward the midline

  • Lateral: farther from the midline

  • Intermediate: between two structures

  • Superficial: toward the surface of the body

  • Deep: toward the interior of the body

Diagrammatic Example (from Figure 1.21)

  • The relative location of organs (e.g., lungs, heart, liver) can be described using these terms: Superior, Inferior, Medial, Lateral, Proximal, Distal, etc.

1.5 Anatomical Terms – Body Planes

  • Parasagittal plane: divides body (or organ) into left and right portions; not necessarily equal.

  • Midsagittal (median) plane: divides body into equal left and right portions.

  • Frontal (coronal) plane: divides body into anterior and posterior parts.

    • Note: Frontal plane is described as dividing the body into front and back; common mnemonic: “cuts off your face.”

  • Transverse (axial) plane: divides body into superior and inferior parts (also called cross-sectional or horizontal plane).

  • Oblique plane: divides body on an angle.

Planes and Organ Description

  • The body and many organs can be described in terms of frontal, sagittal (lateral), transverse, or oblique planes.

1.5 Anatomical Terms – Planes, Sections, and Descriptions

  • Planes are used to produce sections of the body for medical imaging and anatomical study.

  • The diagrams illustrate how planes intersect the body and organs to create sections.

1.5 Anatomical Terms – Body Cavities

  • There are four main body cavities:
    1) Cranial Cavity
    2) Vertebral (spinal) Cavity
    3) Thoracic Cavity (includes Pleural, Mediastinum, Pericardial)
    4) Abdominopelvic Cavity (includes Abdominal and Pelvic)

Details of Each Cavity

  • Cranial Cavity: contains the brain.

  • Vertebral Cavity: contains the spinal cord and beginning of spinal nerves.

  • Thoracic Cavity:

    • Pleural Cavities: surround the lungs (pleura)

    • Mediastinum: central compartment containing the heart, thymus, esophagus, trachea, major vessels

    • Pericardial Cavity: surrounds the heart (within the mediastinum)

  • Abdominopelvic Cavity:

    • Abdominal Cavity: contains stomach, spleen, liver, gallbladder, intestines, etc. (organs of digestion and other associated organs)

    • Pelvic Cavity: contains urinary bladder, portions of large intestine, internal reproductive organs

    • Peritoneum: serous membrane that lines the walls and covers the abdominal organs; supports and surrounds viscera

Serous Membranes

  • Serous membranes are thin, slippery, double-layered membranes that cover organs within the thoracic and abdominal cavities and line the walls of the thorax and abdomen.

  • Three parts:

    • I. Parietal layer — lines the walls of the cavities

    • II. Visceral layer — covers the viscera

    • III. Serous fluid — lubricating fluid between layers

1.5 Abdominopelvic Quadrants

  • The abdominopelvic cavity can be divided into four quadrants:

    • Right Upper Quadrant (RUQ)

    • Left Upper Quadrant (LUQ)

    • Right Lower Quadrant (RLQ)

    • Left Lower Quadrant (LLQ)

Quadrant Contents (summary)

  • RUQ: Right lobe of liver, gallbladder, right kidney, portions of stomach, small & large intestines

  • LUQ: Left lobe of liver, stomach, pancreas, left kidney, spleen, portions of large intestine

  • RLQ: Cecum, vermiform appendix, portions of small intestine, reproductive organs (e.g., right ovary/male right spermatic cord), right ureter

  • LLQ: Most of small intestine, portions of large intestine, left ureter, reproductive organs (e.g., left ovary, left spermatic cord)

1.6 Properties of Living Things

  • All living organisms share certain characteristics that distinguish them from nonliving matter.

  • Homeostasis: regulation of multiple factors within the body to maintain stable internal conditions; essential for normal function and life.

  • Homeostatic imbalance leads to disease.

  • Homeostasis is maintained by feedback systems, both positive and negative.

Homeostasis and Feedback — Core Concepts

  • Definition: Homeostasis is the property of a system in which variables are regulated so that internal conditions remain stable and relatively constant.

  • Examples of regulated variables: body temperature, pH, blood glucose, etc.

  • Regulation typically involves three components:
    1) Receptor (detects a change)
    2) Control center (integrating center, processes information)
    3) Effector (responds to adjust the condition)

  • Regulated by: nervous system (rapid) and hormones (slower).

Effectors (examples)

  • Skeletal muscle

  • Smooth muscle

  • Cardiac muscle

  • Endocrine glands

Feedback Loops

  • Negative feedback loop: the response counteracts the original stimulus, restoring homeostasis. Example: regulation of body temperature.

  • Positive feedback loop: the response enhances the original stimulus, leading to a greater change; typically drives processes to completion.

    • Example: Pregnancy/childbirth — stimulates mechanisms that intensify until the outcome (birth) occurs.

1-Minute Paper (Study Prompt)

  • What is your name?

  • Where are you from? (city, province, country)

  • Why are you taking Pre-Health Science?

  • Fun Fact about yourself.