Lecture 15/ Chapter 15&16: Nervous System 3

General sense organs

widely distributed throughout the body. They are found in the skin, muscles, joints, and internal organs. These detect sensations like pain, temperature, touch, pressure, and body position.

Special sense organs

localized in specific, complex structures like the eyes, ears, nose, and tongue. These senses include vision, hearing, balance, smell, and taste.

How many pieces of information do the sensory receptors send to the brain?

4

What are the four main pieces of information the sensory receptors send and what do they do?

1. Modality – What kind of stimulus is it? (touch, temperature, pain, etc.)

2. Location – Where is it coming from? Determined by the receptive field, the area of the body connected to that receptor.

3. Intensity – How strong is the stimulus? Stronger signals increase the firing rate of neurons.

4. Duration – How long the stimulus lasts. Some receptors respond continuously, while others respond briefly.

Explain the sensory receptor response. 

When a receptor is stimulated, it generates a receptor potential (a local electrical change). If the stimulus is strong enough, the receptor will send action potentials along sensory neurons to the brain.

Adaptation

a decrease in receptor sensitivity when exposed to a constant stimulus.

what’s an example of adaptation?

when you first put on clothes, you notice the sensation, but after a few minutes you don’t

Describe the distribution of both sensory receptors in the body.

General sense receptors: scattered throughout the body (skin, muscles, joints and internal organs)

Special sense receptors: grouped in specific structures (eyes, ears, tongue and nose)

what are exteroceptors?

 at or near the surface of the body; detect external stimuli like touch and temperature.

what are Interoceptors (Visceroceptors)?

inside organs; monitor internal conditions like blood pressure or digestion.

what are propioceptors?

in muscles, tendons, and joints; help with body position and movement awareness, tells the brain where the body is in space

free nerve endings

simple, detect pain and light touch. this goes along with a receptor, the type of it

encapsulated endings

enclosed in connective tissue, detect pressure, vibration, and specific touch qualities

what do Mechanoreceptors do?

detect and touch, pressure, stretch, or movement

what do Thermoreceptors do?

receptor for temperature; detect heat and cold changes and adapts quickly

what do Nociceptors do?

receptor for pain; detect pains and warn of tissue damage and adapts slowly

what do Chemoreceptors do?

detect chemical changes (including taste and smell)

what do Photoreceptors do?

detect light (only in the eyes)

what do receptors help us with?

These allow us to move smoothly, avoid injury, and interact physically with our environment

referred pain

when pain is felt in an area different from where the problem actually is. This happens because internal organs and skin share nerve pathways.

examples of referred pain are:

1. Heart attack pain can be felt in the left arm or chest.

2. Kidney pain may be felt in the lower back

Olfaction is the sense of:

smell

Gustation is the sense of:

taste

where is olfaction located?

in the ____ epithelium in the upper nasal cavity

where is gustation located?

Taste receptors are located in taste buds, mainly on papillae of the tongue

olfaction structure

receptor cells have cilia that bind odor molecules

olfaction functions

Signals go through cranial nerve I directly to the brain regions linked to emotion and memory, which is why smells can trigger strong memories

gustation function.

Taste signals travel through: CN VII (Facial nerve) for the front of the tongue & CN IX (Glossopharyngeal nerve) for the back

taste and smell correlation

closely connected, food tastes bland when your nose is congested

what are the five basic tastes?

sweet, salty, sour, bitter and umami