NERVOUS SYSTEM (SENSES (Receptors based on stimulus type: (Chemoreceptors …
Eye components and visual pathway:
(highly vascular, darkly pigmented membrane under sclera) - nourishes other layers, absorbs light, prevents scattering;
(ciliary muscle and ciliary processes, ciliaray zonule) - acts to focus lens;
(circularly arranged and radiating smooth muscle fibers) - acts to vary the size of the pupil (sphincter and dilator pupillae muscles).
(thin pigmented layer and thicker neural layer, under choroid) - absorbs light (contains photoreceptor cells: rod and cone cells);
(runs from the eye to the brain)
( white dense connective tissues) - provides shape and anchoring site for extrinsic eye muscles;
(transparent, avascular, connective tissue) - light-bending apparatus of the eye.
Pathway: Cornea -> lens ->retina -> optic nerve -> optic chiasma ->optic tract -> midbrain ->thalamus -> primary visual cortex.
Olfaction components and pathway:
Nasal conchae -> olfactory sensory neurons -> olfactory bulb -> olfactory tract -> limbic region and primary olfactory cortex.
Receptors are in the roof of nasal cavity, part of olfactory epitheium (pseudostratified columnar ep.), olfactory sensory neurons, olfactory stem cells, olfactory cillia
Receptors based on stimulus type:
Chemoreceptors - chemicals in solution.
Photoreceptors - light (eyes).
Thermoreceptors - temperature changes.
Nociceptors - pain.
Mechanoreceptors - touch, pressure, stretch, vibrations.
Gustation components and pathway:
Taste buds in mucosa of pharynx and mouth, papilla, gustatory epithelial cells, basal epithelial cells, gustatory hairs, taste pore.
Taste buds with receptor cells ->3 cranial nerves (facial (VII), glossopharyngeal (IX), vagus (X)) -> medulla oblongata ->thalamus -> primary gustatory cortex in the insula lobe.
Receptors based on stimulus origin:
Interoceptors - changes in chemical concentration, taste, stretching, temperature (internal organs such as: lungs, bladder, digestive tube).
Proprioceptors - degree of stretch (musculoskeletal organs).
Exteroceptors - environment (skin, special senses such as: sight, hearing, taste, olfaction, smell, equilibrium balance).
Ear components and pathway:
Middle ear:medial and lateral boundary, oval and round window, epitympanic recess, mastoid antrum, pharyngotympanic tube, auditory ossicles, malleus, incus, stapes, skeletal muscles: tensor tympani and stapedius.
Internal ear: bony labyrinth, membranous labyrinth, endolymphatic flluid, perilymphatic fluid, cochlea.
External ear: auricle (pinna), helix, lobule, external acoustic meatus, tympanic membrane.
Acoustic meatus -> tympanic membrane -> middle ear ->auditory ossicles ->cochlea ->cochlea nerve -> vestibular nerve (VIII) -> medulla oblangata ->pons -> midbrain -> thalamus -> primary auditory cortex in temporal lobe.
NERVOUS SYSTEM ORGANIZATION
PNS main structures and functions:
Structure: cranial nerves, spinal nerves, ganglia.
Function: gathers sensory information, passes it on.
Somatic division/motor: voluntary; conducts impulses from the CNS to skeletal muscles (mainly skin, body torso, skeletal muscles).
CNS main structures and functions:
Structure: brain and spinal cord
Function: integrating and command center of the nervous system; receives incoming sensory signals, interprets, and dictates motor responses.
Autonomic division/motor:involuntary; conducts impulses from the CNS to cardiac muscles, smooth muscles, and glands (mainly ventral body cavity).
Sympathetic (mobilizes body systems during activity)
Parasympathetic (conserves energy).
Cell body, neuron processes (dendrites and axons), synapses.
Sensory(afferent), motor(efferent), and interneurons
Multipolar, bipolar, unipolar
ANATOMY OF NERVOUS SYSTEM
Myelinated and unmyelinated axons (nerve fibers surrounded by Schwann cells) enclosed by wrappings of connective tissue (endoneurium, perineurium, epineurium).
Glial cells:location, description:
Astrocytes (most abundant, regulating neurotransmitter levels, signaling increased blood flow through capillaries, controlling ionic environment).
Ependymal (forms a simple epithelium that lines the central cavity of the spinal cord and brain).
Oligodendrocytes (myelin sheaths creation).
Satellite (regulates what goes in/out of neuron cell bodies).
Schwann (myelin sheaths production).