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48 Cards in this Set
- Front
- Back
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In the sympathetic N.S, what are the preganglionic neurons composed of and where are they located?
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The preganglionic neuron is composed of a cell body in the spinal cord (thoracic segments and upper 2, 3 lumbar segments-IML column on lateral horn of spinal gray matter) and has the neurotransmitter-Acetylcholine. In the CNS. Their axons leave through the ventral roots.
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In the Sympathetic N.S., what are the postganglionic neurons composed of and where are they located?
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The postganglionic neuron contains a cell body in the periphery. It's NT is norepinephrine (catecholamine).
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In parasympathetic N.S., what are the preganglionic neurons composed of? and where are they located?
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The preganglionic parasymp neurons are located in cell bodies in the brainstem (CN: III, VII, IX, X) and the NT is Ach.
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In parasympathetic postganglionic neurons, where are they located and what is their NT?
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Located in cell body in the peripheral ganglia and also secrete ACh as a NT.
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What are the sympathetic vs parasympathetic N.S. eye responses to stimulation?
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For the sympathetic-pupil dilates and the ciliary muscle relaxes to increase lens thickness for far vision.
Parasympathetic-pupil contricts and ciliary muscle contracts for near vision. |
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What is the vascular response mediated by?
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It's mediated by the sympathetic nervous system only. The vasodilation is produced by norepi (alpha 1 adrenergic receptors) and it increases blood pressure and causes a decrease in the diameter of arterioles.
The vasodilation is caused by release of epi (Beta 2 adrenergic receptor) during exercise and plays a role primarily in skeletal muscle vasculature. |
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What innervates the carotid sinus baroreceptors? Where are they located?
What pathway are they part of? |
Glossopharyngeal IX CN
In the dorsal medulla: nucleus of the solitary tract (NST) Afferent pathway |
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What innervates the aortic arch baroreceptors? What pathway is it part of?
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Vagus nerve X
In dorsal medulla: nucleus of solitary tract Afferent pathway |
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What is the sympathetic efferent pathway?
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From NST-->caudal ventral lateral medulla (CVLM)-->rostral ventrolateral medulla (RVLM)="pressor area"--> spinal cord intermediolateral (IML) cell column=preganglionic neurons--> postganglionic neurons
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What is the parasympathetic efferent pathway?
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NST-->cardiac preganglionic neurons=dorsal motor nucleus of X (DMX) and nucleus ambiguus (NA) --> postganglionic neurons--->heart
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What are the effectors (responders of the autonomic baroreceptor system?
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Heart, arterioles, veins.
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What makes the adrenal medulla so special as part of the sympathetic nervous system?
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Usually preganglionic fibrers travel near to sp. cord (sympathetic chain or prevertebral ganglia) but the adrenal medulla is directly innervated by preganglionic sympathetic fibers.
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What is an afferent peripheral nerve?
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It takes sensory information from periphery to CNS.
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What is an efferent peripheral nerve?
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It is a motor neuron that originates in the CNS and gathers information from CNS to periphery-mainly muscle.
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What is the structure of a primary afferent neuron?
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-Cell body in sensory ganglion
-Peripherally directed process ending in skin, muscle, joints and a central process ending in the CNS. |
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What is the structure of a primary efferent neuron?
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-Cell body located in ventral horn of spinal cord
-Axons to muscle |
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What are the two types of afferent nerve fibers? The divisions are based on size and conduction speed.
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1. A fibers-largest, lots of myelin with:
a. A-beta fibers being the largest, thick myelin and very fast (30-60 m/s b. A-delta fibers are thinly myelinated, slower conduction (2-3 m/s) c. A-alpha fibers are EFFERENT (motor), very fast (>70 m/s) and in PNS 2. C fibers-are very thin, no myelin ( <2 m/s) |
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What are sensory receptors and where are they located?
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They are located only on afferent fibers. They are a neurostructure that transduces one form of energy into another. (changes in membrane potential that may lead to an action potential)
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What are the 4 types of sensory receptors?
