Intro to autonomic nervous system

Question 1

What are the 2 divisions that the nervous system is divided into?

Answer 1

-Central nervous system(CNS)
-Peripheral nervous system(PNS)

Question 2

What does the autonomic nervous system provide?

Answer 2

Provides involuntary information from CNS to peripheral organs
-E.g. increasing heart rate during exercise

Question 3

What are the 3 divisions in the ANS?

Answer 3

-Sympathetic
-Parasympathetic
-Enteric

Question 4

What does the enteric system control?

Answer 4

Control GI tract

Question 5

What does the ANS innervate in the heart?

Answer 5

-Sino-atrial node
-Atrioventricular nodes
-Cardiac myocytes

Question 6

What does the sinoatrial node regulate?

Answer 6

-This regulates heart rate

Question 7

What does the atrioventricular node cells regulate?

Answer 7

-Regulate electrical conduction through heart

Question 8

What do cardiac myocytes regulate?

Answer 8

-Regulates contractility of heart

Question 9

What does ANS innervation do to smooth muscles?

Answer 9

-ANS contracts or relaxes smooth muscle cells which are present in many tissues/organs
-e.g. blood vessels, airways, intestine, bladder

Question 10

What does ANS innervation to gland cell cause?

Answer 10

-ANS causes secretions from glandular cells
-e.g. release of saliva, sweat, gastric acid, insulin, glucagon

Question 11

What is the structure of the ANS like in terms of efferent nerves?

Answer 11

-There are 2 efferent(away from) neurons arranged in series conducting electrical activity from CNS to peripheral tissue/organ
-There’s an autonomic ganglion between the pre-ganglionic and post-ganglionic nerve

Question 12

How does the ANS differ from somatic motor nerves?

Answer 12

-ANS differs to somatic motor nerves as somatic nerves are where a single efferent neuron connects CNS to skeletal muscle

Question 13

What is the structure of parasympathetic nerves?

Answer 13

-Long pre-ganglionic/ short post-ganglionic

Question 14

What is the structure of sympathetic nerves?

Answer 14

-Short pre-ganglion/ long post-ganglionic

Question 15

What is the overview of chemical transmission?

Answer 15

1. Synthesis of neurotransmitter
2. Storage of neurotransmitter in vesicles
3. Arrival of action potential at synaptic terminal
4. Terminal depolarises, activation of voltage-gated Ca2+ channels, Ca2+ influx
5. Ca2+ dependent release of neurotransmitter
6. Neurotransmitter binds to receptors and induces response
7. Uptake/breakdown of neurotransmitter

Question 16

What do all pre-ganglionic sympathetic and parasympathetic nerves release in ANS? And where does this neurotransmitter act at?

Answer 16

-All pre-ganglionic sympathetic and parasympathetic nerves release Ach
-Ach acts at nicotinic receptors at all autonomic ganglia

Question 17

What do postganglionic para-sympathetic nerves release and where do they act at?

Answer 17

-Post-ganglionic parasympathetic nerves release Ach which acts at muscarinic receptors

Question 18

What is an exception for postganglionic parasympathetic nerves releasing Ach?

Answer 18

-Exception is non-adrenergic-non-cholinergic(NANC) nerves which use other chemicals such as nitric oxide

Question 19

What do postganglionic sympathetic nerves release and where do they act?

Answer 19

-Post ganglionic sympathetic nerve release Noradrenaline which acts at alpha or beta adrenoceptors

Question 20

What is an exception for postganglionic sympathetic nerves releasing Noradrenaline?

Answer 20

-Exception: in sweat glands, sympathetic nerves release Ach which acts at muscarinic receptors

Question 21

What does stimulation of pre-ganglionic sympathetic fibres innervating the adrenal gland release and what percentage and from where?

Answer 21

-Stimulation of pre-ganglionic sympathetic fibres, innervating the adrenal gland, release adrenaline(80%) and noradrenaline(20%) from adrenal glands

Question 22

What fibres are not involved in innervation of adrenal glands?

Answer 22

-No post-ganglionic fibres are involved in innervation of adrenal glands

Question 23

What do the sympathetic and parasympathetic innervation of the heart results in?

Answer 23

-Sympathetic increases heart rate and force of contraction
-Parasympathetic decreases heart rate and force of contraction

Question 24

What does the sympathetic and parasympathetic innervation of the intestines result in?

Answer 24

-Sympathetic decrease motility
-Parasympathetic increases motility

Question 25

What does the sympathetic and parasympathetic innervation of the iris results

Answer 25

-Sympathetic dilates
-Parasympathetic constricts pupils

Question 26

What do both sympathetic and parasympathetic innervation of the salivary gland result in?

Answer 26

-Both sympathetic and parasympathetic increase secretions from the salivary gland

Question 27

What organs are only innervated by sympathetic?

Answer 27

-Sweat glands, Kidney, Blood vessels

Question 28

What organs are innervated by parasympathetic?

Answer 28

-Pancreas, secretory cells of stomach, lungs(But airway contains beta-adrenoceptors, modulated by circulating adrenaline released by sympathetic nerves on adrenal gland)

Question 29

What is the ANS important in mediating and how is this achieved?

Answer 29

-ANS is of primary importance in mediating homeostatic involuntary mechanism-achieved through feedback systems