The Human Senses

How does our body enable us to TASTE & SMELL?

Sensory nerves associated with taste and smell are located in the mouth and nasal cavity. Once a stimulus is detected an impulse is sent to the brain.

Signals from these nerves work together to create a combined effect in the brain.

Olfactory Nerve: transmits information from sensory receptors in the mouth and nasal cavity to the brain. The brain will enable the body the determine a sense of smell.

Olfactory sensations also contribute to long-lasting memories and emotion.

Taste buds: detect combinations of chemicals that we identify as sweet, sour, salty, bitter and umami.

Umami: represents the taste of the amino acid called glutamate.  It can be described as a pleasant "brothy" or "meaty" taste with a long lasting, mouthwatering and coating sensation over the tongue. 

All other taste sensations, such as coffee, cinnamon, garlic and pepper, are combinations of the primary tastes.

Sound waves enter the auditory canal and cause the eardrum to vibrate. The sound waves continue to the cochlea.

Cochlea: A spiral-shaped cavity of the inner ear that resembles a snail shell and contains nerve endings essential for hearing.

Auditory nerve: transmits information from the inner ear to the brain. The brain will enable the body the determine a sense of sound and balance.

Semicircular canals: three looped fluid-filled tubes, at right angles to one another found in the inner ear. They help determine the sense of orientation and equilibrium (balance).

The skin has many types of sensory receptors:1. Touch2. Heat3. Cold4. Pressure5. Pain

Some sensory receptors become less sensitive and trigger less signals to the brain.

1. Light travels through the pupil to the lens. The iris tissue will change the pupil’s size to allow more or less light in.

2. The lens inverts the image and focuses it on the retina. 3. Rods and cones in the retina provide light-sensitivity and

information about color. 4. The rods and cones are connected to the optic nerve and

help send light & color sensory information to the brain.

Cow Eye Dissection Video http://www.exploratorium.edu/learning_stu

dio/cow_eye/

Eye Vocabulary

Pupil: The dark circle in the center of the eye. It’s a hole that lets light into the inner part of the eye.

Iris: A muscle that controls how much light can enter the eye.

Lens: Clear flexible part of the eye that inverts an image and focuses it on the retina.

Retina: innermost layer of the eye that contains rods and cones

Optic Nerve: transmits information from rods and cones to the brain. The brain will enable the body the determine the sense of sight.

Eye Vocabulary

Pupil: The dark circle in the center of the eye. It’s a hole that lets light into the inner part of the eye.

Iris: A muscle that controls how much light can enter the eye.

Lens: Clear flexible part of the eye that inverts an image and focuses it on the retina.

Retina: innermost layer of the eye that contains rods and cones

Optic Nerve: transmits information from rods and cones to the brain. The brain will enable the body the determine the sense of sight.

http://www.colorschemer.com/online.html

Evolution of Human Color Vision

Humans gained the ability to see color at the expense of losing the sensitivity to smell and the ability to detect pheromones (tasteless and odorless chemical substances that activate a behavioral response from the opposite sex of the same species).

Human color vision has become the primary sense that we depend on for all aspects of our lives, from love to survival.