The Nervous System Part 1: The ANS Flashcards
The ANS
- Effector organs: ..?.. control of ..?.. muscle, ..?.. muscle and ..?..
- Efferent pathways and ganglia: uses ..?.. neurons- ..?.. neuron (in the CNS, thin and lightly ..?..); ..?.. neuron in the the ..?.. ganglion ..?.. the CNS (thinner and ..?..). Conduction is ..?… Many pre and postganglionic fibres are incorporated into ..?../..?.. nerves. 1 ..?.. and 2 ..?.. with ganglions
- Target organ response to neurotransmitters: effect may be ..?.. or ..?… Releases ..?.. or ..?..
- involuntary; smooth; cardiac; glands
- two; preganglionic; myelinated; post ganglionic; autonomic; outside; nonmyelinated; slower; spinal; cranial; afferent; efferent
- excitatory; inhibitory; ACh; norepinephrine
Somatic NS
- Effector organs: ..?.. ..?.. muscle control
- Efferent pathways and ganglia: motor neuron cell ..?.. are in the ..?… Axons extend as ..?.. or ..?.. nerves to the muscles they innervate. Fibres are ..?.. and heavily ..?… They conduct impulses ..?… There is 1 ..?.. and 1 ..?.. with no ..?… Receptors are directly on ..?..
- Target organ responses to neuro transmitters: effect is always ..?… All somatic motor neurons release ..?..
- voluntary; skeletal
- bodies; CNS; spinal; cranial; thick; myelinated; rapidly; afferent; efferent; ganglion; target organs
- excitatory; ACh
What other systems is the ANS divided into?
- Sympathetic NS
- Parasympathetic NS
Where does the sympathetic NS originate from?
Thoracolumbar region
Where does the parasympathetic NS originate from?
Cranial and sacral regions
Describe the length of the preganglionic and postganglionic neurones in the ANS
- Sympathetic NS: short pre and long post
- Parasym NS: long pre and short post
What are the ganglionic neurotransmitters involved in the ANS?
- Sym NS (white communication rami): ACh
- Parasym NS: ACh
What are the postganglionic neurotransmitter and transmission involved in the ANS?
- Sym NS: norepinephrine (also stims adrenal medulla to release NE)
- Parasym NS: ACh
Fibres that release ACh are called..?..
Cholinergic fibres
Fibres that release norepinephrine are called ..?..
Adrenergic fibres
Noradrenaline:
- Synthesis: synthesis from ..?.., occurs at the ..?..
- Storage: in ..?.. in second neuron ….. nerve endings
- Release: released when an ..?.. reaches the ..?.. (and Ca2+ dependent ..?..)
- Breakdown: a little bit is absorbed by the ..?.. and metabolized by ..?.. (COMT)
- Degradation: some by ..?.. (MAO) in ..?..)
- Termination of effects: most ..?.. by the ..?..(some stored in ..?.. again)
Tyrosine; nerve terminal
- vesicles; sympathetic
- AP; nerve ending; exocytosis
- effector cells; catecol-O-methyl-transferase
- mono-amine-oxidase; mitochondria
- reabsorbed; nerve endings; vesicles
Acetylcholine:
- Synthesis: from ..?.. and choline by ..?..
- Storage: in synaptic ..?.. in ..?..
- Release: released when an ..?.. reaches the ..?.. (and ..?.. dependent ..?..)
- Degradation: ..?.. (AChE) in the synaptic cleft and ..?.. membrane (split into ..?.. and ..?.., choline gets re-uptaken in the ..?.. membrane)
- Termination of effects: ACh binds only ..?.. to receptors. Following ..?.. from the receptor, the ACh is rapidly ..?.., choline is actively ..?.. by the ..?.. and ..?.. in synthesis
- acetyl coenzyme A; choline; acetyltransferase
- vesicles; nerve endings
- AP; nerve ending; CA2+; exocytosis
- acetylcholinesterase; postsynaptic; choline; acetic acid; presynaptic
- bteiefly; dissociation; hydrolysed; reabsorbed; nerve endings; re used
Describe the principal receptors, ion channels and second messenger systems involved in mediating the autonomic actions of:
Noradrenalin on adrenergic receptors and target tissues
G protein-coupled receptors resulting in a cAMP second messenger cascade, which in turn stimulates protein kinase
Describe the principal receptors, ion channels and second messenger systems involved in mediating the autonomic actions of:
Acetylcholine in ganglia and at target tissues
- Nicotinic: ..?.. gated ion channel; allows ..?.. and ..?.. diffusion and ..?… Nicotinic receptor is used as the ..?.. (skeletal) – ions used because its ..?..
