Anatomy and Physiology I Lab BSC 2085L Laboratory 8

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Anatomy and Physiology I LabBSC 2085LLaboratory
8

• Introduction to the Nervous System
• Brain-sheep and human
• Meninges and CSF

Associate Professor Pamela L. Pannozzo pannozzp_at_pb
cc.edu
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Introduction to the Nervous System

• Functions of the Nervous System
• Communication between regions of the body
• Coordination of body functions
• Orientation to the environment
• Assimilation of information
• Nervous System has two divisions
• Central Nervous System (CNS)
• Peripheral Nervous System (PNS)

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Introduction to the Nervous System

• The Nervous System has two parts
• Central Nervous System (CNS)spinal cord and
  brain
• Peripheral Nervous System (PNS)peripheral
  sensory and motor nerves

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Central Nervous System

• Assesses sensory information from PNS
• Generates nerve impulses called action potentials

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Peripheral Nervous System

• Somatic Nervous System
• Sensory nerves transmit information to CNS
• Motor nerves transmit commands from CNS to
  skeletal muscle
• Autonomic Nervous System
• Sensory nerves transmit information to CNS
• Motor nerves transmit commands from CNS to smooth
  muscle, cardiac muscles, and glands

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Nervous Tissue

• Neuroncell that carries out the activity of
  nerve tissue, composed of cell body and axon stem
  (one cell can be 1 m long!)
• Neuroglia or glia cells that support neurons
• Nerve cord composed of numerous (several to over
  one million) neuron axons bound together by
  connective tissue
• Gangliaa cluster of neuron cell bodies enclosed
  on connective tissue
• Gray Matter brain and spinal cord tissue
  comprised of neuron cell bodies and the site
  where synapses occur
• White Matter bundles of neuron axons covered by
  myelin

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Structure of a Neuron

• Cell body perikaryon soma
• single, central nucleus with large nucleolus
• cytoskeleton of microtubules neurofibrils
  (bundles of actin filaments)
• Vast number of short dendrites
• for receiving signals
• Singe axon (nerve fiber) arising from axon
  hillock for rapid conduction

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3 Fundamental Properties of Neurons

• Excitability (irritability)
• ability to respond to changes in the body and
  external environment called stimuli
• Conductivity
• produce traveling electrical signals
• Secretion
• when electrical signal reaches end of nerve
  fiber, a chemical neurotransmitter is secreted

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Fundamental Types of Neurons
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Chemical Synapse Structure

• Presynaptic neurons have synaptic vesicles with
  neurotransmitter and postsynaptic have receptors

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Brain Directional Terms and Landmarks

• Rostral (toward the forehead) - Caudal (toward
  the cord)
• Major parts of the brain - cerebrum, cerebellum,
  brainstem
• cerebrum is 83 of brain volume cerebellum
  contains 50 of the neurons
• brain weighs 3 to 3.5 pounds

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Brain

• Longitudinal fissure separates 2 cerebral
  hemispheres.
• gyri are the folds and sulci the grooves
• surface layer of gray matter is called cortex
  deeper masses of gray matter are called nuclei
• bundles of axons (white matter) are called tracts

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Lateral View of the Brain
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Inferior View of the Brain
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Median Section of the Brain
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Posterior View

• Cerebellum
• Corpora quadrigemma
• Superior colliculi
• Inferior colliculi
• Pineal gland

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Cerebellum

• Right left hemispheres connected by vermis

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Cerebellum

• White matter (arbor vitae) visible in sagittal
  section
• Sits atop the 4th ventricle

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Superior Inferior Colliculus

• Tectum (4 nuclei) called corpora quadrigemina
• superior colliculus (tracking moving objects )
• inferior colliculus (reflex turning of head to
  sound)

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Ventral Surface

• Olfactory bulbs
• Olfactory tract
• Optic chiasma
• Optic nerves
• Mammillary body
• Infundibulum
• Midbrain
• Pons
• Medulla Oblongata

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Hindbrain Medulla Oblongata

• Ascending descending nerve tracts
• Nuclei of sensory motor cranial nerves (IX, X,
  XI, and XII)
• Cardiac center adjusts rate force of heart beat
• Vasomotor center adjusts blood vessel diameter
• Respiratory centers control rate depth of
  breathing
• Reflex centers for coughing, sneezing, gagging,
  swallowing, vomiting, salivation, sweating,
  movements of tongue head

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Medulla and Pons
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Pons

• Bulge in the brainstem, rostral to the medulla
• Ascending sensory tracts
• Descending motor tracts
• Pathways in out of cerebellum
• Nuclei concerned with sleep, hearing, balance,
  taste, eye movements, facial expression, facial
  sensation, respiration, swallowing, bladder
  control posture
• cranial nerves V, VI, VII, and VIII

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Sagittal View

• Corpus callosum
• Septum pellucidum
• Lateral ventricle
• Thalamus
• Hypothalamus
• Third ventricle
• Fourth ventricle
• Cerebral aqueduct
• Arbor vitae

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Third ventricle
Corpus callosum
Pineal Gland
Lateral ventricle
Thalamus
Fourth ventricle
Hypothalamus
Arbor vitae
Central canal
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Hypothalamus

• Functions
• hormone secretion pituitary
• autonomic NS control
• thermoregulation (thermostat)
• food water intake (hunger satiety)
• sleep circadian rhythms
• memory (mammillary bodies)
• emotional behavior

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Brain Ventricles
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Cerebrospinal Fluid

• Clear liquid fills ventricles and canals bathes
  its external surface (in subarachnoid space)
• Functions
• buoyancy -- floats brain so it neutrally buoyant
• protection -- cushions from hitting inside of
  skull
• chemical stability -- rinses away wastes
• Escapes from 4th ventricle to surround the brain
• Absorbed by arachnoid villi into venous sinus

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Flow of Cerebrospinal Fluid
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Meninges

• Meningesconnective tissue surrounding the brain
  and spinal cord
• Dura mater outermost layer of connective tissue
• Arachnoid middle layer of connective tissue
• Pia mater innermost connective tissue layer,
  vascularized, adheres to spinal cord and brain
  surface
• Filium terminale extension of pia mater
  extending to coccyx

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Meningal Spaces

• Epidural space space between dura mater and
  cranial bones and vertebrae, filled with
  connective tissue, blood vessels, and adipose
  tissue
• Subdural spacespace between dura mater and
  arachnoid, filled with lymphatic fluid
• Subarachnoid spacespace between arachnoid and
  pia mater, filled with cerebrospinal fluid

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