Lecture Notes: The Human Senses

Introduction to the Human Nose

• The human nose can recognize up to 1 billion fragrance compositions.
• Emphasis on the importance of smell in our lives.

Smell and the Criminal Justice System

• Forensic Osmology: Specialists can collect and secure odor traces at crime scenes, comparing them to suspects' scents.
• Example of a criminal being identified by smell despite not leaving physical evidence.

Role of Smell in Attraction

• We subconsciously judge the attractiveness of potential partners by their smell.
• The concept of histocompatibility: More chemical differences between two people lead to a greater attraction.
• The phrase "to feel chemistry" has a biological basis.

Overview of the Senses

• Focus on three main senses: taste, smell, and touch.
• Discussion of the role of each sense and the location of their respective receptors.

Sense of Taste

Functions of Taste

• Assessing food suitability: Helps identify potentially poisonous substances (e.g., bitterness symbolizes venom).
• Digestive efficiency: Taste stimulation increases digestive enzyme secretion and peristalsis.

Anatomy of Taste

• Taste buds: Located on the tongue and are the organs of taste.
• Composed of taste cells or chemoreceptors.
• Ability to recognize five basic tastes: sweet, salty, sour, bitter, and umami (taste of glutamate).
• Spicy taste: Not a recognized taste. Caused by capsaicin, which irritates pain receptors in the mouth.

Sense of Smell

Role of Smell

• Crucial for distinguishing different flavors and enhancing food experiences.
• Example: Odorization of natural gas: Tetrahydrothiophene is added for safety.

Anatomy of Smell

• Olfactory epithelium: Located in the upper nasal cavity, about 4 cm² in area.
• Contains olfactory receptors (olfactory cells).

Sense of Touch

Receptors and Function

• Touch receptors include specialized sensory bodies or free nerve endings found in the skin.
• Function: Protective, informs about danger, and triggers reflexes to avoid harm.

Conclusion

• Appreciation expressed for student support and participation.
• Reminder to stay healthy and look forward to the next lesson.