Review of the Sympathetic Nervous System Flashcards Preview

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Flashcards in Review of the Sympathetic Nervous System Deck (38)
1

Which tract supplies the sympathetic preganglionic neurones?

Reticulospinal tract

2

What is the sympathetic chain?

Where the cell bodies of postganglionic sympathetic neurones lie

3

What is the superior cervical ganglion?

Most superior sympathetic ganglion which projects into cervical region but isn't connected to cervical ventral roots

4

Describe how sympathetic postganglionic fibres travel

Form nerve plexuses around the carotid arteries and enter the skull with the carotids

5

How do thoracic and abdominal preganglionic sympathetic neurones differ?

Thoracic have short preganglionic neurones whereas abdominal have long ones so sympathetic ganglia is a long way from the spinal cord and have different names (e.g. coeliac ganglion)

6

Describe the coeliac ganglion and what is supplies

Present below diaphragm and anterior to aorta, supplies stomach and initial parts of small intestine

7

What is the mesenteric ganglia?

Found around the lower abdominal aorta and has superior and inferior types

8

What does the superior mesenteric plexus supply?

Innervates small intestine, ascending and transverse colon

9

What does the inferior mesenteric plexus supply?

Innervates descending colon and rectum

10

What is the consequence of coeliac ganglion stimulation?

Sphincter contraction, abdominal vasoconstriction, mobilisation of liver glycogen and secretion of adrenaline (adrenal medulla)

11

What is the consequence of superior mesenteric ganglion stimulation?

Relaxation of small intestine and colon walls

12

What is the consequence of inferior mesenteric ganglion stimulation?

Relaxation of small intestine and colon walls, constriction of sphincters and relaxation of urinary bladder and genital vasoconstriction

13

How is adrenaline produced?

Tyrosine --> DOPA --> dopamine --> noradrenaline --> adrenaline

14

What are catecholamines?

Dopamine, noradrenaline and adrenaline

15

What axon type are sympathetic preganglionic neurones?

Myelinated type B

16

How do sympathetic preganglionic neurones activate postganglionic neurones?

Release ACh

17

What type of receptor is present on all autonomic ganglia?

Cholinergic nicotinic receptor

18

What is the role of sympathetic postganglionic neurones?

Project to smooth muscle in arterioles --> vasoconstriction

19

What type of axon do sympathetic postganglionic neurones have?

Unmyelinated type C

20

How do sympathetic postganglionic neurones activate smooth muscle in

Noradrenaline release --> alpha 1 adrenoreceptors --> vasoconstriction

21

What is the main function of the sympathetic nervous system?

Regulates blood distribution around the body

22

What is the role of the sympathetic nervous system in preventing postural hypotension?

Normally keeps all arterioles of vascular beds slightly constricted to maintain blood pressure in the leg muscles when you stand

23

What happens in the fight or flight response?

Vasoconstriction in non-working muscles (e.g. digestion), adrenaline release, pupil dilation

24

Which sympathetic ganglion is involved in pupillary dilation and thickened salivary secretions?

Superior cervical ganglion

25

Which sympathetic ganglion is involved in ejaculation and voiding the bladder?

Hypogastric ganglion

26

Which sympathetic ganglion is involved in peristaltic inhibition of the gut?

Coeliac ganglion

27

What does sympathetic activation of alpha receptors achieve?

Constriction of vessels in gut --> shunt to working muscles

28

What does sympathetic activation of beta 1 receptors achieve?

Increase CO

29

What does sympathetic activation of beta 2 receptors achieve?

Relax bronchial SM and increase glycogenolysis and lipolysis

30

What does sympathetic activation of beta 3 receptors achieve?

Increase glycogenolysis and lipolysis

31

How do stressors affect the sympathetic nervous system?

Stressors activate SNS ad hypothalamo-pituitary-adrenal axis --> adrenocorticotrophic hormone --> cortisol release from adrenal cortex --> stimulates adrenaline and noradrenaline synthesis

32

How does the sympathetic nervous system react to injury or haemorrhage?

Constriction of veins increases (increase/maintain venous return to heart to maintain BP and CO), severe blood loss --> vasoconstriction to non-essential organs, renin and ADH release to reduce urine flow and fluid loss (increase BP), alpha receptors in vascular SM --> constriction and sensitise platelets to collagen to make endothelium 'sticky' --> clotting

33

Describe sympathetic alpha adrenoreceptors

a1 = on vascular smooth muscle --> constriction
a2 = on presynaptic sympathetic nerve terminals (negative feedback for noradrenaline release)

34

Describe sympathetic beta adrenoreceptors

B1 = on cardiac muscle to increase HR and contraction force
B2 = relaxes bronchial smooth muscle
B3 = on adipose tissue --> lipolysis

35

What molecule do alpha adrenoreceptors mainly respond to?

Noradrenaline

36

What molecule do beta adrenoreceptors mainly respond to?

Adrenaline (but can respond to noradrenaline)

37

How do beta blockers work?

Antagonist of B1 receptors to reduce HR and contraction force in hypertensive patients

38

How does salbutamol work?

Agonist of B2 receptor --> bronchodilation