Neuropsychology Exam 2

Chapters 5-7

otto loewi

He discovered the neurotransmitters acetylcholine (ACh) and epinephrine(EP)

Cholinergic Neurons

Release ACh

Epinephrine Neurons

Release EP

Noradrenergic Neurons 

Release norepinephrine (NE) or noradrenalin (NA)

Step 1 in Neurotransmission

Synthesis: some neurotransmitters are transported from the call nucleus to the terminal button. others are made from building blocks imported into the terminal, are packaged into vesicles there,

Neurotransmitters

they can be excitatory or inhibitory ( ACh inhibitory in the parasympathetic nervous system, NE excitatory in the parasympathetic nervous system, ACh is inhibitory on organs in the ANS but excitatory on body muscles )

Presynaptic Membrane

Membrane on the axon terminal

synaptic cleft 

Space between the axon terminal and the dendritic spine 

Postsynaptic Membrane

Membrane on the dendritic spine

Synaptic Vesicles and Storage Granules- Other specialized structures

Located inside the axon terminal, contains the neurotransmitter

Functional Brain Imaging (fMRI) advantages

can display changes in neural activity and it has high spatial resolution

fMRI Disadvantages 

it has poor temporal resolution, its expensive(not expensive as PET), and can be difficult for patients to endure 

Single-cell recording 

It has the highest resolution, lowest generalizability. Its invasive 

EEG

Its uncomplicated and inexpensive

Step 1 in Neurotransmission

Synthesis: some neurotransmitters are transported from the cell nucleus to the terminal button. Others are made from building blocks imported into the terminal, are packaged into vesicles there 

Step 2 in Neurotransmission

Release: in response to an action potential, the transmitter is released across the membrane by exocytosis

Step 3 in Neurotransmission

Receptor action: the transmitter crosses the synaptic cleft and binds to a receptor

Step 4 in Neurotransmission

Inactivation: The transmitter is eother taken back into the terminal or inactivated in the synaptic cleft

Diffusion

diffuses away from synaptic cleft

degradation

enzymes in cleft break down neurotransmitter

Reuptake

transmitter taken back into presynaptic axon terminal for reuse

The main neurotransmitter at the neurpmuscular junction is 

Acetylcholine 

Renshaw loop

Motor neuron axon projects to a muscle, its axon collateral remains in spinal cord to synapse with an inhibitory Renshaw interneuron, the interneuron synapses on the motor neuron. Interneuron contains glycine, which can inhibit the motor neuron

Drug Actions in Synapses

Drugs can influence any component of neurotransmission

Drug Agonists

Drugs that increase the effectiveness of neurotransmissions

Otto Loewi’s Experiment

He used electrical stimulation of the vagus nerve to decrease the beating of a frog heart immersed in a fluid. The fluid was then transferred to container with a second frog heart. The beating of the second frog heart decreased as well

Otto Loewi Conclusion

The vagus nerve releases a chemical that slows down the heart

Axodendritic

Axon-dendrite

Axomuscular

Axon- muscle

When the motor neuron in a Renshaw loop fires to release ACh, what happens next?

Small-Molecule Transmitters

Small organic molecules, Synthesized and packaged in axon terminals. Derived from the food we eat. It is quick acting

Amines

Chemicals that contain an amine group, NH, in their structure; Dopamine, Norepinephrine, and Epinephrine are synthesized by the same biochemical pathway

L-Dopa

Can be used to bypass the rate-limiting factor, is used to treat Parkinson’s Disease

Serotonin (5-HT)

Regulates mood, aggression, appetite, arousal, pain, and respiration. Derived from trytophan

Amino Acids

Gluatmate(excitatory), GABA (inhibitory), Glycine (Inhibitory), Histamine (causes constriction of smooth muscles)

Neuropeptides

Multifunctional chains of amino acids made by the cell’s DNA

peptide transmitters

Serves as hormones, activate in response to stress, encourage mother-child bonding, facilitate learning , regulate eating and drinking, respond to pleasure and pain

Transmitter Gases

Synthesized as needed by the cell, can be produced in many regions of the cell, diffuse away from the cell after production

Nitric Oxide (NO)

Controls muscles in intestinal walls, dilates blood vessels in the brain and in the genital organs.

Viagra 

Acts by enhancing action of NO

SIDS

Is a sudden unexplained death of an infant under 1 year of age, Infants who die of iy show reduction in serotonin neurons.

Sleep Apnea

Form in which the brain fails to tell the muscles to breathe. Indivuals with it have abnormalities in serotonin neurons

Noradrenergic System

Learning and emotions. Decreases may lead to Major Depression, ADD, ADHD, and increases may lead to Mania 

Serotonergic system

Waking pattern, learning, emotion. Decreases are related to depression, increases are related to schizophrenia, obsessive- complusive disorder, decreases for sudden infant death syndrome

Cholinergic System

Normal waking behavior and memory, degernerate during parkinsons disease

Dopaminergic system

Nigrostriatial Pathway – Movement
• Degenerates during Parkinson’s disease
– Mesolimbic Pathway – Affected by Addictive Drugs
• Produces pleasure
• Excessive dopamine may lead to schizophrenia

Sympathetic division

Cholinergic neurons from the CNS synapse on noradrenergic neurons in the ANS

Parasympathetic division

Cholinergic neurons from the CNS synapse on cholinergic neurons in the ANS