HSCI 101: Chapter 1 - Introduction to Anatomy & Physiology

Anatomy vs. Physiology

Definitions and Scope

Anatomy and physiology are foundational sciences in understanding the human body. Anatomy focuses on the structure of body parts, while physiology explores their functions and how they work together to sustain life.

• Anatomy: The study of the structure of body parts and their relationships to one another.

• Physiology: The study of the function of the body and how its parts work to carry out life-sustaining activities.

• Example: Anatomy describes the heart's chambers and valves; physiology explains how the heart pumps blood.

Additional info: Anatomy can be further divided into gross (macroscopic) anatomy and microscopic anatomy (histology and cytology).

Levels of Organization in the Human Body

Hierarchical Structure

The human body is organized into several levels, each building upon the previous one. Understanding these levels helps explain how complex functions arise from simpler components.

• Chemical Level: Atoms and molecules essential for life (e.g., water, proteins, DNA).

• Cellular Level: Cells are the basic structural and functional units of life (e.g., muscle cell, neuron).

• Tissue Level: Groups of similar cells performing a common function (e.g., muscle tissue, nervous tissue).

• Organ Level: Structures composed of two or more tissue types working together (e.g., heart, liver).

• Organ System Level: Groups of organs that perform closely related functions (e.g., digestive system).

• Organismal Level: The complete living being (the human body as a whole).

Example: Muscle cells (cellular level) form muscle tissue, which makes up the heart (organ), which is part of the cardiovascular system (organ system).

Organ Systems of the Human Body

Overview and Functions

The human body contains 11 major organ systems, each with specific functions and associated organs.

• Integumentary System: Protects the body, regulates temperature, and provides sensory information. Organs: Skin, hair, nails.

• Skeletal System: Provides support, protection, and aids in movement. Organs: Bones, joints, cartilage.

• Muscular System: Produces movement, maintains posture, and generates heat. Organs: Skeletal muscles.

• Nervous System: Fast-acting control system, responds to internal and external changes. Organs: Brain, spinal cord, nerves.

• Endocrine System: Glands secrete hormones that regulate processes. Organs: Pituitary gland, thyroid, adrenal glands, pancreas.

• Cardiovascular System: Transports blood, nutrients, gases, and wastes. Organs: Heart, blood vessels.

• Lymphatic System: Returns fluid to blood, defends against pathogens. Organs: Lymph nodes, lymphatic vessels, spleen.

• Respiratory System: Supplies blood with oxygen and removes carbon dioxide. Organs: Lungs, trachea, bronchi.

• Digestive System: Breaks down food, absorbs nutrients, eliminates waste. Organs: Stomach, intestines, liver, pancreas.

• Urinary System: Eliminates nitrogenous wastes, regulates water and electrolytes. Organs: Kidneys, bladder, ureters.

• Reproductive System: Produces offspring. Organs: Testes, ovaries, uterus.

Additional info: Each system interacts with others to maintain homeostasis.

Examples of Physiology in Action

Processes and Applications

• Metabolism: Breaking down carbohydrates into glucose molecules (catabolism) and building new molecules (anabolism).

• Response to Stimuli: Withdrawing your hand when you feel something hot (nervous system response).

• Growth: Increase in size due to cell division and enlargement.

• Reproduction: Formation of new cells or organisms.

• Homeostasis: Maintaining stable internal conditions (e.g., body temperature, pH).

Anatomical Position and Directional Terms

Standard Reference Position

The anatomical position is a standard body orientation used as a reference in describing anatomical structures and locations.

• Definition: The body is standing upright, facing forward, arms at the sides, palms facing forward, feet slightly apart.

• Purpose: Provides a consistent frame of reference for anatomical terminology.

Directional Terms

Directional terms describe the locations of structures relative to other structures or locations in the body.

• Superior (Cranial): Toward the head or upper part of a structure.

• Inferior (Caudal): Away from the head or toward the lower part of a structure.

• Anterior (Ventral): Toward the front of the body.

• Posterior (Dorsal): Toward the back of the body.

• Medial: Toward the midline of the body.

• Lateral: Away from the midline of the body.

• Proximal: Closer to the point of attachment to the trunk.

• Distal: Farther from the point of attachment to the trunk.

• Superficial: Toward or at the body surface.

• Deep: Away from the body surface; more internal.

• Contralateral: On the opposite side of the body.

• Ipsilateral: On the same side of the body.

Example: The heart is medial to the lungs. The skin is superficial to the skeleton.

Summary Table: Directional Terms

Term	Definition	Example
Superior	Toward the head/upper part	The head is superior to the chest
Inferior	Away from the head/lower part	The stomach is inferior to the heart
Anterior	Toward the front	The sternum is anterior to the spine
Posterior	Toward the back	The heart is posterior to the sternum
Medial	Toward the midline	The nose is medial to the eyes
Lateral	Away from the midline	The ears are lateral to the nose
Proximal	Closer to point of attachment	The elbow is proximal to the wrist
Distal	Farther from point of attachment	The fingers are distal to the elbow
Superficial	Toward the surface	The skin is superficial to the muscles
Deep	Away from the surface	The bones are deep to the skin
Contralateral	Opposite side	The right hand is contralateral to the left foot
Ipsilateral	Same side	The right hand is ipsilateral to the right foot

Practice and Application

Sample Question

• Fill in the blank: The skin is superficial to the skeleton.