Transcript General knowledge about nervous system

The Brain
• 3 primary divisions:
– Forebrain
• cortex (folded stuff)
• limbic system, etc (stuff around brain stem)
– Midbrain (top of brainstem)
– Hindbrain (bottom of brainstem + cerebellum)
Hindbrain
Medulla
Pons
Cerebellum
Pons
Medulla
Cerebellum
http://wwwunix.oit.umass.edu/~psyc335c/lectures/hindbrain.gif
Medulla:
Controls vital reflexes: breathing,
heart rate, vomiting, salivation,
coughing, sneezing
- Via cranial nerves
Damage to medulla can be fatal
Large doses of opiates can be fatal
b/c suppress activity of
medulla…why…?...b/c receptors
there!
Pons:
Also has cranial nerves
Location of axon decussation
(where axons cross from one side
of the brain to the other…so left
brain controls right body and vice
versa)
Reticular formation: motor control,
arousal, consciousness
Midbrain:
Cerebral aqueduct
More cranial nerves
Superior colliculus (visual info)
Inferior colliculus (auditory info)
Substantia nigra: dopamineproducing cells, structure that is lost
in Parkinson’s Disease
http://en.wikipedia.org/wiki/Midbrain
Brainstem
Medulla
Pons
Midbrain
Some
forebrain
structures
Senses: Information comes in the cranial nerves and eventually ends up in the cortex
Cranial Nerves
Table 4.4, page 87
Olfactory nerve:
Smell
http://www.besthealth.com/besthealth/bodyguide/reftext/images/
cranial_nerves.jpg
Cranial Nerves
Table 4.4, page 87
Optic nerve:
Vision
http://www.besthealth.com/besthealth/bodyguide/reftext/images/
cranial_nerves.jpg
Cranial Nerves
Table 4.4, page 87
Occulomotor
nerve:
Eye movement,
pupil constriction
http://www.besthealth.com/besthealth/bodyguide/reftext/images/
cranial_nerves.jpg
Cranial Nerves
Table 4.4, page 87
Trochlear nerve:
Eye movement
http://www.besthealth.com/besthealth/bodyguide/reftext/images/
cranial_nerves.jpg
Cranial Nerves
Table 4.4, page 87
Trigeminal nerve:
Skin senses from
face
Jaw muscles for
chewing and
swallowing
(muscles of
mastication)
http://www.besthealth.com/besthealth/bodyguide/reftext/images/
cranial_nerves.jpg
Cranial Nerves
Table 4.4, page 87
Abducens nerve:
Eye movements
http://www.besthealth.com/besthealth/bodyguide/reftext/images/
cranial_nerves.jpg
Cranial Nerves
Table 4.4, page 87
Facial nerve:
Taste
Facial
expressions
Crying
Salivation
Dilation of head’s
blood vessels
http://www.besthealth.com/besthealth/bodyguide/reftext/images/
cranial_nerves.jpg
Cranial Nerves
Table 4.4, page 87
Acoustic nerve:
Aka
vestibulocochlear
or statoacoustic
Hearing
Equilibrium
http://www.besthealth.com/besthealth/bodyguide/reftext/images/
cranial_nerves.jpg
Cranial Nerves
Table 4.4, page 87
Glossopharynge
al nerve:
Taste
Swallowing
Salivation
Throat
movements
during speech
http://www.besthealth.com/besthealth/bodyguide/reftext/images/
cranial_nerves.jpg
Cranial Nerves
Table 4.4, page 87
Vagus nerve:
Sensation from
neck and thorax
Control of throat,
esophagus,
larynx
Parasympathetic
nerves to
stomach,
intestines, etc
http://www.besthealth.com/besthealth/bodyguide/reftext/images/
cranial_nerves.jpg
Cranial Nerves
Table 4.4, page 87
Spinal accessory
nerve:
Aka Accessory
nerve
Neck and
shoulder
movements
http://www.besthealth.com/besthealth/bodyguide/reftext/images/
cranial_nerves.jpg
Cranial Nerves
Table 4.4, page 87
Hypoglossal
nerve:
Muscles of
tongue
http://www.besthealth.com/besthealth/bodyguide/reftext/images/
cranial_nerves.jpg
Cranial nerve signs help determine
the location of a lesion in the brain
• Essential element in clinical neuroanatomy
• Neurological exam:
http://www.vhct.org/case1799/neurologic_
examination.shtml
• Example: patient is asked to stick out
tongue. If the tongue deviates to the left,
the lesion involves the nucleus of the left
hypoglossal nerve.
