Class 1: Introduction to Human Physiology

Feedback Mechanisms in Human Physiology

• The primary function of a negative feedback system in the body is to maintain homeostasis by counteracting changes in the internal environment.
• Parturition (childbirth) is an example of a positive feedback loop.
• In the context of glucose regulation, the role of negative feedback is to decrease or increase glucose production or uptake to maintain a stable plasma glucose level.
• The endocrine system is primarily responsible for regulating glucose levels within the plasma.
• A 'set point' in human physiology refers to the ideal or desired value of a physiological parameter, such as body temperature or blood glucose level.

Glucose Regulation

• The small intestine absorbs glucose into the plasma through a process facilitated by the hormone insulin.
• When fasting, the liver engages in glycogenolysis and gluconeogenesis to maintain glucose levels.
• It is crucial for the body to tightly regulate glucose levels within the plasma to maintain proper cellular function and prevent diseases like diabetes.

Cell Function and Homeostasis

• A fundamental characteristic of cells that makes them the smallest unit capable of demonstrating life processes is their ability to reproduce.
• Cells contribute to homeostasis in the human body by regulating physiological parameters, such as body temperature and blood glucose levels, through negative feedback mechanisms.
• In the context of cell function, reproduction is crucial for maintaining homeostasis because it allows cells to replace damaged or dying cells and maintain tissue integrity.

Feedback Systems

• A key function of feedback systems in physiology is to maintain homeostasis by counteracting changes in the internal environment.
• The main purpose of negative feedback loops in maintaining homeostasis is to return a physiological parameter to its set point after a disturbance.
• The primary function of a feedback system in human physiology is to maintain homeostasis by regulating physiological parameters.

Feedforward Mechanisms

• A feedforward mechanism is a regulatory mechanism that anticipates and prepares for a change in the internal environment.
• An example of a feedforward mechanism is the preparation of the digestive system for food absorption before eating in response to hunger.
• Understanding feedforward systems is important in studying human physiology because it helps to explain how the body prepares for and responds to changes in the internal environment.

Comparison of Feedback Systems

• The main purpose of comparing and contrasting negative and positive feedback and feedforward systems in human physiology is to understand how the body maintains homeostasis and responds to changes in the internal environment.
• A key difference between negative and positive feedback systems is that negative feedback systems counteract changes in the internal environment, while positive feedback systems amplify changes.
• Feedforward systems differ from negative and positive feedback mechanisms in that they anticipate and prepare for changes in the internal environment, rather than responding to changes after they occur.