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BIO201 Anatomy & Physiology
Lecture Outline 8: The Brain
(Loads of great info/images at Harvard's Whole Brain Atlas)
(Excellent neuroscience history & biographies of Neuroscientists)
I. Protection of Brain:
A. Cranial Bones (8)
B. Cranial Meninges
1. Dura mater
2. Arachnoid mater
3. Pia mater
4. Meningitis (see also
infectious
CNS diseases)
II. Cerebrospinal Fluid
A. Choroid plexus
B. Functions
C. Production and Circulation (for more info see CSF Flow)
D. Lumbar Puncture (good site for Spinal Tap info)
III. Blood Supply
A. Circle of Willis
1. cerebrovascular disease (stroke,
aneurysm, CVA info here)
B. Oxygen requirements
C. Glucose requirements
IV. Blood-Brain Barrier
A. Tight junctions
B. Basement membrane specialization
C. Astrocytes
D. Drugs passing BBB
V. Brain Structure:
A. Brainstem
(various Brainstem
sections with labels)
1. Medulla Oblongata
a. vital functions
i. cardiovascular center
ii. respiratory rhythm center
iii. swallow/vomit reflexes
b. contains pyramids (pyramidal decussation of motor tracts)
2. Pons
a. "bridge" between cerebellum and brainstem
b. also contains respiratory centers (works with medulla)
3. Midbrain
a. Corpora quadrigemina (also called "tectum")
i. superior colliculi
aa. controls visual reflexes
ii. inferior colliculi
aa. controls auditory reflexes
b. Substantia nigra
i. helps fine-tune voluntary motor activity
ii. dopamine-producing neurons
iii. degenerates in Parkinson's
disease
c. Red nucleus
d. Reticular formation
i. extends along entire brainstem
ii. maintains consciousness and alertness
iii. releases norepinephrine to higher brain areas ("wake-up call")
B. Cerebellum
1. Compares intended action with actual motor actions
2. Oversees learned actions (e.g. bicycle riding)
3. Ipsilateral control (right cerebellar lobe regulates right side motor function)
4. Structural features
a. Folia (surface "wrinkles")
b. Vermis (central connecting region)
c. Arbor vitae (white matter branches "tree of life")
d. Cerebellar peduncles (attaches to brainstem "feet")
C. Diencephalon
1. Thalamus
a. Major sensory relay center
i. medial geniculate nucleus
aa. relays auditory signals
i. lateral geniculate nucleus
bb. relays visual signals
2. Pineal
a. produces melatonin hormone
i. (check out Mayo
Clinic Letter on melatonin)
b. regulates circadian rhythm
3. Hypothalamus
a. Location
b. Many functions (homeostasis, examples)
i. thirst, hunger centers
ii. sleep & wake centers
iii. thermoregulatory center
iv. blood osmolarity center
v. emotional aspects
vi. MAJOR endocrine center (controls pituitary)
c. mammillary bodies
i. triggers smell-induced memories
d. infundibulum
D. Limbic System
1. System of structures communicating together
2. Functions of limbic system
a. governs learning, memory & emotions
3. Major structures involved
a. amygdala
i. rage, fear, emotions
b. hippocampus
i. located in temporal lobe (deep)
ii. memory processing
iii. severely affected in Alzhiemer's disease)
c. fornix
i. fiber tract connecting hypothalamus and hippocampus
d. mammillary bodies
E. Basal Nuclei
1. Several regions working with cerebral cortex & cerebellum for motor control and muscle tone
2. Corpus striatum ("striped body")
a. caudate nucleus
b. lenticular (lentiform) nucleus
F. Cerebrum
1. Review Structural terms (gyri/sulci; grey/white matter; lobes/hemispheres; etc.)
2. Major Functions of each lobe
a. Frontal lobe
i. motor, precentral gyrus (damage causes apraxia)
ii. speech motor in Broca's area (damage causes of aphasia)
iii. aggression/motivation/personality/judgement in prefrontal area
iv. (Learn about Walter Freeman's Lobotomies)
3. Parietal lobe
a. sensory, postcental gyrus speech understanding in Wernicke's area
4. Temporal lobe
a. auditory, memory processing
b. hippocampus
5. Occipital lobe
a. visual cortex
b. visual association area (damage causes agnosia)
6. Cerebral Lateralization
a. right hemisphere
i. spatial, artistic, imagination, left side motor & sensory cortex
b. left hemisphere
i. language, reasoning, logic, mathematics, right side motor & sensory cortex
7. Corpus Callosum
a. largest fiber tract in brain
b. connects R & L hemispheres
c. involvement in certain forms of epilepsy
VI. Cranial Nerves (Try an interactive cranial nerve tutorial...)
I. Olfactory
II. Optic
III. Oculomotor
IV. Trochlear
V. Trigeminal
VI. Abducens
VII. Facial
VIII. Vestibulocochlear (auditory)
IX. Glossopharyngeal
X. Vagus
XI. Spinal Accessory
XII. Hypoglossal
VII. Neurotransmitters
A. Acetylcholine
1. all neurons exiting CNS release Ach
B. GABA
1. derived from glycine
2. major inhibitory neurotransmitter in CNS
3. Valium enhances GABA's "calming" effects - alleviates anxiety
D. Catecholamines
1. derived from tyrosine
2. dopamine
a. produced in substantia nigra
b. dopaminergic cells degenerate in Parkinson's disease
3. norepinephrine
a. produced by RAS - wakefullness, alertness center
b. effects enhanced or mimicked by cocaine, amphetamines ("speed"), ritalin
E. Serotonin (5-HT)
1. derived from tryptophan
2. possible roles in sleep, psychoses, schizophrenia, hallucinogenic effects of LSD
3. Prozac
enhances effects of serotonin - alleviates depression
F. Enkephalins & Endorphins
1. peptide neurotransmitters
2. pain modulators
3. morphine, heroin, codeine mimic endorphins
G. Substance P
1. pain signal neurotransmitter
2. capsacin (in hot peppers) triggers release
H. Nitric oxide (NO)
1. newly discovered neurotransmitter
2. only neurotransmitter not stored in vesicles
3. role in CNS unclear - possibly involved in memory
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Brain Tutorial: (Covers both anatomy and physiology of the brain (over 200 multiple choice questions) in an interactive tutorial to challenge your cortical synapses!!) |