Download MCB 135E Discussion

MCB 135E
Discussion
GSI: Jason Lowry
September 27- October 1
Blood Flow
• Fetal
– Umbilical VeinDuctus
VenosusIVCRight
AtriaForamen
OvaleLeft AtriaLeft
VentricleAortaCoronar
y Arteries, Carotid Arteries
– Superior Vena CavaRight
AtriaRight
VentriclePulmonary
ArteryDuctus
Arteriosus Descending
Aorta Umbilical Arteries
• Adult
– Pulmonary
VeinsLeft
AtriaLeft
VentricleAortaInfe
rio/Superior Vena
CavaRight
AtriaRight
VentriclePulmonary
Arteries
Nervous System
• Major Functions
– Communication with external/internal environment
– Regulation of…
• Major Components
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–
–
–
–
–
Neurons
Neuroglia
Mylenated nerve fibers
Microglia
Ground Substance
Blood Vessels and CSF
Development of the Nervous
System
•
•
•
•
Morphological Development
Biochemical Development
Functional Development
Sexual Differentiation
Morphological Development
• Neurulation
• Cells derived from neuroepithelium
• Know Handout
Neurulation
• N.S. – Arises from ectoderm on dorsal portion of
embryo
• 3-4 Weeks – Cells proliferate along middle plate
• 5-6 Weeks – Plate folds to form neural groove
• 6-7 Weeks – Groove closes into neural tube
– Brain develops from anterior portion
– Spinal cord develops from the posterior portion
Neural Epithelium
• Neuroblast
– Neuron
• Spongioblast
– Migratory Spongioblast
• Oligodendria
• Astrocytes
– Astrocytes
– Ependyma
Biochemical Development
• Neuronal Plasticity
• Energy Sources
• Role of thyroid hormone
Energy Sources
• Carbohydrates
– Primarily maternal
glucose
– Stored as glycogen
• Under influence of
glucocorticoids
• In fetus
– Insulin levels high
– Insulin sensitivity high
– Hypoglycemic
• Anaerobic Glycolysis
– Glyceraldehyde-PDehydrogenase
• Glycolitic enzyme
• High in postnatal brain
• During same period
the oxidative enzyme
– Succinic Dehydrogenase
– Much lower
Thyroid Hormone
• Functions
– Promotion of body growth
– Development of CNS through:
• Promotion of neorogenesis
• Promotion of myelination
• Promotion of brain metabolism
– Stimulates oxygen consumption in all cells
• Abnormalities
– Hypothyroidism
• Cretinism
• Short stature, low metabolic rate, skin changes
• Treatable if given Thyroxine at an early age
Thyroid Hormones
Functional Development
• Neuronal Connections
• Differential Development of N.S.
– Neurotransmitter activity in different brain regions
• Perinatal Behavior
– Reflexes
• Respiratory (17-24 weeks)
• Gastrointestinal (24th week)
• Startle (Presence of excessive activity after birth is an indicator
of delayed development of certain brain centers)
• Suckling - Postnatal
• Education
– Better educated appear to live longer with less disability
– Several pieces of evidence discussed for this in class
Sexual Differentiation
• Steroid hormone action on brain
development
– Androgen action on sexually dimorphic nucleus
of the preoptic area (SDN-POA)
• Male Rats – After puberty responsible for male
behavior, large SDN-POA present
• Female Rats (low androgen levels) – After puberty Small SDN-POA (reversible with androgen
treatment)
– No lordosis (arching of back when sexually receptive)