Midterm 2

• Central Nervous System: cerebrum, cerebellum, brainstem, and spinal cord. Analysis and integration of sensory and motor informative.
• Peripheral Nervous System: Motor Components: Visceral Motor System: sympathetic, parasympathetic, and enteric divisions, autonomic ganglia and nerves. Somatic Motor System: motor nerves. Effector: smooth muscles, cardiac muscles, and glands. Skeletal (striated) muscles.
• Peripheral Nervous System: Sensory Components: sensory ganglia and nerves, sensory receptors (at surface and within the body). Internal and external environment.
• Terminology: used to describe location in 3D. Neuraxis: imaginary line beginning at base of spinal cord and ending at front of brain. Based on quadrupeds. Spinal cord complicated because at right angle to quadrupeds. MEMORIZE
• Planes: Sagittal, horizontal, coronal
• Unilateral: one side. Bilateral: both sides. Ipsilateral: same side. Contralateral: opposite side.
• Afferent: carry to a location (usually toward CNS) sensory
• Efferent: carry from a location (usually away from CNS) motor
• Spinal Cord: attached to brain stem. Conduit of sensory and motor information (brain and body). Gray matter, butterfly shape: dorsal and ventral horns. Dorsal root: somatic and visceral sensory, afferents. Ventral Root: somatic and visceral motor, efferents. Spinal nerves are mixed. Dorsal Root Ganglia: contains somas of sensory neurons
• Brain Stem and 12 Cranial Nerves: olfactory, optic, vestibular, cochlear etc. Brain stem: center of heart rate, respiration, cough reflex, vomiting. Can live without cortex. 12 nerves numbered from anterior to posterior. Sensory or motor or both. Mostly innervate head,
• Somatic NS: innervates skin, joints, muscles. Sensory and motor subdivisions. Autonomic (visceral) innervates internal organs, blood vessels, glands. Sympathetic and parasympathetic subdivisions. Enteric: brain in the gut.
• Sympathetic: Fight or flight. dominates during times of stress, excitement and exertion. Increases heart rate and blood pressure, stimulates secretion of adrenaline, increases blood flow to skeletal muscles.
• Parasympathetic: Rest and digest. dominates when energy reserves can be conserved and stored for later use. Increases salivation, digestion, and storage of glucose and other nutrients, slows heart rate, decreases respiration
• Meninges: covering. CNS does not come in direct contact with bone. Inflamed in meningitis. 3 membranes: 1) Dura mater "hard mother" tough/thick. 2) arachnoid membrane: spider-like projections. Subarachnoid space between contains CSF / blood vessels. 3) Pia mater "gentle mother" adheres to brain surface
• Subdural hematoma: trauma damages tiny veins within the meninges. Blood accumulates rapidly, causing pressure to rise within the brain. Results in loss of consciousness, paralysis or death.
• Subarachnoid hemorrhage: bleeding into the space between the arachnoid mater and the pia mater, subarachnoid space. CSF mizes with blood. Sudden severe headache, usually with loss or impairment of consciousness. Frequently a sign of a ruptures aneurysm.
• Ventricles: cerebroventricular system. Cerebrospinal fluid (CSF) filled caverns and canals inside brain, brain floats in it. Cushions, delivers nutrients, removes waste. Produced by choroid plexus (ependymal cells). Circulates through ventricles and out into subarachnoid space, waste. Absorbed by blood vessels in arachnoid villi, normal flow very important - hydrocephalus.
• Development of CNS: specifically timed, genes turning on and off. Differentiation.
• Embryonic development of human brain: 25 days neural tube forms. By 40 days, forebrain, midbrain, hindbrain, spinal cord. 50 days Diencephalon, telencephalon. 100 days cerebral hemisphere, cerebellum, pons, medulla.
• Adult Brain: *GRAPH* Neocortex, basal ganglia, limbic system, thalamus, hypothalamus, mesencephalon, cerebellum, pons, myelencephalon, spinal cord
• Embryo: Flat disk. 3 germ cell layers: 1) Ectoderm: NS and skin. 2) Endoderm: lining of internal organs. 3) Mesoderm: bones and muscles
• Neurolation: neural plate becomes neural tube. E17 valley of foid called neural groove, edges neural folds. E22 As tissue folds ends of neural groove come together to form neural tube. E23 neural folds pinch off on either side of neural tube to become neural crests. Neural tube - CNS. Neural crest - PNS.
• Neural tube defects: neurrulation complete by E22. failure of anterior tube to close leads to anencephaly. Failure of posterior tube to close leads to spina bifida. Folic acid deficiency increases neural tube defects, supplements easily prevent.
• Three Primary Brain Vesicles: neural tube becomes forebrain, midbrain, hindbrain (and spinal cord) by E35 through differentiation.
• three primary vesicles become five secondary vesicles - telencephalon, diencephalon, mesencephalon, metencephalon, myelencephalon
• Telecephalon: cerebral hemispheres, olfactory bulbs, basal telencephalon. Becomes Olfactory lobes, hippocampus, cerebrum.
• Diencephalon: thalamus, hypothalamus. Becomes retina, epithalamus, thalamus, hypothalamus
• Mesencephalon becomes midbrain
• Metencephalon becomes cerebullum and pons
• Myencephalon becomes medulla
• Telecephalon: cerebral cortex - subdivisions. Seat of perception, cognition, consciousness, voluntary action. Analyzes sensory input to command motor output.
• Telecephalon: basal ganglia - voluntary movement, procedural memory
• Telencephalon: limbic system. amygdala: emotion. hippocampus: memory (spatial learning)
• Diencephalon: thalamus - gatway to cortex, have to pass through. Relay most sensory information from periphery. Not olfactory. Motor portions
• Hypothalamus: very varied, overall function is homeostasis. Regulates body temperature, salt water balance, hunger, thirst, energy metabolism, reproductive behaviors, emotional response. Mediates circadian rhythms (SCN). Controls ANS. controls HPA - axis and stress response.
• Descending axons: contains axons descending from cortex to brainstem and spinal cord. Corticospinal tract: motor cortex to spinal motor neurons
• Ascending Axons: information conduit from spinal cord and brainstem to forebrain
• Tectum differentiates to: superior colliculus (receives sensory info from eye). Inferio collicus (receives sensory info from ear). Relay for auditory info in route to thalamus.
• Tectum differentiates to: Tegmentum substania nigra (black substance). Cell bodies of DA neurons, important for motor control. Project to striatum. Red nucleus: rubrospinal tract. Periaqueductal Gray (PAG) cell bodies. Rich in opioid receptors, important in pain modulation, relief.
• Hindbrain: Rostral Hindbrain (metencephalon): cerebellum and pons "bridge." Caudal Hindbrain (myelencephalon): medulla oblongata.