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Nervous System (SENSES (TYPES OF RECEPTORS BASED ON STIMULUS TYPE…
Nervous System
SENSES
THE EYE COMPONENTS AND VISUAL PATHWAY
COMPONENTS OF THE EYE: TUNIC #1: FIBROUS LAYER (PART OF THAT IS THE SCLERA). DENSE CONNECTIVE TISSUE, PROTECTANT, ANCHOR FOR MUSCLES, 'EXTRINSIC EYE MUSCLES' GIVES SHAPE TO OUR EYES. THERE IS ALSO THE CORNEA HERE. IN THE VASCULAR LAYER #2 - CHOROID (NURISHES THE OTHER LAYERS. DEEPLY PIGMENTED, IT ABSORBS LIGHT AND PREVENTS LIGHT FROM SCATTERING. THE CHOROID IS CONTINUOUS WITH THE CILIARY BODY. THE INNER LAYER #3 - RETINA. VERY THIN AND DELICATE LAYER THAT ALLOWS US TO SEE. IS A PHOTORECEPTOR. THE AXONS CONVERGE TO FORM OPTIC NERVES.
VISUAL PATHWAY: CORNEA ----> PUPIL ----> LENS ----> POSTERIOR SEGMENT -----> RETINA
OLFACTION COMPONENTS AND PATHWAY
IN THE SUPERIOR NASAL CONCHA. OLFACTORY NERVES ARE CONNECTED TO THE OLFACTORY EPITHELIUM. IN THE ROOF OF THE NASAL CAVITY, THERE IS PSEUDOSTRATIFIED COLUMNAR EPITHELIUM TISSUE.
OLFACTORY RECEPTORS -->OLFACTORY SENSORY NEURON WITHIN THE OLFACTORY BULB --->OLFACTORY TRACT ---> LIMBIC SYSTEM (EMOTIONAL BRAIN) ---> PRIMARY OLFACTORY CORTEX
TYPES OF RECEPTORS BASED ON STIMULUS TYPE
CHEMORECEPTOR: SENSITIVE TO CHEMICALS (EXTERORECPTORS INCLUDE: CHEMICALS IN THE AIR, WATER AND BLOOD). (INTERCEPTORS ARE CALCIUM, SODIUM AND POTASSIUM FOUND IN OUR BODY).
NOCICEPTOR: DANGEROUS FOR US - MAKES US SENSITIVE TO PAIN SO WE KNOW TO STAY AWAY FROM IT.
PHOTORECEPTOR: SENSITIVE TO LIGHT (EXTERORECEPTORS)
MECHANORECEPTOR: SENSITIVE TO PRESSURE, TOUCH, VIBRATION AND STRETCH.
THERMORECEPTOR: TEMPERATURE (COLD SENSITIVE RECEPTORS AND WARM SENSITIVE RECEPTORS)
BARORECEPTOR: TYPE OF MECHANORECEPTOR THAT MEASURES THE BODIES INTERNAL BLOOD PRESSURE.
GUSTATION COMPONENTS AND PATHWAY
INCLUDES THE TONGUE, INNER CHEEKS, POSTERIOR WALLS OF THE PHARYNX. THEY ARE PEG LIKE STRUCTURES OF EPITHELIUM TISSUE AND EPITHELIUM CELLS THAT MAKE UP OUR TASTE BUDS.
THERE ARE THREE CRANIAL NERVES: FACIAL NERVE (VII), GLOSSAPHARYNGEAL NERVE (IX) AND VAGUS NERVE (X). THEY GO THROUGH THE MEDULLA OBLANGATA --> THALAMUS --->GUSTATORY CORTEX IN THE INSULA
TYPES OF RECEPTORS BASED ON STIMULUS ORIGIN
INTEROCEPTORS: (INSIDE) LOCATED DEEPER WITHIN US.
PROPRIOCEPTORS: STIMULIS ORIGIN IS OUR MUSCLES (INCLUDING TENDONS, LIGAMENTS AND JOINTS).
EXTEROCEPTORS: (OUTSIDE) STIMULUS COMES FROM OUR ENVIRONMENT. LOCATED IN: SKIN AND SPECIAL SENSES
EAR COMPONENTS AND PATHWAY
STRUCTURE: EXTERNAL ACOUSTIC MEATUS IN THE TEMPERAL BONE, ELASTIC CARTILAGE IS COVERED WITH STRATIFIED SQUAMOUS EPITHELIUM CALLED AURICLE. THE AURICLE DRAWS THE SOUND IN, AND AMPLIFIES THE SOUND WAVES. IN THE MIDDLE EAR: TYMPANIC MEMBRANE (EAR DRUM) AND AUDITORY OSSICLES. PATHWAY: THE VESTIBULORCOCHLEAR NERVE (VIII) ---> SEPERATES AFTER AWHILE, AND THE COCHLEAR BRANCH OF COCHLEAR NERVE (VIII) GO TO THE MEDULLA OBLONGATA ---> PONS ----> MIDBRAIN ---> THALAMUS ---> PRIMARY AUDITORY CORTEX (IN THE TEMPORAL LOBE.)
