BIOL 235 1-10

• Single-celled organisms have a shorter distance for substances to enter the cell compared to multicellular organisms
• Multicellular organisms have a larger distance due to a higher surface area to volume ratio
• Multicellular organisms require specialised exchange surfaces for efficient gas exchange of carbon dioxide and oxygen
• In multicellular organisms, the distance for substances to enter cells is larger due to a higher surface area to volume ratio
• Planes and Sections:

  • Imaginary flat surfaces that pass through body parts
  • Sagittal plane: vertical plane that divides into left and right portions
  • Midsagittal: equal left and right sides
  • Parasagittal: unequal left and right sides
  • Frontal plane: divides body into anterior and posterior portions
  • Transverse plane: divides body into superior and inferior portions
  • Oblique plane: passes through the body or organ at an oblique angle (any angle other than 90)
• Section: a cut of the body or one of organs made along one of the planes
• Body cavities:

  • Spaces that enclose internal organs, separated bones, muscles, ligaments, and other structures
  • Posterior body cavity: enclosed bone, contains brain and spinal cord
  • Cranial cavity: formed by cranial bones, contains continuous with vertebral canal
  • Vertebral canal: formed by vertebral column, contains spinal cord and beginnings of spinal nerves
• Body cavities (cont.):

  • Meninges: 3 layers of protective tissue: dura mater, arachnoid mater, pia mater
  • Anterior body cavity: most complex, contains majority of visceral organs
  • Separated by diaphragm into thoracic and abdominopelvic cavities
  • Thoracic cavity: chest cavity, contains pleural and pericardial cavities and mediastinum
• Thoracic cavity (cont.):

  • Pleural cavities: two fluid-filled spaces between the visceral and parietal pleurae, one around each lung
  • Pericardial cavity: small potential space between the visceral and parietal layers of the serous pericardium that contains pericardial surrounds the heart
  • Mediastinum: anatomical central portion of thoracic cavity between the extends from sternum to vertebral column and from first rib to contains heart, thymus, esophagus, trachea, and several large blood vessels (not lungs)
• Thoracic cavity (cont.):

  • Diaphragm: dome-shaped muscle that separates the thoracic cavity from the abdominopelvic cavity
  • Abdominopelvic cavity: subdivided into abdominal and pelvic cavities
  • Abdominal cavity: contains stomach, spleen, liver, gallbladder, small intestine, most of large intestine
  • Pelvic cavity: contains urinary bladder, portions of large intestine, and internal reproductive organs
• Thoracic and Abdominal Cavity Membranes:

  • Membrane: thin flexible tissue that covers, lines, partitions, or connects structures
  • Serous membrane: a membrane that lines a body cavity that does not open to the exterior
  • Parietal layer: a thin epithelium that lines the walls of the
  • Visceral layer: thin epithelium that covers and adheres to the viscera within the cavities
  • Between the two layers is a potential space that contains a small amount of lubricating fluid (serous fluid)
• Every chemical reaction involves energy changes
• Potential energy is energy stored in matter due to position
• Examples of potential energy include water stored behind a dam and a person poised to jump
• Kinetic energy is energy associated with matter in motion
• Examples of kinetic energy include dam gates opening and a person jumping, where potential energy is converted to kinetic energy
• Chemical energy is a form of potential energy stored in the bonds of compounds and molecules
• The total amount of energy present at the beginning and end of a chemical reaction is the same, according to the Law of Conservation of Energy
• Energy can neither be created nor destroyed, only change form
• Conversion of energy from one form to another generally releases heat, some of which is used to maintain body temperature
• Energy transfer in chemical reactions involves chemical bonds, which represent stored chemical energy
• Chemical reactions occur when bonds are formed or broken
• Exergonic reactions release more energy than they absorb
• Endergonic reactions absorb more energy than they release
• In chemical reactions, when one substance is oxidized, another is reduced at the same time
• When a food molecule like glucose is oxidized, the energy produced is used by a cell to carry out various functions
• Techniques to visualize structures include X-ray, MRI, and CT scans
• Pathological anatomy involves studying structural changes (from gross to microscopic) associated with diseases
• Neurophysiology focuses on the functional properties of nerve cells
• Endocrinology deals with hormones (chemicals that run in the blood) and how they control body functions
• Cardiovascular physiology studies the functions of the heart and blood vessels
• Immunology explores the body's defenses against disease-causing agents
• Respiratory physiology focuses on the functions of the airways and lungs
• Renal physiology studies the functions of the kidneys
• Exercise physiology examines the changes in cell and organ functions due to muscular activity
• Pathophysiology looks at functional changes associated with disease and aging
• Levels of Structural Organization and Body Systems:

  • Chemical Level: includes atoms and molecules
  • Atom: unit of matter that makes up a chemical element, consisting of a nucleus (with protons and neutrons) and electrons orbiting the nucleus
  • Molecule: a combination of two or more atoms that share electrons
  • Atoms essential to maintain life: Carbon, hydrogen, oxygen, nitrogen, phosphorus, calcium, sulfur
• In single-celled organisms, substances can easily enter the cell due to the short distance they need to cross
• Multicellular organisms have a larger distance for substances to cross due to a higher surface area to volume ratio
• Multicellular organisms require specialised exchange surfaces for efficient gas exchange of carbon dioxide and oxygen due to their higher surface area to volume ratio