DSA: Autonomy Flashcards
Describe a simple reflex arc involving skeletal muscle
- Afferent (sensory) stimulus detects unexpected stretch of a muscle
- Sends signal to muscle spindle located in the dorsal root ganglion of the spinal cord–> ventral root
- Synapse on alpha-motor neuron of stretched muscle
- FIRES
- Release ACh at the NMJ
- Causes contraction (shorterning of the stretched muscle
Did we use our brain for the reflex arch involving the skeletal muscle?
No.
In the autonomic NS, sensory information tells our body what?
When there is a change in our homeostasis.
Are we aware of the of the stimulus that activates our ANS?
No.
But ones that are, we do not control the responses.
What are sensory stimuli that can modify our ANS?
BP, PaO2, pH.
What controls the activation of somatic reflexes?
Any level of the CNS: but many of them are generated in the spinal cord.
What controls the activation of the ANS?
Lower levels of the brain: medulla–> hypothalamus.
Efferent (motor) neuron in the somatic reflex is made up of how many neurons?
1 alpha-motor neuron
Efferent (motor) neuron in the ANS is made up of how many neurons?
2: pre-ganglionic and post-ganglionic
How does your sympathetic NS respond to stimuli?
- Increase O2 to the “right” parts of the body by [increase HR and blood flow]
- Increase glucose;
- [liver]–> glucose to the blood for use by skeletal muscles.
- Other less important tissue will use FFA.
- We need to be able to clearly identify threats and responses
- control focus and pupil (dilate)
How does your parasympthatetic NS respond to stimuli?
- Decrease O2 and decrease HR
- Sends blood to digestive tract
-
Increase digestion
- Glands in GI tract–> secrete enzymes/electrolytes
- Increases instestinal motility
- Relax sphincters so contents can from one part of the digestive tract to the other -
Store NRG
- Liver–> store glucose; decrease ability to release
- Adipose tissue–> store FFA
What are functions of the parasympathetic NS?
- Pupils
- Saliva production
- HR
- Bronchi
- Digestive organs
- Bladder-
Other?
- Constricts pupils
- Increase saliva production
- Decrease HR
- Constricts bronchi
- Stimulates digestive organs, pancreas, bladder
- Causes erection
What are functions of the sympathetic NS?
- Pupils
- Saliva production
- HR
- Bronchi
- Digestive organs
- Bladder-
Other?
- Dilates pupils
- Decreases saliva production
- Increases HR
- Dilates the bronchi
- Inhibits digestive organs, pancreas and gallbladder
- Relaxes bladder
- adrenal medulla release of NE and EPI
- Stimulates orgasm
Describe the pathway of parasympathic NS and sympathetic NS
Post-ganglionic neurons in the sympathetic NS bind to what type of receptors?
Adrenergic
How are post-ganglioic cells different from pre-ganglionic cells?
Post-ganglioni cells have swellings called varisosities along the axon that allow the release of NT.
Describe the synaptic cleft of post-ganglionic cells?
Larger, more open to the interstitial fluid because it does not make direct contact with the target organ. Thus, receptors for NT are distributed along the target organ
What are the effects of the synaptic cleft of the post ganglionic cells being larger and more open? (3)
- NT have to travel further,
- More are detected in the blood
- Receptors can be activated by NT that are diffused from original point of release.
What type of receptors are adrenergic?
Metabotropic (serpentine)– > thus they + 2nd messengers
What type of receptors do post-ganglionic neurons in the parasympathetic NS bind to?
Muscarinic, which are metabotropic.
Muscarinic Gi receptors
Found on heart
Binding causes -AC–> - cAMP production–> increase K+ efflux from nodal cells–> decrease HR
Muscarinic Gq recetors
Found on glands
+IP3 and DAG–> release of Ca2+
The synapse between a neuron that traveled through the sympathetic chain and synapsed on a chromaffin cell in the adrenal medulla.
Nicotenic cholinergic
Alpha-1 receptor activation
Causes radial muscles to contract–> dilates the pupil
Beta-2 activation
ciliary muscles relax–> [flattens lens]
Beta-1 and Beta-2 activation
Increases HR and contraction
Alpha-1 activation
Vasoconstriction–> increases BP
Beta-2 activation
Bronchodilation
Are SNS and PNS an off an off switch?
No. They work together and can work at the same time.
Which receptor increases stroke volume and heart rate?
Beta 1 adrenergic
Which receptors constrict smooth muscle, as a general rule?
Alpha adrenergic
Which receptors increase glandular secretions in the lungs?
Beta adrenergic
What regions of the heart are affected by beta 1 receptors?
AV / SA node