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1. Somatic receptor-tells about body sensation
2. Photo receptors-eye 3. Sound receptors-inner ear (pressure receptors) 4. Chemoreceptors-activated by specific chemicals or molecules (taste, smell, etc.) |
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Name the cutaneous receptors of the somatic sensory component.
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1. Mechanoreceptors-tactile receptors
A beta fibers that detect touch, pressure, stretch or vibration 2. Thermal receptors-(within 2-3 deg) A delta fibers-detect cold C fibers detect warm 3. Nociceptors-detect pain and are activated by intense, potentially damaging stimuli. A deltas-detect sharpness C fiber(45 degree+ heat temps and cold, notious chemical irritants. Itch) |
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Name the receptors in joints, tendons, and muscles that are part of the somatic sensory component.
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1. Proprioceptors-detect body position by stretch and movement
2. mechanoreceptors-touch (A-beta receptors) 3. nociceptors- A-delta-sharpness C fibers-intense cold, heat, chemical irritants |
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Name the receptors in viscera (of somatic sensory receptors).
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1. Mechanoreceptors-sense stretching of stomach.
2. Nociceptors-pain-chemical/mechanical stimulent-eg. kidney stone |
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What are photoreceptors?
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Sensory eye receptors that detect electromagnetic energy of specific wavelengths via neural activity (change in membrane potential)
*Rods and cones are the photoreceptors of the eyes. |
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What are sound receptors?
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Pressure receptors in the inner ear.
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What are chemoreceptors?
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Sensory receptors that bind specific molecules for Eustation (taste), olfaction-etc.
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What are the receptors found in bone?
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Nociceptors that detect mechanical and chemical stimuli (like cancer).
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What is Mullers Law of Specific Nerve Energies?
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A sensory receptor is excited by one type of stimulus-very specific.
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What are the 4 events (steps) that occur in transduction (activation of receptors)?
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1. adequate stimulus-there must be a stimulus that the receptor is sensitive to. (eg-displacement of arm hair)
2. change in membrane potential-of receptor. -receptor potential or generator potential -summation of these receptor potentials occurs at the level of the receptor. 3. transmission of action potential- along the axon into the CNS -frequency code-is the number of action potentials over time "code" that the PNS provides to the CNS where if the rate of discharge is increased, the intensity of the stimulus potential increases (location, duration, quality). 4. Adaptation- -receptor activity decreases either very rapidly adapted or slow adaptation. |
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What is the difference between tonic and phasic receptors? Give examples.
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Tonic receptors are always active (eg-proprioceptors) and phasic receptors are not normally active (eg. nociceptors)
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What are the 5 senses that the somatic sensory system covers?
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1. Mechanical stimulation of skin.
2. Temperature-hot, cold 3. Noxious stimulation of skin 4. Proprioception-position of parts of body 5. Steriognosis-size/shape by touching |
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How does information from the skin mechanoreceptors get to the cerebral cortex?
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1. 1st order neurons-sensory info from skin through spinal cord to brainstem
2. 2nd order neurons-these are located in the brainstem and go to the thalamus 3. 3rd order neurons-located in the thalamus and send info to cerebral cortex |
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What are the functions of the skin and what types exist?
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*Either glabrous (hairless) or hair skin
1. Protective 2. Thermal regulation 3. Secretes and absorbs fluid 4. Sensory function |
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What are the encapsulated skin receptors? Hint-2 layered capsule types and 1 thin capsule type.
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Layered capsule types:
1. Pacinian corpuscles 2. Meissner corpuscles Thin capsule- Ruffini endings |
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Where are nonencapsulated skin receptors located?
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These are accessory structures located in endings around hairs and Merkel endings are free nerve endings.
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What are the following characteristics of Pacinian corpuscles?
