Chapter 1: The Human Body – An Orientation (Anatomy & Physiology Study Notes)

Introduction to Anatomy and Physiology

Overview

Anatomy and physiology are foundational sciences in understanding the human body. Anatomy is the study of the structure of body parts and their relationships to one another, while physiology is the study of the function of body parts and how they carry out life-sustaining activities. These disciplines are closely linked, as structure often determines function.

• Anatomy: Focuses on the form and organization of body structures.

• Physiology: Explores how those structures work and interact to maintain life.

Example: The structure of the heart (anatomy) enables it to pump blood (physiology).

Reference Standards in Anatomy & Physiology

Reference Male and Female

• Reference male: Healthy, young male weighing about 155 pounds (70 kg).

• Reference female: Healthy, young female weighing about 125 pounds (57 kg).

These standards are used for physiological reference values in textbooks and clinical practice.

Anatomical Variations

Variability in Human Anatomy

• Humans exhibit slight variations in both external and internal anatomy.

• Over 90% of anatomical structures match textbook descriptions, but some differences exist:

  • Nerves or blood vessels may be positioned differently.

  • Some small muscles may be absent.

• Extreme anatomical variations are rare and usually incompatible with life.

Biological Orientations: Sex and Gender

Definitions

• Sex: Set of biological attributes based on chromosomes, gene expression, and hormone action; reflected in reproductive anatomy and physiology (male or female).

• Gender: Psychosocial construct including behaviors, expressions, and identities (e.g., man, woman, transgender, non-binary).

Divisions of Anatomy

Gross (Macroscopic) Anatomy

• Study of large body structures visible to the naked eye.

• Regional anatomy: Examines all structures in a specific area.

• System anatomy: Focuses on one organ system (e.g., cardiovascular, nervous).

• Surface anatomy: Studies internal structures as they relate to the skin surface (e.g., visible muscles, veins).

Microscopic Anatomy

• Deals with structures too small to be seen without magnification.

• Cytology: Study of cells.

• Histology: Study of tissues.

Developmental Anatomy

• Traces structural changes throughout the lifespan.

• Embryology: Study of developmental changes before birth.

Divisions of Physiology

Organ System-Based Physiology

• Renal physiology: Functions of the kidney.

• Neurophysiology: Functions of the nervous system.

• Cardiovascular physiology: Functions of the heart and blood vessels.

Physiology often focuses on cellular or molecular events, emphasizing how chemical reactions in cells underpin body functions. Understanding physiology requires knowledge of basic chemical and physical principles (e.g., electrical currents, pressure, lever systems).

Principle of Complementarity of Structure and Function

Key Concept

• Structure and function are inseparable; what a structure can do depends on its specific form.

• This is known as the principle of complementarity.

Example: The thin walls of alveoli in the lungs (structure) allow efficient gas exchange (function).

*Additional info: The above notes are based on the provided textbook slides and expanded with standard academic context for clarity and completeness.*