Learning Objectives

• Define anatomy and physiology and understand their differences.

• Describe the levels of structural hierarchy in the human body.

• Identify major organ systems and their general functions.

• Explain homeostasis and interpret questions related to homeostatic mechanisms.

• Discuss positive and negative feedback mechanisms and their components.

• Apply anatomical terminology to body planes, regions, and directions.

• Classify body cavities and divisions of the abdomen.

Chapter 1: Anatomy Terminology, Homeostasis

Anatomy and Physiology: Introduction

Anatomy is the study of the structure of the body and how these structures are designed for specific functions. Physiology investigates the processes or functions of the human body and how they regulate the body within a narrow range of values.

• Anatomy Subdivisions:

  • Gross Anatomy

  • Surface Anatomy

  • Microscopic Anatomy (Histology, Cytology)

  • Developmental Anatomy

• Physiology Subdivisions: Renal, Cardiovascular, Neurophysiology, etc.

Complementarity of Structure and Function

• Structure follows function and function determines structure.

• Form and function are intimately entwined; sometimes the relationship is obvious, other times more subtle.

• Example: The thin walls of alveoli in the lungs facilitate gas exchange.

Levels of Structural Organization

The human body is organized into hierarchical levels, each with increasing complexity.

• Chemical Level: Atoms, elements, molecules, organelles.

• Cellular Level: Basic living unit; all life forms are composed of cells.

• Tissue Level: Groups of similar cells performing a common function (e.g., epithelial, connective, muscular, nervous).

• Organ Level: Composed of two or more tissue types working together (e.g., lungs, bronchi).

• Organ System Level: Groups of organs working together (e.g., respiratory system).

• Organismal Level: The complete individual; can be unicellular or multicellular.

Organ System Overview

The body is composed of several organ systems, each with specific functions.

• Integumentary System: Skin, dermis, glands. Regulates and protects, prevents water loss.

• Skeletal System: Bones, cartilage, ligaments, tendons. Protection, support, blood cell production.

• Muscular System: Muscles attached to bones. Movement, posture, heat generation.

• Nervous System: Brain, spinal cord, nerves, sensory receptors. Regulation and coordination of sensation and movement.

• Endocrine System: Glands (pituitary, thyroid, adrenal, etc.). Regulation and maintenance of growth, metabolism.

• Cardiovascular System: Heart, blood vessels, blood. Transport of nutrients, waste, immune function.

• Lymphatic System: Vessels, nodes, spleen, thymus, tonsils. Immune response, fat absorption.

• Respiratory System: Nasal passages, pharynx, larynx, lungs, bronchi. O2 and CO2 exchange.

• Digestive System: Mouth, esophagus, stomach, intestines, glands. Mechanical and chemical breakdown, absorption.

• Urinary System: Kidneys, ureters, bladder, urethra. Waste removal, water balance.

• Reproductive System: Male (testes, prostate, penis), Female (ovaries, uterus, vagina).

Homeostasis

Homeostasis and Control Systems

Homeostasis is the existence and maintenance of a relatively constant environment within the body (e.g., 37°C, pH = 7.40), regardless of external changes.

• Set Point: The ideal value for a physiological parameter.

• Normal Range: Acceptable range of values around the set point.

• Stimulus: Any change that disrupts homeostasis.

• Receptor: Detects the stimulus.

• Control Center: Processes information and determines response (includes afferent and efferent pathways).

• Effector: Carries out the response.

• Response: Action taken to restore homeostasis.

Feedback Mechanisms

• Negative Feedback: Any deviation from the normal set point is resisted or diminished. Most homeostatic control mechanisms are negative feedback.

  • Example: Heart rate regulation due to changes in blood pressure.

  • Example: Release of hypothalamic hormones in response to blood levels of hormones.

• Positive Feedback: Rare; deviation from the set point causes the deviation to become larger.

  • Example: Blood pressure changes due to trauma.

  • Example: Childbirth (oxytocin release increases contractions).

The Language of Anatomy

Anatomical Position and Directional Terms

• Terminology: Anatomy terms are combinations of prefixes and suffixes; breaking down words helps interpretation.

• Anatomical Position: Standing erect, heels together, arms at side with palms anterior and thumbs lateral. Always assume this position when studying anatomy.

• Axial: Pertaining to the head, neck, and trunk.

• Appendicular: Pertaining to the limbs and their attachments to the trunk.

Basic Directional Terms

• Torso: Prone, Supine

• Superior: Above

• Inferior: Below

• Cephalic: Toward the head

• Caudal: Toward the tail

• Anterior (Ventral): Front

• Posterior (Dorsal): Back

• Medial: Toward the midline

• Lateral: Away from the midline

• Superficial: Toward the surface

• Deep: Away from the surface

• Limbs: Distal (farther from trunk), Proximal (closer to trunk)

Specific Regions of the Body

• Head: Cephalic, Frontal, Orbital, Nasal, Buccal

• Neck: Cervical

• Trunk: Thoracic/pectoral, Sternal, Acromial, Mammary, Abdominal, Umbilical

• Pelvis: Coxal, Inguinal, Perineal, Pubic, Pudendal

• Upper Extremity: Axillary, Brachial, Antebrachial, Olecranon, Carpal, Manual, Digital

• Lower Extremity: Femoral, Geniculate, Crural, Fibular (Peroneal), Sural, Tarsal, Pedal, Dorsum, Plantar, Digital

Divisions of the Abdomen

• Quadrants: Upper Right (URQ), Upper Left (ULQ), Lower Right (LRQ), Lower Left (LLQ)

• Major Organs in Quadrants:

  • LRQ: Appendix, cecum

  • ULQ: Spleen, pancreas

  • URQ: Liver, gallbladder, duodenum

  • LLQ: Descending and sigmoid colon

• Abdominal Regions: Nine regions for more precise location (e.g., right hypochondriac, left lumbar, umbilical, etc.)

Body Planes and Sections

• Sagittal/Median Plane: Parallel to the midline from anterior to posterior surface.

  • Midsagittal: Section down the midline.

  • Parasagittal: Not on the midline, but parallel.

• Frontal (Coronal) Plane: Divides body into anterior and posterior sections.

• Horizontal (Transverse) Plane: Cuts body horizontally; reference for cross sections.

• Oblique Plane: Section through the body at an angle.

Body Cavities

• Dorsal Body Cavity:

  • Cranial cavity

  • Vertebral cavity

• Ventral Body Cavity:

  • Thoracic cavity (pleural, mediastinal, pericardial)

  • Abdominal cavity

  • Pelvic cavity

  • Retroperitoneal cavity (posterior)

Serous Membranes

• Ventral body cavities are covered with two layers of membrane that secrete fluid for lubrication.

• Visceral membrane: Layer that covers the organ.

• Parietal membrane: Layer that covers the wall of the cavity.

Table: Comparison of Feedback Mechanisms

Key Equations

• Homeostasis (Generalized):

Additional info: Academic context and examples have been expanded for clarity and completeness. All major topics from the provided notes have been covered and organized for effective exam preparation.