Anatomy and Physiology of Special Sensory Organs
Sensory organs can be labeled as special sensory structures that permit sight, hearing, odor, and flavor. Sensory structures permitting proprioception, touch, thermal, and pain perception can be classified as more advanced sensory organs. The sensory neurons are trained to find out modifications in the external and internal conditions so that a person's body can react to that change. A stimulus is the first signal that is recognized by any sensory receptor of the body. Stimulus is an impulse generated when there is a change in the surroundings of a person. For example, a heated environment will alert the brain through the thermal sensory organs and generate a reflex accordingly.
Sensory Receptors
The human sensory system is one of the most complex and highly evolved structures, which processes a myriad of incoming messages. This well-coordinated system helps an organism or individual to respond to external stimuli, appropriately. The sensory receptors are an important part of the sensory system. These receptors are specialized epidermal cells that respond to external environmental stimuli. These receptors consist of structural and support cells that form the peripheral unit of the receptor and the neural dendrites which receive and detect the external stimuli.
- **No Fur:**
- If the vertebrate does not have fur, we move to the next set of distinguishing features.
3. **Feathers vs No Feathers (for vertebrates without fur):**
- **Feathers:**
- If the vertebrate has feathers, it is classified as a **Bird**.
- **No Feathers:**
- If the vertebrate does not have feathers, we proceed further into the classification.
4. **Dry Skin vs Moist Skin (for vertebrates without fur or feathers):**
- **Dry Skin:**
- If the vertebrate has dry skin, it is classified based on the presence or absence of scales.
- **Scales:**
- Vertebrates with dry skin and scales are classified as **Reptiles**.
- **Moist Skin:**
- Vertebrates with moist skin are further classified into:
- **No Scales:**
- Vertebrates with moist skin but no scales are classified as **Amphibians**.
- **Scales:**
- Vertebrates with moist skin and scales are classified as **Fish**.
**Purpose of the Classification Flowchart:**
This flowchart is used for:
- **(A) Ident](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F5ef43a59-4757-4198-aa58-d5c76c34d5fd%2F402e9c1e-e195-4508-8548-e8dcdfbc774b%2Fps9wf1w_processed.jpeg&w=3840&q=75)
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**Multiple Choice**
**Question 5**
*What is the purpose of a dichotomous key?*
[Audio playback interface with the following options: Play, Pause, Rewind, and Fast-Forward. The current position is at 0:00 of a 0:10 long recording. Speed: 1x.]
[Below the audio interface is part of a diagram, cut off in this image. It appears to include a branching tree structure, likely related to biological classification, with "Vertebrate" at the top. Two arrows point downwards, diverging to different categories or sub-categories, although specific details are not fully visible.]
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