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Nervous System (Senses (Receptor types (based off stimulus type)…
Nervous System
Senses
Eye components and visual pathway
Layers
Inner (retina):
Near optic disc. Lines inner part of the back of the eye. Converts received light into neural signals sent to the brain.
Fibrous
Sclera:
White part of eye. Dense connective tissue. Anchor for muscles. Protective, gives shape.
Cornea:
In anterior part of eye. Clear. Part of eye that focuses light.
Vascular (choroid):
Nourishes other layers and retina. Absorbs light and prevents scattering.
Cells
Rods:
Sensitive to light and dark. Most abundant.
Cones:
Color vision in bright light
Parts of eye
Iris:
Location - In front of the lens and behind the cornea. Function: Controls how much light comes through the eye.
Optic disc:
Location - The back of the eye. Function: Where optic nerve fibers leave retina
Lens:
Location - Behind iris and pupil. Function: Changes focal distance of eye.
Macula lutea:
Located exactly opposite from the pupil. Function - Provides the sharpest vision.
Fovea centralis:
Location - Within macula lutea. Function - Central point within the macula lutea in which your vision is the absolute clearest.
Segments
Posterior:
Boundary = Lens & ciliary body - posterior wall. Takes up most of space. Filled with vitreous humor. Gel-like.
Anterior:
Boundary = Lens - cornea. Anterior chamber is from cornea - iris. Posterior chamber is from iris - lens.
Visual pathway:
Cornea --> Lens --> Retina --> Optic nerve --> optic chiasm --> optic tract --> mid brain --> thalamus --> primary visual cortex in occipital lobe.
Olfaction components and pathway
Cribiform foramina:
In ethmoid bone. Has holes for axons to go trough to deeper tissue
Pseudostratified columnar epithelium:
Has olfactory sensory neurons within it going to the olfactory bulb and tract.
Pathway:
Pseudostratified columnar connective tissue --> olfactory receptors --> olfactory bulb --> olfactory tract --> limbic region OR primary olfactory cortex in temporal lobe
Receptor types (based off stimulus type)
Nociceptor:
Pain receptors.
Mechanoreceptor:
Receptor to physical-type things. Such as touch, pressure, vibration, stretch.
Chemoreceptor:
Chemical receptors. In blood, nose, tongue.
Photoreceptor:
Located in eyes. Light receptor.
Thermoreceptor:
Temperature, cold and warm receptors. In skin and internal organs.
Baroreceptor:
Changes in pressure. Blood pressure, specifically.
Gustation components and pathway
Taste buds:
On the tongue, inner cheeks, pharynx, palate, epiglottis
Cranial nerves involved:
7 (facial nerve), 9 (glossopharyngeal), 10 (vagus)
Pathway:
Gustation --> Taste buds --> 3 cranial nerves --> medulla oblongata --> thalamus -->primary gustatory cortex in the insula
Receptor types (based off stimulus origin)
Proprioceptors:
Have to do with movement and body position. Located in muscles, tendons and ligaments
Interoceptors:
Stimulus origin is internal organs. i.e.: Fullness
Exteroceptors:
Stimulus origin is the environment. Located in skin and special sense areas
Ear components and pathway
External ear
Auricle:
AKA pinna. Gathers and funnels sound waves. Amplifies sound.
External auditory meatus
Middle ear
Tympanic membrane:
Vibrates and transmits vibrations to auditory ossicles
Auditory ossicles:
Transmits vibrations to cochlea
Pathway:
Tympanic membrane --> middle ear --> auditory ossicles --> transmits vibrations --> cochlea --> cochlear and vestibular nerve --> CN #8 --> cochlear nerve --> medulla oblongata --> pons --> midbrain --> thalamus --> primary auditory cortex in temporal lobe
Nervous system organization
PNS main structures and functions
Cranial nerves:
Connected to brain. Gathers sensory info from receptors and passes it on to the CNS
Spinal nerves:
Connected to spinal cord. Gathers info from receptors and passes it on to CNS
Ganglia:
Clusters/groups of neuron cell bodies
CNS main structures and functions
Structure:
Brain and spinal cord
Function:
Receives, processes and responds to sensory input
Autonomic division:
Mainly to ventral body cavity contents (intestines, liver, stomach, etc). Includes smooth muscle, cardiac muscle, glands, arrestor pili muscle, smooth muscle of blood vessels, sweat glands
Somatic division:
Mainly to skin, body wall (torso/trunk), skeletal muscles. Basically everything besides the ventral body cavity contents.
Neurons
Structural types
Bipolar:
Two processes from centrally located cell body.
Unipolar:
One process from cell body that branches into two.
Multipolar:
Many dendrites and one axon
Functional types
Motor:
Efferent. Go away from CNS. Structure: Multipolar.
Sensory:
Afferent. Go towards CNS. Structure: Unipolar
Interneurons:
Between neurons. In CNS only. Structure: Multipolar.
Major components
Cell body
Nucleus and nucleolus
Chromatophilic substance
Dendrites
Axon hillock
Axon
Axon collaterals
Terminal arborization
Terminal boutons (axon terminals)
Anatomy of nervous system
Nerve components
CNS
Myelination (Oligodendrocytes):
Creates myelin sheath in CNS.
White matter:
Tracts in brain and spinal cord. (Mostly) myelinated axons.
Gray matter:
Cell bodies in brain. Cortex = outer layer. Deep gray matter is in the center of the brain.
Nucleus:
Cluster of neuron cell bodies in CNS.
Tract:
A bundle of axons (but not actually a nerve) in the CNS.
Nerve:
Bundle of axons in CNS.
PNS
Satellite cells:
Surround neuron cell bodies in ganglia. Function: Supportive, help regulate what goes in and out of neuron cell bodies.
Myelination (Schwann cells):
Creates myelin sheath in PNS.
Ganglion:
Cluster of neuron cells in PNS.
Glial cells; location and brief description
Astrocytes:
Most abundant glial cells. Processes contact other cells through their axons and capillaries. Help maintain proper chemical environment.
Microglia:
Phagocyte. Eats invading microbes.
Ependymal cells:
Located in ventricles (spaces) filled with cerebrospinal fluid. Cilia help circulate fluid. Simple cuboidal/columnar epithelium with cilia on one end.