Unit 5 - ANS, Special Senses Flashcards
What is the difference between sensation and perception? What are the types of sensory modalities?
sensation: conscious/subconscious awareness of changes in environment
perception: conscious interpretation of sensations mainly performed by cerebral cortex
each type of sensation is called a sensory modality
general senses: somatic (tactile, thermal, proprioception), visceral (pressure, chemicals, stretch, nausea, hunger, temp)
special - smell, tase, vision, hearing, equilibrium
What sensation do free nerve ending detect?
pain, temperature, tickle, itch and some touch
What sensations do encapsulated nerve ending sense?
pressure, vibration, and some touch
enclosed in a capsule of CT
Describe exteroreceptors, interoreceptors, and proprioceptors. How are they grouped?
some receptors are grouped based on location/origin of the stimuli that activate them
exteroreceptors - at or near external surface of body
- hearing, vision, smell, taste, touch, pressure, vibration, pain
interoreceptors - monitors the body’s internal environment (blood vessels, visceral organs, etc.)
proprioreceptors - provide info about body position, muscle length/tension, and position/movement of joints
What are the 3 types of sensory receptors that are based on microscopic structure?
- free nerve endings (bare dendrites) - pain, thermal, tickle, itch and some touch
- encapsulated nerve endings (dendrites with CT) - pressure, vibration, and some touch
- separate cells - receptors synapse with first-order sensory neurons
- located in retina, inner ear, and taste buds
What are the 6 types of receptors that are classified by the type of stimulus detected?
- mechanoreceptors - detect mechanical stimuli (touch, pressure, vibration, hearing, stretching of blood vessels, etc)
- thermoreceptors - detect changes in temp
- nociceptors - respond to painful stimuli from physical or chemical damage to tissue
- photoreceptors - detect light that strike the retina
- chemoreceptors - detects chemicals in mouth, nose and bodily fluids
- osmoreceptors - detect chemicals in moth, nose and body fluids
What are the somatic sensations and what are the tactile sensations?
somatic - tactile, thermal, pain and proprioceptive
tactile - touch, pressure, vibration, itch and tickle
What are the two types of pain? What is superficial somatic pain?
fast - acute, sharp, or prickling
- perceived within 1 second
- A fibers, note felt in deeper tissue
slow - chronic, burning, aching, throbbing
- perceived a second of more after the stimulus
- C fibers, increases intensity over time
superficial somatic pain - pain that arises from skin receptors
Describe deep somatic and visceral pain. What is referred pain?
deep somatic - affects skeletal muscles, joints, tendons and fascia
visceral - stimulation of pain receptors in visceral organ
- presents in or deep to the skin that overlies the simulated organ
referred pain - a type of diffuse visceral pain
- felt in a surface area far from the stimulated organ
Describe muscle spindles, tendon organs and joint kinesthetic receptors and their role with proprioception
muscle spindles - type of proprioceptor, found in skeletal muscle
- monitors muscle length, involved in stretch reflexes
tendon organs - type of proprioceptor, found at junction of muscle/tendon
- protects muscles/tendons from damage due to overstretching
joint kinesthetic receptors - type or proprioceptor, exits in and around the joint capsule of synovial joints
- respond to pressure, acceleration and deceleration during movement, help prevent strain
Describe the following tactile receptors: Meissner and pacinian corpuscles, hair root plexus
Meissner - capsule surrounding mass of dendrites in dermal papillae of hairless skin
- onset of touch and low-frequency vibration
Pacinian - oval, layered capsule surrounds dendrites in dermis and subQ, submucosal tissue, joints, periosteum and viscera
- high frequency vibration
hair root plexus - free nerve endings wrapped around hair follicles in skin
- movements on skin that move hair
Describe the following tactile receptors: tactile discs, Ruffini corpuscles, itch and tickle receptors
tactile discs - saucer shaped free nerve ending that make contact with tactile epithelial cells in epidermis
- touch and pressure
Ruffini - elongated capsule surrounds dendrites deep in dermis and in ligaments and tendons
- skin stretching and pressure
itch and tickle - free nerve ending and mucous membranes
- itching and tickling
Describe the somatic sensory pathway. What are the three neurons that this pathway consists of?
