Unit 1.6D - Smell, Taste, Touch, and Pain

Olfactory System definition

Responsible for our sense of smell (olfaction)

Olfactory System how it works

Molecules from scents in the air enter the nose and dissolve in the mucus of the olfactory epithelium

These molecules stimulate olfactory receptors on specialized neurons, which then send signals to the olfactory bulb in the brain

Bypasses the thalamus and goes to the limbic system and olfactory cortex (linked to emotion and memory)

Epithelium

A tissue at the top of the nasal cavity

Gustation

Scientific word for taste

Taste buds

Specialized structures located on the tongue that contain taste receptors

Primary Taste Categories

Sweet: Sugar, which signals energy-rich foods

Sour: Acidic foods, which may indicate spoilage

Salty: Sodium, essential for body functions

Bitter: Can signal toxins, leading to aversion

Umami: A savory taste, often linked to proteins

Oleogustus: A newer term for the taste of fat, which plays a role in food preferences

Taste Receptors

Located within taste buds, these detect chemicals dissolved in saliva and send signals to the brain via the gustatory pathway

Types of Tasters

Supertasters, Medium Tasters, and Nontasters

Supertasters

People with more taste buds than average, making them highly sensitive to certain flavors, especially bitter ones

Medium Tasters

Most people fall into this category, having a moderate number of taste buds

Nontasters

People with fewer taste buds, meaning they have a reduced sensitivity to tastes, especially bitterness

Skin Receptors

The skin contains specialized receptors that detect pressure, temperature, and pain. These receptors send signals to the brain for processing

Mechanoreceptors

Detect pressure and texture (e.g., when touching a smooth surface)

A type of skin receptor

Thermoreceptors

Detect change in temperature

A type of skin receptor

Nociceptors

Detect pain (damage to tissues)

A type of skin receptor

Somatosensory Cortex

Located in the parietal lobe of the brain, this area processes touch sensations. The body is mapped onto the cortex in a way that reflects the sensitivity of different areas (e.g., hands and lips have more representation due to their high sensitivity)

Thalamus

Acts as a relay station, sending touch information from the body to the somatosensory cortex

What is pain?

The body’s way of signaling potential harm and encouraging protective behaviors. It is processed through both physical and emotional pathways.

Gate Control Theory

Suggests that the spinal cord contains a neurological “gate” that either blocks or allows pain signals to pass to the brain

Phantom Limb Sensation

Refers to the experience of feeling sensations, including pain, in a limb that has been amputated

Occurs because the brain’s sensory map still includes the missing limb, and sometimes misfires