ANS control of the heart

Question 1

HR, BP, temp etc
Response to exercise
Response to stress
are all controlled by what?

Answer 1

Autonomic nervous system - involunatry

Question 2

What are the effectors of the ANS?

Answer 2

Smooth muscle
Exocrine glands
Heart- rate and force

Question 3

What is the enteric nervous system?

Answer 3

Network of neurones found in GI tract controlled by sympathetic and parasympathetic fibres.

Question 4

Which branch of the ANS predominates in Basal conditions?

Answer 4

Parasympathetic

Question 5

Do the parasympathetic and sympathetic nervous systems work together?

Answer 5

Yes the oppose one another to achieve a balance.

Question 6

In the eye which receptors are found in the iris muscle and what neurotransmitter innervates them to do what action?

Answer 6

alpha 1- adrenaline- dilation

M3- Acetyl choline - contraction

Question 7

What do M3 receptors in the lungs do?

Answer 7

Broncho-constrict

Question 8

What neurotransmitter is at NMJ of parasympathetic nerves?

Answer 8

Acetyl choline

Question 9

What receptor type is at the NMJ of most parasympathetic nerves?

Answer 9

mAChR

Question 10

What is Qiss Qiq

Answer 10

A memory aid to help remember what receptor is where.
alpha1 Q vasoconstriction
alpha2 I inhibits nerotransmitter release
beta 1 S heart (inc, HR and inotropy)
beta 2 S lungs bronchodilation

M1 Q glands
M2 I heart (decrease HR and force)
M3 Q lungs (bronchoconstriction)

Question 11

What does parasympathetic innervation do to sweat glands?

Answer 11

No effect

Question 12

What causes sweat gland activity?

Answer 12

Sympathetic effect

Question 13

Is the sympathetic effect systemic or localised?

Answer 13

More often than not it is localised but in fight or flights its systemic.

Question 14

Which nerve slows the heart?

Answer 14

Vagus nerve pre-ganglionic fibres innervate post-ganglionic cells on the epicardial surface or with n the walls at the SAN or AVN.

Question 15

Which nerve speeds up heart rate?

Answer 15

Sympathetic trunk feeds into cardiac accelerator nerve

Question 16

Does the ANS initiate the heart beat?

Answer 16

NO

SAN is automated. The vagal nerve slows the intrinsic heart rate down in normal circumstances but does not initiate it.

Question 17

Venoconstriction is controlled by?

Answer 17

ANS

Question 18

How do M2 slow heart rate?

Answer 18

Slow AVN conduction velocity.

Question 19

What neurotransmitter is released at M2 receptors?

Answer 19

Acetyl choline

Question 20

B1 stimulation has positive inotropic and chronotropic effects where are the receptors in the heart and what stimulates it?

Answer 20

Noradrenaline

SAN, AVN and myocardium

Question 21

B1 is the predominant sympathetic receptor affecting the heart but what other types are there?

Answer 21

B2 and B3

Question 22

Outline the baroreceptor reflex if pressure is high.

Answer 22

Baroreceptors detects pressure changes and respond to stretch. They feedback to the cardiovascular centre by the glossopharyngeal nerve. The vagus nerve will relay a signal to slow the heart to post ganglionic cells at the SAN and AVN.

Question 23

Where do you find baroreceptors?

Answer 23

Arch of the Aorta

Carotid Sinus

Question 24

If pressure is low what happens ?

Answer 24

Atrial receptors detect low pressure and communicate with the cardiovascular centre. An intermediate neurone carries it from the medulla oblongata to the spinal cord. The sympathetic trunk receives input and sends a sympathetic signal via the cardiac accelerator nerve. This nerve innervates SAN, AVN and ventricular myocardium.

Question 25

Where in the brain do you find the cardiac centre?

Answer 25

Medulla Oblongata

Question 26

Outline SAN potential.

Answer 26

Funny current - slow conductance Na+ channel slowly depolarises cell to threshold. Ca2+ channel open, fast upstroke to +10mV Ca2+ channels shut and K+ channels open to repolarise

Question 27

How long is an SAN AP?

