Lecture 17- Autonomic nervous system

Question 1

What is the effect of the sympathetic nervous system on the kidney?

Answer 1

1.beta 1 receptor=increase in renin secretion rates 2.alpha 1B receptor=decrease in Na+ absorption 3.alpha 1A receptor= decrease in renal blood flow -more retention of water in tubule, lower blood flow

Question 2

What does most of visceral activity need?

Answer 2

-visceral motor system

Question 3

What are the differences between somatic, sympathetic and parasympathetic nerves?

Answer 3

-somatic motor neurons= have body in CNS and protected form the environment by the blood brain barrier and go to target -ANS- has an intrevening synapse, in ganglia

Question 4

What is the difference in sympathetic and parasympathetic nerves?

Answer 4

• parasympathetic= the ganglia are within the tissue of the target so the postganglion fibre is short
• opposite with the sympathetic

Question 5

Why is it good that the ANS neurons have that extra synapse?

Answer 5

-the ganglion, the extra neuron gives us more modulation, which we want in ANS where have to weigh more factors

Question 6

Where are the cell bodies of sympathetic neurons?

Answer 6

• intermediolateral cell column
• in thoracic and lumbar spinal cord only

Question 7

What does the sympathetic trunk look like?

Answer 7

sympathetic trunk= ganglia, in the swelling is where the ganglion cells are pregaglionic= myelinated -postganlionic cells= grey -another group of ganglionics= prevertebral ganglion = goes to the gut -these are usually in the midline of the gut

Question 8

Where are the cell bodies of parasympathetic neurons?

Answer 8

• parasympathetic cells=
  1. in the brainstem

2-sacral spinal cord in=midbrain and medulla

• long projections, many project via the vagus nerve
• preganglionic in different regions! symp vs parasym

Question 9

Where in the midbrain are the parasympathetics?

Answer 9

• nucleus ambiguus
• dorsal motor nucleus of vagus
• salivatory nucleii

Question 10

What innervates the blood to penis?

Answer 10

-parasympathetic (ejaculation is stimulated by sympathetic)

Question 11

Do tissues receive innervation from both parasympathetic and sympathetic?

Answer 11

-yes -often the innervation goes to different cells in the tissue, -pupil size= para=constricts, symp= makes them bigger -each goes to different muscles -same in pancreas

Question 12

What is the special example of sympathetic and parasympathetic innervation?

Answer 12

-the same muscles or cells get the innervation from sympathetic and parasympathetic— heart pacemaker cells parasympathetic= slows heart rate, sympathetic= faster heart rate (faster firing of the pacemaker cells)

Question 13

Via which receptor and transmitter does the somatic nervous system work?

Answer 13

• N1 nicotine acetylcholine receptor
• via acetylcholine

Question 14

What receptor and neurotransmitter does the parasympathetic nervous system use (both pre and postganglionic)?

Answer 14

• preganglionic= N2 receptor, (Acetylcholine)
• postganglionic= M (muscarinic acetyl choline receptor)
• in both acetylcholine

Question 15

What receptor and neurotransmitter does the sympathetic nervous system use (both pre and postganglionic)?

Answer 15

2 types:

1. pre-N2 receptor (acetylcholine) then post alpha and beta adrenergic receptors (norepinephrine)
2. pre- N2 receptor (acetlycholine) and release eponephrine via adrenal medulla

Question 16

Where does adrenal medulla receive innervation from?

Answer 16

-adrenal medulla= receives input from pre ganglion neuron and releases adrenalin into the circulation -adrenal medulla part of the sympathetic

Question 17

Which nerves constrict blood vessels?

Answer 17

-sympathetic

Question 18

What is the cascade of adrenaline?

Answer 18

-catacholamines -adrenergic receptors -dopamine is precursor to noradrenaline

Question 19

How do dopamine and norepinephrine get made?

Answer 19

• activate postsynaptic and presynaptic receptors
• noradrenaline gets taken back in as does dopamine= cycling
• many drugs (cocain etc) block the transporters that take up the noradrenaline and dopamine

Question 20

What input do most organs receive?

Answer 20

-receive input from the autonomic nervous system, not all organs receive input from both e.g. many blood vessels = SNS only

Question 21

What does the autonomic nervous system consist of?

Answer 21

-of two neurons connected in series -the neuron innervating the target occurs outside the CNS

Question 22

What are the preganglionic axons of the sympathetic division like?

Answer 22

-short -the ganglionic axons project long distances to contact the target tissue

Question 23

What are the preganglionic axons of the parasympathetic division like?

Answer 23

-long -the ganglionic axons are locate in ganglia in the target tissue

Question 24

What does the stimulation of sympathetic and parasympathetic innervation have?

Answer 24

-often reciprocal actions -in life work synergistically or under different conditions

Question 25

What neurotransmitter do preganglionics (ANS) use?

Answer 25

-acetylcholine -acts on ionotropic nicotine receptors N2

Question 26

What transmitters do ganglionics use?

Answer 26

-sympathetic= noradrenaline (adrenoceptors) -parasympathetic= acetlycholine (muscarinic receptors)

Question 27

What nervous system does the intestine have?

Answer 27

-extensive nervous system that receives input from the autonomic nervous system but can function independently = enteric nervous system

Question 28

Where are complex inputs integrated?

Answer 28

-complex sensory inputs from the viscera and higher senses are integrated to enable co-ordinated functioning of the autonomic nervous system -hypothalamus is a major conductors of these co-ordinated responses

Question 29

What is the anatomy of the pituitary, thalmus etc.?

Answer 29

-

Question 30

What is the pathway of viscera(ANS) informing the higher centres?

Answer 30

• the preganglionic neurons on their own do not do that much,
• how the brain integrates information to drive the output according to need
• the motor pattern
• end organs provide feedback(the end organ that is important is brain, provides feedback to itself to tell if it is getting enough glucose)
• (baroreceptor reflex)
• the feedback goes to the medulla, the nucleus of the solitary tract
• within the medulla there are loops that can go back to the end organ (baroreceptor reflex is one of these)
• when you get up = barocreceptor reflex makes sure that the blood doesn’t pool in your limbs but goes to the head! so you don’t faint
• unconscious control 2nd loop= from nucleus of solitary tract to hypthalamus, then amygdala then to the cortex= this is the signals that we are aware of= constricted gut etc.
• the info gets processed in the brain, in hypothalamus is important= conductor, from there many projections (to brainstem, etc.)
• hypothalamus sends lot of information and regulates amygdala plays an important role in fearful situations,

Question 31

Why is hypothalamus key?

Answer 31

• hypothalmus is key, projects to the motor neurons and the endocrine system (via vasopressin for example)
• receives info, contextual and sensory