What type of neurons are in the

Central Nervous System?

What is the tract that reflexes take?  

(ie unconscious-spinal cord and brainstem)

Sensory Neurons--> Interneurons--> Motor Neurons--> Effector (muscle or gland)

all neurons synapse in the Spinal Column

What tract do conscious ones take?

(Cortex)

1st Order Sensory Neuron--> 2nd Order SN--> 3rd Order SN--> Interneuron--> Motor Neuron-> Effector.

(1-3 SN synapse in the SC, then Thalmus and Thalmus.

Interneuron synapses in the ganglia of the SC)

• Simple Receptors
• Complex Receptors
• Special Sense Receptors

What structural category of receptor does this belong in:

Free nerve endings- like temp/pain receptors

What structural category of receptor does this belong in:

Encapsulated in Connective Tissue

1. Chemoreceptors- Chemicals signals
2. Mechanoreceptors- Touch and Pressure
3. Photoreceptors- Light
4. Thermoreceptors- Heat and Cold

1. Cutaneous (Somatic)
2. Special Senses

A receptor that is fast adapting.  When stimulus is applied the intensity is fast at first but begins to slow as it adapts.

(like the smelly monkey house at the zoo-- you don't notice after a few minutes)

A receptor that is slow-adapting

When stimulus is applied it starts and maintains a constant frequency.

No.  Sometimes too much stimulus can stimulate other receptors

i.E. when you get hit (pain/pressure receptor) but you see stars.

Depolarization to threshold in a Sensory Receptor.

Must be large enough of a stimulation to generate an action potential.

Receptors found in the Skin!

They detect Touch, Pressure, Heat, Cold and Pain

What type of Cutaneous Receptor detects pressure and is located:

1) Between the Epidermis and Dermis

2) In the Hypodermis

1. Meissner's Corpuscle- light pressure
2. Pacinian Corpuscle- deep pressure

1. Merkel's Disc- Between the Epidermis/Dermis.                                                -Detects light touch
2. Ruffini Ending- In the Hypodermis                        -Detects deep touch

Heat, Cold and pain in the skin.

Found between the Epidermis/Dermis

A receptor in the mouth that opens in response to heat.

-Both Heat and the chemical capsaicin open these receptors. 

(we also have receptors that detect menthol/cold)

When multiple Receptive Fields share the same 2^o Sensory Neuron.

(2 or more 1^o SN but 1 2^o SN) 

The capacity of a neuron to reduce the activity of its neighbor.

(ie- if a blunt object is placed on the skin, many 1^o SN will detect it, but when they synapse with the 2^o SN, the strongest stimulated neuron will inhibit the surrounding ones so that their signal discontinues)

1. Modality
2. Location
3. Intensity
4. Duration
5. Aquity

The Somatosensory Cortex

(Located behind the Central Sulcus)

1. Touch (pressure)
2. Temperature
3. Nociceptors                                                 -Pain                                                       -Itch   

Intensity is based on the frequency

of the Action Potential.

The more frequent the AP is, the more intense it is.