Learning Objectives

Question 1

1.1 Define the internal environment and name the fluids which are part of it

Answer 1

Internal environment is the fluid that surrounds and bathes the cells within an organism. It’s crucial for maintaining homeostasis

Blood and interstitial fluid

Question 2

1.2 Draw and label or describe a box diagram of the body showing its subdivision into extracellular fluid (ECF), plasma, interstitial fluid (IF), and intracellular fluid (ICF).

Answer 2

Intracellular Fluid (ICF): Located within cells.
Extracellular Fluid (ECF): Located outside cells.
Plasma: Within blood vessels.
Interstitial Fluid (IF): Surrounds cells, between cells and blood vessels.

Question 3

1.3 Describe the relative osmolalities of intracellular fluid (ICF) and extracellular fluid (ECF).

Answer 3

Under normal conditions, intracellular fluid (ICF) and extracellular fluid (ECF) maintain a state of osmotic equilibrium
. This means they have approximately equal osmolalities

Question 4

1.4 Describe the relative distribution of the following ions between the intracellular fluid (ICF) and extracellular fluid (ECF): Na+, K+, Cl-, and Ca2+

Answer 4

ICF - high concentration of K+
ECF - high concentration of Na+, Cl-, Ca2+

Low concentration of the ions not mentioned between each other

Question 5

1.5 Diagram and describe the phospholipid structure of a cell membrane

Answer 5

Structure of a phospholipid:
- Head - Composed of a glycerol molecule linked to a phosphate group
- Tail - Composed of two fatty acid chains

(Alcohol on glycerol reacts with carboxylic acid in fatty acid)

Question 6

1.6Define homeostasis and give examples of the vital parameters that it regulates

Answer 6

Homeostasis is the maintenance of a stable internal environment within an organism. It’s essential for the proper functioning of cells and tissues. Key vital parameters regulated by homeostasis include:

-Body temperature
- Blood glucose levels
- Blood pressure
- Blood pH
- Fluid and electrolyte balance

Question 7

1.7 Diagram or describe the basic components of a homeostatic negative feedback loop

Answer 7

Components of a Negative Feedback Loop:

• Sensor (Receptor): Detects changes in the internal or external environment.
• Control Center: Receives information from the sensor and compares it to the set point (desired value).
• Output signal - Signal from control centre to effector
• Effector: Carries out the necessary response to bring the variable back to the set point.