Homeostasis
Define homeostasis in one sentence.
The process of keeping internal conditions stable for cell survival.
What is an organ system?
A group of organs that work together to perform a specific function.
Name the two main fluid compartments in the human body.
Intracellular fluid and extracellular fluid (interstitial + plasma).
In simple terms, what does “mass balance” mean?
What goes in must come out to keep things balanced.
Why is water balance important for homeostasis?
Because water is the medium for all cellular reactions and solute transport.
What is the main purpose of homeostasis?
To maintain a stable internal environment despite external changes.
Give one function for each of the four major tissue types.
- Muscle: movement
- Nervous: communication
- Connective: support
- Epithelial: protection
What percentage of body weight is made up of water?
About 60%.
What happens if input exceeds output in mass balance?
The body accumulates excess substances, disrupting homeostasis.
Which part of the brain acts as a control center for many homeostatic processes?
The hypothalamus.
What are the three parts of a homeostatic control system?
Sensor (receptor), integrating center (control center), and effector.
Name the four main tissue types.
Muscle, nervous, connective, and epithelial tissue.
What maintains the difference in sodium and potassium concentrations across the cell membrane?
The sodium-potassium pump (Na⁺/K⁺-ATPase).
Give two examples of substances regulated through mass balance.
Sodium and water (others include glucose and CO₂).
Give an example of a physiological system that uses feedback control.
The endocrine system (e.g., insulin and glucagon regulating blood glucose).
What would happen if homeostasis failed in the human body?
Internal instability would occur, leading to diseases or organ failure.
Describe the hierarchy of biological organization in the human body.
Cells → Tissues → Organs → Organ Systems → Organism.
Compare the ion composition of intracellular and extracellular fluids.
ICF: high in K⁺ and phosphate; ECF: high in Na⁺ and Cl⁻.
Which organ is primarily responsible for maintaining mass balance?
The kidneys.
Why is the sodium-potassium pump essential for both homeostasis and cell function?
It maintains ionic gradients and electrical balance required for nerve and muscle activity.
Explain how negative feedback maintains homeostasis and give one example.
Negative feedback detects changes and reverses them to restore balance. Example: body temperature regulation through sweating.
How does cellular differentiation contribute to the body’s structure and function?
It allows cells to specialize and form tissues with specific roles.
Explain how osmotic gradients control water movement between compartments.
Water moves toward areas with higher solute concentration to balance osmotic pressure.
Define the principle of mass balance and explain its physiological significance.
Input must equal output to maintain stable internal concentrations of substances.
How do fluid compartments, homeostasis, and mass balance work together to maintain life?
They interact to keep body conditions stable: fluids carry solutes, homeostasis regulates variables, and mass balance maintains total amounts.