1. Location 2. Receptor ending 3. Adaptation speed 4. Functions |
Pacinian corpuscles:
1. Located in deep subcutaneous tissue 2. Have many layers that rap the nerve endings and each of these layers diminish the pressure. High action potentials but they dissipate quickly 3. Rapidly adapting (millisec-sec) 4. Functions: vibration and texture discrimination. 4. |
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What are the following characteristics of Meissner corpuscles?
1. Location 2. Receptor ending 3. Adaptation speed 4. Functions |
Meissner corpuscles:
1. Located in grooves between dermal papillae in glandular, hairless, thick skin. 2. Receptor endings within capsule with stack of epithelial cells 3. Rapidly adapt 4. Functions: vibration, touch and texture discrimination. (make up 40% of all receptors in our fingertips) |
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What are the following characteristics of Raffini endings?
1. Location 2. Receptor ending 3. Adaptation speed 4. Functions |
Raffini endings are encapsulated receptors with a thin capsule.
1. Located: dermis of hairy and glandular skin 2. Receptor endings are covered by membranes and collagen. 3. Slowly adapt 4. Functions: sense pressure and stretching of skin |
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What are the following characteristics of nonencapsulated receptors with accessory structures?
1. Location 2. Receptor ending 3. Adaptation speed 4. Functions |
Nonencapsulated receptors with accessory structure are endings around hair.
1. Location: hairy skin-wraps around follicle 2. Receptor endings wrap around follicle 3. Rapidly adapt 4. Functions as touch receptors of skin. |
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What are the following characteristics of Merkel endings (corpuscles)?
1. Location 2. Receptor ending 3. Adaptation speed 4. Functions |
Merkel corpuscles are located in the basal membrane.
2. Receptor endings: the merkel cell contacts 5-10 nerve endings 3. Mainly slowly adaptive 4. Functions in detecting light pressure and texture discrimmination -Merkel plus meissner corpuscles in human fingertips ensures height sensitivity here. |
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What are the following characteristics of nonencapsulated receptors-free nerve endings?
1. Location 2. Receptor ending 3. Functions |
1. Located in dermis
2. Receptors are in free nerve endings 3. Function as pain, thermal receptors mainly but also a few mechanoreceptors too. |
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What is a receptor field? What type of receptor always has one?
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A receptor field is a particular area in the periphery where adequate mechanical stimulation produces the response of a single mechanoreceptor. The more sensitive the area, the smaller the receptive field.
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What are the 2 types of afferent fibers?
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1. A-beta fibers-that are myelinated 6-12 microns in diameter (cv of 30-70 m/s) and all in encapsulated and accessory structures.
2. C fibers-are non-myelinated, small-diameter (<1.5 microns dia) with a conduction velocity of 0.5-2 m/s and in free nerve endings. |
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What is the term for pain produced by a stimuli that would normally produce pain?
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Allodynia
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What is the term for an enhanced sensitivity to pain where the pain threshold is decreased and the pain stimuli increases?
For example-sunburn |
Hyperalgesia
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What are the functional types of nociceptors and what are the neurotransmitters?
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The nociceptors respond to:
1. Mechanical pain 2. Intense heat and cold 3. Chemicals Most are A-delta fibers and C-fibers. that are polymodal. N.T.s-glutamate, neuropeptides (substance p, CGRP, calcitonin, geno-related peptide) |
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What type of information is encoded by nociceptors?
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Nociceptors are in all tissues, in free nerve endings.
1. Location of stimuli 2. Quality of stimuli 3. Intensity (encoded in discharge rate of nociceptors) |
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What are the 2 zones of hyperalgesia?
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1. Primary-where hyperalgesia occurs at the site of injury.
2. Secondary-surrounds primary zone where the hyperalgesia affects spread into surrounding, uninjured tissue. |
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Chemicals released in the damaged tissue (from say, a burn) mediate inflammatory mediators that can sensitize nociceptors. What are these 4 mediators?
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1. Bradykinin
2. Serotonin from platelets 3. Histamine 4. Protons that have an acidic pH |
