Fundamentals of the Nervous system
Sensory Receptors
Structures that are sensitive to stimulus.
Externoceptors: Stimulus origin is environment.
Internoceptors: Stimulus origin is internal organs
Proprioceptors: Located in tendons, ligaments, and joints; monitors degree of stretch.
Thermoreceptors; Sensitive to temperature; located in skin
Photoreceptors: Sensitive to light; located in eye
Chemoreceptors: Sensitive to chemicals; located in nose and tongue
Nociceptors: Sensitive to pain.
Mechanoreceptors: Sensitive to touch, pressure, vibrations, stretch; located in skin.
Baroreceptors: Sensitive to blood pressure; located in blood vessels.
General senses are widely spread outs, special senses are located in the head
Anatomy of the eye.
Fibrous layer
Sclera: White part of the eye, dense regular connective tissue, anchor for muscles, extrinsic muscle, very protective and gives eye shape.
cornea: Transparent, allows light into the eye. Apart of the eye that helps focus light.
Vascular layer
choroid: Nourishes other layers, very pigmented, absorbs light, prevents scattering.
ciliary body: attached to lens, changes lens shape.
Inner Layer
Retina: Very thin layer. Has photoreceptors
Cones: Gives color vision, works best in bright light.
Rods: Most abundant, sensitive to light and dark
Lens: important in focusing light on retina.
Iris: Anterior to lens, Posterior to cornea, intrinsic muscle for dialation of pupil. Pupil is a hole.
Optic disc: No photoreceptors, Nerves exit here.
Macula lutea: Part of retina, exactly in direct line with the pupil. Clearest vision.
Fovea centralis, With in the macula.
Posterior segment: From the ciliary body to the posterior wall. Filled with vitreous humor, a gel like subtance. Vitreous humor transmits light and maintains pressure with in eye.
Anterior Segment: Cornea to Lens. Split up into two cahmbers, Posterior and anterior. The iris splits the chambers. Aqueous humor is located in the anterior segment. Aqueous humor maintains intraoccular pressure, and nourishes lens and cornea.
Pathways
Olfaction
pseudostratified solumnar epithelium with offactory sensory nerves
Olfactory bulb
Olfactory Tract
Primary Olfactory cortex in temporal lobe
Lymbic system: Emotional Brain
Gustation: Tastebuds located on tongue, inner cheek, pharynx, palate, epiglottis. chemoreceptors
taste buds: epithelial cells.
Glossopharyngeal Nerve: Cranial Nerve IX
Vagus Nerve: Cranial nerve X
Facial Nerve: Cranial Nerve VII
Taste Buds with receptor cells
3 cranial nerves
Medulla oblongate
Thalamus
Primary gustatory cortex in insula
Auricle (pinna): external ear, funnels sound waves, then to external acoustic meatus
Tympanic Membrane: Vibrates and transmits vibration
Middle ear
auditory ossicles
Colchlea
vastibulocolchlear nerve: Cranial Nerve VIII; Helps with equallibrium; located in temporal region.
Organization of the nervous system
Central Nervous system
Peripheral Nervous system
Brain and Spinal cord
Cranial nerves, spinal nerves, connected to spinal cord or brain.
Gathers sensory information from all the receptors and passes it to CNS
Recieves, processes and responds to information
Sensory Input: afferent; Goes to CNS
Motor Output: Efferent; Goes away from CNS
Somatic motor: Travesl mainly to skin, body wall, and skeletal muscles. Everything except venrtal body cavity.
Autonomic motor: Mainly travels to your ventral body cavity
Somatic sensory: Travels from skin, skeletal muscles, joints, hearing, equallibrium, and vision
Visceral sensory: travels from ventral cavity organs, gustation and olfaction
types of glail cells
CNS
Astrocytes: Most abundant, processes contact axons of neruons. capillaries, helps maintain proper chemical environment.
Microglia: Phagocyte, destroys invading microbes and damaged or dying nervous tissue.
Ependymal cells: resembles simple cuboidal or columnar. Is a type of epithelium. Epenymal are ciliated. located in ventricles, which are spaces in our brains. Ventricles are filled with cerebospinal fluid. The cilia keeps the cerebospinal fluid circulating.
PNS
Salellite cells: Surrounding neural bodies in gangliu. Supportive
Myelination: Myelin shealth, covers axons with lipids and some protiens. In both PNS and CNS. Myelin acts as an insolator and helps signals travel faster. Myelin does not cover all of axon.
CNS Myelination: Oligodendrocytes:Attaches to multiple axons. Wraps its membrane around the axons..
PNS: Schwann cells: Wraps around one part of the axon.
CNS vs PNS
Nucleusm(CNS) vs ganglion(PNS): clustures of neural cell bodies
Tract(CNS) vs nerve(PNS): bundles of axons
Gray matter vs White matter
Grey matter: Outlines brain, center of spinal cord, Outer part of brain is called cortex.Grey matter is not myelinated.
White mater, in middle of brain, outerpart of spinal cord. White mater are tracts in the brain. White matter is myelinated.
Visual Pathway
Light passes through cornea
Lens
Retina
Optic Nerve: Cranial Nerve II
Optic chiasma: "swtiches sides"
Optic tract
Midbrain
Thalamus
Primary visual cortex in the occipital lobe
Parts of neurons.
Cell body: Middle part
Nucleus and nucleolus: Creates Ribosomes
Chromatophilic substance: Outside nucleus, rough endoplasmic reticulum, creates plasma membrane.
Dendrites: Receptive cites
Axon hillock: Start of the axon from cellbody
axon: Long rope transmitter
axon collateral: Branched off axon from main axon
Terminal boutons: end of axon; axon terminals.
anatomy of a nerve
Axon is wrapped in the myelin sheath.
A layer called the endonerium covers the axon; endonerium is loose connective tissue. Endoneurium is only around some axons
A lot of axons bundles together is called a fascicle.
the layer that covers a fascicle is the perineurium.the perineurium is covered in fibrous connective tissue
A lot of fascicles together make up the nerve. The nerve is covered by epineurium.
Nerves also have blood vessels.
Structures and funtions of neurons:
multipolar: Many processes extend from cellbody; located on motor neurons and interneurons
bipolar: Two processes are on cell body; located in special sensory
unipolor: on process is on the cell body; located in general senspory nerves