1. 12
The Central Nervous System: Part 3 –CSF, BBB, CVA

2. Brain Video
Neurotransmitters – Noradrenalin, serotonin, dopamine and endorphins

3. Cerebrospinal Fluid (CSF)
Composition
Watery solution formed from blood plasma
Less protein and different ion concentrations than plasma
Constant volume
MDufilho

4. Cerebrospinal Fluid (CSF)
Functions
Gives buoyancy to CNS structures
Reduces weight by 97%
Protects CNS from blows and other trauma
Nourishes brain and carries chemical signals
MDufilho

5. Normal volume ~ 150 ml; replaced every 8 hours
Choroid Plexuses
Hang from roof of each ventricle; produce CSF at constant rate; keep in motion
Clusters of capillaries enclosed by pia mater and layer of ependymal cells
Ependymal cells use ion pumps to control composition of CSF and help cleanse CSF by removing wastes
Normal volume ~ 150 ml; replaced every 8 hours
MDufilho

6. containing glucose, oxygen, vitamins, and ions (Na+, Cl–, Mg2+, etc.)
Figure 12.24b Formation, location, and circulation of CSF.
Ependymal
cells
Capillary
Section
of choroid
plexus
Connective
tissue of
pia mater
Wastes and
unnecessary
solutes absorbed
CSF forms as a filtrate
containing glucose, oxygen,
vitamins, and ions
(Na+, Cl–, Mg2+, etc.)
Cavity of
ventricle
CSF formation by choroid plexuses
MDufilho

7. Right lateral ventricle (deep to cut) Interventricular foramen
Figure 12.24a Formation, location, and circulation of CSF.
Slide 1 4
Superior
sagittal sinus
Arachnoid villus
Choroid plexus
Subarachnoid space
Arachnoid mater
Meningeal dura mater
Periosteal dura mater 1
Right lateral ventricle
(deep to cut)
Interventricular
foramen
Third ventricle 3
Choroid plexus
of fourth ventricle
Cerebral aqueduct
Lateral aperture
Fourth ventricle
1 The choroid plexus of each
Ventricle produces CSF.
Median aperture 2
2 CSF flows through the ventricles
and into the subarachnoid space via
the median and lateral apertures.
Central canal
of spinal cord
3 CSF flows through the
subarachnoid space.
(a) CSF circulation
4 CSF is absorbed into the dural
venous sinuses via the arachnoid villi.
MDufilho

8. Figure 12.25 Hydrocephalus in a newborn.
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9. Helps maintain stable environment for brain
Blood Brain Barrier
Helps maintain stable environment for brain
Separates neurons from some bloodborne substances
Composition
Continuous endothelium of capillary walls
Thick basal lamina around capillaries
Feet of astrocytes
Provide signal to endothelium for formation of tight junctions
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10. Capillary Neuron Astrocyte
Figure 11.3a Neuroglia.
Capillary
Neuron
Astrocyte
Astrocytes are the most abundant CNS neuroglia.
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11. Blood Brain Barrier: Functions
Selective barrier
Allows nutrients to move by facilitated diffusion
Metabolic wastes, proteins, toxins, most drugs, small nonessential amino acids, K+ denied
Allows any fat-soluble substances to pass, including alcohol, nicotine, and anesthetics
Absent in some areas, e.g., vomiting center and hypothalamus, where necessary to monitor chemical composition of blood
MDufilho

12. Homeostatic Imbalances of the Brain
Traumatic brain injuries
Concussion—temporary alteration in function
Contusion—permanent damage
Subdural or subarachnoid hemorrhage—may force brain stem through foramen magnum, resulting in death
Cerebral edema—swelling of brain associated with traumatic head injury
MDufilho

13. Brain requires more blood flow and oxygen
Blood Flow to the Brain
Brain requires more blood flow and oxygen
Receives 15 – 20% of body’s blood flow
Uses 15 – 20% of body’s oxygen
Mickey Dufilho
4/19/2017

14. Figure 19.22b Arteries of the head, neck, and brain.
Ophthalmic artery
Basilar artery
Branches of
the external
carotid artery
Vertebral artery
Internal
carotid artery
• Superficial
temporal artery
• Maxillary artery
• Occipital artery
• Facial artery
• Lingual artery
• Superior thyroid
artery
External
carotid artery
Common
carotid artery
Thyrocervical
trunk
Larynx
Costocervical
trunk
Thyroid gland
(overlying trachea)
Subclavian
artery
Clavicle (cut)
Brachiocephalic
trunk
Axillary
artery
Internal thoracic
artery
(b) Arteries of the head and neck, right aspect

