Anatomy and Physiology 241 Chapter 1

Homeostasis

• Refers to "unchanging," representing dynamic physiological processes.
• Essential for maintaining an internal environment conducive to normal body functions.

Feedback Loops

• Vital for regulating physiological systems around a set point, classified as positive or negative feedback.

Parts of a Feedback Loop

• Comprised of four elements: Stimulus, Receptor (Sensor), Control, and Effector.

Negative Feedback Loop

• Produces responses that counteract the initial stimulus.
• Common in bodily systems, ensuring stability through minor adjustments (e.g., temperature regulation).

Positive Feedback Loop

• Initiates responses that enhance the original stimulus.
• Rare and unstable, can lead to rapid changes (e.g., childbirth contractions, blood clotting).

Stimulus in Feedback Loop

• An event that shifts a physiological set point out of its normal range (e.g., body temperature increase).

Receptor or Sensor

• Specialized area (e.g., thermoreceptors) that identifies changes in the set point.

Control in Feedback Loop

• The regulatory center, often located in the brain, that maintains the set point.

Effector in Feedback Loop

• The entity that executes responses to restore the set point. For example, if the body temperature exceeds normal, blood vessels dilate and sweat glands are activated.

Abnormal Feedback Loop Consequences

• Can lead to diseases or disorders, as seen in blood sugar regulation issues (e.g., diabetes).

Blood Sugar Regulation

• Operates as a negative feedback loop.
• Managed by the pancreas through the release of hormones (Insulin and Glucagon).
• Insulin lowers blood glucose by facilitating cellular uptake, while Glucagon raises blood glucose by signaling liver and muscle glycogen breakdown.

Diabetes Types

• Type 1 Diabetes: Autoimmune destruction of insulin-producing pancreatic cells, necessitating insulin injections for glucose regulation.
• Type 2 Diabetes: Insulin is produced but body cells show reduced responsiveness, often manageable through diet alone.

Anatomy

• Means "to cut up," focusing on the body's structure, observable through dissection and examination.

Physiology

• Defined as "the study of nature," concerning the functions and operations of body systems.

Levels of Organization

• Hierarchical arrangement includes: Atom, Molecule or Compound, Organelle, Cell, Tissue, Organ, Organ System, and Organism.