ANS Flashcards
what does ans control
visceral organs
internal organs - relates to heart rate, contraction of muscle in digestive tract, regulates breathing, diameter of blood vessels
monitors inside and feeds into cns
what is ans
sensory motor system
senses what goes on inside body
monitor internal body state and relay info to cns
has output system that uses info to regulate internal organs
what is ans concerned with
homeostasis = maintenance of stable internal environment in face of changing external conditions
name 3 divisions of ans
sympathetic
parasympathetic
enteric
what do divisions of ans innervate
sympathetic and parasympathetic divisions innervate cardiac and smooth muscle and glandular tissue
enteric system controls digestive tarct
describe ans systems
sympathetic = arousal system, heart beat harder, breathing shallower and faster, pupils dilate, palms sweat
parasymapthetic = slows heart, contractions in digestive tract, breathing slow and deep, constricts pupil
complementary antagonistic functions in body = work to maintain homeostasis and balance between systems
what effects do parasympathetic and sympathetic systems have on target tissues
opposite effects
describe sympathetic system
emergency fight or flight reactions
describe parasympathetic system
rest and digest
is only sympathetic or parasympathetic working at a time
both active all the time and work together to regulate internal organs and maintain them within a normal physiological range
in certain circumstances one is more active than other
where do axons of sympathetic preganlionic neurons emerge from
ventral roots of thoracic and lumbar regions of spinal cord along with axons of motor neurons
where do postganglionic neurons project for sympathetic
target organs
describe neurons of sympathetic system
1 st neuron = preganglionic = very short, synapse right outside spinal cord and makes synapse on to post ganglionic neuron
axons leave spinal cord to make synapse
what is nucleus vs ganglia
ganglia = pns
nucleus = cns
organized group of synapses, cell bodies and dendrites in cns
where are synapses between preganglionic and postganlionic sympathetic neurons clustered
right outside spinal cord in sympathetic ganglia
chains run along spinal cords
thoracic and lumbar regions
pregang out spinal cord –> postgang –> target organs
what do sympathetic preganglionic neurons release
acetlycholine = activates nicotinic actelycholine receptors on post ganglionic neurons
what do sympathetic post ganglionic neurons release
norepi
actiavtes alpha and beta adrenergic receptors on tagret
describe nicotinic ach receptors
excitatory
ion channels open in response to ach and depolarizes neuron and sends ap down
describe adrenergic receptors
postganlionic neuron (very long) releases norepi on these receptors
metabotropic receptors = change biochemistry and phsyiology of cells
describe effect of norepi on heart
heart contacts more
but if released in lung = smooth muscle bronchiole relaxes, effect depends on tissue
what do beta blockers do
block adrenergic = heart wont beat hard when neurons
where do axons of parasympathetic preganglionic neurons emerge from
brainstem = cranial nerves iii, vii, ix, x
sacral spinal cord
describe pregang neurons of parasymp
extend almost all the way to peripheral targets
then postgang extend remaining short distance
describe vagus nerve
parasympathetic input to visceral organs - heart, lungs, etc
describe facial and glossopharyngeal nerves
innervate salivary gland
describe oculomotor nerve
innervates smooth muscle responsible for contraction and relaxation of pupils of eye
what do parasympathetic projections from sacral spinal cord innervate
bladder
large intestine
reproductive organs
describe cranial nerves
output comes through nerves that emerge from brainstem
iii = oculomotor nerve, for pupils
vii = facial nerve - controls face
ix = glossopharyngeal nerve, innervates mouth and some parasym effects
x = vagus nerve, very important, innervates body
sacral spinal cord - some nerves here too
how many cranial nerves
12 emerge from brainstem
what do parasym preganglionic neurons release
ach
actiavtes postsynaptic nicotinic ach receptors
what do parasym postganglionic neurons release
also release ach
activates muscarinic ach receptors
where are parasymp ganglia located
near target organ
describe muscarinic ach receptors
Activated by muscarin
metabotropic = changes physiology
describe effect of ach on heart
makes heart slow down
but on lungs = constricts
describe when stimulate sympathetic
increase heart rate and strength of contractions
bigger faster
describe when stimulate parasympathetic
decrease heart rate and contraction
slower weaker
what does enteric system control
gastrointestinal tract covered by smooth muscle
pancreas
gallbladder
smooth muscle in gut and local blood vessels and secretion by mucosa
how many neurons does enteric system contain
100 mil
as many as spinal cord
