Introduction to Biology - BIO 101

Introduction to Biology - BIO 101

• The human body is composed of several organs and glands, including the adrenal gland, thyroid, pancreas, pituitary gland, brain, ovary, testicle, and thymus.

Level of Organization

• The body has levels of organization: atom, molecule, macromolecule, organelle, cell, tissue, organ, organ system, and organism.

Tissue

• Tissues are groups of cells with similar structure and function.
• Tissues perform specific activities.
• Tissues are held together by extracellular fluid and fibers.
• There are four major tissue types: epithelial, connective, muscle, and nervous.
  • More than 200 different cell types exist in the body, which constitute these tissues.

Epithelial Tissue

• Composed of tightly packed cells in layers.
• Acts as barriers to fluids and microbes.
• Lines cavities, forms tubes and ducts.
• Forms the epidermis of the skin and lines internal surfaces such as the gastrointestinal tract (GIT).
• Cells in this tissue are polarized (apical and basal side).

Connective Tissue

• Made up of diverse cell types, including fibroblasts, fat cells, and blood cells.
• Supports and connects other tissues and organs.
  • Different types of connective tissues, including loose connective tissue, fibrous connective tissue and cartilage, are shown in illustrative visuals.
  • Blood is also a connective tissue, pictured and described in detail.

Muscle Tissue

• Essential for movement, posture, and blood circulation.
• Composed of cells called muscle fibers able to contract.
  • Three types of muscle tissue include skeletal (voluntary), smooth (involuntary), and cardiac (heart).

Nervous Tissue

• Highly specialized tissues for sensing and transmitting information.
• Consists of neurons and glial cells.
  • Neurons are the functional units of the nervous system.
  • Glial cells support neuronal function.

Organ

• A collection of tissues working together to perform a specific function.
  • Examples include the stomach, liver, lungs, heart, pancreas, spleen, kidneys, and eyes.

Organ Systems

• Groups of organs with coordinated functions.
  • Cardiovascular system: circulates blood, carrying oxygen and nutrients to cells, and removing waste.
  • Respiratory system: brings in oxygen and removes carbon dioxide. Other systems and the organs they comprise are also described.

Major Organ Systems

• Organ systems work together to ensure proper functioning of the whole organism.
  • Different systems (cardiovascular, lymphatic, digestive, endocrine, integumentary, muscular, nervous, reproductive, respiratory, skeletal, urinary, and immune) have specialized functions.
  • These are elaborated upon with descriptions of their functions, involved organs, tissues and structures.

Organs in Systems

• Organs in a system work in coordination to perform a specific task or process.
  • A particular illustration of how the digestive system functions is shown to explain the importance of coordinated actions.

Organ Systems Working Together

• Organ systems cooperate to maintain the body's overall function.
  • The respiratory and circulatory systems work in tandem to deliver oxygen and remove carbon dioxide, which is visually illustrated.

Control and Coordination

• The nervous and endocrine systems control and coordinate body functions.
  • The nervous system uses electrical impulses to regulate quick responses to stimulations.
  • The endocrine system uses hormones regulated by feedback mechanisms—to control body functions and processes slowly.

Gland

• Glands are organs that produce and release substances with specific functions.
• Two types of glands: endocrine and exocrine.
  • Endocrine glands release hormones into the bloodstream to regulate a variety of bodily functions.
  • Exocrine glands release substances through ducts to the external parts of the body.
    • Different illustrations explain the differences in the functioning of endocrine and exocrine glands, and their functions.

Endocrine Glands

• Part of the endocrine system; produce and release hormones into the bloodstream to regulate bodily functions.
• Examples include the pituitary, thyroid, adrenal, pancreas, ovaries, and testes.

Exocrine Glands

• Release substances through ducts to the exterior of the body.
• Examples include the salivary, sweat, mammary, sebaceous, and lacrimal glands.

Common Glands and Hormones

• Various glands produce certain hormones with specific roles. Specific glands and their roles, and the hormones produced by them are detailed in tables.

Who Regulates the Regulators?

• The endocrine system is regulated through a network of negative feedback loops.
• This helps to maintain homeostasis.
• An example of blood glucose regulation is detailed.

Explore the basics of human biology in this introductory quiz. Learn about the levels of organization within the body, the types of tissues, and the functions of epithelial tissue. This quiz will test your knowledge of the human body's structure and function.