Anatomy and Physiology

• The digestive system includes organs such as the mouth, esophagus, stomach, small intestine, and large intestine.
• Anatomy is the science of body structures and the relationships among them
• Anatomy was first studied by dissection, which is the careful cutting apart of body structures to study their relationships
• Physiology is the science of body functions—how the body parts work
• Chemical level is compared to the letters of the alphabet and includes atoms, the smallest units of matter that participate in chemical reactions, and molecules, two or more atoms joined together
• Certain atoms essential for maintaining life include carbon (C), hydrogen (H), oxygen (O), nitrogen (N), phosphorus (P), calcium (Ca), and sulfur (S)
• Two familiar molecules found in the body are deoxyribonucleic acid (DNA), the genetic material passed from one generation to the next, and glucose, commonly known as blood sugar
• Cells are the basic structural and functional units of an organism, composed of chemicals
• Cells are the smallest living units in the human body
• Types of cells in the body include muscle cells, nerve cells, and epithelial cells
• Tissues are groups of cells and surrounding materials that work together to perform specific functions
• There are four basic types of tissues in the body: epithelial, connective, muscular, and nervous tissue
• Epithelial tissue covers body surfaces, lines organs and cavities, and forms glands
• Connective tissue connects, supports, and protects organs while distributing blood vessels
• Muscular tissue contracts to make body parts move and generates heat
• Nervous tissue carries information through nerve impulses
• At the organ level, different types of tissues are joined together to form organs
• Organs are composed of two or more different types of tissues, have specific functions, and recognizable shapes
• Examples of organs include the stomach, skin, bones, heart, liver, lungs, and brain
• Organ systems consist of related organs with common functions
• An example is the digestive system, which breaks down and absorbs food
• Organs in the digestive system include the mouth, salivary glands, pharynx, esophagus, stomach, small intestine, large intestine, liver, gallbladder, and pancreas
• The pancreas is part of both the digestive system and the hormone-producing endocrine system
• An organism is compared to a book, where all parts of the human body function together to constitute the total organism
• Metabolism is the sum of all chemical processes that occur in the body
• Catabolism is the breakdown of complex chemical substances into simpler components
• Anabolism is the building up of complex chemical substances from smaller, simpler components
• Example: digestive processes catabolize proteins in food into amino acids, which are then used to anabolize new proteins for body structures like muscles and bones
• Responsiveness is the body's ability to detect and respond to changes
• Internal environment change example: increase in body temperature during a fever
• External environment change example: turning head toward the sound of squealing brakes as a response to a potential threat
• Nerve cells respond by generating electrical signals known as nerve impulses (action potentials)
• Muscle cells respond by contracting, generating force to move body parts
• Movement includes motion of the whole body, individual organs, single cells, and tiny structures inside cells
• Growth is an increase in body size resulting from an increase in the size of existing cells, an increase in the number of cells, or both
• Differentiation is the development of a cell from an unspecialized to a specialized state
• Precursor cells that can divide and give rise to cells undergoing differentiation are known as stem cells
• Reproduction refers to the formation of new cells for tissue growth, repair, or replacement, or the production of a new individual
• Anatomical position:

  • Subject stands erect facing the observer
  • Head level and eyes facing directly forward
  • Lower limbs parallel with feet flat on the floor and directed forward
  • Upper limbs at the sides with palms turned forward
• Prone position:

  • Body is lying facedown