somatic sensory pathway - carries info from somatic sensory receptors to primary somatosensory area and cerebellum
three neurons:
- first order neurons: impulses from somatic receptors to the brainstem/spinal cord
- second order neurons: impulses from brainstem/spinal cord to thalamus
- third order neurons: impulses from thalamus to primary somatosensory area of the cortex on the same side
What do both the posterior and anterior spinocerebellar tract do? What is it important for?
both posterior and anterior spinocerebellar tract carry proprioceptive impulses to cerebellum
both pathways important for posture, balance, and coordination of skilled movement
What are lower motor neurons?
nerves that extend out of the brain stem/spinal cord
LMNs innervate skeletal muscles of the face and head through cranial nerves, skeletal muscles of the body through spinal nerves
- only LMNS provide output from the CNS to skeletal muscle fibers
What are the 4 functions of the cerebellum?
- monitoring intentions of movement
- monitoring actual movement - input from proprioceptors
- comparing command signals with sensory information
- sensing out corrective feedback
- feedback to UMNs: continuously provides error corrections to UMNs, decreases errors and smoothes motion
What are the 4 integrative functions of the cerebellum?
- wakefulness and sleep
- relies on reticular activating system (RAS)
- REM/non-REM sleep - coma - state of unconsciousness in which an individual has little or no response to stimuli
- learning and memory
- immediate - ability to recall ongoing experiences for few seconds
- short term - ability to recall memories for few minutes
- long term - language
- Wernike’s association area
- Broca’s motor area
Describe Parkinson’s
60+
too little dopamine
tremor and hypokinesia - muscle has decreased range in motion
What are some major differences between somatic and autonomic motor systems?
somatic - effect is always excitation
autonomic - can be exciting or inhibiting
hard to control ANS
Somatic NT’s - ACh
Autonomic - ACh, NE, (chromaffin - EPI and NE)
What are the divisions of the ANS and what is dual innervation?
sympathetic - fight of flight
- increased alertness and metabolic activities that help prepare for emergency
parasympathetic - rest and digest
- conserve and restore body energy during times of rest
- output mostly to GI and respiratory tracts
dual innervation - receive impulses from both sympathetic and parasympathetic neurons
What are the two motor neurons that are found in each division of the ANS?
preganglionic neuron: cell body is located in the brain/spinal cord and exits the CNS via nerve
SYMPATHETIC - thoracolumbar division - cell bodies in lateral gray horns in T1-L3
PARASYMPATHETIC - craniosacral division - located in nuclei of CN of the brainstem - III, VII, IX, X, in the lateral gray matter of S2-S4
postganglionic neuron: entirely in PNS - cell body and dendrites located in autonomic ganglion
- autonomic ganglion: where they synapse
Describe the sympathetic trunk ganglia
lie in vertical row on wither side of the vertebral column, extending from the base of the skull to the coccyx
- innervates organs above the diaphragm (head, neck, shoulders, heart)
- neck has specific sympathetic trunk ganglia: superior, middle and inferior cervical ganglia
since they are near the spinal cord, sympathetic PREGANGLIONIC axons are short, most sympathetic postganlgionic axons ae long
Describe the pre vertebral (collateral) ganglia of the sympathetic nervous system
lies anterior to the vertebral column and close to the large abdominal arteries
-innervates organs below the diaphragm
5 major pre vertebral ganglia: celiac ganglion, superior mesenteric, inferior mesenteric, aorticorenal ganglion, renal ganglion
Describe the parasympathetic ganglia
Preganglionic axons of parasympathetic division synapse with postganglionic neurons in terminal (intramural) ganglia
- located close to or actually within the wall of visceral organ
terminal ganglia in the head have specific names: ciliary ganglion, pterygopalatine, submandibular, otic ganglion
because terminal ganglia are located close to or in the wall of the visceral organ - parasympathetic preganglionic axons are long
Once axons of the sympathetic preganglionic neurons pass to the sympathetic trunk ganglion, what are the 4 ways that they connect with postganglionic neurons?
