Organization of the Nervous System/ Spinal Reflex Connections

What is going to make up computational units of a neural circuit?

Brain and ganglia

What is the afferent division of the PNS?

Sensory receptor neurons

What is the efferent division of the PNS?

carries motor commands from CNS to PNS muscles and glands

Somatic efferent neurons will go where?

Voluntary motor output to muscles

Where does visceral stimuli come from?

Organs/ internal receptors - not always aware of it

What is the functional unit of the nervous system?

Neurons - editable cells transmitting electrical impulses

Soma cells are ____?

Amitotic - dont divide (lack centrioles) but make neuropeptides

Dendrites do what?

The sight of synapse to receive singals

The axon is the site of neural output _____ will generate AP and ____ will release neurotransmitters?

Axon hillock - ap starts

Synaptic terminals - release neurotransmitters

____ are glia cells that provide structural support and nutrients. ____ provide immune support?

Astrocytes

Microglia

What are the stem cells that line the brain and move CSF?

Ependymal cells

_____ is a cell that provides myelination of axons in the CNS, ____ Does in the PNS?

Oligodendrocytes

Schwann cells

What will Aa fivers do?

Very fast carry muscle spindle and Golgi tendon info

What will AB do?

Mechanoreceptor for proprioception and touch of muscle spindles

Agama will do what?

Less fast pain and temp - mechanical receptors

C fibers are ___ and ___ and therefore they are ____ and carry ___?

Small non-myelinated, slow carry pain on nociceptors

What will we lose first in spinal compression and why?

Large diameters like touch sensation will be lost before pain

What prognosis is for an animal w/ spinal compression that can't feel pain?

C- fibers affected (small fibers) poor prognosis

The corticalspinal tract is also called what?

Pyramidal tract

Lateral corticospinal tract crosses ______.

Ventral corticospinal tracts crosses in the _____.

Medula

Spinal corred

LMN will leave the spinal cord from where?

Ventral horn

What are the voluntary UMN tracts?

Pyramidal tracts (corticospinal)

What are the involuntary nervous tracts?

Extapyramidal

Most reflexes are?

Built in, unlearned responses

What are the 5 basic neural pathways to accomplish a reflex?

Receptor

Afferent

Integrating

Efferent

Effector

What is the Golgi tendon?

A sensory receptor in the musculotendinous junction that, causes the stretched muscle to relax

What is the Muscle spindles?

Muscle spindles are receptors for the stretch reflex. When a muscle shortens it needs to shorten too or it wont be able to signal

What is the monosynaptic stretch reflex?

Reflex when a muscle contracts in response to its being quickly stretched VIA A motor neurons very fast

Group Ia will affect ____ and ____ to detect ____ of ____?

Nuclear bag, and nuclear chain fibers

Velocity of length of change

Group II afferents will affect ____ and detect ____?

Nuclear chain

Length of muscle fivers

What does a-y coactivation?

Activating extrafusal fibers making the intramural fibers shorten

What is polysynaptic stretch reflex?

2 or more synapses in which extensors are activated and flexors inhibited

What is the Polysynaptic pain reflex?

2 or more synapses in which flexors are activated. and extensors are inhibited.

What is going to stimulate the flexor withdraw reflex?

Nociceptor type 3 A-gamma free nerve endings (pain reflex)

What is the crossed extensor reflex?

opposite limb supports body during withdrawal of injured limb

Using a noxious stimulus test you find that opposite limb extends when the dog is in lateral recumbency and the primary limb is being pinched. Is this normal, if not why?

There is a spinal cord inj to the UMN, contralateral extensor should be inhibited but isn't Hyperreflexia is seen

What is the cutaneus trunci reflex?

Sensory Nerves of the cutaneus are stimulating and should result in contractions, if not there is a lesion up stream

What is a segmental reflex? Give an example?

One or few segments/ brain divisions are affected.

- Patellar flexion

What is a intersegmental reflex? Give an example?

Several segments of spinal cord / brain divisions

-cutaneous trunci reflex

What is a long loop intersegmental reflex? Give an example?

Many segments entering and exiting the CNS at the same locations

-knuckling test in dogs

Explain the 5 components reflex using the menace response?

Receptor: photoreceptors

Afferent: CN II

Integrator: Optic cortex of cerebrum

Efferent: CN VII

Target organ: Orbicularis oculi / eyelid closure