Nerve key
Nerve
Type of function
On
Optic
Some = sensory
Old
Olfactory
Say
Olympus
Occulomotor
Marry = motor
Towering
Trochlear
Money
Tops
Trigeminal
But = both (S&M)
A
Abducens
My
Fin
Facial
Brother
And
Acoustic*
Says
German
Glossopharyngeal
Bad
Viewed
Vagus
Boys
Some
Spinal accessory**
Marry
Hops
Hypoglossal
Money
* Acoustic-vestibulocochlear, stateocochlear
** Spinal accessory = accessory
Forebrain
•
•
•
•
•
•
•
Thalamus
Hypothalamus
Pituitary gland
Basal ganglia
Basal forebrain
Hippocampus
Limbic system
Thalamus:
Relay station for all sensory info on its way to brain (except
olfactory info)
Many specialized nuclei (ex: LGN, MGN…don’t have to know
these!)
Hypothalamus
Communicates with pituitary gland to alter hormone release
Involved in feeding, drinking, temperature regulation, sexual
behavior, fighting, arousal (activity level)…4 Fs
Pituitary gland
Endocrine gland (hormone producing)
Attached to base of hypothalamus by stalk
Makes and releases hormones into bloodstream
Basal Ganglia
Motor control, but also
memory and emotional
expression
Lose dopamine neurons in
SN  Parkinson’s Disease
http://www.uni.edu/walsh/basalganglia-2.jpg
thalamus.wustl.edu/ course/cbell6.gif
Lose dopamine neurons in
caudate & putamen 
Huntington’s chorea
Don’t memorize image!!! Just
understand that this is a very
complex system!
Basal forebrain
Anterior and dorsal to
hypothalamus
Important for arousal,
wakefulness, attention
http://memorylossonline.com/summer2003/glo
ssary/basalforebrain.jpg
Lose cells in nucleus
basalis  decreased
attention & intellect (AD,
PD)
Hippocampus
Memory formation
HM: temporal lobes
removed for intractable
epilepsy  no longer
formed new memories
http://www.hermespress.com/Perennial_Tradition/hippocampus.gif
http://www.umassmed.edu/bnri/graphics/crusiofig1.gif
Limbic System
important for motivated & emotional behaviors (eating,
drinking, sexual activity, aggressive behavior)
Ventricles
Contain
cerebrospinal fluid
(CSF)
CSF reabsorbed
into blood vessels,
so continuous
turnover
Protective
Reservoir for
hormones, nutrients
http://mywebpages.comcast.net/epollak/PSY255_pix/ventricles.PNG
Ventricle size can indicate
problems
• Enlarged ventricles
as in Alzheimer’s
patients (cell loss).
• Lack of ventricles
due to tumors etc.
Cortex
• 2 hemispheres
– Communicate via
corpus callosum &
anterior commisure
• 4 lobes
http://pegasus.cc.ucf.edu/~Brainmd1/brmodelc.gif
http://www.urmc.rochester.edu/neuroslides/slides/slide201.jpg
http://trc.ucdavis.edu/mjguinan/apc100/modules/Nervous/grosscns/images/brain10.jpg
6 laminae (layers of cells)
The lobes of the cortex
• Frontal
– Thinking
– Prefrontal cortex
• Planning
• Working memory
• Socially
appropriate
behavior
• Delayed-response
task
• Lobotomies
– Primary motor
cortex
• Broca’s aphasia
The lobes of the cortex
• Parietal
– Sensing
• Primary sensory
cortex
Homunculus
The lobes of the cortex
• Temporal
– Spoken language
comprehension
• Wernike’s aphasia
– Hearing
– Vision
• Movement
perception
• Face recognition
– Emotional
motivational
behavior
The lobes of the cortex
• Occipital
– Vision
• Primary visual
cortex
• Damage
causes
“cortical
blindness”
Evolution of Gene Related to
Brain's Growth
• A gene that helps determine the size of the human
brain has been under intense Darwinian pressure in
the last few million years.
• It has changed its structure 15 times since humans and
chimps separated from their common ancestor.
• Evolution has been particularly intense in the five
million years since humans split from chimpanzees
Changes in the architecture of the ASPM protein over the
last 18 million years are correlated with a steady
increase in the size of the cerebral cortex (2002) Dr.
Bruce T. Lahn at U. Chicago. A disrupted form of this
gene was identified as the cause of microcephaly
(people born with an abnormally small cerebral cortex).
Functions
• Forebrain
– the cool stuff (thinking, perceiving, big part of emotion)
• Midbrain
– sensory pathways
• Hindbrain
– motor control, reflexes (breathing, heart rate, etc)