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BIO 435
Autonomic Nervous System
| Question | Answer | |
|---|---|---|
| What does the sympathetic nervous system (SNS) do? | prepares body for heightened activity; fight or flight | |
| What does the parasympathetic nervous system (PNS) do? | facilitates normal body maintenance; rest and reset | |
| Where do the preganglionic neurons of the sympathetic nervous system come from? | thoracic and lumbar spinal cord | |
| Where do the preganglionic neurons of the parasympathetic nervous system come from? | brainstem and the sacral spinal cord | |
| Where does the input for both the sympathetic and parasympathetic NS come from? | Input for both comes from the brain | |
| What part of the brain can regulate activation of the ANS? | hypothalamus; the hypothalamus activates appropriate preganglionic neurons | |
| Which NTs are in the preganglionic neurons for both sympathetic and parasympathetic neurons? | Acetylcholine (ACh) nicotinic receptors and some metabotropic | |
| Which NTs are in the postganglionic neurons in the PARASYMPATHETIC NS? | ACh | |
| Which NTs are in the postganglionic neurons in the SYMPATHETIC NS? | Norepinephrine (NE); metabotropic | |
| How many types of adrenergic (NE) receptors are there? | 3 | |
| Describe the a1 adrenergic receptor | causes smooth muscle contraction; result in depolarization | |
| Describe the a2 adrenergic receptor | can result in either the inhibition of transmitter release or smooth muscle contraction; results in depolarization | |
| Describe the B adrenergic receptors | causes dilation of skeletal muscles, heart muscle contraction, and smooth muscle relaxation | |
| How does the SNS affect the adrenal medulla? | The SNS causes the adrenal medulla to release epinephrine into the bloodstream and locally onto neurons | |
| What type of reflexes are used to maintain homeostasis? | Autonomic/visceral reflexes | |
| Describe the enteric nervous system | -neurons associated with the gastrointestinal tract -controls the secretion of digestive enzymes, fluids, etc.-there is cross talk between the CNS and the enteric NS | |
| What occurs during a stress response? | There is enhanced function of systems that are necessary for survival/critical systems (circulatory, respiratory, skeletal, muscle, brain) and reduced function of non-critical systems (reproductive, digestive, urinary, and immune) | |
| What are the 2 primary components of the stress response? | 1. Sympathetic NS activation 2. Hypothalamic-pituitary-adrenal (HPA) axis activation | |
| Describe SNS activation | - Norepinephrine (NE) is released on the smooth muscle glands- Epinephrine is released into bloodstream | |
| Describe HPA axis activation | -Cortisol is released into the bloodstream -Take about ONE hour after stressor initiated | |
| Describe the systems that send input to the hypothalamus (PVN) so it can initiate a stress response | 1. somatosensory system = visceral stressors (pain, pressure, temperature) 2. immune system | 3. limbic system = emotional stressors 4. brain stem= homeostatic stressors |
| What does the activation of PVN cells lead to? | CRH transcription and release | |
| Where is CRH released to after PVN cells are activated? | Into the hypophyseal portal system from where it then travels to the anterior pituitary | |
| What NT does CRH cause the anterior pituitary to release? | Acetylcholine (ACh) | |
| After ACh and ACTH is released and stimulates the adrenal cortex, what is released into the blood stream? | cortisol | |
| Describe the effects of cortisol | - increases alertness- promotes the release of blood glucose release -inhibits the immune system- affects memory | |
| How is cortisol different from epinephrine and norepinephrine? | Cortisol lasts longer in the system that epinephrine and NE (these two have shorter half lifes and are broken down faster). | |
| What kind of feedback does the glucocorticoid, cortisol, produce? | Negative feedback; the release of cortisol results in the decrease in the release of CRH and ACTH (adrenocorticotropic hormone) | |
| What happens to CRH levels when the body experiences extreme stressors? | CRH is continuously released despite the negative feedback | |
| Why does cortisol have a greater influence on memory? | Cortisol has a higher affinity for mineralocorticoid receptors (cortisol [a glucocorticoid, GR]) transforms into cortisone which then transforms into aldosterone [a mineralocorticoid, MR]) | There is greater memory performance when MRs are saturated and there is lower memory performance when GRs are activated. |
| Why do MRs improve memory compared to GRs? | MRs enhance LTP magnitude while GRs reduce LTP. | |
| What effect does chronic stress have on the hippocampus? | -Upregulates NMDA receptors -causes increase in Ca2+ which can lead to excitotoxicity and apoptosis -chronic cortisol put the cells at an energy crisis | |
| Why does chronic cortisol from chronic stress put the cell at an energy crisis? | The extra Ca2+ requires more ATP to pump it out and makes the cell more vulnerable to other processes that could reduce ATP levels (stroke and trauma) |
Created by:
keiannaowens
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