- axon synapses with the first postganglionic neuron it reaches
- axon may ascend or descend to higher/lower ganglion
- axon may continue without synapsing, go through the sympathetic trunk ganglion and end at the pre vertebral ganglion
- axon may extend to chromaffin cells on the adrenal medullae
What is divergence? How does the sympathetic nervous system display it?
projection of one single sympathetic preganglionic fiber has many axon collaterals that can synapse with 20+ postganglionic neurons
- helps explain why many sympathetic responses affect almost the entire body simultaneously
Does the parasympathetic response have a whole body response like the sympathetic response?
No - responses typically are localized to single effectors
parasympathetic presynatpic neurons usually only synapse with 4-5 postsynaptic neurons that all supply a single visceral effector
What are autonomic plexuses? Where re they?
autonomic plexuses - network of axons of both sympathetic and parasympathetic in the thorax, abdomen, and pelvis
- lie along major arteries
What are the autonomic plexuses in the thorax?
cardiac plexus - supplies the heart
pulmonary plexus - supplies the bronchial tree
What are the autonomic plexuses in the abdomen and pelvis?
Celiac (solar) plexus - the largest autonomic plexus and surrounds the celiac trunk
- two large celiac ganglia
- two aorticorenal ganglia
superior mesenteric plexus - contains the superior mesenteric ganglion - small and large intestines
inferior mesenteric plexus - contains the inferior mesenteric ganglion
- extends through the hypogastric plexus - anterior to the L5: supplies the pelvic viscera
renal plexus - contains the renal ganglion - supplies the renal arteries within the kidneys and uterus
Describe the organization of sympathetic trunk ganglia
pair - anterior and lateral to the vertebral column, one on each side
3 cervical, 12 thoracic, 5 lumbar, 5 sacral sympathetic trunk ganglia
- 1 coccygeal ganglion
- right and left coccygeal ganglion are fused together and usually lie on the midline
extends from neck to coccyx, but only receive preganglionic axons from the thoracic and lumbar segments of spinal cord
What is Horner’s syndrome?
sympathetic innervation to one of the side of the face is lost due to inherited mutation, injury or disease
- affects sympathetic outflow through the superior cervical ganglion
symptoms: ptosis (eyelid droop), miosis (constriction of pupil), anhidrosis (no sweat)
What is a cholinergic autonomic neuron? What neurons in the ANS are cholinergic?
neuron that releases ACh, includes:
- all sympathetic and parasympathetic pre ganglionic neurons
- sympathetic postganglionic neurons that innervate most sweat glands
- All parasympathetic post ganglionic neurons
What are the cholinergic receptors? What are the two types?
cholinergic receptor - binds ACh
nicotinic receptor- when ACh binds, excitation - found in:
- plasma membrane of dendrites/cell bodies of sympathetic and parasympathetic postganglionic neurons
- chromaffin cells
- neuromuscular junction
muscarinic receptors - can be excitation or inhibition - found in:
- plasma membrane of all effectors
- most sweat glands
nicotine does not activate muscarinic receptors, muscarine does not activate nicotinic receptors
ACh quickly inactivated by acetylcholinesterase - effects are short
Describe adrenergic neurons
release norepinephrine
most SYMPATHETIC POSTGANGLIONIC neurons are adrenergic
NE can either cause excitation or inhibition of effector cell
Describe the relationship between adrenergic receptors and NE and EPI
can bind NE and epi
NE can be released either as:
- NT by sympathetic post ganglionic neurons
- hormone by chromaffin cells of adrenal medullae
EPI released as hormone
NE - stimulates alpha receptors more strongly than beta
EPI - strong stimulator of both alpha and beta receptors
NE - taken up by axon or enzymatically inactivated - remains in synaptic cleft longer than ACh
Describe adrenergic neurons. What is alpha and beta?
