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Biology for Secondary Schools

control centre, and an effector as seen of an integrating centre is the hypothalamus
in Figure 5.1. Receptors are the sensory which is located near the pituitary gland
components that detect changes in the found in the brain. It plays a crucial role
internal or external environment. Examples in many important body functions such as
include chemoreceptors, which detect releasing hormones and regulating body
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changes in the organism’s blood pH and temperature. The result of that response
baroreceptors which monitors blood feeds the effector, either enhancing it with
pressure. The role of receptor organs is to positive feedback or depressing it with
sense changes in the external or internal negative feedback. An effector is any organ
environment and send the information to or cell that receives information from the
the control centre. The detectable changes control centre as feedback. It acts to bring
in the internal or external environment that about the changes required to maintain
result in a functional activity or response is homeostasis. Example of an effector organ
called stimulus. The control centre process is the kidney which tends to retain water
the information received from receptors and when blood pressure of an organism is
initiates appropriate responses to maintain too low to maintain proper circulation and
homeostasis. The most important example prevent dehydration.
Stimulus

Receptor Control centre Effector Response

The response to stimulus leads to a change
Figure 5.1: Components of the homeostatic control mechanism

Role of the gut microbiome in hormonal balance, digestion, support
homeostasis nutrient absorption and energy
The gut microbiota refers to the vast balance, affecting conditions such
community of microorganisms (bacteria, as obesity and diabetes.
viruses, fungi, and other microbes) that (b) Immune response: Gut bacteria
live in the digestive tract, primarily in the interact with the immune system to
large intestine. These are critical factor regulate inflammation and prevent
in maintaining homeostasis. The diverse autoimmune diseases.
microorganisms in the gut contribute to: (c) Neurotransmitter production:

(a) Metabolic regulation: The gut Some microbiome in the gut plays a
microbiota influences metabolism, crucial role in brain function through

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