PR Psych

Question 1

reciprocal inhibition

Answer 1

muscle stretch reflex – two parts: (1) detects stretching of one muscle, sends a signal to a motor neuron to tell the quadricep muscle to contract = a monosynaptic reflex arc which only involves two neurons and one synapse; (2) the initial sensory neuron also synapses with an inhibitory interneuron, which forms an inhibitory synapse with a motor neuron in the hamstring, letting it relax = integrative nature of the nervous system. The two concurrent activities is also an example of reciprocal inhibition

Question 2

What determines the effect (depol., hyperpol, etc.) on the postsynaptic potential?

Answer 2

The receptor for a NT and its associated ion channel. The same NT can be inhibitory or excitatory, and postsyn neurons may have many different receptors.

Question 3

The PNS is separated into the:

Answer 3

(1) Somatic nervous system – responsible for voluntary movement
(2) Autonomic NS – responsible for involuntary control of organs

Question 4

Somatic neurons:

• efferent vs afferent neurons
• NTs that each use

Answer 4

• efferent neurons, or motor neurons: innervate skeletal muscles, use ACh, cell bodies are located in brain stem or ventral spinal cord
• afferent neurons or sensory neurons: cell bodies located in DRG, dendrites extend to DRG from a sensory receptor, axon extends from DRG into the spinal cord and synapse at the cord or in the brain

Question 5

Autonomic neurons:

-efferent vs. afferent neurons

Answer 5

• efferent: preganglionic neuron w soma in brainstem/spinal cord, then axons to autonomic gangliong which is located outside the spinal cord. synapses with postganglionic neuron which axons to an effector
• afferent: similar to somatic afferent, but they can also synapse at the PNS with autonomic efferent neurons to create a short reflex

Question 6

Efferent autonomic neurons:

• Sympathetic
• Parasympathetic (mnemonic?)
• -anatomy
• -NT that each uses

Answer 6

• sympathetic: THORACIC LUMBAR SYSTEM – all preganglionic sympathetic somas are in thoracic or lumbar (chest or lower back) of spinal cord, with short preganglion that terminates in a few, large ganglia outside of the spinal cord.
• • sympathetic pregang uses ACh, sympathetic postgang uses NE, and epi released from adrenal medulla (directly innervated by preganglionic neurons) to augment NE release
• parasymathetic: CRANIOSACRAL SYSTEM – all pregang located in brainstem or sacral (very top or very bottom), send a long . pregang to small ganglion close to the effector, and short post gang that reaches effector right away
• • parasym pregang and postgang both use Ach

-MNEMONIC: PARA LONG PRE

Question 7

Parasympathetic NS Anatomy

Vagus nerve

Answer 7

• 12 pairs of cranial nerves (nerves to and from brainstem), 31 pairs of spinal nerves (nerves to and from the periphery to the spine)
• Vagus nerve: important cranial nerve that goes to/from the brainstem and hear/GI tract; PARASYMPATHETIC ACTIVITY (decrease heart rate, increase GI activity)