CRS Human Physiology: Homeostasis

Study Notes

Homeostasis involves maintaining stable internal conditions within the human body despite external changes.
It is crucial for good health, preventing disease by keeping various variables within narrow limits.
Seven key conditions (variables) are monitored for homeostasis: body fluid volumes, blood pressure, body fluid composition, body fluid pH, blood gases, blood glucose, and body temperature.

Total Body Water (TBW) is approximately 60%, with 40% being intracellular fluid and 20% extracellular fluid.
The cell membrane is critical in separating and regulating these fluid compartments.

Blood pressure (BP) is influenced by body fluid volume and composition; low fluid volume leads to decreased BP.

Composed of essential ions (potassium, sodium, chloride, calcium) and small molecules.
Ions and water migrate across cell membranes via transport mechanisms like diffusion, osmosis, and active transport.

The normal pH range is between 7.37 and 7.43, optimal for cellular enzyme activity and membrane integrity.

Homeostasis includes the regulation of blood gases, primarily carbon dioxide and oxygen.

Stable blood glucose levels are vital for cellular metabolism and energy production.

Maintaining a stable body temperature is essential for enzymatic reactions and overall metabolic functions.

Composed of a phospholipid bilayer and proteins, the cell membrane functions as a selective barrier.
The fluid mosaic model describes the arrangement where hydrophilic heads face outward and hydrophobic tails face inward.

Lipid-soluble substances (e.g., oxygen, carbon dioxide) can easily cross the membrane, while water-soluble substances (e.g., sodium, glucose) require channels or carriers.
Types of transport include:
- Diffusion: Movement of molecules from high to low concentration.
- Osmosis: Diffusion of water across a semipermeable membrane.
- Facilitated Diffusion: Passive transport through channel proteins.
- Active Transport: Energy-dependent movement against a concentration gradient.
- Bulk Transport: Movement of large substances via vesicles.

RMP is established by the normal ion composition and is critical for neuronal and muscular communication.
Action potentials are electrical signals transmitted by neurons and muscle cells, enabling communication and function.

Various organ systems work collaboratively to sustain homeostatic conditions, each contributing to the overall balance of the body's internal environment.

Regular monitoring of vital signs is essential for assessing homeostasis and detecting potential health issues early, ensuring timely intervention and treatment.