Autonomic Nervous System Flashcards
1
Q
ANS regulates activity of internal organs and vasculature for
A
- circulation
- respiration
- digestion
- metabolism
- secretions
- reproduction
2
Q
Where are receptors of the ANS present
A
- present in the musculature of visceral wall and blood vessels, skin
3
Q
Receptors of the ANS
A
- Mechanoreceptors: pressure and stretch
- Chemoreceptors: O2, CO2, H+ ions, blood glucose, electrolyte concentrations
- Nociceptors: stretch and ischemia
- Thermoreceptors: skin and blood temperatures
4
Q
Mechanoreceptors
A
- carotid sinuses
- aortic baroreceptors
- stretch receptors in lungs
- autonomic stretch receptors in smooth muscles of arteries, veins/venules, bladder, and intestines
5
Q
Peripheral Chemoreceptors
A
- carotid & aortic bodies
- respond to O2, CO2, H+ in the stomach, taste buds, and olfactory bulbs
6
Q
Central Chemoreceptors
A
- respond to H+ & CO2 in medulla
- respond to blood glucose levels & electrolyte concentrations in the hypothalamus
7
Q
ANS nociceptors
A
- in the viscera & walls of arteries
- respond to changes in stretch & ischemia
8
Q
ANS thermoreceptors
A
- in the hypothalamus & skin
- Peripheral cutaneous receptors respond to changes in external temp.
- Central receptors in the hypothalamus respond to small changes in blood temp.
9
Q
How does information from visceral receptors enter the CNS
A
- through cranial nerves into the brainstem
- through dorsal roots into the spinal cord
10
Q
Cranial nerves that bring in autonomic afferent information
A
- primarily IX and X but also I and VII
- IX brings BP/blood chemical info from carotid sinus/body
- X brings BP info from aortic arch, stretch and nociceptive info from visceral organs
- smell (I) and taste (VII, IX, and X) are the only afferent info felt consciously
11
Q
Central regulation of visceral function
A
- visceral afferent info coming from CNs converge in solitary nucleus in medulla
- then go to visceral control areas in pons/medulla (reticular formation)
- lastly goes to modulatory areas in hypothalamus, thalamus, emotion/motivation areas
12
Q
Differences between somatic motor and autonomic efferent systems
A
- Somatic: voluntary control, cannot be exerted by hormones, act on musculoskeletal structures, directly under control of brain, consist of 1 neuron in peripheral pathway
- Autonomic efferent: automatic control/nonconsious, can be exerted by hormones, acts on musculature of internal organs, under control of lower centers/local NS, consist of 2 neurons that synapse outside CNS
13
Q
Efferent pathways of the ANS
A
- Sympathetic activity: includes norepinephrine & epinephrine, via adrenergic neurons or adrenal hormones released in blood
- Parasympathetic activity: includes Ach, via cholinergic neurons and vagus nerve, Ach can also be found in the neuromuscular junctions
14
Q
Sympathetic nervous system
A
- fight or flight system
- neurons originate from the lateral horns of spinal cord gray matter from T1 to L2 (thoracolumbar flow)
- synapse at paravertebral sympathetic ganglia
- ganglia are interconnected to form sympathetic chain/trunk
15
Q
Where do sympathetic efferents go
A
- adrenal medulla to release NE/epinephrine into the bloodstream
- head, UE, LE
- thoracic visceral organs
- abdominal & pelvic visceral organs
16
Q
Functions of the sympathetic efferents to head, trunk, UE, and thoracic viscera
A
- regulate tone in arteries of face, UE, and trunk
- dilate pupils
- elevate upper eyelid (superior tarsal muscle)
- increase HR/contractility
- dilate bronchi
17
Q
Functions of sympathetic efferents to abdominal and pelvic organs
A
- regulate tone in arteries of LE and trunk
- contract GI sphincters
- decrease peristalsis
- decrease GI blood flow
- decrease GI secretions
- inhibits bladder/bowel movements
- elicit ejaculation
18
Q
Other functions of the sympathetic system
A
- regulation of body temperature: release of epinephrine by adrenal medulla increase BMR, release of NE causes skin arterioles to contract and activate sweat glands
- regulation of BP with postural changes: constricts the capacitance vessels (veins) in the muscles to prevent OH
19
Q
Loss of what sympathetic controls causes Horner’s syndrome
A
- dilate pupils
- assistance in elevating upper eyelid
- innervation to lacrimal gland
20
Q
pupil change based on system
A
- Parasympathetic: controls pupillary sphincter which constricts the pupil
- Sympathetic: controls dilator papillae which dilates the pupil
- atropine blocks parasympathetic activity by blocking Ach release
21
Q
Differential activation of sympathetic receptors
A
- Beta 1 adrenergic receptors: increase HR and contractility, blocked by Beta 1 blockers such as Metoprolol which decreases HR and BP without affecting airways
- Beta 2 adrenergic receptors: dilate bronchioles, Beta 2 agonist (Albuteral) keeps airways dilated in COPD and asthma
- Alpha adrenergic blockers: Carder and Minidress reduce high BP by blocking alpha receptors and cause vasodilation
22
Q
Parasympathetic nervous system
A
- rest and digest system
- neurons originate from the brainstem & lateral horns of sacral spinal cord (craniosacral outflow)
- synapse at parasympathetic ganglia
- info travels to brainstem with CNs III, VII, IX, X
- info from sacral region originates from lateral horns of S2-S4 to pelvic organs
- parasympathetic system does not innervate limbs or body wall
23
Q
Functions fo tes parasympathetic system
A
- CN III constrict pupil & increase convexity of lens = pupillary light reflex
- CN VII and IX innervate salivary glands
- CN VII innervates lacrimal glands
- most fibers to thoracic & GI organs are carried by CN X
- sacral parasympathetic efferents empty bladder/bowel, cause penile erection, & vaginal lubrication
24
Q
Regulation of bladder function by opposing actions of the ANS
A
- visceral afferent neurons entering spinal cord synapse with visceral efferent neurons to generate autonomic reflexes
- visceral ascending neurons enter spinal cord reach brainstem, hypothalamus, thalamus, and cortex
25
Q
Processing of nociceptive information
A
- visceral nociceptive afferents have additional connections with somatic nociceptive afferents (referred pain) and general somatic efferents (muscle guarding)
26
Q
Unopposed actions of the ANS
A
- Sympathetic: effect on limbs, face, body wall, vasoconstriction of limb, trunk, & face vasculature, sweating from skin, and erection of skin hair
- Parasympathetic: effect on increasing eye lens convexity
27
Q
Horner’s syndrome
A
- lesion somewhere in sympathetic efferent to head
- Ptosis: eyelid droops due to secondary muscle not connected anymore
- Miosis: inability to dilate pupil
- skin vasodilation
- Anhydrosis: absence of sweating
28
Q
Chronic regional pain syndrome (CRPS)
A
- pain in arm thought to be due to sympathetic overactivity
- treatment by stellate ganglion block which decreases sympathetic stimulation of the sensitized autonomic nociceptors in skin
- side effect is Horner’s syndrome
29
Q
Effects of spinal cord injury on bladder function
A
- injury above S2 results in a spastic bladder
- injury at conus medullaris or below results in a flaccid bladder
