8.2.1 Components of Homeostatic Mechanisms

Adjustment of physiological systems within the body is called homeostatic regulation. It involves three parts or mechanisms: the receptor, the control center, and the effector.

Definition

Homeostatic Regulation: Adjustment of physiological systems within the body is called homeostatic regulation. It involves three parts or mechanisms: (1) the receptor, (2) the control center, and (3) the effector.

Receptor: The receptor receives information that something in the environment is changing. It responds to changes in the environment, either external or internal. Receptors include thermoreceptors and mechanoreceptors etc.

Control Center: The control center or integration center receives and processes information from the receptor.

Effector: The effector responds to the commands of the control center by either opposing or enhancing the stimulus.

Main Idea

• Adjustment of physiological systems is called homeostatic regulation.
• It involves three parts:
• The receptor receives information about changes.
• The control center processes the information.
• The effector responds to the commands.
• This ongoing process continually works to restore and maintain homeostasis.

Core Concept

• Receptor = receives information about changes
• Control center = processes information
• Effector = responds to commands
• Receptors include = thermoreceptors, mechanoreceptors
• Control centers include = renin-angiotensin system (RA)
• Effectors = blood vessels, sweat glands, etc.
• Set point = specific value to be maintained

Detailed Explanation

Components of Homeostatic Mechanisms

Adjustment of physiological systems within the body is called homeostatic regulation. It involves three parts or mechanisms: (1) the receptor, (2) the control center, and (3) the effector.

Receptor

• The receptor receives information that something in the environment is changing.
• It responds to changes in the environment, either external or internal.
• Receptors include thermoreceptors and mechanoreceptors etc.

Control Center

• The control center or integration center receives and processes information from the receptor.
• The control centers include the renin-angiotensin system (RA).

Effector

• The effector responds to the commands of the control center by either opposing or enhancing the stimulus.
• This ongoing process continually works to restore and maintain homeostasis.
• For example, during body temperature regulation, temperature receptors in the skin communicate information to the brain (the control center) which signals the effectors: blood vessels and sweat glands in the skin.
• As the internal and external environments of the body are constantly changing, adjustments must be made continuously to stay at or near a specific value: the set point.

For Your Information

• Also known as the renin-angiotensin-aldosterone system (RAAS).
• A critical hormonal system that regulates blood pressure and fluid balance.
• It is the system of hormones, proteins, enzymes and reactions.
• It regulates your blood pressure by increasing sodium (salt) reabsorption, water reabsorption (retention) and vascular tone (the degree to which your blood vessels constrict, or narrow).
• The RAAS consists of three major substances, including Renin (an enzyme), Angiotensin II (a hormone), and Aldosterone (a hormone).

Summary Table of Components

Summary of Homeostatic Regulation

Intermediate Level

Components of Homeostatic Mechanisms

Detailed Description of Each Component

Renin-Angiotensin System (RAS)

Formula / Mathematical Form

Not applicable to this topic.

Solved Example

Not applicable to this topic (descriptive topic).

Important Points

• 1. Homeostatic regulation is adjustment of physiological systems.
• 2. It involves three components.
• 3. Components are receptor, control center, and effector.
• 4. Receptor receives information about changes.
• 5. Receptor responds to changes.
• 6. Receptors include thermoreceptors and mechanoreceptors.
• 7. Control center receives and processes information.
• 8. Control centers include renin-angiotensin system.
• 9. Effector responds to commands.
• 10. Effector either opposes or enhances stimulus.
• 11. Effectors include blood vessels and sweat glands.
• 12. Process continually works to restore homeostasis.
• 13. Temperature receptors in skin communicate with brain.
• 14. Brain signals effectors: blood vessels and sweat glands.
• 15. Adjustments must be made continuously.
• 16. Set point is the specific value to be maintained.
• 17. Renin-angiotensin system regulates blood pressure.
• 18. RAS regulates fluid balance.
• 19. RAS consists of renin, angiotensin II, and aldosterone.
• 20. RAS increases sodium and water reabsorption.

Remember

• - Receptor = receives information about changes
• - Control center = processes information
• - Effector = responds to commands
• - Receptors include = thermoreceptors, mechanoreceptors
• - Control centers include = renin-angiotensin system (RA)
• - Effectors = blood vessels, sweat glands, etc.
• - Set point = specific value to be maintained
• - RAAS = renin-angiotensin-aldosterone system
• - RAAS substances = renin, angiotensin II, aldosterone

Common Mistakes

• 1. Confusing the three components — Receptor, control center, effector.
• 2. Mixing up the functions — Receptor detects; control center processes; effector responds.
• 3. Forgetting the role of the receptor — Detects changes.
• 4. Mixing up the control center — Processes information.
• 5. Forgetting the role of the effector — Responds to commands.
• 6. Mixing up the examples — Thermoreceptors, mechanoreceptors = receptors; RAS = control center; blood vessels, sweat glands = effectors.
• 7. Believing homeostasis is static — It is a dynamic process.
• 8. Forgetting the set point — Specific value to be maintained.
• 9. Mixing up the RAS components — Renin, angiotensin II, aldosterone.
• 10. Thinking homeostatic mechanisms are simple — They are complex and involve many components.

Quick Revision

Adjustment of physiological systems within the body is called homeostatic regulation. It involves three parts or mechanisms: (1) the receptor, (2) the control center, and (3) the effector. The receptor receives information that something in the environment is changing. It responds to changes in the environment, either external or internal. Receptors include thermoreceptors and mechanoreceptors etc. The control center or integration center receives and processes information from the receptor. The control centers include the renin-angiotensin system (RA). The effector responds to the commands of the control center by either opposing or enhancing the stimulus. This ongoing process continually works to restore and maintain homeostasis. For example, during body temperature regulation, temperature receptors in the skin communicate information to the brain (the control center) which signals the effectors: blood vessels and sweat glands in the skin. As the internal and external environments of the body are constantly changing, adjustments must be made continuously to stay at or near a specific value: the set point. The renin-angiotensin system (RAS), also known as the renin-angiotensin-aldosterone system (RAAS), is a critical hormonal system that regulates blood pressure and fluid balance. It is the system of hormones, proteins, enzymes and reactions. It regulates your blood pressure by increasing sodium (salt) reabsorption, water reabsorption (retention) and vascular tone. The RAAS consists of three major substances, including Renin (an enzyme), Angiotensin II (a hormone), and Aldosterone (a hormone).

60-Second Revision

• Receptor = receives information about changes
• Control center = processes information
• Effector = responds to commands
• Receptors include = thermoreceptors, mechanoreceptors
• Control centers include = renin-angiotensin system (RA)
• Effectors = blood vessels, sweat glands, etc.
• Set point = specific value to be maintained
• RAAS = renin-angiotensin-aldosterone system
• RAAS substances = renin, angiotensin II, aldosterone
• Warning: Homeostatic regulation involves receptor, control center, and effector

NEXT TOPIC

• Chapter:
• 8. Thermoregulation and Homeostasis

• Topic:
• 8.2.2 CONTROL OF HOMEOSTATIC MECHANISM

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