Answer 27

0.8 s

Question 28

The SAN node carries HCN, why is this important when considering the action of sympathetic innervation at the SAN speeding up HR?

Answer 28

B1 receptors are Gs. Adenylyl cyclase activated so ATP converted to cAMP. HCN are cyclic dependent- i.e. activated by cAMP. More HCN activation means a faster pacemaker potential- faster heart rate

Question 29

How does parasympathetic innervation slow heart rate?

Answer 29

M2 are Gi receptos so reduce cAMP . The beta gamma subunit also increases K+ conductance making the cell more hyper-polarised.

Question 30

Outline the steps of NA increasing contractility of the heart?

Answer 30

cAMP activates PKA. PKA phosphorylates calcium channels. Increased Ca2+ entry in plateau Calcium induced calcium release is increased Increased calcium sensitivity of the contractile machinery More forceful contratin

Question 31

Which vessels carry parasympathetic receptor?

Answer 31

Erectile Point and Shoot Erection - Para-sympathtic Ejaculation - Sympathetic

Question 32

Which vessels contain B2 receptors as well as alpha 1?

Answer 32

Coronary vessels and skeletal muscle vessels

Question 33

How does the sympathetic system generate vasodilation?

Answer 33

decrease from basal sympathetic tone.

Question 34

Noradrenaline stimulates which sympathetic receipt preferentially in vascular smooth muscle?

Answer 34

Alpha 1

Question 35

What stimulates beta 2 receptors in vascular smooth muscle?

Answer 35

Circulating adrenaline

Question 36

Circulating adrenaline can stimulate alpha 1 as well as beta 1 in vascular smooth muscle, under what circumstance is this the case?

Answer 36

High concentrations of circulating adrenaline

Question 37

How do Beta 2 receptors in smooth muscle cause vasodilation?

Answer 37

Increase cAMP- PKA activated K+ channels open and MLCK inhibited smooth muscle relaxes.

Question 38

What do local metabolites do in smooth muscle of vasculature?

Answer 38

Vasodilate

Question 39

Name some vasodilating local metabolites

Answer 39

K+ H+ CO2

Question 40

Which has the greater vasodilating affect in coronary vessels and skeletal muscle vessels local mediators or Beta 2 receptors?

Answer 40

Local mediators.

Question 41

How do we increase mean arterial pressure?

Answer 41

``` Barorecetor detects drop in pressure afferent pathway to brain Brain coordinate an output Efferent pathway Heart beats slower and less hard while vessels dilate ```

Question 42

In hypertension why don't the bar receptor reflexes lower it?

Answer 42

Reset to a higher level of pressure to induce an effect.

Question 43

List drug types that act on the ANS in CVS

Answer 43

alpha- adreno-receptor agonist beta adreno-recpetor agonists adrenoreceptor antagonists Muscarinc agonists and antagonists.

Question 44

Which sympathomimetic is given in cardiac arrest?

Answer 44

adrenaline

Question 45

What would you give in cariogenic shock?

Answer 45

dobutamine B1 agonist- increase hearts rate and force

Question 46

Why would you give adrenaline in anaphylaxis?

Answer 46

vaso-constriction

Question 47

Why would you want to antagonise alpha 1 receptors?

Answer 47

Resistant hypertensives

Question 48

Name a nonselective beta blocker and why you would give it.

Answer 48

Propranolol used to slow HR and reduce BP | Risk bronchoconstriction

Question 49

Selective beta 1 blockers are known as cardio-selective, what do they do and give an example?

Answer 49

Atenolol | Inhibit Beta 1 receptor in heart only so decrease inotropy and chronotropy

Question 50

The iris muscarinic receptor is in the sphincter and when stimulated causes contraction. What pharmaceutical agent is used to agonise this?

Answer 50

Pilocarpine

Question 51

Tropicamide is a.... and is used to .... the pupil by antagonising on the .... receptors on the .... muscle

Answer 51

antimuscarinic dilate M3 sphincter