Nervous system- Autonomic system Flashcards
Autonomic System
What is branched off from the peripheral nervous system?
Autonomic (involuntary)
Somatic (voluntary)
What is included within the autonomic?
Parasympathetic nervous system (PNS)
Sympathetic nervous system (SNS)
What does the autonomic system have an effect on. Whys it involuntary?
Lungs, heart etc
Because it keeps us alive, something that has to happen without thinking
What does somatic nervous system have an effect on. Whys it voluntary?
Skeletal muscle etc.
You have to think about it, doesnt happen naturally
What is an afferent signal?
(sensory)
An ascending signal from our external components into nervous sytem which then sends signals to organs or muscles which is also known as the descending efferent motor signal
What is the function of the Autonomic nervous system?
Sympathetic and parasympathetic divisions of the ANS often work simultaneously in a reciprocal and complementary manner maintaining homeostasis
What is the role of the sympathetic nervous system?
Orchestrates the stress response and energy consumption associated with ‘fight or flight’ reactions, but also has very important ongoing activity
What is the role of the parasympathetic nervous system?
Regulates many functions, some of which are restorative and energy conserving ‘rest and digest’
How does the ANS maintain homeostasis in the skin?
Thermoregulation by controlling contraction and relaxation of smooth muscle in the vasculature
How does the ANS maintain homeostasis in the liver/pancreas?
Metabolism of glucose and lipids
How does the ANS maintain homeostasis in the lungs?
Ventilation to control partial pressures and pH
How does the ANS maintain homeostasis in the heart and vasculature?
Blood pressure by contraction and relaxation of smooth muscle in the vasculature
How does the ANS maintain homeostasis in the kidneys?
Fluid balance
Homeostasis generally involves a negative feedback loop which has three parts. What are these three parts?
A sensor
A comparator/integrator
An effector
Where are the sensors relayed to? And what happens after this?
CNS that acts as a comparator it compares it to how it should be and then the effector is chosen to what fits best
What is included as a sensor?
- Central chemoreceptors- H+
- Peripheral chemoreceptors - O2, CO2, H+
- Pulmonary receptors- stretch
- Joint and muscle receptors- stretch, tension
What is included as an effector?
Diaphragm
Respiration- external intercostals, accessory muscles
Expiration- internal intercostals, abdominal muscles
Describe the anatomy of the ANS
neurons that drive the signals to the effectors from CNS from efferent pathways
Where do the dendrites extending from the cell attach to?
Synapses, where they receive information
The neuron then extends into the axon hillock and then the myelin sheath
What does the myelin sheath serve as?
protective layer that can speed up the process of the signals
What do both the parasympathetic and sympathetic nervous system have in common?
- Both have pre and post ganglionic fibres
- axons both stretch out of the CNS
- both pre are myleninated whereas the post are unmyelinated
Why is the preganglionic fibre in the parasympathetic longer than in the sympathetic?
Stretches all the way to the organ/tissue its effecting on
What is released from the preganglionic fibres into the nicotinic acetylcholine receptor?
Acetylcholine
What is released from the postganglionic fibres into the muscarinic receptors? PNS
Acetylcholine
Where is acetylcholine released into in the SNS?
Noradrenaline which binds to many adrenoreceptors
a1,a2,b1,b2
Where are alpha and beta adrenoreceptors commonly seen?
Alpha - smooth muscle, vasculature
Beta- heart
What does non-adrenergic, non-cholinergic transmission mean (NANC)
Sometimes transmission in ANS isnt caused by a result of noradrenaline or acetylcholine
What is an intermediate and slow response NANC transmission in the PNS?
intermediate- Nitric oxide
slow- vasoactive intestinal peptide
What is a rapid, intermediate and slow response NANC transmission in the SNS?
rapid- ATP
intermediate- noradrenaline
slow- neuropeptide Y
Where would vasodilation and vasoconstriction occur in the PNS and SNS?
PNS- vasodilation
SNS- vasoconstriction
What is the endogenous agonist of cholinoreceptors nicotinic/muscarininc?
Acetylcholine (Ach)
Where are nicotinic acetylcholine receptors located and what type of receptors are they?
Present in the ganglia
Ligand-gated ion channels
Where are muscarinic acetylcholine receptors found and what type of receptors are they?
Present in the effector cells
G-protein-coupled receptors
Noadrenaline and adrenaline are the endogenous agonists of a family of adrenoreceptors that are what type of receptors?
G-protein coupled receptors
from most to least potent agonist, rank noradrenaline, adrenaline and isoprenaline for alpha and beta adrenoreceptors
alpha- noradrenaline>adrenaline>isoprenaline
beta-
isoprenaline>adrenaline>noradrenaline
Pair whether para or sympathetic are from craniosacral or thoracolumbar origins
Sympathetic- thoracolumbar
Parasympathetic- craniosacral