Alpha receptors and Beta receptors - found on visceral effectors innervated by sympathetic post ganglionic axons
- subtypes based on specific responses they select by selective binding of drugs that activate/block them
- A1/B1 - typically produces excitation
- A2/B2 - typically cause inhibition
- B3 - present only on cells of brown adipose tissue for thermogenesis
cells of most effectors contain either alpha or beta receptors, come visceral effectors have both
What are receptor agonist and antagonist and give an example
Agonist - binds and activates receptor - mimicking the effect of natural NT or hormone
- phenylephrine - adrenergic agonist - reduces mucus production and relieves nasal congestion
antagonist - binds and blocks receptor, prevents natural NT or hormone to exert effects
- atropine - blocks muscarininc ACh receptors - dilated pupils, reduces gland secretion and relaxes smooth muscle of GI tract
What is autonomic tone
balance between sympathetic and parasympathetic activity
- regulated by the hypothalamus
What are the structures that only receive sympathetic innervation?
sweat glands erector pili muscles kidneys spleen most blood vessels adrenal medullae
What effects are longer, sympathetic or parasympathetic stimulation? Why?
sympathetic stimulation are longer and more widespread due to:
- sympathetic post ganglionic axons diverse more extensively - many tissues activated simultaneously
- ACh-ase quickly inactivated ACh, but NE remains in synaptic cleft for al longer period
- EPI and NE secreted into the blood from the adrenal medullae
- blood borne hormones circulate through the body and effect all tissues with A/B receptors
- NE/EPI destroyed by enzymes in the liver
What are the parasympathetic responses that are the “three decreases”? What is SLUDD?
- decrease heart rate
- brochoconstriction
- constriction of the pupils
SLUDD - salivation, lacrimation, urination, digestion and defecation
What are autonomic reflexes? What are they good for? Describe a pathway. What is the hypothalamus important for?
autonomic reflexes - responses that occur when nerve impulses pass through an autonomic reflex arc
- plays key roll in regulating controlled conditions in the body
- adjusts activity in visceral effector without conscious perception
- receptor
- sensory neuron - impulse from receptors to CNS
- integrating center - HYPOTHALAMUS AND BRAINSTEM
- some integrate in the spinal cord (pee poop) - preganglionic and post ganglionic neuron
- effectors - smooth muscle, cardiac muscle and glands
hypothalamus - major control and integration center of the ANS
- connected to both the sympathetic and parasympathetic divisions
What are the accessory structures of the eye? What are the functions of the palpebra? Function of the lacrimal caruncle?
eyelids, eyelashes, eyebrows, lacrimal apparatus, extrinsic eye muscles
palpebra functions - shade for eyes during sleep, protect eyes from excessive light/foreign objects, spread lubricating secretions over the eyeball
lacrimal caruncle - contains sebaceous and sudoriferous (sweat) glands
What is the tarsal plate and its glands? What another name for its glands? What happens when the tarsal glands get infected?
tarsal plate - thick layer of CT that gives support and form to the palpebra
tarsal glands - Meibomian glands
- secrete fluid that helps keep the palpebra from adhering to one another
Chalazion - when tarsal glands get infected and produce a cyst
What is the conjunctiva and what is it function? Where is it found? What happens when it gets infected?
conjunctiva - protective mucous membrane, composed of nonkeratinized stratified squamous epithelium, numerous goblet cells and supported by areolar CT
- palpebral: lines inner space of eyelids
- bulbar: lines surface of eyeball - sclera but no cornea
dilation/congestion of blood vessels of the bulbar conjunctiva causes bloodshot eyes
What are the purpose of eyelashes and eyebrows? What structures are important for them, and what happens when that structure gets infected?
protect the eye from foreign objects, perspiration and direct sun rays
contain sebaceous ciliary glands that release lubricating fluid to the follicles
- infection of these glands cause sty - painful, pus filled swelling
What is the lacrimal apparatus? What is lacrimal fluid? What is its function?
group of structures that produces/drains lacrimal fluid or tears
lacrimal gland - secretes lacrimal fluid that drains from 6-12 excretory lacrimal ducts
- tears emptied onto surface of conjunctiva of upper lid
lacrimal gland supplied by parasympathetic fibers of facial (VII) nerves
lacrimal fluid - contains salts, some mucus and lysozyme - protective bactericidal enzyme that cleans, lubricates the eye
- each gland produces about 1mL of lacrimal fluid per day