ANS 1 Flashcards
describe the organisation of the nervous system
- CNS - brain and spinal cord
- PNS - motor & sensory neurons, somatic and ANS divisions
- ANS - parasympathetic vs sympathetic
what is the peripheral NS?
where are the cell bodies and peripheral nerves?
- anything not in the brain or spinal cord
- cell bodies are located in the spinal cord or in ganglia (collection of cell bodies)
- peripheral nerves are either - somatic NS (sensory and motor nerves) or autonomic NS (controls smooth muscle and gland secretions and enteric NS)
what is the ANS and briefly describe what it controls
- ANS controls multiple systems that maintain homeostasis
- eg it controls blood pressure, metabolism, gut mobility, digestion, reproductive function etc
- involuntary - subconscious
what does the NTS stand for?
nucleus tractus solitarri - nuclei in the brainstem that receives many inputs from the cranial nerves
how are the efferent nerves organised in the ANS?
- two distinct branches
- pre and post ganglionic neurons
what 2 branches is the ANS divided into?
- parasympathetic
- sympathetic
Describe the parasympathetic system PNS
eg functions
- rest and digest functions
- GI acid secretion
- GI motility - increases motility
- pupil constriction and lens adjustment
- heart rate - reduces
- often overridden by the SNS
describe the sympathetic NS
- often described as ‘fight or flight’
- functions include increasing the hr, airway dilation (bronchodilation), dilates pupil of eye, decreases gut motility and secretions
what are the **3 different types of interaction **between the SNS and the PSNS?
- **antagonistic **- act in opposing directions
- **complementary **- both act similarly
- co -operative - both play a role at some stage in overal function
describe the **antagonistic effects **of the SNS and PSNS
- heart rate - SNS increases it and PNS decreases it
- gut motility - SNS decreawes contraction and PNS increases contraction
- pupil pf the eye - SNS dilates the pupil and PSNS constricts the pupil
what is an example of a **complimentary effect **of SNS and PNS?
- saliva
- primarily controlled by the PNS in response to various stimuli - eg if there is food in the mouth etc
- SNS input changes the composition of saliva but not the volume made (makes it thicker and conatin more protein)
Describe the **co-operative effects **of the SNS and PNS
2 examples
- **pupil of the eye and lens **
* sns causes dilation of the pupil and pns causes focussing of the lens - reproduction
* PNS causes erection through the dilation of blood vessels
* SNS causes ejaculation by constriction of smooth muscle
what is a pre-ganglionic vs post ganglionic neuron?
- pre-ganglionic neuron - cell body in the brain stem or spinal cord
- post ganglionic neuron - collection of cell bodies outside the CNS
what is the anatomical definition of the SNS?
- thoraco-lumbar (T1-L2)
What is the** anatomical definition** of the PSNS?
- cranio-sacral
- crain nerves III,VII,IX and X)
- sacral segments S2-S4