Nervous System
Senses
Anatomy of Nervous System
Nervous system organization
Neurons
Receptors: detect stimuli
and send signals to the CNS
Based on stimulus type
Based on stimulus origin
Chemoreceptor
Interocepters
Proprioceptors
Exterocepters
Sensitive to stimuli outside the body. Ex: touch, pain, pressure, pain in skin.
Sensitive to stimuli from visceral organs. Ex: Changes in chemical concentration.
Located in the musculoskeletal organs. They send inputs on body movement to the CNS.
Photoreceptor
Thermoreceptor
Nocireceptor
Mechanoreceptor
-touch, pressure, stretch, vibrations, and even blood pressure detected by t he BARORECEPTOR.
Temperature changes
Chemical change in solution and changes in blood chemistry
Responds to light
-respond to harmful stimuli that result in pain.
Vision
Eye components
Visual pathway
Inner layer
Vascular layer
Fibrous layer
Cornea
Sclera
choroid
iris
Ciliary body
Optic nerve
retina
white layer that protects the eyeball and provides it with shape.
transparent layer through which light enters the eye.
ring of thick tissue that encircles the lens
colored part of the eye which has the pupil- a hole that allows light in.
highly vascular and pigmented membrane that helps nourish other parts in the eye
nerve that runs from eye to brain
Made of the outer pigmented layer and inner neural layer, it helps to absorb light and detect light with its photoreceptors.
lens
thick transparent disc that changes shape to allow focusing of light on retina
Segments
Anterior
Posterior
Anterior chamber
Posterior chamber
Filled with vitreous humor. Transmits light, helps support the neural layer and helps maintain pressure
between cornea and iris. contains aqueous humor that helps nourish the avascular lens and cornea.
between iris and lens
Cornea>Lens>Retina>Optic nerve>Optic chiasm> Optic tract> Midbrain>Thalamus>Primary visual cortex in the occipital lobe
Olfaction
Pathway
Roof of nasal cavity(olfactory sensory neurons)> Through Cribiform foramina> Olfactory bulb> Olfactory tract> Limbic region and primary olfactory cortex
Gustation
Pathway
Taste buds> 3 cranial nerves ( Facial, Glossopharngyeal, Vagus)> Medulla oblungata>Thalamus> Primary gustatory cortex in insula lobe
Hearing and equilibrium
auditory pathway
Outer ear(auricle) > External acoustic meatus> Ear drum> Middle ear> cochlea> Cochlear nerve and vestibulocochlear nerve> medulla oblungata> pons> midbrain>thalamus> primary auditory cortex in temporal lobe
Central nervous system
Peripheral nervous system
integrates sensory information and responds
Brain
Spinal cord
Gathers information and passes it on to the CNS.Includes the spinal nerves, the cranial nerves and ganglia.
Divisions
Afferent division
Efferent division
Visceral sensory
Somatic nervous system
Somatic sensory
Autonomic nervous system
General: Temperature, pressure, pain, touch in skin, body walls and limbs.
Special: Equilibrium, vision, hearing
Specific: Gustation, olfaction
General: stretch, pain, temperature, chemical changes and irritation in viscera.
motor innervations of all skeletal muscles
motor innervation of smooth muscle, cardiac muscle, and glands.
Nerve components
Glial cells- supporting cells
Axons
Connective tissue
carry signals away from the cell body. Some axons are covered in myelin sheath. A bundle of axons make a fascicle
Endoneurium
perineurium
epineurium
loose connective tissue that covers each axon
fibrous connective tissue that covers fascicles
tough fibrous connective tissue that covers the entire nerve
In the CNS
In the PNS
Astrocytes- most abundant cells that help to maintain a proper chemical environment. Their processes attach to axons and capillaries.
Microglia- smallest glial cells that act as phagocytes.
Ependymal cells- simple cuboidal epithelium that have cilia and microvilli. They help circulate the cerebrospinal fluids.
Oligodendrocytes- wrap their cell process around axons and produce myelin sheaths.
Satellite cells- surround neuron cell bodies within ganglia. they help regulate what goes in and out of the cell body.
Schwann cells- only wraps one axon and maybe even multiple times. They create the myelin sheaths.
Structural types
Functional types
Major components
Bipolar- has two processes that extend in opposite sides
Unipolar- has one short single process that emerges from cell body and then divides.
Multipolar - has more than two processes. Usually multiple dendrites and one axon
motor neuron- signals muscle cells or gland cells
Interneuron- lies between sensory and motor neuron or is completely confined to the CNS.
Sensory neuron- specialize in carrying information from sensory receptors
Neuron processes- dendrites and axons responsible for receiving and sending signals respectively. Axons arise in the axon hillock, may contain branches( axon collateral) and end at the axon terminal.
Cell body- contains nucleus and chromatophilic substance responsible for renewing membranes and proteins.
Synapse- although not a part of the neuron, its is the site where neurons communicate.