Biology Chapter: Characteristics of Living Things

Characteristics of Living Things

• Metabolize complex chemical substances.
• Respond to stimuli.
• Move.
• Grow and develop.
• Reproduce.

Anatomy and Physiology

• Anatomy studies structures and their relationships.
• Physiology studies function.
• Structure and function are interrelated.

Levels of Structural Organization

• Chemical level.
• Cellular level.
• Tissue level.
• Organ level.
• System level.
• Organismal level.

Organ Systems

• An organ system is a group of organs with independent functions working together.
• Organ systems are interdependent.
• Humans have 11 organ systems: integumentary, skeletal, muscular, nervous, endocrine, cardiovascular, lymphatic/immune, respiratory, digestive, urinary, and reproductive.

Body Fluids

• Extracellular fluid is fluid outside cells.
• Interstitial fluid is between tissue cells.
• Blood plasma is the fluid component of blood.
• Lymph is fluid inside lymph vessels.
• Maintaining body fluid volume and composition is crucial for survival. Dysregulation can cause issues like high or low blood pressure.

Homeostasis

• Homeostasis is the dynamic maintenance of internal conditions within set parameters.
• It relies on receptors, control centers, and effectors.
• Negative feedback loops reverse changes to maintain homeostasis (e.g., blood pressure regulation).
• Positive feedback loops enhance initial change, moving away from homeostasis (e.g., childbirth). Homeostasis is usually restored by negative feedback or attenuation.

Homeostatic Imbalances

• Prolonged imbalances lead to disorders, diseases, and death.
• Disorders are abnormal body functions.
• Diseases are disorders with specific causes, signs (measurable), and symptoms (reported).

Anatomical Terminology

• Anatomical position is a standardized reference point.
• Supine is facing up; prone is facing down.
• Regional terms describe general body areas (e.g., cervical for neck).
• Directional terms describe relative locations (e.g., medial, lateral, proximal, distal, superior, inferior).

Planes and Sections

• Planes are imaginary flat surfaces dividing the body (e.g., transverse separates superior and inferior).
• Sections are cuts along a plane.

Body Cavities

• Body cavities protect, hold, and support internal structures.
• Dorsal cavities include the cranial (brain) and vertebral canal (spinal cord).
• Ventral cavities include the thoracic and abdominopelvic cavities, separated by the diaphragm.
• Viscera are the organs within ventral cavities.
• Serous membranes (pleura, pericardium, peritoneum) line the cavities and organs and contain serous fluid for lubrication and protection.

Thoracic Cavity

• Formed by ribs, intercostal muscles, sternum, and thoracic vertebrae.
• Contains the pericardial cavity (heart), pleural cavities (lungs), and mediastinum (organs except lungs).

Abdominopelvic Cavity

• Extends from diaphragm to groin.
• Abdominal cavity contains digestive organs and glands.
• Pelvic cavity contains urinary bladder and reproductive organs.
• The peritoneum lines the abdominal cavity; peritoneal and retroperitoneal viscera are identified. Retroperitoneal viscera examples include kidneys, adrenal glands, pancreas, duodenum, ascending and descending colon etc.

Abdominopelvic Regions and Quadrants

• Nine regions are defined by midclavicular, subcostal, and transtubercular lines.
• Four quadrants are formed by midsagittal and transverse lines at the umbilicus.
• Regions are used for detailed discussions; quadrants are used for quick assessments.

Summary

• Anatomy is the study of structure; physiology is the study of function.
• The human body has 11 interdependent organ systems.
• Homeostasis is maintained primarily through negative feedback loops.
• Anatomical terms provide precise communication about the body.