Download AUTONOMIC NERVOUS SYSTEM REVIEW QUESTIONS:

AUTONOMIC NERVOUS SYSTEM REVIEW QUESTIONS:
Diagram of the Brain:
1. Describe the neural organisation of the autonomic nervous system and the
differences in the two divisions.
The Parasympathetic and Sympathetic Systems divide the autonomic nervous
system
Functions of the two divisions:
o
o
often referred to as the 'fight-or-flight' response because the
sympathetic division prepares the body to fight against or flee from a
threat.
parasympathetic division - regulates important body functions such as
digestion & 'slows down' the body after a 'flight-or-flight' response
('rest & digest')
2. What are the three sympathetic ganglionic groups and where would you find
them?
Sympathetic chain ganglia: Found either side of the spinal column, “sympathetic
nerves”.
Targets thoracic cavity organs and head (eg: heart, lungs, salivary glands etc)
Collateral ganglia: Found on the aorta, below sympathetic chain ganglia.
3 of them: caeliac, mesenteric, hypogastric.
Adrenal medulla: Modified sympathetic ganglion in itself.
Releases its neurotransmitters directly into bloodstream, not onto effector organ.
Targets organs throughout the body with long-lasting effects.
3. What's so special about the adrenal medulla?
The adrenal medulla consists of masses of neurons that are part of the sympathetic
branch of the autonomic nervous system. Instead of releasing their neurotransmitters
at a synapse, these neurons release them into the blood. Thus, although part of the
nervous system, the adrenal medulla functions as an endocrine gland.
The adrenal medulla releases:


adrenaline (also called epinephrine) and
noradrenaline (also called norepinephrine)
4. Compare and contrast activation of the sympathetic and parasympathetic nervous
systems.
SYMPATHETIC
PARASYMPATHETIC
Fight or flight
Rest and repose
Short pre-ganglionic neurons
Long preganglionic neurons
Near spinal column
Near target organ
Long postganglionic neurons
Short postganglionic neurons
Releases Ach and noradrenalin
Releases Ach
T1 – L2
S2-S4 and cranial nerves
4. How can the responses of sympathetic and parasympathetic activation be
explained in terms of activation of adrenergic and cholinergic receptors?
Adrenergic receptor activation:
Alpha and Beta adrenergic receptors.
Alpha receptors have affinity for binding noradrenaline.
A1 – activation increases Ca2+ in cell, causing excitatory response which contracts
peripheral blood vessels shunting blood to brain and other needed organs.
A2 – activation decreases cAMP (2ns messenger molecule), which inhibits
parasympathetic effects.
Beta receptors have affinity for binding adrenaline.
B1 – activation increases cell activity, heart rate and force of heart contraction.
B2 – decreases cell activity and relaxes smooth muscle in bronchioles to dilate and
increase respiratory capacity.
Cholinergic (sympathetic)
Some fibres release Ach and some release NO.
Ach – activates sweat glands in skin and some brain blood vessels.
NO – potent vasodilator and increases blood flow.
Cholinergic (parasympathetic) (both release Ach)
Nicotinic cholinergic receptors – activation directly gates Na+ channel.
Muscarinic cholinergic receptors – 2nd messenger system, either excitatory or
inhibitory responses.
6. What is autonomic tone? Why does it matter?
Both systems are “on” most of the time. This background activity of both systems is
termed autonomic tone. It allows for precise control of organ function.
7. How can emotional states effect such things as digestive and cardiac function?
Control of the ANS is overseen by higher centres – for example the thalamus and the
hypothalamus. Therefore, emotional states can affect visceral organ activity.
Emotional states may influence increased heart rate, or decreased digestion under
conditions of stress or high emotion.