170 likes | 179 Views
This discussion explores the development of the nervous system, including morphological, biochemical, and functional aspects. Additionally, it examines the blood flow in the circulatory system and the major components involved.
E N D
MCB 135EDiscussion GSI: Jason Lowry September 27- October 1
Fetal Umbilical VeinDuctus VenosusIVCRight AtriaForamen OvaleLeft AtriaLeft VentricleAortaCoronary Arteries, Carotid Arteries Superior Vena CavaRight AtriaRight VentriclePulmonary ArteryDuctus Arteriosus Descending Aorta Umbilical Arteries Adult Pulmonary VeinsLeft AtriaLeft VentricleAortaInferio/Superior Vena CavaRight AtriaRight VentriclePulmonary Arteries Blood Flow
Nervous System • Major Functions • Communication with external/internal environment • Regulation of… • Major Components • 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
Carbohydrates Primarily maternal glucose Stored as glycogen Under influence of glucocorticoids In fetus Insulin levels high Insulin sensitivity high Hypoglycemic Anaerobic Glycolysis Glyceraldehyde-P-Dehydrogenase Glycolitic enzyme High in postnatal brain During same period the oxidative enzyme Succinic Dehydrogenase Much lower Energy Sources
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
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)