Module 1
Theme 1: Structure and Function
Conceptual Definition: Structure and function are inextricably linked; the way something is built determines what it can do.
Structure: Refers to an object’s form, makeup, or arrangement.
Function: Refers to an object’s job, role, task, or responsibility.
Determination: In this context, to determine means to cause, direct, or govern. Therefore, structure governs function.
Anatomy vs. Physiology:
Anatomy: The formal study of body structures.
Physiology: The formal study of the function of those body structures.
Mechanical Analogy: Hand tools (such as pliers or wrenches) serve as examples where specific physical structures (jaws, handles, hinges) make them uniquely suited to their specific functions (gripping, turning).
Theme 2: Hierarchical Levels of Organization
Levels of Hierarchy (from simplest to most complex):
Atoms: Non-living level.
Molecules: Non-living level.
Cells: The first level of organization where life is observed. The cell is considered the basic unit of all life.
Tissues: Built from groups of cells.
Organs: Built from groups of tissues.
Organ Systems: Groups of organs working together.
Organism: The complete living body.
Principles of Biological Hierarchy:
Each level is composed of parts from the level immediately below it.
Complex structures are fundamentally built out of simpler parts.
Simple structures can be combined in many different ways to produce diverse outcomes.
Life, Metabolism, and Information Flow
Characteristics of Living Things: Life is characterized by the continuous flow of matter, energy, and information.
Information Flow: Life requires information flow within individual cells and between the organism and its environment. This necessitates the ability to detect and respond to stimuli from the world outside the cell.
Metabolism: This involves the transformation and transfer of matter and energy in various ways to build the organism and carry out the work of life. Organisms must obtain this matter and energy from the outside world.
Emergent Properties
Definition: Each new level of organization possesses characteristics that were not present in the level below. These are called emergent properties.
Mechanism: Different organization creates different functions. When the same component parts are organized in a different way, new properties emerge.
Chemical Example: Sodium and Chlorine individually have very different properties than the compound they form (Sodium Chloride/Table Salt).
Biological Example: When biological macromolecules (Carbohydrates, Proteins, Nucleic Acids, Lipids) are organized ‐just so,‐ the emergent property of Life appears at the cellular level.
Theme 3: Homeostasis and Regulation
Homeostasis: The ability of the body to maintain a relatively constant internal environment despite changes occurring in the external environment (e.g., maintaining body temperature).
Critical Limits: Changes that stray too far from normal physiological limits can result in illness or death.
Regulatory Systems: The Nervous and Endocrine systems are the primary regulators of homeostasis. They use chemical messengers to affect organ systems and coordinate activity across different body locations.
Homeostatic Loop Components:
Sensor/Detector/Receptor: Monitors a specific variable and detects changes.
Control Center: Knows the "set-point," interprets input from the sensor, makes a decision, and sends a command.
Effector: A muscle or gland that responds to the command to change the variable.
Negative Feedback Mechanisms
Definition: Negative feedback is the primary mechanism for homeostasis. It counteracts the original stimulus so that conditions remain stable and return toward the set-point.
Process: Sensor detects change > Control center relays information > Effector responds to counteract the stimulus.
Examples:
Body Temperature: Operates like a thermostat. If temperature increases, cooling mechanisms (sweating) activate to decrease it. If temperature decreases, heating mechanisms (shivering) activate to increase it.
Blood Glucose: Normal levels are maintained through regulation. After a meal (Lunch), blood sugar increases; after exercise, it decreases. The liver stores glucose as glycogen or converts glycogen back to glucose to maintain balance.
Blood pH, Blood Pressure.
Positive Feedback Mechanisms
Definition: Positive feedback leads to a change in the same direction as the stimulus, reinforcing
and intensifying it. It is a self-amplifying cycle that does not return to homeostasis until the stimulus is removed.
Examples:
Labor and Delivery: Pressure from the baby activates stretch receptors in the cervix. The brain signals the master gland to release the hormone oxytocin. Oxytocin causes the uterus to contract, which increases pressure on the cervix, stimulating more oxytocin. This continues until the baby is delivered.
Blood Clotting.
Milk Let-down: A baby suckling leads to milk being ejected.
Theme 4: Integration of Systems
Interdependence: No body system functions in isolation. All systems are integrated and function together to keep the organism alive. Dysfunction in one system can and will affect others.
Functional Groupings:
Control and Regulation: Includes the Nervous System (brain, spinal cord, peripheral nerves) and the Endocrine System (various glands producing hormones).
Exchange of Materials with the Environment: Includes the Digestive System and Respiratory System.
Fluid Transport within the Body: Includes the Cardiovascular System and Urinary System.
Structure, Support, and Movement: Includes the Skeletal System and Muscular System.
Protection Against Pathogens: Includes the Immune/Lymphatic Systems and the Integumentary System.
Reproduction: The Reproductive Systems.
Detailed Organ System Functions
Nervous System: Functions as the control center for homeostasis, directs body movement, and allows communication between body parts.
Endocrine System: Regulates homeostasis by producing hormones that alter mood, sleep, tissue function, sexual function, metabolism, growth, and development. Key glands include the Pineal, Hypothalamus, Pituitary, Thyroid, Parathyroid, Thymus, Adrenal, Pancreas, Ovaries, and Testes.
Skeletal System: Provides the body framework, protects organs, stores minerals, and works with muscles to move the body. Components include bones and ligaments.
Muscular System: Consists of skeletal, cardiac, and smooth muscle. Functions to move bones, the heart, and hollow organs. It also helps regulate body temperature.
Digestive System: Functions to break down food and absorb nutrients. Major parts include the salivary glands, esophagus, stomach, liver, gallbladder, pancreas, and intestines.
Respiratory System: Allows gas exchange, moving Oxygen () into the body and Carbon Dioxide () out. It also helps regulate blood pH.
Cardiovascular System: Transports Oxygen, nutrients, and Carbon Dioxide/Nitrogen waste. It helps regulate fluid balance in tissues and body temperature.
Urinary System: Filters blood to remove nitrogen-containing wastes. It helps regulate blood pH and blood volume (Kidneys, Ureters, Bladder, Urethra).
Lymphatic & Immune Systems: Protect against pathogens, absorb and transport fats, and maintain fluid balance.
Integumentary System: Protects the body against the outside world (skin, hair), eliminates metabolic waste, and regulates temperature.
Reproductive Systems: Function is to produce offspring.
Questions & Discussion
Prompt: Think about a part of the body where the way the part is structured determines its function. Describe how the structure might give rise to its function.
Graphing Homeostasis: When drawing a line to show a positive feedback mechanism, it would show a continuous upward or downward trend away from the set-point, unlike the fluctuating wave of negative feedback which stays near the set-point.
System Interaction: Consider how an event in one system (e.g., a respiratory failure) would change the function of another (e.g., the cardiovascular system).