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Functional Histology VBMS 408 > Brain Structures > Flashcards

Flashcards in Brain Structures Deck (48):
1

Embryonic subdivisions of the Brain

Forebrain (Proencephalon), Midbrain (mesencephalon), Hindbrain (Rhombencephalon)

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Telencephalon

dorsal part of prosencephalon; composed of cerebral hemispheres

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Diencephalon

ventral part of prosencephalon; thalamus and hypothalamus

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Cerebrum

convoluted cortex of gray matter covering a central mass of white matter (Medulla_

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Five subdivisions of the Cerebrum

Frontal, occipital, parietal, temporal, olfactory lobes

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Frontal lobe

part of cerebrum; motor functionsl higher functions (reasonings)

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Parietal Lobe

pain, temperature, touch, taste

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Temporal Lobe

hearing

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Occipital lobe

vision

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olfactory lobe

smell

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Outer cerebral Cortex of cerebrum

Neurons, neuron cell processes, CNS glial cells

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Inner medulla of Cerebrum

Axons, CNS glial cells, blood vessels

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Stratification of cerebrum

MOOIIM (Molecular layer, outer granular layer, outer pyramidal cell layer, inner granular layer, inner pyramidal cell layer, multiform (fusiform) Cell layer.

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Diencephalon components

Thalamus, hypothalamus, optic chiasm

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Thalamus

Primary relay station for sensory information (Excluding olfaction) going to cerebrum; assists cerebral cortex with higher functions (alertness, pattern recognition, emotions, data analysis and assimilation; directing motor activities.

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Hypothalamus

intermediary between nervous and endocrine systems; control and integration of ANS; feeding, satiety and thirst centers; maintenance of wake and sleep cycles; regulations of body temperature

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Optic chiasm

where fibers of axons of optic nerves cross over

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Rhombencephalon divisions

Metencephalon and Myelencephalon

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Cerebellum Gross Anatomy

Vermis, sulci, folia

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Vermis

midline mass that separates two lateral cerebral hemispheres

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folia

narrow ridges that cover cerebellum

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Sulci

grooves on cerebellum

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Function of the cerebellum

receives information regarding head movements; muscle, tendon, joint, and ligaments stretch stretch from ipsilateral/ Modulates pools of motor neurons in the ipsilateral spinal cord to coordinate posture and movement.

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arbor vitae

white matter of cerebellum; looks like a tree

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What is the ventricle system?

a number of interconnecting cavities which are remants of the lumen of the embryonic neural tube

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CSF composition

blood, and secretions from cells lining interior of ventricle system; low calcium, potassium, glucose, and protein; but more magnesium, sodium and chloride

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How is CSF produced?

formed from choroid plexus

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where is the majority of CSF produced?

lateral ventricles

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How does reabsorption of CSF occur?

Absorption of CSF occurs at arachnoid villi and is controlled by CSF/blood pressure gradients.

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Arachnoid villi

evaginations of arachnoid layer into dural sinuses of brain/ acts as pressure-dependent, unidirectional valves.

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Hydrocephalus

water on brain; result of accumulating CSF within ventricles from obstruction of ducts (i.e foramen of monro); excessive CSF pressure damages CNS neurons

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Head trauma and CSF

Trauma causes bleeding into dural sinuses creates excess pressure which collapses arachnoid villi and shits down CSF absorption damaging CSF neurons. Increased sinus blood pressure can comprress central veins and efferent lymphatics of the optic nerve causing swelling of retinal veins, whcih can damage vision.

33

What fibers are utilized in the autonomic nervous system?

GVE; General visceral efferent fibers

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What kind of neuronal system does the ANS employ?

a 2-neuron system; preganglionic neurons and axons & postganglionic neurons and axons

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2 - Neuron System overview

1) pre-ganglionic neurons 2) pre-ganglionic axons 3) postganglionic neurons 4) postganglionic axons

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Pre-ganglionic neurons

located in the CNS

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pre-ganglionic axons

nerve fibers extending from pre-ganglionic neuron. Synapse on postganglionic neuron

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post-ganglionic neuron

located in an autonomic ganglion of PNS

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Postganlionic axon

nerve fibers extending from post-ganglionic neuron; synapse with an effector organ

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Where do sympathetic nerve impulses originate? Step#1 SNS

1) Sympathetic impulses originate from preganglionc sympathetic neurons located in the intermediolateral cell column of the thoracolumbar spinal cord (T1-L3-4)

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Step #2 SNS

Preganglionic sympathetic axons synapse on post ganglionic sympathetic neurons in sympathetic ganglia (i.e Cranial nerve).

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Step # 3 SNS

Postganglionc sympathetic axons synapse on structures of effector organs (i.e dilator muscle of eye, smooth muscle in the walls of blood vessels)

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Where do parasympathetic nerve impulses originate? Step # 1

Impulses originate from preganglionic parasympathetic neurons in nuclei located in the brainstem or sacral spinal cord

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Step # 2 PNS

preganglionic parasympathetic axons exit midbrain and hindbrin with cranial nerves III, VII, IX, & X; synapse on post-ganglionic parasympathetic axons of parasympathetic ganglia

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Step #3 PNS

Post-ganglionic parasympathetic axons synapse on structures of effextor organs.

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Parasympathetic vs. Sympathetic

Parasympathetic - effects specific, discrete, local vs Sympathetic -effects more widespread

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Postganglionic axon of sympathetic vs. parasympathetic

Sympathetic axons are adrenergic (release norepinepphrine); parasympathetic axons cholinergic (release acetylcholine)

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Preganglionic axon of sympathetic vs. parasympathetic

both cholinergic (release ACH)