NERVOUS SYSTEM ORGANIZATION
PNS MAIN STRUCTURE AND FUNCTIONS
INCLUDES: CRANIAL NERVES, SPINAL NERVES AND GANGLIA
FUNCTION OF THE PNS: THIS IS THE PART OF THE NERVOUS SYSTEM THAT IS NOT IN THE BRAIN OR SPINAL CORD. THE CRANIAL NERVES ARE ATTACHED TO THE BRAIN, THE SPINAL NERVES ARE ATTACHED TO THE SPINAL CORD, AND TRAVEL TO THE ENDS OF EXTREMITIES, AND A GANGLIA IS A CLUSTER OR GROUP OF NEURONS OUTSIDE THE CNS.
SOMATIC DIVISION
SOMATIC SENSORY, OR AFFERENT (CARRYING TOWARD) (CNS) - SIGNALS ARE PICKED UP BY SENSORY RECEPTORS THROUGHOUT THE BODY
INCLUDES: TOUCH, PAIN, PRESSURE, VIBRATION, TEMPERATURE AND PROPRIOCEPTION (WHICH MEANS THAT YOU CAN FEEL EXACTLY WHICH JOINTS AND MUSCLES ARE GETTING USED. THE SS ALSO INCLUDES: HEARING, EQUILIBRIUM, AND VISION.
SOMATIC MOTOR, OR EFFERENT - SIGNALS ARE CARRIED AWAY FROM THE CNS BY NERVE FIBERS OF THE PNS
INCLUDES THE TRAVELING (OUTPUT) TO SKELETON MUSCLES. THIS SYSTEM IS COMMONLY REFERRED TO AS THE VOLUNTARY NERVOUS SYSTEM.
CNS MAIN STRUCTURE AND FUNCTIONS:
INCLUDES: BRAIN AND SPINAL CORD
FUNCTION OF THE CNS: THE BRAIN AND SPINAL CORD ARE CONSTANTLY RECEIVING AND PROCESSING INCOMING SIGNALS, AND THEN APPROPRIATELY RESPONDING TO THEM (EITHER WITH A MUSCLE OR A GLAND).
AUTONOMIC DIVISION (VISCERAL SENSORY)
VISCERAL SENSORY, OR AFFERENT (CARRYING TOWARD) (CNS) - SIGNALS ARE PICKED UP BY SENSORY RECEPTORS THROUGHOUT THE BODY
INCLUDES: STRETCH, PAIN, TEMPERATURE, CHEMICAL CHANGES, IRRITATION IN VISCERA; NAUSEA AND HUNGER. ALSO INCLUDES TASTE AND SMELL.
VISCERAL MOTOR, OR EFFERENT - SIGNALS ARE CARRIED AWAY FROM THE CNS BY NERVE FIBERS OF THE PNS
HANDLES THE CONTRACTIONS OF SMOOTH AND CARDIA MUSCLE, AS WELL AS SECRETION OF THE BODY'S GLANDS. THE NEURONS LOCATED IN THE VM MAKE UP THE AUTONOMIC NERVOUS SYSTEM (ANS) AND IT'S INVOLUNTARY.
NEURONS
STRUCTURAL TYPES OF NEURONS
THERE ARE THREE STRUCTURAL TYPES OF NEURONS: UNIPOLAR BIPOLAR, AND MULTIPOLAR
UNIPOLAR NEURONS: ALSO CALLED PSEUDOUNIPOLAR. ONE PROCESS STARTS AT THE CELL BODY AND FORMS BOTH A CENTRAL PROCESS AND A PERIPHERAL PROCESS.
BIPOLAR: THIS PROCESS IS FOUND IN THE SPEICAL SENSES AND ALSO THE RETINA. IT'S WHEN TWO PROCESSES (BI) START FROM THE CELL BODY. ONE IS A DENDRITE AND THE OTHER IS AN EXON.
MULTIPOLAR NEURONS: MANY PROCESSES START AT THE CELL BODY. ALL THE PROCESSES ARE DENDRITES EXCEPT FOR ONE AXON.
