Autonomic Nervous System Flashcards
chief goals of the autonomic nervous sytem
- maintain homeostasis
- allostasis
- adjustments sometimes, but rarely, require voluntary actions and awareness of internal state sometimes comes to consciousness via emotional experience
homeostasis
-steady state of bodily function centered around a set point
allostasis
-stability through change
multi-units
- involve large numbers of postganglionic fibers, each in close contact with smooth muscle fibers
- this arrangement provides independent and more precise control of contraction
single units
- involve small numbers of postgangionic fibers, which only contact a small number of muscle fibers
- the smooth muscle fibers not in direct contract either receive transmitter via diffusion or are activated via gap junctions
- the fibers contract in synchrony
Sympathetic effect on pupil: ciliary muscle
dilation!: increases light
-ciliary relaxation leads to far vision
parasympathetic effect on pupil and ciliary muscles
pupil: contracts (sphincter)—> decreases light
ciliary muscle contracts –> near vision
sympathetic effects on lacrimal, salivary glands
-vasoconsriction, slight secretions and decreased digestions! This allows blood to flow to muscles
parasympathetic effects on lacrimal, salivary glands
- vasodilation; copious- this cleans the cornea
- watery secretions- increase digestion
sympathetic effects on the heart
- increased heart rate, increased force of contraction, and ouput; coronary vasodilation (B)
- these all seek to enhance cardiovascular performance
parasympathetic effects on the heart
- decreased heart and cardiac output
- heart is at rest
sympathetic effects on bronchi and lungs
-bronchodilation (B), decreased secretions, and increased respirations
parasympathetic effect on the bronchi and lungs
- bronchoconstriction and increased secretions
- this helps remove contaminants
sympathetic effects on the stomach, pancreas, and intestines
decreased peristalsis, decreased secretion, and vasocconstriction
parasympathetic effects on the stomach, pancreas, and intestines
-increased peristalsis and secretion; vasodilation
sympathetic effects on urinary bladder
-constriction of internal sphincter; urinary retention
parasympathetic effects on the urinary bladder
-contraction of detrusor muscle; relaxation of internal sphincter
sympathetic effects on extremities
- sweat secretion, vasoconstriction, piloerection, vasodilation in muscles (B)
- this redistributes blood flow to the muscles and it decreases temperatures
sympathetic effects on the face
-vasodilation and blushing
mydriasis
-dilation of the pupil
superior cervical ganglion
-gives out sympathetic dilatory fibers
ciliary ganglion
-gives out parasympathetic fibers
pupillary light reflex is mediated by
-parasympathetic system
accessory oculomotor nucleus is also called the
-Edinger-Westphal
how will the pupillary light reflex show unilateral optic nerve damage?
-the reflex will be abolished in both eyes, but only when light is shown into the ipsilateral eye
how will unilateral oculomotor nerve damage affect the pupillary light reflex?
-will abolish then reflex in the ipsilateral eye, regardless of where light is shown
a patient with fixed and dilated eyes may be suspected of having
-damage to the midbrain
What drug can suppress the pupillary light reflex?
-atropine
what is the main pacemaker of the heart? What is its backup?
- the sinatrial node is the main pacemaker of the heart (SA node)
- the atriventricular node (AV) can operate as pacemaker if the SA node is disabled
sympathetic innervation to the heart comes from the
-paravertebral chain and extends beyond the nodes to the cardiac muscle itself
do many autonomic nerves carry sensory fibers and motor fibers?
-YES!
sensory cells of the autonomic nervous system
- typically pseudounipolar
- soma typically in cranial or dorsal root ganglia
- most are thin Ad or c fibers
- can be nociceptors, chemoreceptors, and mechanoreceptors
where do chemoreceptors of blood gases lie in the body?
-carotid body: between the internal and external branches of the carotid artery
chemoreceptor cells release transmitter onto afferents of which cranial nerve?
glossopharyngeal nerve
where does the glossopharyngeal project to after it receives transmitter from the chemoreceptors
nucleus of the solitary tracts
the nucleus of the solitary tracts will alter the activity of the
-reticulospinal neurons and increase respiratory rate and increase blood flow to the brain
where do stretch receptors lie? what do they do?
-stretch receptors detect blood pressure and lie within the carotid sinus of the carotid artery
the caudal nucleus of solitary tract (NTS) receives
visceral afferents signals from the vagus and glossopharyngeal nerves
the efferents of the NTS include
ascending inputs to other nuclei that regulate autonomic function like the hypothalamus and the limbic system
Horner’s syndrome
associated with interruption of the sympathetic input to the head, usually as a result of a tumor to the superior cervical ganglion
- unilateral
- face is warm due to lack of sympathetic input
- drooping eyelids
- maybe caused by internal carotid dissection which could lead to massive strokes
