homeostasis & hormonal control

Define Homeostasis and it’s importance.

Homeostasis is the maintenance of a constant internal environment

Homeostasis ensure that the conditions, such as temperature and water potential, of blood and tissue fluid are kept within narrow limits.

State the examples of homeostasis in humans

• regulating body temperature

• regulating water potential of blood and tissue fluid

• Regulating blood glucose concentration

Why must body temperature be regulated/ kept constant? Why is a high fever dangerous?

Body cells must be kept at constant temperature. Enzymes in the body can only work within a certain range of temperature. Changes in body temperature result in enzyme inactivation or enzyme denaturation.

Why must the water potential of blood and tissue fluid be regulated?

The composition of blood plasma and tissue fluid must be kept within very narrow limit to ensure that they are kept at constant water potential and prevent cell damage by osmosis. Drastic changes in water potential will affect cells. If blood/tissue fluid water potential is higher than normal, water enters body cells by osmosis causing the cells to swell and burst (lyse). On the other hand, if blood/tissue fluid water potential is lower than normal, water leaves body cells via osmosis, causing the cells may crenate.

Why must blood glucose concentration be regulated?

Body cells require glucose for cellular respiration, cellular respiration provides cells with energy to perform vital activities, a drastic change in blood glucose concentration can be dangerous

Explain the rise and fall blood glucose concentration

• Blood normally contains 70-90mg of glucose per 100cm3 of blood

• Glucose levels in blood rise after a sugary meal and fall during vigorous physical exercise or starvation

how does the pancreas aid in regulating blood glucose concentration?

In the pancreas, there are groups of gland cells known as the islets of langerhans. These islets secrete the hormones insulin and glucagon which are important in the regulation of blood glucose concentration in the body.

How does the body respond when the water potential of your blood increases above normal level or decreases below normal level?

If water potential of your blood increases above the normal level, it is detected by a receptor(detector) in your body. Your body will respond by returning the water potential to the normal level.

Similarly, if the water potential of your blood decreases below normal level, your body will respond and cause the water potential to rise to normal level again.

What is the negative feedback process in homeostatic control?

In homeostatic control, your body reacts to bring an opposite effect to the changes detected. If the system (your body) is disturbed, the disturbance sets in motion a sequence of events that tend to restore the system (your body) to its original state. This is the negative feedback process

What organs and structures can detect changes in the body condition?

the organs and structures that can detect changes in the body condition are known as receptors or sense organs. Any changes from normal condition is called the stimulus.

What are the conditions for negative feedback to take place?

for negative feedback to take place, there must be:

• a normal level or set point to be maintained

• a stimulus, which is a change in the internal environment

• a receptor that can detect the stimulus and send signals to the control centre

• a corrective mechanism, which brings about the reverse effect of the stimulus

  
  

when Receptors detect that the set point is reached, it causes the corrective mechanism to stop.

using numbers label the phases of the negative feedback process, for when condition decreases below normal and condition rises above normal.

above normal:

1. Normal (set point )

2. Stimulus (condition rises above normal)

3. Receptor (detects the stimulus)

4. Control centre

5. Corrective mechanism

6. Condition decreases

7. Normal set point

Receptors detect that set point is reached, causing corrective mechanism to stop.

below normal:

1. Normal (set point)

2. Stimulus (condition decreases below normal)

3. receptor (detects the stimulus)

4. Control centre

5. Corrective mechanism

6. condition rises

7. Normal (set point)

Receptors detect that set point is reached, causing corrective mechanism to stop.