Dividing the Nervous System actually a single uniform structure divisions may be made on the basis of structural continuity function developmental homology

Communication from the CNS to the PNS is via Spinal Nerves begin at the junction of the dorsal and ventral roots of spinal cord innervate muscles and sensory receptors

Cranial Nerves attached to the ventral surface of the brain innervate muscles and sensory receptors of the head exception: the vagus nerve or CN X innervates the thoracic and abdominal cavity

Meninges three layers of connective tissue which cover the nervous system

three layers Dura Mater Arachnoid Membrane Pia Mater

Dura Mater Arachnoid Membrane Pia Mater "hard mother" outermost layer thick, tough, and flexible but not stretchable Arachnoid Membrane "spider" membrane soft and spongy covers only the CNS - not found in the PNS Pia Mater "pious mother" closely attached to the brain and spinal cord follows every surface convolution

Subarachnoid Space space between the arachnoid membrane and pia mater filled with CSF cushions and protects the brain

note: The PNS is covered with only two layers of meninges note: The PNS is covered with only two layers of meninges. The arachnoid membrane covers only the brain and spinal cord; it does not extend to the peripheral system.

The Blood Brain Barrier

What constitutes a BBB? (tight junction) endothelial cells flat cells that line blood vessels particularly densely packed (tight junction) in the blood vessels that transport oxygen and nutrients to the brain.

How do nutrients get into the brain? small lipophilic (fat loving) molecules enter readily hydrophilic (water loving) molecules are restricted e.g. morphine is hydrophilic and does not easily enter the brain while heroin, a morphine derivative is lipophilic and enters readily

active transporters there are systems which operate to specifically transport some hydrophilic molecules into the brain e.g. the amino acids phenylalanine and tryptophan must be actively carried into the brain by these transport mechanisms

Peripheral Nervous System (PNS)

Somatic Division receives sensory information from the sensory organs cell bodies located in dorsal root ganglia afferent neuron controls movements of the skeletal muscles cell bodies located in the gray matter of the spinal cord efferent neurons

Spinal Reflexes rapid, automatic response to stimuli monosynaptic or polysynaptic

Autonomic Division regulates smooth muscle, cardiac muscle, and glands smooth muscle is found in skin, blood vessels, eyes, gut, bladder, and gall bladder two subdivision sympathetic division parasympathetic division

Sympathetic Division of ANS fight or flight system involved in activities that expend energy increase HR, BP, RPM dilate pupils cause piloerection in animals responsible for the 4 Fs

Parasympathetic Division of ANS supports activities that increase the body's store of energy controls salivation, intestinal motility, secretion of digestive juices the "LDHN" (lye down and have a nap) system (I made that up)

The Central Nervous System (CNS)

Divide the Brain into 3 Major Sections: Forebrain Cortex subcortical structures Midbrain Tectum Tegmentum Hindbrain Pons Cerebellum Medulla Oblongata

Structures of the Forebrain cerebral cortex basal ganglia limbic system thalamus hypothalamus

Structures of the Midbrain Tectum Tegmentum

Structures of the Hindbrain pons cerebellum medulla oblongata

Cortex & Subcortical Structures The Forebrain Cortex & Subcortical Structures

Subcortical Structures

Limbic System consists of mediates emotion and memory the limbic cortex or cingulate gyrus hippocampus fornix mammillary bodies olfactory bulbs amygdala mediates emotion and memory "old" part of the mammalian brain

The Basal Ganglia subcortical nuclei anterior and inferior to the lateral ventricles consists of caudate (tail) putamen (shell) globus pallidus (pale globe) involved in the control of movement damage or loss of particular components may yield Parkinson's like symptoms uncontrollable movements

Thalamus "inner chamber" immediately medial and caudal to the basal ganglia most neural input to the cerebral cortex comes from the thalamus a relay station

Hypothalamus lies at the base of the brain inferior and anterior to the thalamus largely responsible for homeostasis regulates eating, drinking, sexual drive and other species specific behaviors regulates hormones via anterior and posterior pituitary

The Midbrain

The Tectum means "roof" includes superior colliculus responsible for visual/vestibular reflexes inferior colliculus responsible for auditory/vestibular reflexes

The Tegmentum means "floor" or covering as in a rug ventral to the tectum includes: rostral end of reticular formation periaqueductal gray matter high concentration of endogenous opiate receptors

Substantia Nigra or Dark Substance sends informtion to the basal ganglia (caudate and putamen) loss of these DA neurons results in Parkinson's Disease

The Hindbrain

Cerebellum "little brain" two hemispheres covered by cerebellar cortex receives variety of sensory information visual auditory vestibular somatosensory kinestetic proprioceptive largely responsible for smooth volitional movement damage results in impaired standing, walking, coordinated movement produces jerky, poorly coordinated and/or exaggerated movements

Pons Pons = bridge the "bulgy" part of the brainstem rostral to medulla ventral to cerebellum

contains a portion of the reticular formation occupies core of the brainstem responsible for sleep and arousal attention muscle tone movement

Medulla most caudal portion of the brainstem most caudal portion is rostral border of the spinal cord responsible for arousal reticular formation vital functions damage coma or death

Reticular Formation