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Nervous system and Senses (Major Components of Neurons (The Cell Body The…
Nervous system and Senses
Senses
Three Types of Sensory Receptors-origin based
I
nteroreceptors
: Stimulus origin is our internal organs.
Propioreceptors
: Stimulus origin is the muscle, their tendons, ligaments and joints.
Exteroreceptors
: Our environment is the stimulus origin. Skin and special Senses- Sight, Hearing, Olfaction, and equilibrium
Type of Stimulus-Based sensory receptors
Thermoreceptors
- cold and warm receptors, skin and inernally
Photoreceptors
Light, in our eyes
Chemoreceptors
Chemicals, nose and tongue, our blood
Nocireceptor
-Pain
Mechanoreceptor
-touch, pressure, vibration
Baroreceptor
-Measures and is sensitive to blood pressure
Components of the Eye
Three Tunics (Layers)
Vascular Layer
The Choroid, which is contiguous with the Ciliary Body, nourishes other layers, and is pigmented. The pigment absorbs light, prevents scattering.
Inner Layer
Contains the 1.)Retina, which contains photoreceptors. Axons from these receptors converge to form the optic nerve. 2.) the Lens, which is important for focusing light on the retina. 3.) The Iris, which is the colored part of the eye, for dilation and constriction of the the pupil. 4.) The pupil, which is the aperture hole.
Fibrous Layer
Made up of 1.)Sclera, dense connective tissue which is an anchor extrinsic eye muscles. Protects and gives shape. 2.) The Cornea, which is transparent, and allows light into the eye, and focuses light.
Visual Pathway
- Cornea-->Lens-->Retina-->Optic Nerve-->Optic Chiasm-->Optic Tract-->Thalamus-->Primary Visual Cortex(Occipital Lobe)
Olafaction
Olfactory Epithelium is located at the roof of the nasal cavity. Pseudo-stratified Columnar. Primarily, Olfactory sensory neurons, the Olfactory bulb, and Olfactory tract
Olfactory Pathway
Olfactory Neurons-->Olfactory Bulb-->Olfactory Tract-->Goes to Both Imbic Region and Primary Olfactory Cortex (Temporal Lobe)
Gustation
Taste Buds are located in the tongue, inner cheeks pharynx, palate, epiglottis. The Facial Nerve, Glossopharyngeal and Vagus Nerves all transmit information to the brain.
Gustatory Pathway
Taste Buds w/receptor cells-->Three Cranial Nerves-->Madula Oblongata-->Thalamus-->Primary Gustatory Cortex
Hearing
Auricle
Our outer ear, collects and funnels sound waves to amplify
Tympanic Membrane
ear drum transmits those vibrations to the middle ear auditory ossicles
Auditory Ossicles
Transmits those vibrations to the Cochlea
Auditory Pathway
Cochlear Nerve-->Madula Oblongata-->Pons-->Thalamus-->Primary Auditory Cortex (Temporal Lobe)
Central Nervous System
Located in the Brain and Spinal cord. Receives, processes, and responds to sensory input.
Peripheral Nervous System
Off to the side. Gathers sensory information from all receptors and passes it on. Includes, Spinal Nerves, Cranial Nerves, and ganglia
Somatic Motor Division
Mainly towards skin, torso/trunk body wall, skeletal muscle. Every thing but/except the Ventral Body Cavity contents
Autonomic Motor Division
Mainly Towards the Ventral Body Cavity. Smooth Muscle, Cardiac Muscle, Glands, Erector Pilli, Smooth Muscle of the blood vessels
Anatomy of the Nervous System
A typical nerve is made up of individual Axons. Each Axon is covered by insulated coating, the Endoneurium. Each Axon is a one way traffic signal either going in or out. Some Axons, are covered by a myelin sheath. The Axons are bundled together to form Fasicles, which is covered by the Perineurium. All the Fasciles are then wrapped by the Epineurium.
Glial Cells
There are six Glial Cells, Four in the Central Nervous System and two in the Peripheral Nervous System
Central Nervous Sysem
Microglia
Phagocyte- destroys invading microbes and damaged/dying nervous tissue
Ependymal Cells
Located in ventricles, filled with cerebospinal fluid. Simple Cuboidal Columnar Epithelium w/cilia and microvilli
Astrocyte
Most abundant, processes contact-Axons and capillaries. Supportive, helps maintain proper chemical environment.
Oligodendrocytes
Creation of Myelin Sheath
Peripheral Nervous System
Satellite Cells
Found in the ganglion, surrounds the neuron cell body. helps regulate what goes in and out of the neuron cell bodies. Surrounds the neuron cell bodies.
Schwann Cells
Wraps one piece of the one Axon. Non-myelinated, creates Myelin Sheath in PNS
Major Components of Neurons
The Cell Body
The cytoplasm surrounding the nucleus
Chromatophillic Substance
Region of Rough Endoplasmic Reticulum and free Ribosomes. Creates Plasma Membrane and other proteins,
Dendrites
Processes that branch from the cell body to form/function as receptive sites.
Nucleus and Nucleolus
the Nucleolus is the main central control center of the Nucleus
Axon
Impulse generators and conductors that transmit nerve impulses away from their cell body. Thin processes that arise from the cone-shaped region of the cell body called the
Axon Hillock
Axon Hillock
where the Axon leaves the cell
Axon Collateral
Branch of Axon from the main Axon body
Structural Types of Neurons
Multipolar
Many processes extend from the cell body; all are dendrites except for a single Axon
Bipolar
Two process extend from the cell body; One is a fused Dendrite; other is an Axon
Unipolar
One process extends from the cell body and forms central and peripheral processes which together comprise and Axon.
Functional Type of Neurons
Interneurons
Most multipolar neurons are Interneurons that conduct impulses within the CNS, integrating sensory input or motor output.
Motor
Neurons
Efferent Neurons- Conduct impulses along the efferent pathways from the CNS to an effector (muscle/glands)
Sensory Neurons
Afferent Neurons- Transmit impulses toward the CNS from the sensory receptors in the PNS.