Autonomic Nervous System Flashcards
What does the autonoic nervous sytem control?
the visceral organs
What is the goal of the autonomic nervous system?
Concerned with the maintenance of homeostasis
What are the three division of the autonomic nervous system?
- Sympathetic system
- Parasympathetic system
- Enteric System
How ar ethe parasympathetic and sympathetic systems related?
Both of these systems are outputs that come out from the CNS and work together to maintain homeostasis
T/F:The parasympathetic and sympathetic systems typically do the opposite?
True
Where is the enteric system and what does it do?
Lines the entire digestive tract and controls the contractions of the GI tract and secretion of susbtances into the GI tract
When is the sympathetic system activated?
During fight or flight situations
When is the parasympathetic system activated?
When you are resting
What does the sympathetic system cause?
-Increased heart rate
-Pupil dilation
Sweating
What does the parasympathetic system cause?
-Increased contraction in the digestive tract
-Slows down heart rate
-Slows breathing
Are the sympathetic and parasympathetic systems always active?
Yes, but one can be more active during specific situations
What are the two neurons of the sympathetic system?
- Preganglionic neuron
- Postganglionic neuron
Where does the preganglionic neuron of the sympathetic system originate and where deos its axon exit?
-Originates in the middle of the gray matter of the spinal cord
-Axon exits through the ventral root of the spinal cord and then synapses with the postganglionic neuron
Where is the postganglionic neuron of the sympathetic system located and describe the axon?
-Originates just outside the spinal cord
-Long axon extend to the target
What is a ganglion?
Organized cluster of neuron cell bodies in the PNS
What is the sympathetic ganglia and where is it located?
Located at the postganglionic neuron
What portions of the spinal cord are the preganglionic sympathetic neurons located?
Lumbar and thoracic
WHat axons share the ventral root with the axons of the preganglionic neurons of the sympathetic system?
Motor neuron axons
Describe the sympathetic ganglia
-Run along either side of the spinal cord
-Have connections between them which results in the sympathetic system getting activated all together
Describe what happens when the preganglionic neuron of the sympathetic system fires an action potential?
- Preganglionic neuron fires an action potential
- This will release acetylcholine which will activate nicotinic receptors on the postganglionic neuron dendrites(excitatory)
- Ion channels will open and Na+ will flow in and depolarize the neuron and then it will fire an action potential
- Action potential will cause the release of norepinephrine on the target.
- Norepinephrine will activate adrenergic receptors on the target and affects the physiology of the target cell
What are the two types of adrenergic receptors?
- Alpha-adrenergic receptors
- Beta-adrenergic receptors
What type of receptors are the adrenergic receptors?
Metabotropic since they trigger a biochemical event inside the heart that produces secondary messenger molecules
T/F: The activation of adrenergic receptors by Norepinephrine depend on the type of cell that it targets?
True
In the heart it causes the heart rate to increase
In the bronchial tube it causes the smooth muscle to relax (epi pen)
Beta-blockers?
Prevent nervousness by preventing the binding of norepinephrine to beta adrenergic receptors and preventing increase in heart rate
Where are the preganglionic neurons of the parasympathetic system originating and where do their axons exit?
Brainstem
-Their axons exit through nerves in the brainstem and they are very long and synapse onto the postganglionic neurons
Where are the postganglionic neurons of the parasympathetic system?
-Near the target, has a short axon
Are the parasympathetic ganglia lined up ?
No, since the postganglionic neurons are at there targets which are all over the body
This means the parasympathetic system is not all activated at once instead it is activated in a more selective way
Describe what occurs once the preganglionic neuron of the parasympathetic system fires an action potential?
- Preganglionic neuron fires an action potential
- Releases acetylcholine which binds to nicotinic receptors on the postganglionic neuron
- That neuron then fires an action potential which will also release acetylcholine
- Acetylcholine will then activate muscarinic acetylcholine receptors (found on visceral organs)
What type of receptors are muscarinic receptors?
Metabotropic, activate the production of secondary messenger molecules
What is the vagus nerve?
Cranial nerve, axon of preganglionic parasympathetic output goes through the nerve
How are cardiac contractions affect by the activation of the sympathetic system?
-Contractions get larger and faster
How are the cardiac contractions affected by the activation of the parasympathetic system?
-Contractions slow down and are less forceful
Can the enteric system function without inputs from the rest of the nervous system?
Yes
Who does the enteric system recieve inputs from ?
Parasympathetic and sympathetic systems
How do the parasympathetic and sympatheitc systems regulate the enteric system during stress?
Sympathetic system will be active and enteric system will slow down digestion (can digest food later when the stressor is gone)
What does the enteric system do?
Controls the contraction of the smooth muscle in thr GI tract
How does the enteric system respond to norepinephrine?
Since norepinephrine is comparable to the sympatheitc system it will cause the enteric system to contract smooth muscle less
How does the enteric system respond to acetylcholine?
Since acetylcholine is comparable to the parasympathetic system this will cause the enteric system to contract smooth muscle more
What are the two layers of neurons in the intestine?
- Myenteric plexus
- Submucous plexus
What does the submucous plexus of neurons control?
Regulates the secretion of various digestive enzymes and substances into the inside of the intestine
What does the myenteric plexus of neurons do?
Innervates the smooth muscle and regulates the contractions
What are the two layers of smooth muscle in the small intestine?
- Circular smooth muscle(contraction of intestine inward)
- Longitudinal smooth muscle(contraction of smooth muscle longitudinally)
Why does the autonomic system need sensory inputs?
Need to know whats going on outside of the body in order to maintain homeostasis inside the body
How does sensory information from the visceral organs reach the CNS?
- Through the vagus nerve
2.By inputs to the spinal cord
What is the role of the brainstem in sensory input and the autonomic nervous system?
- The brainstem integrates visceral sensory inputs and autonomic outputs and project to higher brain centers involved in homeostasis
Master controller of homeostasis?
Hypothalamus
What is a nucleus?
Organized cluster of neurons in the CNS
What is the role of the hypothalamus?
Monitors what is going inside the body and controls homeostasis through three different output pathways
What three pathways does the hypothalamus use to maintain homeostasis?
- Autonomic nervous system
- Endocrine system
- Behavioural system
what are the five basic needs that the hypothalamus regulates?
- Blood pressure and electrolyte balance
- Body temperature
- Energy metabolism
- reproduction
- Emergency response to stress
T/F: The hypothalamus regulates the brainstem which is regulating outputs?
True
How does the hypothalamus work when you are cold?
The hypothalamus has a set point of 37 if your body is 35 then the hypothalamus will send outputs to bring body temp. back up. Will communicate with the enodcrine system to release thyroxine. Will communicate with the cerebral cortex to make you feel uncomfortable and motivated to put on a sweater. Will communicate with the autonomic nervous system by making you shiver
What happens to the hypothalamus when you have a fever?
- Set point is increase by immune system to 40
- Now you get chills because your body temp. is 37
- When you break the fever the set point goes back to 3
- Now you have sweats because body temp is still 40
What does the amygdala do ?
Involved in the connections between feelings and physiological states and their relation to learning
Amygdala and cerabral cortex interact with the hypothalamus and autonomic nervous system which relates the visceral responses to concious feelings and connects emotions to memories
Yes
