Patellar reflex is controlled by
Spine - L2-L4
Spinal reflex
Brain does not control at all
Input/output solely via spinal cord
Sensory input of patellar reflex
Rapid muscle stretch (quad) - detected via stretch receptors (muscle spindle nerve fiber)
Motor output of patellar reflex
Contraction of quadricep muscle (reflex)
Relaxation of hamstring
Pt with T6 injury - how would patellar reflex work?
Reflex still intact - if eyes closed, may not know it happened
Electrical signals between cells
Fast communication
Most often found in cardiac cells
Communication via neuronal cells is done via
Chemical signals
What determines if a neurotransmitter causes an excitatory or inhibitory action?
The kind of ion channel that opens on second cell
Sodium channel opens - creates a ____ effect
Excitatory
Depolarization on second cell results in ____ effect
Excitatory
Potassium channel opens - creates a ____ effect
Inhibitory
Hyperpolarization on second cell results in ____ effect
Inhibitory
Most common type of neurotransmitters in brain
Amino acids
2 most common amino acids in brain
Glycine, glutamate
Catecholamines
Type of monoamine
Dopamine, Norepinephrine, Epinephrine
Co-released with neurotransmitters
Neuropeptides
neuropeptides carry out
Neuromodification
Modify response by second cell, “upregulate”
Neuromodification
Neuromodification is thought to be
LTP - one theory of learning in the brain
Synapse consists of
presynaptic cell
post synaptic cell
synaptic cleft (space in between the 2 cells)
Vesicles of NT are manufactured where
Cell body
Signal to release NT
AP reaching axon terminal
After AP reaches terminal, what occurs
Axon terminal depolarizes
After axon terminal depolarizes, what occurs?
Opening of voltage gated ca2+ channels, Ca2+ flows in
What creates exocytosis
Calcium
Exocytosis
Vesicles filled with neurotransmitters merge with cell plasma membrane, contents dump out
After exocytosis occurs, what happens next?
Acetylcholine floods synaptic cleft, diffuses across, binds to Ach receptor on post-synaptic cell
Binding of Ach to post-synaptic cell results in
Ion channels opening, sodium enters post synaptic cell, AP & muscle contraction occur
Most common amino acids NTs
Glutamate, GABA, Glycine
Inhibitory NT
GABA, Glycine
Excitatory NT
Glutamate
Monoamines
ACh
Serotonin
Histamine
Catecholamines
Portion of cleft where NTs release/bind to receptors
Active zones
-causes darkening on microscopic image
Neuropeptides
Enkephalin Substance P Endorphin Somatostatin ADH Vasopressin
Reason for decreased levels of protein in CSF v plasma
Amino acids (NTs) in CSF would wreak havoc
Where else are neuropeptides found?
Enteric nervous system (GI fxn)
Hormones
Neuropeptide vs hormone
SAME molecule - DIFFERENT location
Neuropeptide in brain is NOT a hormone (if released in neuronal cell)
Hormone - any chemical messenger released into bloodstream & acts systemically by binding to receptors
Cells that need to work together
Electrically coupled
Ion channels that bride the gap between two neighboring cells
Gap junctions
Example of gap junctioned to act as a single unit
Photoreceptors