MAJOR COMPONENTS OF A NEURON
THE CELL BODY, NEURON PROCESSES, DENDRITES, AXONS AND SYNAPSES
FUNCTIONAL TYPE OF NEURONS
THERE ARE THREE FUNCTIONAL TYPES OF NEURONS: MOTOR (EFFERENT) NEURONS, SENSORY (AFFERENT) NEURONS, AND INTERNEURONS (ASSOCIATION NEURONS)
SENSORY (AFFERENT) NEURONS - THE MAJORITY OF THESE NEURONS ARE UNIPOLAR, BUT IN THE SPECIAL SENSES THEY ARE BIPOLAR. THE CELL BODIES ARE LOCATED IN THE GANGLIA OF THE PNS. THE GANGLIA ARE FOUND NEAR TO THE SPINAL CORD, AND THEY ARE UNIPOLAR.
INTERNEURONS (ASSOCIATION NEURONS) - INTER "BETWEEN" . THEY ARE ONLY FOUND IN THE CNS. THEY ARE MULTIPOLAR AND ARE WHAT THE MAJORITY OF THE NEURONS IN OUR BODYS ARE.
MOTOR (EFFERENT) NEURONS - THESE ARE MULTIPOLAR. THE CELL BODY IS IN THE CNS, AND THEN IT MOVES TO THE MUSCLES AND GLANDS OF THE PNS.
ANATOMY OF NERVOUS SYSTEM
NERVE COMPONENTS
CONNECTIVE TISSUE WRAPPINGS: EACH NERVE CONSISTS OF MANY AXONS. THE AXON IS THE PART OF THE NEURON THAT CARRIES A SIGNAL. THE MYELIN SHEATH IS THE 'INSULATION' THAT COVERS SOME AXONS. THERE CAN BE BOTH MYELINATED AND NONMYELINATED AXONS. WITH EACH NERVE (WHICH HAVE MANY AXONS); EACH OF THOSE AXONS IS SURROUNDED BY SCHWANN CELLS. BUNDLES OF AXONS IS REFERRED TO AS A FASCICLE. ANOTHER TYPE OF CONNECTIVE TISSUE, THE PERINEURIUM - IS FIBROUS CONNECTIVE TISSUE AND IS SURROUNDS EACH FASCICLE. LASTLY, SURROUNDING THE SCHWANN CELLS, IS A DELICATE LAYER OF LOOSE CONNECTIVE TISSUE, CALLED ENDONEURIUM.
SENSORY NEURONAL ELEMENTS: THE NERVES THAT ARE SENSORY SIGNMALS WILL ALWAYS BE SENSORY NERVES. USUALLY NERVES ARE MIXED, HOWEVER, AND HAVE BOTH SENSORY AND MOTOR NEURONS.
MOTOR NEURONAL ELEMENTS: THE NERVES THAT ARE MOTOR NERVES WILL ALWAYS BE MOTOR NERVES.
GLIAL CELLS (LOCATION AND BRIEF DESCRIPTION)
IN CNS:
EPENDYMAL CELLS: SIMPLE CUBOIDAL TO SIMPLE COLUMNAR EPITHELIUM. CILIA ON ONE SIDE AND MICROVILLI ON THE OTHER SIDE. THEY LINE SPACES FILLED WITH CEREBROSPINAL FLUID IN THE BRAIN AND SPINAL CORD, CALLED VENTRICLES. THE CILIA HELPS TO KEEP THIS FLUID MOVING AND PROTECTS THE BRAIN BY ALLOWING IT TO FLOAT AND BE SAFELY CUSHIONED.
MYELINATION - OLIGODENDROCYTES: THE MYELINATION IS A COVERING OF LIPID AND PROTEIN (PRIMARILY OF LIPID). THEY WRAP THEIR PLASMA AROUND SEVERAL PORTIONS OF AN AXON.
MICROGLIA: THESE ARE THE PHAGOCYTES OF THE CNS. THESE MONITOR AROUND, LOOKING FOR BACTERIA, VIRUSES, OR WORN OUT/OLD/USELESS CELLS. THEY REMOVE MIBROBES AND DAMAGED NERVE TISSUE.
ASTROCYTES: MOST NUMEROUS TYPE OF GLIAL CELLS. MANY PROCESSES THAT CONTACT NEURONS AND CAPILLARIES. THEY SUPPORT NEURONS AND HELP TO MAINTAIN THE APPROPRIATE CHEMICAL ENVIRONMENT FOR THE BODY.
IN PNS:
SATELLITE CELLS: SURROUND NEURON CELL BODIES WITHIN THE GANGLIA
SCHWANN CELLS:MAKES OUR MYELIN SHEATH FOR CRANIAL NERVES AND SPINAL CELLS. THE SCHWANN CELLS WRAP THEIR PLASMA MEMBRANE AROUND ONE PORTION OF ONE AXON (THIS SPEEDS UP TRAVEL TIME).