- Muscarinic: ..?.. receptor resulting in a ..?.. cascade, mainly ..?.. and ..?.. (IP3). Muscarinic receptors are involved in ..?.. control, ..?.. muscles; e.g. mucus
- ligand; Na+; K+; depolarisation; NMJ; fast
- G-coupled protein; second messenger; catamount; inositol triphosphate; exocrine; smooth
Explain the mechanism of action in each case, describe the changes in target tissue function
- alpha 1adrenergic
- mechanism of action: Phosphose lipase C to make IP3 (releases Ca2+) and DAG (activates protein kinase C)
- changes in target tissue: Constricts blood vessels and visceral organ sphincters, dilates pupils
Explain the mechanism of action in each case, describe the changes in target tissue function
- alpha 2 adrenergic
- mechanism of action: Negative feedback mechanism: binding NE to these receptors inhibits NE release by decreasing cAMP levels. In presynaptic, so no organ
Changes in target tissue: Inhibits NE release from adrenergic terminals, Inhibits insulin secretion, Promotes blood clotting
Explain the mechanism of action in each case, describe the changes in target tissue function
- beta 1 adrenergic
- mechanism of action: Increase in cAMP
Only in the heart, muscle, kidneys - changes in target tissue: Increases heart rate and force of contraction; Stimulates kidneys to release renin
Explain the mechanism of action in each case, describe the changes in target tissue function
- beta 2 adrenergic
- mechanism of action: increase in cAMP
- changes in target tissue: Effects mostly inhibitory, dilates blood vessels and bronchioles, relaxes smooth muscle walls of GIT and urinary organs, relaxes uterus
Explain the mechanism of action in each case, describe the changes in target tissue function
- beta 3 adrenergic
- mechanism of action: increases cAMP
- changes in target tissue: Stimulates lipolysis of fat cells to increase blood glucose for energy
Explain the mechanism of action in each case, describe the changes in target tissue function
- Muscarinic
- mechanism of action: Use G proteins as their signalling mechanism
- changes in target tissue: All parasympathetic target organs (Excitation in most cases, inhibition of cardiac muscle); Limited sympathetic targets (eccrine sweat glands: activation)
What effect does muscarinic receptors have on the PNS?
- decrease heart rate
- constricts the bronchioles
- constricts pupils, stimulates lacrimal glands, stimulates ciliary muscles so lens bulges for close vision
- increased peristalsis and amount of secretion by digestive organs, relaxes sphincters for food to move through, excites gall bladder to expel bile
- contracts smooth muscle of bladder wall, relaxes urethral sphincter, promotes voiding
- causes erection (vasodilation)
- stimulates secretion of watery saliva
What is the effect of beta 1 receptors in the sympathetic NS?
- increases rate and force of heart beat
What is the effect of beta 2 receptors in the sympathetic NS?
- dilates bronchioles
- decreases activity of glands and muscles of digestive system. constricts sphincters, inhibits (relaxes gallbladder)
- Weakly dilates vessels of skeletal muscles during exercise
What is the effect of alpha 1 receptors in the sympathetic NS?
- constricts vessels of abdominal viscera ad skin to divert blood to muscles, brain and heart when necessary. Weakens BP.
- dilates pupils, inhibits secretory activity and constricts blood vessels supply lacrimal gland, weakly inhibits ciliary muscle which flattens the lens for far vision
- relaxes smooth muscle of bladder wall, constricts urethral sphincter, inhibits voiding
- causes ejaculation
- stimulates secretion of thick, viscous saliva
What are the 3 levels of motor control?
- Segmental level (lowest)
- Projection level (middle)
- Precommand level (highest)
What does the segmental level of motor control contain?
- spinal cord
- central pattern generators
What does the projection level of motor control contain?
- primary motor cortex: pyramidal pathways
- brain stem nuclei: vestibular, red, reticular formation ect.
What is the function of the projection level of motor control?
- conveys instructions to the spinal cord motor neurons and sends a copy of that information to higher levels
What does the precommand level of motor control contain?
- cerebellum
- basal nuclei
What is the function of the precommand level of motor control?
Programs and instructions (modified by feedback)
Where are lower motor neurons located?
- Ventral horn OR
-Anterior nerve roots (spinal LMNs) OR - Brainstem nuclei (cranial nerve LMNs)
What is the function of intrafusal fibres?
Serve as proprioceptors- detect the amount and rate if change in the length of a muscle. Rate of stretch determines the rare of firing of afferent fibres.
What is the function of extrafusal fibres?
Standard effector fibres of the muscle that cause contraction and tension.
Intrafusal fibres
- structure: ..?.. enclosed fibres in a ..?.. within the ..?.. of a ..?… The ..?.. regions lack ..?.. and are ..?..
Intrafusal fibres
- sensory neurons: ..?.. types of axon endings. ..?.. endings: large axons that wrap around the ..?.. , stimulated by ..?.. and ..?.. of ..?… You also have ..?.. endings that are formed by ..?.. axons that supply the ..?.. ends, stimulated by only a degree of ..?..
2; allunospiral; spindle centre; rate; degree; stretch; flower spray; smaller; spindle; stretch