Lab 9 The Nervous System: Histology and The Brain

Objective 1 Neuron Structure

Multipolar Neuron model Dendrites (receive)  Cell Body (process)  Axon (send)  Axon Terminals (transfer) Axon Terminals Main parts of a neuron

Dendrites (receptive regions) Cell body (biosynthetic center and receptive region) Nucleus Nucleolus Axon (impulse generating and conducting region) Impulse direction Dendrite Neuron cell body Nissl bodies (rough ER) Neurofibrils

Impulse direction Neurilemma (sheath of Schwann) Schwann cell (one internode) Node of Ranvier Axon Axon hillock

Terminal branches (Telodendria) Axon terminals (secretory component) Impulse direction

Cell Body Spinal Cord Smear – Motor Neuron What you need to draw and label

Schwann cells - supporting cells of the PNS that myelinate axons. myelin sheath Schwann cell nucleus axon neurilemma Node of Ranvier Myelin sheath – whitish lipoprotein that surrounds and insulates the axon (nerve fiber) Neurilemma - external layer containing bulk of cytoplasm with nucleus and organelles

Nodes of Ranvier - Gaps between successive Schwann cells along the length of the axon

What you need to draw and label Node of Ranvier Neurilemma Axon

Objective 2 Neuron Classification

Pseudounipolar: -a short process emerges from the cell body and divides into proximal and distal branches -most sensory neurons soma Distal process (toward periphery)Proximal process (toward CNS )

Pseudounipolar Cell Bodies in the Dorsal Root ganglion of a Spinal Nerve

Spinal Cord Dorsal Root Ganglion Centrally located nuclei Pseudounipolar cell bodies

Bipolar neuron -a single axon and a single dendrite attached to opposite sides of the cell body -found in special sense organs (eye, ear, etc.) Bipolar neurons Human retina

Bipolar neurons Bipolar neurons in the human retina

Purkinje cell of the Cerebellum Pyramidal cell of the hippocampus Neuron from the cerebral cortex Multipolar: -multiple dendrites and a single axon -includes most neurons; all motor neurons and most CNS neurons

Multipolar neurons have diverse morphologies

Silver Stained Neuron In Gray Matter

Multipolar neurons Spinal Cord - Anterior Horn

Multipolar neurons you will be drawing Purkinje cellPyramidal cell

(Low Power – Cerebrum) Pyramidal cell

Purkinje cell (Low Power - Cerebellum)

Objective 3Nerves Nerves are structures of the PNS that consist of axons and dendrites bundled together by connective tissues Fascicle:a bundle of axons or dendrites Epineurium: tough, fibrous connective tissue sheath surrounding a nerve Perineurium: loose, areolar connective tissue sheath surrounding fascicles Endoneurium: delicate connective tissue wrapping around each nerve fiber

a = epineurium b= perineurium

perineurium endoneurium axon

LAB ACTIVITY Draw and label the components of the nerve cross section

Nervous System The Brain Sheep HumanHuman BrainBrain Brain

OBJECTIVES Identify the components of the human brain using models and diagrams Identify the structures of the sheep brain

Objective 4:Anatomy of the human brain Cerebrum (gold area) Diencephalon (Violet area) Brain stem (green area) Cerebellum (pink area)

Cerebrum

Fissure Sulcus Gyrus Ventricles Structures of the Cerebrum Cerebral Hemispheres Left HemisphereRight Hemisphere Gray Matter – Cerebral cortex & Basal nuclei White Matter – Myelinated fiber tracts (axons) Frontal cut

Structures of the Cerebrum Human Brain, Lateral ViewOccipital lobe lobe Frontal Temporal lobe Parietal lobe Gyrus Lateral sulcus Central sulcus Transverse Fissure Parieto-occipital Sulcus

Structures of the Cerebrum Human Brain, Superior View Longitudinal fissure Central sulcus Postcentral gyrus Precentral gyrus Frontal pole Occipital pole

Midsagittal Section of Human Brain Corpus Callosum Fornix Septum pellucidum Parietal lobe Occipital lobe Frontal lobe

Internal Structures of the Cerebrum Frontal Section Corpus callosum Fornix Lateral Ventricles Septum pellucidum Longitudinal fissure

Diencephalon

Functions of the Diencephalon Endocrine System Relay Stations Thalamus

Structures of & related to the Diencephalon Midsagittal Section Corpus callosum Fornix Intermediate mass HypothalamusMammillary body Pineal body/ gland Thalamus

Pituitary gland Thalamus Hypothalamus Infundibulum Sella Turcica

Brainstem

Pons Medulla oblongata Midbrain: Corpora quadrigemina Superior colliculi Inferior colliculi Cerebral peduncle Spinal cord

Corpora quadrigemina Superior colliculus Inferior colliculus Brainstem Posterior Pineal body/ gland

Structures of the Brainstem Inferior View Midbrain (Cerebral peduncle) Pons Medulla oblongata Spinal cord Optic chiasma Infundibulum Mammilary Bodies

Cerebellum “Little Brain”

Arbor Vitae Cerebellar Peduncles Fourth ventricle Structures of the Cerebellum Midsagittal Section

Meninges of the Brain

A mnemonic PAD from deep to superficial the layers of the meninges are pia, arachnoid, dura (they pad the brain)

Cerebral Aqueduct Third Ventricle Fourth Ventricle Ventricles of the Brain The spaces within the brain through which cerebrospinal fluid flows

Cerebrospinal fluid is continually produced by the choroid plexus found in the ventricles Die-cast model

Objective 5: Sheep Brain Dissection

Identify the external structures Inferior Sheep brain structures are the same as the human brain, only slightly different sizes

Remove Dura mater (w/ pituitary gland) Identify the external structures Superior

Identify the external structures Inferior

Pull back the cerebellum to reveal Corpora Quadrigemina & Pineal Gland

Make a midsagittal cut through the brain

Identify the internal structures Midsagittal

Identify the internal structures Midsagittal Lateral Ventricle Third VentricleCerebral AqueductFourth Ventricle