Additional Info.

Properties of Reflexes: a)reflexes are slower than conduction along an axon b)several weak stimuli presented at slightly different times or slightly different location produce a stronger reflex than a single stimulus does c)when one set of muscles becomes excited, a different set becomes relaxed.

temporal summation- repeated stimli within a brief time have cumulative effect.

a set of nerves called the sympathetic nervous system accelerates the heart beat, relaxes the stomach muscles, dilates the pupils of the eyes, and regulates many other organs.

Major synaptic events:

1. The neurons synthasizes chemistries that serve as NT
2. the neuron transports the peptide NT to the axon terminals
3. AP travel down the axon. at the presynaptic terminal, an AP enables CA++ to enter the cell
4. the released molecules diffuse across the synaptic cleft, attach to receptors, and alter the activity of the post-synaptic neuron
5. the NT molecules separate form their receptors
6. the NT molecules may be taken back into the presynaptic neuron for recycling or may diffuse away.

Spatial summation- don't have to be coming from the same portion of the brain, but will have to arrive together.

Temporal summation- simultaneously arriving at the axon hillock and bombarding it with info at different times

Basal Ganglia are a collection of subcortical nuclei and consists of Globus pallidus, Caudate nucleus and putamen. Basal ganglia are involved in the control of movements in the limbic system:

• hippocampus-memory
• Amygdala- aggression, fear
• Mamillary Bodies- looks like boobies!
• Fornix
• Thalamus/Hypo t.
• Cingulate cortex

Cerebral Cortex has two hemispheres and connects by the corpus collosum.

Vestibular system- our sense of balance and movement

• semicircular canals- sensitive to 3 dimensions of space
• saccule
• utricle
  

Gravity and movement displace hair cells- contains "gel" and otoconia
Vestibular system compensates for bodily movements rather than the visual target. If gel is removed, what happens? Sense of balance destroyed? Equalibrium destroyed!!

Somatosensation "Body Awareness"

Cutaneous sense: (on our skin)

• pressure
• temp
• vibration
• pain

pacinian corpuscle: detects sudden displacements or high frequency vibrations on the skin meissners corpuscles: sudden displacement and low frequency vibrations of skin free nerve endings: pain and temp ruffini endings: stretch of skin (indian rug burn) merkels disks: indentation of skin

phantom pain/itching: nerves and azons still try to send signals. The brains cortex for that limb connects to other parts of the body to stay into work. An itch on the chin (new) will feel tickling or touch on arm (amputated).