Autonomic Nervous System Flashcards
What nervous systems does the PNS give rise to?
Autonomic and Somatic
What is the Somatic Nervous System?
System associated with Voluntary control of movement, from information outside of body
What are the 2 functions that serve the Dual function of Somatic nervous system?
Afferent - (sensory nerves)
Efferent - (motor nerves - muscle contraction)
What does the ANS control?
Maintaining Homeostatis and Involuntary Actions
What does the Smooth muscle control?
Contraction or Relaxation
What does the Cardiac muscle control?
Increase/Decrease rate and force of contraction
What does the Glands control?
Increase/Decrease Secretion
What are the differences between Somatic and Autonomic systems?
ANS = 2 neurons to effect SNS= 1 neuron to effector ANS = cardiac/smooth muscle SNS= Skeletal muscle ANS = excitatory and inhibitory SNS= excitatory ANS= ACh and NA SNS= only ACh ANS= Cell bodies out of CNS SNS= Cell bodies in CNS ANS= pre/post gang myelinated SNS= Axons myelinated
What are the 3 anatomical sub-divisions of ANS?
Sympathetic, Parasympathetic, Enteric
Give examples of ANS functions?
Body Temp control, Gut motility, HR, Blood Pressure, Micturation
What does the Sympathetic division do?
Mobilises body during extreme situations ‘fight or flight’ response
What does the Parasympathetic division do?
Unwind whilst doing maintenance ‘Rest and Digest’
What happens to the function of the Heart in Parasympathetic and Sympathetic conditions?
S = Increase HR + Force of contraction P= Decrease HR + Force of contraction
What happens to the function of the Blood Vessels in Parasympathetic and Sympathetic conditions?
S= constriction P= no effect
What happens to the function of the Lungs in Parasympathetic and Sympathetic conditions?
S= Bronchodilation P= Bronchoconstriction
What happens to the function of the GIT in Parasympathetic and Sympathetic conditions?
S= Decrease Motility + Secretions Sphincter contraction P= Increase Motility + Secretions - Spincter relaxation
What happens to the function of the Salivary Glands in Parasympathetic and Sympathetic conditions?
S + P = stimulates Secretion
What happens to the function of the Sweat Glands in Parasympathetic and Sympathetic conditions?
S= Copious Secretion P= Sweating Palms only
What happens to the function of the Eye in Parasympathetic and Sympathetic conditions?
S= Dilation of pupils, Flattening Lens P= Constriction of pupils, Thickening of Lens
What happens to the function of the Urinary Bladder in Parasympathetic and Sympathetic conditions?
S= Relaxation of bladder wall, Sphincter contraction P= Contraction of bladder wall, Sphincter relaxation
What is the Anatomical difference of Sympathetic and Parasympathetic fibres?
S fibres = Originate from Thoracic and Lumbar regions
P fibres = Emerge from brain and spinal cord at Sacral level + Cranial region
Describe the Sympathetic nervous system?
Short Pre-gang fibres, Long Post-gang fibres
Ganglia lie near vertebral column and spinal cord
Axons branch profusely - influence many organs
Describe the Parasympathetic nervous system?
Long Pre-gang fibres, Short Post-gang fibres
Ganglia far from CNS close to organs
Axon branching is diffused and localised
What are the Sympathetic Functions?
Co-ordinating responses to emergencies
In stressful situations adrenaline released from medulla
What are the Parasympathetic Functions?
Conservation and Restoration of energy
Descrete or localised functions on organs
SLUDD - salivation, lacrimation, urination, digestion, defecation
In most organs receiving both P and S innervation’s, what are the systems?
Physiologically Antigonistic e.g P activates to Slow HR, S activates to Increase HR
What happens when the S and P systems both oppose one another?
One dominates, for e.g In the Gut P dominates S as Parasympathetic is the main motor nerve for gut functions
Give some examples of organs only Innervated by One division?
Sweat glands, Piloerecter muscles, Blood Vessels (only sympathetic) - depends on location due to different receptor subtypes e.g S dilates and constricts BV for different things
In the Sympathetic division, what do most Post-Gang axons release?
Noradrenaline (adrenergic) and ACh (muscarinic receptors) - sympathetic cholinergic
In the Parasympathetic division, what do Post-Gang axons release?
ACh (cholinergic) in Pre-gang it is ALWAYS ACh
What are the sections of ANS receptors?
Cholinergic and Adrenergic
What are the 2 Sub-sections of Cholinergic Receptors?
Nicotinic and Muscarinic
What are the 3 Main types of the Nicotinic ACh receptors?
Muscle (NMJ), ganglionic and CNS
How many Subunits do ligand-gated channels form? and how can they vary?
5 subunits, Heteromeric :NMJ - a,b,Gamma
Ganglion - a, b
Homomeric :all alphas (neuronal)
What are muscarinic receptors and subsections?
G-Protein Coupled receptors, 5 Subtypes M1-M5
What is the function and location of M1,4,5?
CNS - activates complex CNS responses such as memory and arousal
M1 also found at gastric parietal cells and autonomic ganglia
What is the function and location of M2?
Heart - lowers conduction velocity and sinoatrial and atrioventricular nodes lowering HR
What is the function and location of M3?
Glands, Smooth Muscle - Produces responses on a variety of organs e.g Bladder, exocrine glands
What is the function and location of a1 Adrenoreceptors?
Smooth muscle, Sweat & Salivary glands, skin, kidney, radial muscles - Excitation leads to contraction -> vasoconstriction-> dilation of pupil -> close sphincters
Increased secretion of sweat and k+ (glands)
What is the function and location of a2 Adrenoreceptors?
Sympathetic nerve terminals, smooth muscles, b cells of pancreas, blood platelets
- Inhibition of norepinephrine secretion-> vasodilation
- Reduce insulin secretion - form plug
What is the function and location of B1 Adrenoreceptors?
Cardiac muscle fibres, posterior pituary, adipose, juxtaglomerula cells of kidney
- Increase force and rate of contraction
- Renin secretion
- Secrete ADH
- Breakdown triglycerides and release fatty acids into blood
What is the function and location of B2 Adrenoreceptors?
Smooth muscles of airways, Wall of visceral organs, Ciliary muscle, Hepatocytes
- Inhibition leading to dilation->Vasodilation
- Relax organ walls
- Inhibit for relaxation-> Glycogenolysis