Homeostasis

Exam and Coordination

  • External examiners in the UK review exam scripts from all three campuses.

  • Current count: 420 scripts pending marking, which will take about a week.

  • Marks will be released by February.

CFR Module Overview

  • Focus on integrating:

    • Cardiovascular system.

    • Endocrine system.

Homeostasis and Control Mechanisms

  • Definition of Homeostasis:

    • Stays stable despite external changes (e.g., temperature fluctuations).

    • Aims to maintain core body temperature around 37 degrees.

  • Feedback Mechanisms:

    • Negative Feedback: Most common regulation method that counteracts changes.

    • Positive Feedback: Amplification processes (cascades) for specific physiological events (e.g., childbirth).

Importance of Homeostasis

  • Homeostasis creates an ideal environment for cellular processes.

  • Key factors influencing homeostasis:

    • pH

    • Oxygen levels

    • Temperature

    • Osmolarity (saltiness)

  • Disruptions lead to protein denaturation, affecting enzyme function.

Protein Structure Influences

  • Amino Acids and Protein Structure:

    • Interactions between amino acids are sensitive to environmental changes.

    • Changes in pH can disrupt hydrogen bonds and tertiary structure, causing denaturation.

Responses to Changes

  • After consumption (like donuts), blood glucose levels rise, necessitating regulatory responses to return to normal levels (5-10).

  • Body uses internal systems to adapt to dramatic external changes without compromising cellular function.

Nervous and Endocrine System Role

  • Communication between systems is vital for homeostasis.

    • Receptors detect changes (e.g., blood pressure, pH).

    • Central Nervous System (CNS) processes this information and issues responses.

    • Reflex Actions: These responses are typically outside conscious control (e.g., heart rate regulation).

Sensors and Integration Center

  • Sensors: Monitor variances (e.g., blood pressure, blood pH).

  • Integration Center:

    • Mainly the hypothalamus for temperature regulation.

  • Effectors: Mechanisms that enact changes to bring conditions back to set levels (e.g., shivering for cold).

Specific Examples of Control Mechanisms

  • Temperature Regulation:

    • Responses include vasoconstriction and shivering to maintain core temperature if environmental temperature drops.

  • Blood Pressure Control:

    • Changes detected by stretch receptors in the arteries.

    • Information relayed to the medulla oblongata to regulate heart function based on blood pressure readings.

Positive vs. Negative Feedback Mechanisms

  • Negative Feedback: Aim to reduce the original stimulus once normal is achieved (e.g., blood pressure normalization).

  • Positive Feedback: Amplifies changes until a specific outcome is achieved (e.g., oxytocin release during childbirth).

Adaptation vs. Acclimatization

  • Adaptation: Genetic changes that allow populations to thrive in different environments (e.g., mountain dwellers adapting to high altitudes).

  • Acclimatization: Temporary physiological adjustments to new environments (e.g., increased red blood cell production when moving to higher altitudes).

Daily Body Temperature Fluctuations

  • Core temperature rises naturally in the morning due to preparation for activity.

  • Avoiding afternoon lethargy can be achieved through light exposure, hence regulating melatonin and energizing the body.