9.7 The Synapse
Synapse – junction between two communicating
neurons
Nerve pathway – nerve impulse travels from neuron to
neuron
Synaptic Transmission
Dendrite  cell body  along axon  synapse (gap)
To complete the signal, a NEUROTRANSMITTER is
released at the gap to signal the next neuron
Excitatory – increase membrane permeability,
increases chance for threshold to be achieved
Inhibitory – decrease membrane permeability,
decrease chance for threshold to be achieved
Types of Neurotransmitters
Acetylcholine – stimulates muscle contraction
Monoamines – Norepinephrine & Dopamine (sense of
feeling good, low levels = depression)
Serotonin (sleepiness)
Endorphins (reduce pain, inhibit receptors)
Synapses are highly susceptible to drugs and fatigue

Curare (poison used by S. American Indians) and atropine stops Acetylcholine from depolarising the postsynaptic membrane, i.e. become paralysed.

Strychnine and some nerve gases inhibit or destroy acetylcholinesterase formation. Prolongs and
enhances any stimulus, i.e. leads to convulsions, contraction of muscles upon the slightest stimulus.

Cocaine, morphine, alcohol, ether and chloroform anaesthetise nerve fibers. (inhibitory)

Mescaline and LSD produce their hallucinatory effect by interfering with nor-adrenaline & serotonin
9.8 Impulse Processing
Neuronal pool – groups of neurons that make hundreds of synaptic connections and work together to
perform a common function
9.9 Types of Nerves
Sensory Nerves – conduct impulses into the brain or spinal cord
Motor Nerves – carry impulses to muscles of glands
Mixed Nerves - contain both sensory and motor nerves
9.10 Nerve Pathways
Reflex arc – simple pathway, includes only a few
neurons (reflexes)
Reflex Behavior – automatic, subconscious
responses to stimulu
Knee-jerk reflex (patellar tendon reflex)
stimulus knee  sensory nerve  spinal cord 
motor nerve
Withdrawal reflex – occurs when you touch
something painful
9.11 Meninges = membranes located between bone
and soft tissues of the nervous system
Dura mater = outmost layer, blood vessels,
nerves
Arachnoid mater = no blood vessels, located
between
Pia mater = contains many nerves and blood
vessels to nourish cells of brain and spinal cord
*Cerebrospinal fluid = between arachnoid and
pia maters
9.12 Spinal Cord - nerve column, passes from brain
down through the vertebral canal
- has 31 segments, each with a pair of spinal nerves
Cervical enlargement = supplies nerves to upper limbs
(neck)
Lumbar enlargement = supplies nerves to the lower limbs
(lower back)
FUNCTION: conducting nerve impulses, serves as a
center for spinal reflexes
Ascending tracts = carry sensory info to the brain
Descending tracts = carry motor impulses from the brain
to the muscles
Spinal reflexes – reflex arcs pass through the spinal cord
9.13 Brain
Three Major Parts:
Cerebrum – largest, sensory and motor functions, higher mental function (memory, reasoning)
Cerebellum – coordinate voluntary muscles
Brain stem – regulate visceral functions
DESCRIBE THE FUNCTIONS:
1. Cerebral Hemispheres
2. Corpus Callosum
3. Convolutions / Sulcus / Gyrus
4. Transverse / Lateral / Longitudinal Fissures
Lobes of the Brain
5. Frontal Lobe
6. Parietal Lobe
7. Temporal Lobe
8. Occipital Lobe
9. Cerebral Cortex
10. Ventricles
11. Cerebrospinal Fluid
Functional Regions:
12. Motor
13. Sensory
14. Association
DIENCEPHALON & BRAIN STEM
1. Diencephalon
2. Thalamus
3. Hypothalamus
4. Optic Tract / Chiasma
5. Midbrain
6. Pons
7. Medulla
8. Pituitary Gland
9. Hippocampus
10. Limbic System
TYPES OF MEMORY: Episodic
| Procedural | Semantic | Working