Homeostasis and negative feedback control (4)

Question 1

What forms the internal environment of the body?

Answer 1

Tissue fluid and blood are extracellular fluids and together form the internal environment of the body.

Question 2

What is tissue fluid?

Answer 2

tissue fluid = fluid that surrounds all body cells The external environment is the surroundings where the organism lives.

Question 3

What must be in place for cells to function properly?

Answer 3

For cells to function properly the optimal levels of many factors in the internal environment must remain constant, e.g. concentration of water, electrolytes, carbon dioxide, oxygen, glucose and other solutes as well as temperature and pH.

Question 4

What is homeostasis?

Answer 4

The process of maintaining the internal environment in a constant optimal state, despite constant changes in the external environment, is called homeostasis. homeostasis = staying the same

Question 5

How is homeostasis maintained?

Answer 5

To be able to keep this ‘steady state’ it is important to detect any change from the set point or norm and then to be able to correct this change or deviation. Thus, homeostasis is the ability of an individual to return a particular factor to the set point or norm.

Question 6

How is homeostasis brought about?

Answer 6

The major mechanism that enables an organism to correct any change from the set point and thus maintain homeostasis is negative feedback.

Question 7

What is negative feedback?

Answer 7

Negative feedback is a control mechanism whereby a change from the set point of any factor is corrected by bringing about a change in the opposite (negative) direction. Put another way, if there is too much of a particular factor, a process is set in motion to reduce that factor; if there is too little, a process is set in motion to increase that factor.

Question 8

What is a negative feedback system made up of? (3)

Answer 8

• a receptor that detects a change (deviation) from the set point and sends information to the control center, usually the brain.
• a control center that processes the information and activates corrective mechanisms that it send to the effector.
• an effector that responds and corrects the change, returning conditions to the set point. homeostasis cannot be If for any reason maintained illness or even death can result.

Question 9

What are examples of negative feedback? (2)

Answer 9

Examples of negative feedback by hormones

1. Glucose (blood sugar) concentration in blood
2. Reproductive hormones