Lesson 2: Sensing the Environment

Vocabulary

• Adaptive behaviour - A behaviour enables the animal to adapt to the changes in the environmental factors/ situations which allows them to survive and reproduce successfully

• Survival - the ability of an organism to survive and reproduce in their environment

• Reproduction - the process in which new individual are created, may it be sexual or asexual.

• Mechanoreceptor - Receptor that is responsible for detecting mechanical stress/ strain (Touch, hearing)

• Thermoreceptor - Receptor that is responsible for detecting temperature changes (heat/ cold)

• Photoreceptor - Receptors that are responsible  for detecting light (eyes)

• Chemoreceptor - Receptor that is responsible for detecting chemicals (taste and smell)

• Magnetoreceptor - Receptor that is responsible for detecting direction, altitude

• Sensory neuron - (Afferent) Neurons that send nerve impulses from receptors to the CNS

• Relay neuron - Neurons that connects sensory neuron to motor neurons

• Motor neuron - (Efferent) Neurons that send nerve impulses from the CNS to effector organs

• Effector - muscle and glands that cause the response to a stimulus

• Stimuli - a change in an organism’s environment to which it can respond

• Reflex arc - an immediate response to a stimulus

Response

The ability to sense the environment allows organisms to respond and adapt to their environment.

An animal’s behaviour is its response to its environment.

A behaviour enables the animal to adapt to the changes in the environmental factors/ situations which allows them to survive and reproduce successfully is referred to adaptive behaviour.

Importance of Sensing the Environment

1. Survival - Adapting to changing conditions is essential for long-term existence.

2. Reproduction - Finding mates via environmental cues is essential for ensuring continuity of the species.
   

3. Navigation - Being able to move in their habitats to optimise resource usage and avoid danger.

Senses

Organisms have receptors in their sense organs to help them detect changes in the environment.

Receptors are specialised for detecting a specific stimulus.

5 Senses are sight, smell, touch, taste, and hearing

• Mechanoreceptor - Receptor that is responsible for detecting mechanical stress/ strain (Touch, hearing)

• Thermoreceptor - Receptor that is responsible for detecting temperature changes (heat/ cold)
  

• Photoreceptor - Receptors that are  responsible  for detecting light (eyes)

• Chemoreceptor - Receptor that is responsible for detecting chemicals (taste and smell)

• Magnetoreceptor - Receptor that is responsible for detecting direction, altitude

Process of Sensing the Environment

1. Detection - sensory organs detect changes/stimuli.

2. Transduction - receptors convert energy turning stimuli into electrical signals.

3. Transmission - Neurons carry signals to the brain for processing

4. Response - The brain sends signals to adjust the behaviour to adapt to the environment.

Example 1:

• your hand touched the hot stove element

• the nerves in your hand detect the pain and send the message to the brain (or spinal cord)

• the brain processes the pain message and decides the correct response

• the brain sends the message back to the hand

• the nerve makes the muscles move the hand away from the hot stove element

Example 2:

• you eat a sour lolly

• chemoreceptors detect the sour tast

• a message is sent to your brain

• the brain processes the message

• a message is sent back to the salivary glands

• your salivary glands produce saliva