Brain, continued

1
Brain, continued
2
Midbrain and hindbrain- relay centers
for sensory and motor pathways Midbrain visual
and auditory reflexes connects with cerebrum and
cerebellum (motor reflexes) Dopaminergic
neurons some required for motor
coordination Others part of mesolimbic
system stimulated by drugs heroin and
morphine- ?production cocaine and
amphetamines- prevent reuptake
3
(No Transcript)
4
See Table 8.3 Stimulants opiates stimulate
opioid receptors cocaine inhibits dopamine
reuptake amphetamines stimulate dopamine
release and so on
5
Hindbrain Metencephalon pons (bridge)-
cranial nerve tracts respiratory
control cerebellum- motor coordination motor
learning- ataxia caused by damage to this
area trained voluntary activity
6
Myencephalon Medulla oblongata- brain stem-
everything must pass through it Many crossed
tracts (pyramids) relay sensory
information cardiovascular responses breathing
RAS- nonspecific activation (wakefulness)
7
(No Transcript)
8
Spinal cord tracts Ascending- send sensory
information to brain Descending-
motor pyramidal- from precentral gyrus (in
cerebrum motor cortex) (corticospinal
tracts) directly into spinal cord other cells
in cortex also contribute many fibers cross
over fine motor activity
9
Extrapyramidal Originate in midbrain and brain
stem many synapses Reticulospinal tracts- many
originate in RAS other tracts activated
10
(No Transcript)
11
Cranial and spinal nerves 12 pairs of cranial
nerves most are mixed nerves except for
those that detect special senses (sensory
only) 31 pairs of spinal nerves- mixed nerves
but separate at ganglion dorsal root-
sensory ventral root- motor Cell bodies of some
autonomic neurons in ganglia outside of spinal
cord
12
(No Transcript)
13
Reflex arc- involuntary response to a
stimulus May consist of a single synapse May
not directly involve the brain at all Some are
much more complicated
14
(No Transcript)
15
(No Transcript)
16
(No Transcript)
17
Spinal reflexes Withdrawal Postural Emptying
(urination, etc.) Can be overridden by higher
brain centers Some local responses are not
controlled by nerves or hormones (blood
vessel dilation, inflammatory response, etc.)