CHAPTER 3: Neural Conduction and Synaptic Transmission

Biological Psychology (Midterms)

Roberto Garcia d Orta

lizard with parkinson disease

tremor-at-rest.

hands shake worse when they are doing nothing at all

Symptoms of Parkinson’s Disease

rigid muscles, a marked poverty of spontaneous movements, difficulty in starting to move, and slowness in executing voluntary movements once they have been initiated.

reptilian stare

describe the characteristic lack of blinking and the widely opened eyes gazing out of a motionless face, a set of features that seems more reptilian than human.

substantia nigra (black substance)

A small group of nerve cells

• unaccountably dying

• These neurons make a particular chemical called dopamine, which they deliver to another part of the brain, known as the striatum.

 microelectrodes

intracellular electrodes, their tips are less than one- thousandth of a millimeter in diameter.

During resting conditions membrane is;

• Permeable to Potassium (K+) (channels are open)

• Impermeable to Sodium (Na+) (channels are closed)

Ionic Basis of the Resting Potential

-70 millivolts

(2) factors that act to distribute ions equally throughout the intracellular and extracellular fluids of the nervous system

RANDOM MOTION

ELECTROSTATIC PRESSURE

RANDOM MOTION

ions in neural tissue are in constant random motion, and particles in

random motion tend to become evenly distributed because they are more likely to move from areas of high concentration to areas

of low concentration than vice versa.

ELECTROSTATIC PRESSURE

Any accumulation of charges, positive or negative, in one area tends to be dispersed by the repulsion among the like charges in the vicinity and the attraction of opposite charges concentrated elsewhere.

4 kinds of ions that contribute significantly to the resting potential:

1. sodium ions (Na*),

2. potassium ions (K*),

3. chloride ions (Cl+),

4. Negatively charged protein ions.

Synapses

The places where neurons connect and communicate with each other

Neurotransmitters

Neurotransmitter molecules are endogenous chemicals that allow neurons to communicate with each other throughout the body.

EXOCYTOSIS

process of neurotransmitter release.

Reuptake

is the process in which the majority of neurotransmitters, once released, are almost immediately drawn back into the presynaptic buttons by transporter mechanisms.

degraded

(broken apart) in the synapse by the action of enzymes proteins that stimulate or inhibit biochemical reactions without being affected by them.

Astrocytes

have been shown to release chemical transmitters, to contain receptors for neurotransmitters, to conduct signals, and to participate in neurotransmitter reuptake.

Gap junctions

are narrow spaces between adjacent neurons that are bridged by fine tubular channels, called connexins, that contain cytoplasm.

Neurotransmitters

- Chemical messengers that allow signals to cross synapses to transmit information from a nerve cell or neutron to a target cell

• Coordinate behavior by stimulating an action or inhibiting an impulse

Amino Acid Neurotransmitters

1. GLUTAMATE

2. GABA

GLUTAMATE

– excitatory neurotransmitter important to memory, cognition, and mood regulation.

High levels

= Parkinson’s Alzheimer’s;

Low Levels

= learning and memory issues

GAMMA-AMINOBUTYRIC ACID (GABA)

- slows down your brain by blocking specific signals in your central nervous system.

Low levels

= mood disorders, anxiety, schizophrenia, autism

Monoamine Neurotransmitters

They are subdivided into 2 groups, catecholamines and indolamines

4 Monoamine Neurotransmitters

DOPAMINE, EPINEPHRINE, NOREPINEPHRINE, SEROTONIN

DOPAMINE

plays a role as a “reward center” and in many body functions, including memory, movement, motivation, mood, attention and more.

 EPINEPHRINE

also known as adrenaline, plays an important role in your body's “fight-or-flight” response.

NOREPINEPHRINE

- increases alertness, arousal and attention and affects your sleep-wake cycle, mood and memory

SEROTONIN

regulates your mood. It’s often called your body’s natural “feel good” chemical. When serotonin is at normal levels, you feel more focused, emotionally stable, happier and calmer.

Acetylcholine

• It is created by adding an acetyl group to a choline molecule.

• the neurotransmitter at neuromuscular junctions, at many of the synapses in the autonomic nervous system, and at synapses in several parts of the central nervous system.

• is a neurotransmitter that plays a role in memory, learning, attention, arousal and involuntary muscle movement.

Medical conditions associated with low acetylcholine levels include Alzheimer's disease and myasthenia gravis.

Unconventional Neurotransmitters

These neurotransmitters are produced in the neural cytoplasm and immediately diffuse through the cell membrane into the extracellular fluid and then into nearby cells

2 Unconventional Neurotransmitters

SOLUBLE GAS and ENDOCANNABINOIDS-

SOLUBLE GAS

includes nitric acid and carbon monoxide.

ENDOCANNABINOIDS-

synthesized from fatty compounds in the cell membrane; they tend to be released from the dendrites and cell body, an anandamide

Neuropeptides

are small proteinaceous substances produced and released by neurons through the regulated secretory route and acting on neural substrates.

5 Neuropeptides

Pituitary peptides, Hypothalamic peptides, Brain gut peptides, Opioid peptides and Miscellaneous Peptides

Pituitary peptides

contains neuropeptides that were first identified as hormones released by the pituitary;

Hypothalamic peptides

contains neuropeptides that were first identified as hormones released by the hypothalamus;

Brain gut peptides

contains neuropeptides that were first discovered in the gut.

Opioid peptides

contains neuropeptides that are similar in structure to the active ingredients of opium,

Miscellaneous peptides

is a catch-all category that contains all of the neuropeptide transmitters that do not fit into one of the mother four categories.