Physiological Psychology: Lectures 5,6,7

• Neurons
• Glia

Main cells of the nervous system

Support cells for the neurons

• Schleiden
• Schwann

Cells

• Soma (cell body)
• Dendrite
• Axon

The cell body which contains all the organelles

Located at the beginning of neurons, they receive information from other neurons and transmit electrical stimulation to the soma

Transmits neural signal from the soma

• Nucleus
• Endoplasmis reticulum 
• Golgi apparatus
• Mitochondria
• Cell membrane - phospholipid bilayer

• Contains DNA
• Controls transcription and translation
• Gene expression occurs by transcription of DNA into RNA
• RNA is exported out of the nucleus and used as a template to make proteins

• Membranous organelle that makes lipids and proteins
• Rough ER
• Smooth ER

Translate and make secreted and membrane-bound proteins

Make lipids

Modifies and stores the proteins and lipids made in the smooth ER

• Powerhouse of the cell
• Produces ATP, which is used as an energy source for chemical reactions

• It contains proteins called ion channels that are selectively permeable to various salts or ions
• The barrier that keeps ions,proteins and other molecules where they are needed and prevents them from diffusing into areas where they should not be

• Contains genetic information
• 23 pairs
• 22 are autosomes
• Last pair are sex chromosomes

An organism’s complete set of DNA

• Specialized compounds that contain a nitrogenous base, a sugar, and a phosphoric acid
• Allow organisms to transfer genetic information from one generation to the next

• DNA
• RNA

• Encodes the genetic material of a cell
• Found in nucleus

• serves as blueprint for proteins
• generally found in the cytoplasm as mRNA and ribosomes

read mRNA and add appropriate amino acids to make protein

• motor
• sensory
• interneuron

• Sensory enters dorsal
• Motor exits ventral

glue” that holds the nervous system together

• Provide nourishment for neurons
• Remove waste and dead neurons
• Form scar tissue in the nervous system
• Direct development of the nervous system
• Provide axonal myelination
• Contribute to blood-brain barrier

• Speeds axonal transmission (action potential jumps from node of ranvier to node of ranvier instead of traveling down entire axon)
• Assist in axon regeneration (shwann cells)

• Designed to keep dangerous substances from entering the brain.
• Found in the capillaries which supply blood to the brain

• The rising phase of an action potential when membrane potential rises to approach zero
• Na+ rushes into cell, making it more positive

The falling phase of an action potential when membrane potential falls below resting membrane potential due to slow closing potassium channels

The point of communication between two neurons

• Oligodendrocytes are in the CNS
• Schwann cells are in the PNS

• Chemical transmissions
• Electrical transmissions

neurotransmitter vesicles fuse with the presynaptic membrane and release neurotransmitters into the synaptic cleft.  Then they diffuse across the cleft and bind to receptors on the postsynaptic neuronal membrane

• Axodendritic
• Axosomatic
• Axoaxonic
• Neuromuscular junction

axon to dendrite

axon to cell body

axon to axon

site at which nerve impulses are transmitted to muscles

• Happens at gap junction
• Depolarization & hyperpolarization
• Action potential propagation

• Salt solution
• The salts dissociate into ions

negatively

positively

No, they must go through channels

• Cl-
• Na+

K+

• The same as equilibrium 
• Outward and inward rates of ion movement are the same

level to which the membrane potential must be depolarized in order to initiate an action potential

• the strength of a response of a nerve cell or muscle fiber is not dependent upon the strength of the stimulus
• a nerve impulse resulting from a weak stimulus is just as strong as a nerve impulse resulting from a strong stimulus

• the period immediately following the firing of a nerve fiber when it cannot be stimulated no matter how great a stimulus is applied
• cell is incapable of repeating a particular action because one is already happening

Sodium channels start resetting to their closed state but it will take a stronger stimulus to get another action potential

• Ligand-gated
• Voltage-gated
• Ion-gated
• Non-gated

Neurotransmitters bind with receptors on these channels and open channel

Depolarization of cell membrane opens this channel

Increased intracellularconcentration of a particular ion opens this channel

Always open

high to low

• postsynaptic
• closed

• neurotransmitter
• open

Action Potential Arrives at axon terminal

Neurotransmitter vesicle docks at release site

The Na+ influx causes depolarization which causes voltage-gated Ca2+ channels to open

The Ca2+ influx causes fusion pore to open and vesicle membrane to fuse with axonal presynaptic cell membrane

Incorporation of vesicle with presynaptic membrane occurs as neurotransmitter is released

Vesicle membrane gets added to axon terminal cell membrane

• Synaptic vesicle fusion
• Pinocytosis of membrane
• Cisterna

decreases a neuron’s responsiveness to inputs (acts at inputs)

decreases a neuron’s ability to release transmitter (acts at output)

• Ionotropic Receptors 
• Metabotropic Receptors

direct link to ion channel

indirectly linked to ion channel

activates the receptor

blocks the receptor

• Direct
• Indirect

• Competes for same site as neurotransmitter
• competitive

• Does NOT compete for same site as neurotransmitter
• noncompetitive