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Chapter 1 : Introduction

What is Physiology? arrow_upward

  • Physiology is the science of body functions.
  • It is the study of mechanical, physical and biochemical properties of living organisms.
  • Physiology incorporates a significant amount of anatomy; anatomy is the science of body structures and their interrelationships.

  • Branches of Physiology arrow_upward

    Levels of Organization of the Human Body arrow_upward


  • The Cell
  • The Tissue
  • The Organ
  • The System
  • The Organism

  • Atom and Molecule (Chemical Level) arrow_upward

  • The chemical level is the basic structure of which all substances are composed which includes:
    • Atoms - The smallest unit of matter that participates in reactions.
    • Molecules - Two or more atoms joined together.

    The Cell arrow_upward

  • The most basic structural and functional unit of an organism is the cell.
  • It is the smallest living unit of the human body.
  • There are many different types of cells in the body including:
    • Nerve cells
    • Blood cells
    • Muscle cells
    • Fat cells

    The Tissue arrow_upward

  • Tissues are groups of cells, and the surrounding environment, which work together to produce a specific function.
  • There are only four types of tissues in the body:
    • Epithelial tissue
    • Connective tissue
    • Muscle tissue
    • Nervous tissue

    The Organ arrow_upward

  • Organs are structures that are made of two or more different types of tissues.
  • They have specific functions and a defined shape.
  • The heart is an example of an organ.
  • It is made of muscle, as well as connective and nervous tissue.
  • The tissues work in concert to move blood through the body.

  • The Organism arrow_upward

  • An organism is the highest level of human body organization.

  • Human Body Systems arrow_upward

  • A system consists of related organs that have a common function.
  • There are eleven organ systems in the body:
    • Integumentary System
    • Skeletal System
    • Muscular System
    • Nervous System
    • Endocrine System
    • Cardiovascular System
    • Lymphatic and Immune System
    • Respiratory System
    • Digestive System
    • Urinary System
    • Reproductive System

    The Integumentary System

  • The skin and derived structures
    • It protects internal organs and helps to maintain body temperature.

    The Skeletal System

  • The bones and joints
    • It provides support and protection to internal organs.

    The Muscular System

  • Skeletal, smooth and cardiac muscles
    • It permits movement of the body, maintains posture, and circulates blood throughout the body.

    The Nervous System

  • Brain, spinal cord, nerves
    • It provides regulation of body functions and sensory perception.

    The Endocrine System

  • Hormone-producing cells and glands
    • Regulation of homeostasis, growth and development.

    The Cardiovascular System

  • Blood, heart and blood vessels
    • Delivery of oxygen and nutrients to the tissues.

    The Lymphatic and Immune System

  • Lymphatic vessels and fluid
    • Defense against infection.

    The Respiratory System

  • Lungs and airways
    • Absorption of oxygen and release of carbon dioxide.

    The Digestive System

  • Organs of the gastrointestinal tract
    • Absorption of nutrients

    The Urinary System

  • Kidneys, ureters and bladder
    • Electrolyte balance and waste removal.

    The Reproductive System

  • Reproductive organs in males and females
    • Controls the biological process by which new individuals are produced.

    Homeostasis and Feedback Systems arrow_upward

  • Homeostasis is the maintenance of a constant internal environment in organisms, for example, same temperature, same pH, etc.
  • How is Homeostasis maintained and controlled?
    • Homeostasis is a highly complex process.
    • Homeostasis is maintained through the regulatory process called “feedback”.

    What is a Feedback Loop? arrow_upward

  • A feedback loop is a cycle of events in which a body condition (such as temperature) is continually monitored and adjusted to be within specific limits.
  • A feedback loop has three main components:
    • A receptor that monitors a particular aspect of physiology.
    • A control center that sets the normal range receives input from the receptor and sends output when changes are needed.
    • An effector that produces a response or effect that changes the physiology.
  • There are two types of feedback loops:
    • Positive loops - where the response enhances the condition.
    • Negative loops - where the response counteracts or antagonizes the condition.

    Negative Feedback Loops in the Body arrow_upward

  • Negative feedback loops are very common in the human body.
  • Negative feedback loops are excellent mechanisms of controlling parameters and allow for the “fine-tuning” of physiological processes, such as blood glucose, oxygenation level and blood pressure.
  • A negative feedback loop tends to bring a system back to equilibrium.

  • Positive Feedback Loops in the Body arrow_upward

  • Positive feedback loops are rare in the human body.
  • A positive feedback loop tends to push a system away from equilibrium.
  • The classic example of a positive feedback loop in the body is the action of oxytocin during labor.

  • Thank You from Kimavi arrow_upward

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