15. Figure 19.22d Arteries of the head, neck, and brain.
Anterior
Cerebral arterial
circle
(circle of Willis)
Frontal lobe
Optic chiasma
• Anterior
communicating
artery
Middle
cerebral
artery
• Anterior
cerebral artery
Internal
carotid
artery
• Posterior
communicating
artery
Mammillary
body
• Posterior
cerebral artery
Temporal
lobe
Basilar artery
Vertebral artery
Pons
Occipital lobe
Cerebellum
Posterior
(d) Major arteries serving the brain (inferior view, right side
of cerebellum and part of right temporal lobe removed)

16. Figure 19.22c Arteries of the head, neck, and brain.

17. Homeostatic Imbalances of the Brain
Cerebrovascular accidents (CVAs or strokes)
Ischemia
Tissue deprived of blood supply; brain tissue dies, e.g., blockage of cerebral artery by blood clot
Hypoxia
condition in which inadequate oxygen is available to tissues
Hemiplegia (paralysis on one side), or sensory and speech deficits
Transient ischemic attacks (TIAs)—temporary episodes of reversible cerebral ischemia
Tissue plasminogen activator (TPA) is only approved treatment for stroke
MDufilho

18. Homeostatic Imbalances of the Brain
Degenerative brain disorders
Alzheimer's disease (AD): a progressive degenerative disease of brain that results in dementia
Memory loss, short attention span, disorientation, eventual language loss, irritable, moody, confused, hallucinations
Plaques of beta-amyloid peptide form in brain
Toxic effects may involve prion proteins
Neurofibrillary tangles inside neurons kill them
Brain shrinks
MDufilho

19. Homeostatic Imbalances of the Brain
Parkinson's disease
Degeneration of dopamine-releasing neurons of substantia nigra
Basal nuclei deprived of dopamine become overactive  tremors at rest
Cause unknown
Mitochondrial abnormalities or protein degradation pathways?
Treatment with L-dopa; deep brain stimulation; gene therapy; research into stem cell transplants promising
MDufilho

20. Homeostatic Imbalances of the Brain
Huntington's disease
Fatal hereditary disorder
Caused by accumulation of protein huntingtin
Leads to degeneration of basal nuclei and cerebral cortex
Initial symptoms wild, jerky "flapping" movements
Later marked mental deterioration
Treated with drugs that block dopamine effects
Stem cell implant research promising
MDufilho

21. Shows effects of stroke and repair Formation of new synapses
Brain Video
Shows effects of stroke and repair
Formation of new synapses
Mickey Dufilho
4/19/2017

22. Physiology of Addiction
Definition
Psychological or Physiological?
Kinds of addictions?
7/2/2012
MDufilho

23. Day in the Life of Nicotine Junkie
1 st Cigarette/chew of the day
Nicotine = ACh
Stimulates release of hormones Epi and NE
Lasts 30 min
2nd, 3rd, 4th cig/chew
Stimulates release of hormone cortisol
Then NT dopamine and glutamate
7/2/2012
MDufilho

24. Why is Nicotine Addictive?
↓ ACh
↑ # Nicotinic of Receptors
So what?
7/2/2012
MDufilho

25. Physiology of Depression
Definition
Psychological or Physiological?
Causes?
Environmental and neurotransmitters
7/2/2012
MDufilho

26. Physiology of Depression
↓ in NE and/or Serotonin
Due to?????
Treatment – dual approaches
MAO Inhibitors (monoamine oxidase)
Tricyclic antidepressants
SSRI (serotonin specific reuptake inhibitors)
7/2/2012
MDufilho

27. What system creates anxiety? Treatment
What about anxiety?
What system creates anxiety?
Treatment
Valium (diazepam), Ativan (lorazepan), Xanax
Rohypnol – date rape drug is in the same family of drugs as Valium, Ativan
Barbiturates (penobarbital) bind to GABA receptor – opens chloride channels which cause hyperpolarization
7/2/2012
MDufilho