2.1 Lecture notes Flashcards
two possible pathways for afferents
- spinal cord (via dorsal roots)
- solitary nucleus (via cranial nerve)
Where does referred pain come from?
- nociception from the viscera joins nociceptive axons and go to the somatosensory cortex
- all axons traveling together in the same group
Where does muscle guarding come from?
when somatic efferents join autonomic efferents
What parts of the brain make the decision on what to do with afferent information that’s received?
pons
medulla
Which cranial nerves are involved in taste?
VII
IX
X
Which cranial nerves are associated with abdominal and thoracic viscera
IX
X
Where is the solitary nucleus located?
medulla
Where does the adrenal medulla secrete epinephrine?
directly into the bloodstream
targets for sympathetic
- heart
- blood vessels
- bronchi
nicotinic receptors: where did the name come from?
- nicotine can bind and competitively inhibit ACh from binding
- activates the receptors
- sensitive to nicotine
Nicotinic receptors are always ______
ionotropic
sympathetic: What levels are the preganglionic nuclei in?
T1-L2
What are the levels in the parasympathetic system?
- cranial nerves III, VII, IX, X
- S2-S4
parasympathetic: preganglionic neuron releases
ACh (nicotinic, fast)
parasympathetic: postganglionic neuron releases
ACh (muscarinic, g-protein, slow)
targets for parasympathetic
- glands
- smooth muscle
- heart
- bronchioles
What happens when nicotine binds to receptors?
- fast effect
- feeling of alertness and calmness
Why is it so difficult for people to quit smoking?
- difficult for ACh to do its job
- don’t get continued stimulation of reward pathway
- nicotine also changes the shape of the synapse
What sort of effects are seen with muscarinic receptors?
slow responses (i.e. peristalsis, slowing down the system)
paravertebral ganglia
- where some of the preganglionic neurons synapse
- don’t have to
To get to the face and arteries of the upper limb, where must sympathetic fibers run?
through cervical paravertebral ganglia
sympathetic T5-T12 supplies
abdominal and viscera
sympathetic T1-T4 supplies
heart and lungs
sympathetic L1-L2 supplies
bowel, bladder, genitals, LE
sympathetic preganglionic axons
short
sympathetic postganglionic axons
long
Where do the cervical ganglia come from?
T1
All sympathetic signals come from HERE
- pons
- medulla
body temperature regulation starts here
adrenal medulla
main function of adrenal medulla
release epinephrine (can also release norepinephrine)
What can epinephrine do?
- increase metabolism
- activate alpha adrenergic receptors
What can norepinephrine do?
- activate alpha adrenergic receptors
What happens when alpha adrenergic receptors are activated?
- increase blood flow to skin
- change in radiation of heat
- erection of hair cells
- activation of sweat glands
What are the skeletal muscle blood vessels called?
capacitance vessels
At rest, what is happening with respect to blood flow in the muscles?
blood pools in the capacitance vessels at rest
How does the sympathetic system regulate blood flow?
- norepinephrine activates alpha adrenergic receptors
- causes vasoconstriction
- blood flows to brain
What does norepinephrine activate to regulate the viscera?
either
- beta 1 adrenergic
- beta 2 adrenergic
beta 1 adrenergic
increases HR + contraction force
beta 2 adrenergic
dilates bronchioles
What do alpha blockers do?
decrease HBP
- block vasoconstriction
What will a patient on alpha blockers also likely be taking and why?
- blood thinner
- don’t want blood to pool
beta 1 blocker
decreases HR and contraction force
beta 2 agonist
decreases asthma symptoms
What effects does epinephrine have on the body?
- increases blood glucose levels
- increases release of norepinephrine
- supercharges metabolism
What does stress cause the release of?
release of
- epinephrine (and norepinephrine)
- cortisol
Why is cortisol a potential problem?
- can feed back and cause additional release of epi/norepi
- random eating habits
- exhaustion
sympathetic efferents in the head
pretty much the same as the body
- pupils dilate
- eyelids open
- decreased salivary output
sympathetic effects on blood flow to the gut
decreases (that’s why the stomach might hurt)
What muscle type is responsible for eyelids opening in response to sympathetic activation?
smooth muscle
parasympathetic efferents come from
- cranial nerve III, VII, IX, X
- sacral S2-S4
parasympathetic: preganglionic neuron is
very long
parasympathetic: postganglionic neuron is
- very short
- sometimes right on the target organ
Where do S2-S4 preganglionic neurons travel?
along pelvic splanchnic nerves
CN III
pupil constriction
CN VII
acts on lacrimal glands
CN VII and IX
work together to act on salivary glands
CN X
- decreases HR
- decreases peristalsis
- decreases contraction force of heart
- constrict bronchi
Of the cranial nerve efferents, about 75% go through this nerve
vagus
How is regulation of HR achieved with sympathetic and parasympathetic systems?
- parasympathetic: works through vagus nerve
- sympathetic: works through spinal cord
afferents from the heart
- projects to and receives efferents from both sympathetic and parasympathetic
- DIRECT innervation of the heart from both
