Regulation of Body Fluid Mechanism & Endocrine System

1. Regulation of Body Fluid Mechanism:

• Body Fluids: All the water in the body, including intracellular fluid (within cells) and extracellular fluid (outside cells).

• Characteristics and Properties of Body Fluid:

• Concentration: The amount of solute dissolved in a given amount of solvent. The concentration of solutes such as ions, glucose, proteins, etc., affects osmotic pressure and cell activity.

• Pressure: The force acting on the surface of the fluid, created by water molecules and solutes in the solution. Osmotic pressure plays a crucial role in the transport of substances across cell membranes.

• Volume: The amount of body fluid. Extracellular fluid volume affects blood pressure and blood flow.

• pH: The acidity or alkalinity of body fluid. pH is maintained at a stable level in the body to ensure normal biochemical reactions.

• Hormones: Chemical substances secreted by endocrine glands, influencing the biological activities of the body, regulating the concentration, pressure, volume, and pH of body fluids.

Note:

• Changes in the concentration, pressure, volume, and pH of body fluids can be a sign of pathology.

• Maintaining the homeostasis of body fluids is essential for ensuring the normal functioning of the body.

2. Endocrine System:

• Endocrine System: A system of endocrine glands that secrete hormones, chemical substances secreted into the blood and extracellular fluid, which regulate the activities of the body.

• Endocrine Glands:

• Pineal Gland: Secretes melatonin, which regulates the sleep-wake cycle.

• Pituitary Gland: Secretes many hormones, regulating the activity of other endocrine glands and other organs and organ systems in the body.

• Hypothalamus: Regulates the activity of the pituitary gland.

• Thyroid Gland: Secretes T3, T4, which regulate energy metabolism.

• Parathyroid Gland: Secretes PTH, which regulates the balance of calcium and phosphorus in the blood.

• Thymus Gland: Secretes hormones that help develop the immune system.

• Pancreas: Secretes insulin and glucagon, which regulate blood sugar levels.

• Adrenal Gland: Secretes cortisol, aldosterone, adrenaline, etc., which regulate stress response, blood pressure, and metabolism.

• Sigmoid Gland: Secretes hormones that help regulate digestive activity.

• Gonads: Secrete sex hormones, which regulate development and reproduction.

Note:

• Endocrine glands work according to a feedback mechanism, ensuring the homeostasis of the body.

• Any disturbance in the activity of the endocrine system can lead to serious diseases.

3. Bioactive Substances:

• Bioactive Substances: Chemical substances that regulate the physiological activities of the body.

• Characteristics of Bioactive Substances:

• Chemical Mediator: Bioactive substances are secreted from one cell and act on target cells.

• Secretion into the body: Bioactive substances are secreted into the blood or extracellular fluid, transmitted to the target cells.

• Regulation of Target Cell Activity: Bioactive substances act on target cells through receptors, activating or inhibiting biochemical reactions in the cell.

Note:

• Bioactive substances can be endogenous (produced by the body) or exogenous (introduced from outside the body).

• Bioactive substances can have a variety of regulatory effects on the physiological activities of the body.

4. Stem Cells:

• Stem Cells: Undifferentiated cells capable of self-replication and differentiation into different cell types.

• Roles of Stem Cells:

• Regeneration and Repair of Damaged Tissues: Stem cells can differentiate into specialized cells to replace damaged cells.

• Development of New Organs and Tissues: Stem cells can be used to create new organs and tissues, used for organ transplantation.

Note:

• Stem cell research is rapidly developing, promising many potential applications in medicine.

5. Definition of Bioactive Substances:

• What is a bioactive substance?: A chemical substance secreted from endocrine cells, which regulates the activity of the body.

• Who secretes it?: Secreted by endocrine cells, which are part of the endocrine glands in the body.

• Where is it secreted into?: Secreted into the blood or extracellular fluid.

• Why is it secreted?: To transmit to target cells and regulate the activity of target cells, affecting the function of organs and organ systems.

Note:

• The questions Who, Where, Why help differentiate between different types of bioactive substances.

6. Drugs and Bioactive Substances:

• Drugs: Exogenous bioactive substances, used to treat diseases.

• Exogenous Bioactive Substances: Bioactive substances created from sources outside the body, often synthesized in laboratories.

Note:

• Drugs can have similar regulatory effects on the physiological activities of the body as endogenous bioactive substances.

• The use of drugs should be prescribed by a doctor to avoid side effects.

7. Regulation of Bioactive Substance Secretion:

• Hypothalamic-pituitary-endocrine gland axis: The main regulatory mechanism in the endocrine system, ensuring the homeostasis of the body.

• Biological Rhythms: The secretion of bioactive substances can change according to the day-night cycle, menstrual cycle, etc.

• Stimulation: External factors such as stress, light, noise, etc. can stimulate the secretion of bioactive substances.

• Feedback Mechanism: A feedback mechanism, regulating the secretion of bioactive substances, ensuring the homeostasis of the body.

Note:

• Understanding the factors influencing the secretion of bioactive substances helps us to have more effective treatment methods for diseases.

8. Important Time Points in Endocrine Testing:

• Time Point of Blood Draw for Testing: This is an important time point, affecting the test results.

• Reasons for Importance:

• Biological Rhythms: The concentration of bioactive substances can change according to the day-night cycle, menstrual cycle.

• Body Condition: Stress, eating, exercise can affect the concentration of bioactive substances.

Note:

• Following the doctor’s instructions on the time of testing helps ensure accurate test results.

9. Receptor:

• Receptor: Specific proteins, located on target cells, capable of binding to bioactive substances, activating or inhibiting biochemical reactions in the cell.

• Location of the Receptor:

• On the Cell Membrane: For water-soluble bioactive substances, such as peptide hormones, catecholamines.

• In the Cytoplasm: For oil-soluble bioactive substances, such as steroid hormones.

• In the Nucleus: For oil-soluble bioactive substances, such as T3, T4 hormones.

Note:

• The specific binding between bioactive substances and receptors is the basis for the regulatory activity of bioactive substances.

10. Bioactive Substances as a Transmission Pathway:

• Bioactive Substances: A transmission pathway for information from endocrine cells to target tissues.

• Mechanism of Action:

• Endocrine Cell: Secretes bioactive substances.

• Bioactive Substance: Transmitted in the blood or extracellular fluid.

• Target Tissue: Receives signals from bioactive substances through receptors.

• Biochemical Reactions: Activates or inhibits biochemical reactions in target cells.

Note:

• Bioactive substances act as “messengers” for the endocrine system, ensuring the coordinated activity of organs in the body.

In conclusion, the endocrine system plays a crucial role in maintaining homeostasis and regulating the physiological activities of the body. Understanding bioactive substances, endocrine glands, and the mechanism of action of the endocrine system provides us with the necessary knowledge to protect our health and treat diseases effectively.