ANS - Sympathetic Division Flashcards
What does acetyl choline do?
Its a neurotransmitter
It’s the first neurotransmitter released at the synapse between the pre and post ganglionic axons in the ANS
From which vertebrae do the pregnanglionic neurons of the sympathetic division extend from the spinal cord?
From T1 to L2
Thoracic 1 to the 2 lumbar
How many nerves extend from the spinal cord at each vertebrae?
Two - a pair of nerves extends
Which are longer, pre or post ganglionic axons and why?
Post are longer - pre are really short because the ganglia (and therefore synapses) are located close to the spinal cord
What are sympathetic ganglia?
Ganglia in the sympathetic division of the ANS
The preganglionic nerves synapse with the postganglionic nerves here
Communication between nerve cells
How many types of ganglia are there in the sympathetic division?
Three
What are the three groups of ganglia in the sympathetic division?
Sympathetic chain ganglia
Collateral ganglia
The adrenal medulla
Which affect is more widespread, the sympathetic or parasympathetic?
The sympathetic
How much divergence is there in the sympathetic division?
1 preganglionic neuron to 24 postganglionic neurons
List the sympathetic targets
(5)
Visceral effectors in the head e.g. eyes and mouth, the thoracic cavity e.g. heart + lungs, and the abdominopelvic cavity (GIT, renal and reproductive systems)
Body wall (sweat glands, skin haor muscle, blood vessels, adipose tissue
Limbs (blood flow to smooth muscle of blood vessels)
Adrenal glands (release hormones)
Adipose tissue
When does increased sympathetic response occur?
(6)
Stress
Anxiety
Physical activity
Fear
Excitement
Use of metabolic resources
The sympathetic response targets the visceral effectors located where?
(3)
In the head e.g. eyes and mouth,
The thoracic cavity e.g. heart + lungs
The abdominopelvic cavity (GIT, renal and reproductive systems)
What parts of the body wall are sympathetic targets?
(4)
Sweat glands
Skin hair muscle
Blood vessels
Adipose tissue
What happens when the sympathetic system targets a gland?
It releases a hormone
Write a note on the adrenal glands
(2)
Located above each kidney
Divided into two regions (cortex and medulla)
Write a note on the adrenal medulla
(3)
Preganglionic axons end on the neuroendocrine cells
These cells secrete adrenaline and noradrenaline hormones into the blood stream
In the blood the hormones are distributed and have widespread responses that are long lasting
What are the American names for adrenaline and noradrenaline?
Epinephrine and norepinephrine
What do the hormones of the sympathetic system do to their target cells?
They cause changes in the metabolic activity of many different cells through the body
How does the nervous and hormonal aspects of the sympathetic NS work together?
The hormonal release will prolong and extend the nervous response
Where are the nerve cell bodies found?
The lateral horn of the grey matter of the spinal ccord
Where do axons of the preganglionic nerve emerge from?
Spinal segments
Where do the nerves synapse with the postganglionic nerve?
Within the ganglion
What controls the activation of the sympathetic division?
The hypothalamus
What affect does sympathetic response have on the heart?
(3)
Increase heart rate
Increased force of contraction of the heart
Increased dilation of the coronary arteries
What affect does sympathetic response have on the blood vessels?
Constriction of blood vessels to some regions of the body
Dilation of blood vessels to other regions of the body
What affect does sympathetic response have on the skin?
(2)
Increase or decrease blood flow to skin
Sweating or activation of adipose tissue
What affect does sympathetic response have on the respiratory tract?
(3)
Dilation of the respiratory tract
Increased respiratory rate
Increased depth of respiration
What affect does sympathetic response have on the GIT?
Decreased GIT (motility and secretions)
Decreased renal function (filtration)
What neurotransmitter is present at the ganglion?
Acetyl choline
What neurotransmitters/hormones are released at the target cell?
(3)
Noradrenaline
Acetyl choline
Nitrous Oxide
What are the two types of responses that can occur in the sympathetic nervous system?
Excitatory response
Inhibitory response
What type of response always follows the release of acetyl choline at the autonomic ganglion?
An excitatory response
What are the receptors on the target organs called?
(3)
They are ‘G’ proteins, which are subdivided into:
- Adrenergic receptors = alpha, beta
- Cholinergic receptors
What do adrenergic receptors react with?
Adrenaline and noradrenaline
What do cholinergic receptors react with?
Acetyl choline
Write a note on adrenergic receptors
(2)
Two types:
alpha-adrenergic and beta-adrenergic
Adrenaline will cause vasoconstriction of blood vessels in some organs and vasodilation in others
Write a note on alpha-adrenergic receptors
(3)
They are found in the skin and kidneys
Reacts with noradrenaline
Two types:
-a1
-a2
Wite a note on a1 receptors
(4)
Reacts with noradrenaline
Cause the release of Ca++ in some tissues
Result in vasoconstriction of blood vessels
Results in constriction (closure) of sphincters of the GIT
Write a note on a2 receptors
(3)
Reacts with noradrenaline
Cause the raising or lowering of cAMP
This lowers the activity of intracellular enzymes in some tissues (cardiac)
Write a note on B receptors
(3)
React with adrenaline and noradrenaline
They result in stimulation of metabolic activity in target tissues by raising cAMP levels
Three types:
-B1
-B2
-B3
Write a note on B1 receptors
(2)
They are found on skeletal and cardiac muscle cells
Stimulation results in increased metabolic activity (including hr and force of contraction)
Write a note on B2 receptors
They are found on the smooth muscle of the airways which facilitates respiration
Write a note on B3 receptors
(2)
They are found on adipose tissue
Activation results in lipolysis
Beta receptors raise cAMP levels, what is cAMP?
(3)
Cyclic adenosine monophosphate
A derivative of ATP
Used for intracellular transduction
Write a note on cholinergic receptors
Two types:
- ach muscarinic receptors
- nitroxidergic receptors
What are muscarinic receptors?
(2)
React with acetyl choline
They result in powerful stimulation of sweat glands and dilation of skin blood vessels
What are nitroxidergic receptors?
(3)
React with nitric oxide
Receptors found in blood vessels of skeletal muscle and the brain
Associated with vasodilation