what does enteric system recieve input from
receives input from sympathetic and parasympathetic systems
highly autonomous and can put function normally in absence of external neuronal input
what does enteric system contain
cholinergic neurons =tend to activate peristaltic contractions of gut
adrenergic neurons = suppress gut and peristalsis
neurons that release neuropeptides, atp and nitric oxide
can intestines contract on their own
intestine contracts in physiological solutions
if put ach = contract bc parasymp
if put norepi = stop contract cause symp
what is intestine made up of
2 layers smooth muscle, longitudinal, circular
2 layers of neurons = myenteric plexus and submucous plexus
what does myenteric plexus control
contractions of smooth muscle
what does mucous plexus control
intestinal secretions
what does ans respond to
variety of sensory inputs
come in through spinal cord and inside body - come through vagus nerve (sensory, parasym output)
give ex of sensory input to ans
stimulation of pain sensing neurons in skin activates sympathetic neurons that regulate local vasoconstriction
where does most sensory info from viscerla organs get to cns from
vagus nerve
inputs to spinal cord
how does visceral sensory info enter brain
glossopharyngeal
facial nerves
what do brainstem regions mediate
direct autonomic reflexes and projects to higher brain areas (like hypothalamus and cerebral cortex)
coordinate autonomic repsonses
what does brain stem do
integrates visceral sensory inputs and autonomic outputs
project to higher brain centers involved in homeostasis
what controls brainstem
amygdala
hypothalamus - sensory info also conveyed here and regulates output from brainstem
describe brainstem nuclei
first level of everything
Sensory input can generate symp and parasymp outputs
brainstem nuclei = continuation of spinal cord
Organizes and controls stereotyped behavioural responses (like cat)
automated response at level of brainstem (chewing, facial expression)
what does hypothalamus integrate
autonomic responses, endocrine function with behviour to maintain homeostasis
name 5 basic physiological needs hypothalamus regulates
blood pressure and electrolyte balance
body temp
energy metabolism - eating, balance of glucose
reproduction
emergency responses to stress - behavioural and metabolic processes
describe what hypothalamus does for temp as ex
compares sensory info with biological set points - ex = 37 degrees for body temp
gets continuous sensory input
describe what hypothalamus does when detect deviation for temp as ex
detects deviation from set point and coordinates autonomic
endocrine and
beahvioural responses to restore homeostaiss
how does brain recieve info about temp
monitors body temp - sensory neuron in body sends info to hypothalamus = indirect measure
neurons in hypothalamus that are sensitive to temp - directly measures itself and generates output pathway
describe if body temp too high
sweating (autonomic)
turn on ac (motivated to act)
describe if body temp too low
shivering - from brainstem, automated response, generates heat, shift where heat retained in body
putting on sweater = cold so motivated to put sweater on (cerebral cortex)
Thyroxin = from pituitary, regulates metabolism = generates heat
describe fever
immune system sets point in hypothalamus to 40 degrees = chills
body temp rises
fever breaks = set point brought down so too hot so sweat
what does ans and hypothalamus interact with
other brain regions
including amygdala
parts of cerebral cortex (relate visceral responses to conscious feelings and connect emotions to memories)
describe cerebral cortex
regions of brain involved in feelings and connections
what happens if in dangerous situation
Physiological changes
fear based on cognitive understanding but also physiological changes
connection between physiological changes and interpreted by brain
describe hippocampus
learning
explicit declarative memory
describe uncus
amygdala in uncus
describe medial regions of cortex and fontal regions of cortex
connect amygdala brainstem and up thalamus to cerebral cortex
connect feeling to cognitive state - why i feel afraid
cognitive interpretation = cerebral cortex
Emotional physiological response - amygdala, hypothalamus, brainstem
what is amygdala for
forms connection between cognitive understanding of world and visceral response normally elicited in response to feelings
amygdala = important for role that emotion and physiological changes play in learning
describe bilateral loss of amygdala
not normal learning
normal subjects = show pics and measure increase in arousal, most neutral pics but some bad, shows strong emotional response = arousal goes up
ppl with amygdala damage = do not have this response
new stack of images but with repeats =
normal people = more likely to remember things that elicit strong emotional response
amygdala lesions = do not remember emotional ones more
