Biology Basics: Scientific Method and Human Body Organization

The Scientific Method

• The scientific method involves a series of steps: hypothesis, experiments, data collection and analysis, and conclusion.

Science and the Human Body

• The scientific method is used to make conclusions about the workings of the human body.

Facts and Theories

• A fact is a statement for which no other conclusion is supported.
• A theory is a set of scientific facts describing a larger process.

Levels of Organization of the Human Body

• The levels of organization of the human body, in order, are: • Chemical level: atoms to complex molecules. • Cellular level: molecules forming structures. • Tissue level: groups of similar cells and external materials. • Organ level: two or more structures combined for specialized tasks. • Organ system level: group of organs. • Organism: the entire living being.

Anatomic Position

• The standard anatomic position is standing upright with feet shoulder-width apart, upper limbs at the sides of the trunk, head and palms facing forward.
• This standard position is important to avoid medical and experimental errors.

Directional Terms

• Directional terms used to describe the human body include: • Anterior/posterior • Superior/inferior • Proximal/distal • Medial/lateral • Superficial/deep

Homeostasis

• Homeostasis is the stable internal environment in the body.
• It is an important concept in understanding the human body because homeostatic imbalances can lead to disease or death.

Feedback Loops

• A feedback loop is a control mechanism used to regulate the body when it is imbalanced.
• A negative feedback loop involves a change that opposes the imbalance.
• A positive feedback loop involves a change that reinforces the imbalance.
• The parts of a feedback loop are: • Stimulus • Receptors • Control center/effector/response

Structure/Function Relationship

• The structure of a part of the body is suited to its function (form follows function).
• Examples include blood vessels.

Gradients

• A gradient is a difference in concentration or amount of something between two connected areas.
• In the human body, the direction of spontaneous movement of matter and energy in an area with a gradient is from high to low concentration.