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body tubes N E R V O U S S Y S T E M (General senses and…
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Nervous system organization
Peripheral Nervous System (PNS)
Structure
: 1. Cranial nerves (attached to brain) 2.Spinal nerves (attached to spinal cord), 3.Ganglia (cluster of neuron cell bodies)
Function
: links all parts of the body to the CNS for communication
Somatic Division
Somatic Sensory
: receptors in the skin, bones & skeletal muscle (outer tube), i.e. touch, pain, pressure, vibration, temperature and body sense (proprioception)
Somatic Motor
:
voluntary
- stimulates contraction of
skeletal muscle
(outer tube)
Visceral (Autonomic) Division
Visceral Motor
:
automatic
regulation of
smooth/cardiac muscle
contraction AND gland secretion (inner tube)
Visceral Sensory
: visceral senses, i.e. hunger, nausea, stretch, pain, chemical changes and temperatures in visceral organs
Central Nervous System (CNS)
Structure
: Brain & Spinal Cord
Function
: Processes all sensory input and sends out responses
General senses and special senses
Eye
Components:
Inner Layer
retina
:
pigmented layer
neural layer
rods: many - black/white images
cones: fewer - color images
Macula lutea: precise posterior pole
optic disc: blind spot - where optic nerve is, no photoreceptors
fovea centralis: center of macula lute - clearest vision
Fibrous Layer
Dense C.T.
cornea
: transparent; most anterior part of eyeball; allows light into eye; involved w/focusing light of retina;
avascular
sclera
: surrounds eyeball except for where the cornea is; white of eye, dense CT, protective, gives shape, provides anchor for extrinsic eye muscles
Vascular Layer
(nourishes)
choroid
: dark pigmented membrane lining sclera, nourishes the other layers, an intrinsic muscle (changes shape of lens),
Posterior Segment
Vitreous Humor
Anterior Chamber of the
Anterior Segment
- filled with aqueous humor
Lens
Posterior Chamber of the
Anterior Segment
- filled with aqueous humor
Iris
eye color
Visual pathway
: Cornea --> pupil --> lens --> posterior segment --> retina --> optic nerve --> optic chiasm --> primary visual cortex in occipital lobe --> retina
Olfaction
components
: olfactory receptors, pseudostradified columnar epithelium w/ olfactory sensory neurons
Pathway
: olfactory receptors --> olfactory sensory neuron in the olfactory bulb --> olfactory tract --> limbic system
OR
primary olfactory cortex in temporal lobe
Receptor Classifications
Receptor location / Stimuli location
(WHERE?)
Interoceptors:
visceral organs, nasal cavity & tongue
Proprioceptors
: Skeletal muscle, joints, ligaments, & tondons
Exteroceptors
: Skin, eyes & ears
Stimulus Type
(WHAT?)
Chemoreceptors
: responds to chemicals tasted or smelled; changes to blood chemistry
Photoreceptors
: responds to light (located in eye)
Thermoreceptors
: responds to temperature changes
Mechanoreceptors:
pressure, touch, vibration, stretch
Baroreceptor
; monitors blood pressure
Nociceptors
: responds to pain
Gustation
Pathway:
Facial nerve VII, Vagus nerve X, glossopharyngeal nerve IX --> medulla oblongata --> thalamus --> gustatory cortex in the insula
components
: tongue, pharynx, epiglottis, insula lobe of cerebral cortex
Ear
Pathway:
cochlear branch of CN VIII --> medulla oblangata --> pons --> midbrain --> thalamus --> primary auditory cortex in the temporal lobe
components
: tympanic membrane (ear drum), auditory ossicles (outer - auricle), cochlea, cochlear nerve, vestibular nerve
Neurons
structural types:
motor (efferent), sensory (afferent), interneurons (association neurons)
functional types
: multipolar, bipolar, unipolar
Components
: cell body, nucleus & nucleolus, chromatophilic substance, dendrites, axon hillock, axon, axon collaterals, terminal arborization, terminal boutons (axon terminals)
Anatomy of the nervous system
Nerve components:
axon, myelin sheath, endoneurium, bundles of axons, perineurium , bundles of fascicles, epineurium --> nerve fibers
Glial cells
Ependymal cells
: simple cuboidal/columnar epithelium - lines ventricles (spaces in brain/spinal cord that are filled with cerebrospinal fluid - cilia keeps fluid moving
Satellite cells
: surround neuron cell bodies in ganglia
Microglia
: phagocytes- removes microbes and damaged nerve tissue
Oligodendrocytes
- myelination of CNS
Astrocytes
: most numerous - helps maintain the appropriate chemical environment
Schwann cells
- myelination of PNS
