a. Synaptic vesicles fuse with cell membrane

b. Exocytosis

c. Diffuses to other side: bind to chemical- or ligand-gated receptor proteins

d. Neurotransmitter action terminated by enzymatic cleavage or cellular uptake

a. Glutamate: major excitatory neurotransmitter

b. Glycine and GABA (gaminobutyric acid) are inhibitory neurotransmitters

Open ligand-gated channels for Cl– Produce an inhibitory postsynaptic potential (IPSP)

a. Epinephrine (adrenaline) and norepinephrine are responsible for the “fight or flight” response

b. Dopamine: used in some areas of the brain that control body movements

c. Serotonin is involved in the regulation of sleep

a. Substance P: painful stimuli

b. Intensity of pain perception depends on enkephalins and endorphins

c. Nitric oxide (NO) A gas; produced from arginine Causes smooth muscle relaxation

a. Spatial summation Many different dendrites produce EPSPs

b. Temporal summation One dendrite produces repeated EPSPs

_______  affects neurons in the brain’s “pleasure pathways” (limbic system)

– Prevents the reuptake of dopamine

– Dopamine survives longer in the synapse and fires pleasure pathways more

– Prolonged exposure triggers the limbic system neurons to reduce receptor numbers

– The user is now addicted

_________ binds to  to specific postsynaptic receptor on

a. Brain adjusts in two ways:

1. Making fewer receptors for the drug

2. Altering the pattern of activation of the drug receptors

_______ have the simplest nervous system

Neurons linked to each other in a nerve net

No associative activity 

a. Hindbrain or rhombencephalon

b. Midbrain or mesencephalon

c. Forebrain or prosencephalon

– Outer layer of the cerebrum4

– Contains about 10% of all neurons in brain

– Gyri and sulci

– Divided into three regions, each with a specific function 

a. Primary motor cortex: Movement control

b. Primary somatosensory cortex: Sensory control

c. Association cortex: Higher mental functions 

a. Aggregates of neuron cell bodies

b. Form islands of grey matter within the cerebrum’s white matter 

– Integrates visceral activities

– Controls pituitary gland

– Forms limbic system, with hippocampus and amygdala

 Responsible for emotional responses

-activating system controls both sleep and the waking state

 Brain state can be monitored by means of an electroencephalogram (EEG)

- Records electrical activity 

– Right hemisphere is adept at spatial reasoning

 Primarily involved in musical ability 

– Short-term memory is stored in the form of transient neural excitations

– Long-term memory appears to involve structural changes in neural connections

memory and thought become dysfunctional

a. Two causes have been proposed

- Nerve cells are killed from the outside in

- External protein: b-amyloid

- Nerve cells are killed from the inside out

- Internal proteins: tau (t)

Reflexes:

– The knee-jerk reflex is monosynaptic

– However, most reflexes in vertebrates involve a single interneuron 

- Axons enter the dorsal surface of the spinal cord and form dorsal root of spinal nerve.

- Cell bodies are grouped outside the spinal cord in dorsal root ganglia.

- Axons leave from the ventral surface and form ventral root of spinal nerve.

- Cell bodies are located in the spinal cord. 

a. Thoracic and lumbar regions of spinal cord

 Most axons synapse in two parallel chains of ganglia right outside the spinal cord 

a. Preganglionic neurons originate in the brain and sacral regions

 Axons terminate in ganglia near or even within internal organs

G protein coupled receptors 

– The receptor is activated by binding to its ligand (Ach, for example)

 The G protein is activated

It activates the effector protein

Sympathetic and parasympathetic divisions

In both, efferent motor pathway has 2 neurons

Preganglionic neuron: exits the CNS and synapses at an autonomic ganglion

Postganglionic neuron: