innervating the heart

Question 1

VAGUS HAS AFFERENTS AS WELL AS EFFERENTS.

Answer 1

Yas

Question 2

if u denervate the heart, will it beat in a faster or slower rate and why?

Answer 2

faster, bc parasympathetic is dominated at rest.

Question 3

***METABOLITES play a major role in making sure the skelteal muscle amd cornory muscle get adequate perfusion

Answer 3

More important than the act of B2 recepters

Question 4

BP=COx TPR

Answer 4

Ok

Question 5

during shock, u wanna give a shot of Adrenaline, why?

Answer 5

to cause vasoconstriction

Question 6

An asmatic patient came with a problem in heart condition & u adminstered propanol, he developed an asmatic attack, why is this so?

Answer 6

Propanol is non selective B antagonist

Its slowers heart rate and reduces force of comtraction but also acted kn the b2 in the lings and causes bronchocomstriction.

Question 7

describe sympathetic activity of vessels

Answer 7

symp. activates a1 for vasoconstriction

Question 8

symapthetic

Answer 8

preganglionic fibres

• innervates SA, AV, Myocardium
• release NE
• acts mainly on B1 adrenocepters

INCREASES heart Rate (chronotropy)
INCREASES FORCE OF contraction (inotrphy)

(B2 & B3 r also in the heart, but main effect is via B1)

Question 9

Effect of administering atenolol?

Answer 9

Its a SELECTIVE b1&raquo_space; therefore causing less risk of bronchocomstriction

Question 10

explain what the vasomotor tone is? what allows this arise?

Answer 10

Bv must always remain PARTIALLY contracted in order to maintain a stable arterial pressure!!

via the vasconstrictor area in the vasomotor centre.

Question 11

We want to examine the eyes of a patient, what do we administer and why?

Answer 11

Atropine» dilates the eyes

Muscuranic antagnoist

Question 12

What r some drugs that work on the ANS

Answer 12

Sympathomimetics

• a adrenorecepters agonists
• b adrenorecepters agonists

adrenorecepter ANTAGONISTS

Cholinergics

Question 13

4. List the probable physiological effects of giving an individual a drug which antagonises the action of noradrenaline at a- adrenoreceptors.

Answer 13

Arteriolar vasodilation, reduces blood pressure and may cause postural
hypotension
Initial increase in heart rate mediated by baroreceptor reflex Relaxes GI and urinary sphincters

Question 14

During excersize, what increases BF to the tissues?

Answer 14

The vasodilation of bv via B2 isnt the main reson why we get increased BF, it is mostly through the action of METABOLITES.

The more active the tissue becomes, the more it will release metabolites! (Adenosine, pottasium, H+, Co2) these act on vascular smooth muscle cells to cause relaxation.

Question 15

What organ is responsible for controlling plasma volume and

how does it do so?

Answer 15

Kidneys, by increased na reabsorbtion

Question 16

Why are baroreceptors not able to control longer term changes
in blood pressure?

Answer 16

Baroreceptors can re-set to higher levels with persistent increases in blood
pressure

Question 17

where r baroreceptors located? what do they do?

Answer 17

they r stretch receptor found:

• carotid sinus (dilated region at the bifurcation)
• aortic arch wall

they detect changes in BP

But only short term regulatiom , bc it tends to reset itself after a few days

Question 18

barorecepters in the carotid sinus send sensory signal via_________ nerve
barorecepters in the aortic arch send sensory signal via_________ nerve

Answer 18

glossopharyngeal

Vagus

Question 19

TPR=______________

Answer 19

Bp/Co

Question 20

A patient with an overactive thyroid gland has an increased
response to sympathetic input to the heart. How will the
patient’s heart rate and cardiac output differ from normal?

Answer 20

The patient will have a fast heart rate and increased cardiac output.

Question 21

When changes in pressure occur, from where r the afferent nerves coming from goint to the brain?

Answer 21

Barorecepters>carotid sinus & carodis body» high pressure
Pressure recepters> atria> low pressure system

Question 22

how does NA increase force of contraction?

Answer 22

acts on B1 G-s Recepters in myocardium> Adeyly cyclase> increase CAMP > PKA

• phosphorylate Ca+ channels
• increased uptake of Ca in SR (increase Ca store)
• increased sensitivity of contractile machinery to Ca

Question 23

most vessels receive sympathetic/parasympathetic innervation?
what type?

Answer 23

sympathetic
mostly a1
B2

Question 24

Effct of prazosin?

Answer 24

A1- antagonist»vasodilaton of bv wil occur

Question 25

explain what the vasomotor tone is? what allows this arise?

Answer 25

Bv must always remain PARTIALLY contracted in order to maintain a stable arterial pressure!! ***u want there to be a tone so either dilation or constriction can occur. via the vasconstrictor area in the vasomotor centre.

Question 26

if we denervate the heart, will it still pump?

Answer 26

yes, electrical activity is activated bc the spontaneous activity of the cell in the ca node.

Question 27

Some individuals react to bee sting or nettle sting with a massive release of chemical mediators tending to dilate blood vessels and constrict the airways of the lung. What substance would you need to inject into some one suffering this 'anaphylaxsis' and why?

Answer 27

Adrenaline Constriction of resistance arterioles caused by a high concentration of adrenaline acting on α1 receptors increases blood pressure Relaxes airways of the lung via action on β2 adrenergic receptors

Question 28

some bv have B2 as well as A1 receptor, describe them and their affinities to circulating adrenaline

Answer 28

a1> vasocontrciotn B2> vasodilation But B2 has an higher affinity to normal circulating levels of NA, but if we increase the amount NA, IT will act on the a1

Question 29

most vessels receive sympathetic/parasympathetic innervation?

Answer 29

sympathetic mostly a1 (but coronory and skeletal muscle vasculature have B2)

Question 30

what is BNP?

Answer 30

brain natriutic peptide, ventricular myoctyes release them in response to high tension. good marker for HF

Question 31

Parasympathetic control of the heart is via the _______nerve

Answer 31

Vagus 10th cranial nerve

Question 32

What effect does PKA have on MLCK? Give an examle where this can be seen

Answer 32

It phosphorolates it>> therefore inhbits it action >> stops comtraction On B2 adrenocepters on the smooth muscle artery wall., vasoldilation occurs

Question 33

How do barorwcpeters rwgulate bp? Is this a short term or longterm regulation?

Answer 33

Short term, it detects rise in bp> stretches> signals sent to medulla in the coordinating centre>efferent signals leave and inhibit sympatheic activity to heart and bv **this is only short term, 7ada bs 1-2 days bs!

Question 34

A pateint developed an anaphylactic shock, what do we give him?

Answer 34

We 2 shots epipen (epinephrine pen) (the shot bl leg) A big dose of Adreneline since that will work on A1 recepters on bv and cause vasoconstriction.

Question 35

what control the levels of sympathetic and parasympathetic outflows?

Answer 35

the cv centre in the medulla oblongata

Question 36

circulating Adrenaline has a higher affinity to B2 or A1 receptors?

Answer 36

B2, but at higher concentrations it will activate A1 as well.

Question 37

What do we use for the treamtnet of glaucoma?

Answer 37

Pilocarpine>>muscuranic agonist>> used in treamtment of glaucoma ** activates constrictor pupillae muscle

Question 38

What is meant when said that the atrial recepter is a "low pressure system"?

Answer 38

Theyre on the low pressure side of the system (gunna detect the venous pressure) unlike the carotid ones

Question 39

A patient had a cardiogenic shock, what can we adminster him?

Answer 39

If u wanna act on the heart bs, use a SELECTIVE B1 agonist-dobutamine

Question 40

The ANS does not initiate electrical activity in the heart

Answer 40

Ok

Question 41

Describe the parastmpathetic input to heart | Recepter type? Neurotransmitter? How would that effect the heart

Answer 41

postganglionic cells release ACh • acts on M2-receptors – decrease heart rate (-ve chronotropic effect) – decrease AV node conduction velocity

Question 42

Sympathetic control of the heart is via the ............. nerves

Answer 42

Cardiac

Question 43

The cardiac output is the product of ................ and ....................... .............................

Answer 43

Sv & HR

Question 44

The cardiac output is the product of ................ and ....................... .............................

Answer 44

Sv & HR

Question 45

If you gave an individual an injection of adrenaline (at a dose higher than the normal circulating levels in exercise) what cardiorespiratory effects would occur?

Answer 45

T h e r e w o u ld b e a n in c r e a s e in h e a r t r a t e , s t r o k e v o l u m e a n d t h e r e f o r e c a r d i a c o u t p u t T h e a r t e r i o le s t o t h e s k i n w o u l d v a s o c o n s t r ic t ( a c t io n o f a d r e n a l in e o n α 1 r e c e p t o r s ) T h e a ir w a y s w o u ld d i l a t e ( a c t io n o f a d r e n a l i n e o n β 2 receptors)

Question 46

What does an individual with a high circulating level of adrenaline look like to an outside observer?

Answer 46

An x i o u s Sw e a t y ( a d r e n e r g ic s w e a t i n g ) Pa l e D i l a t e d p u p i ls

Question 47

In principle, what sort of drug would you use to limit the autonomic effects of poisoning with an acetylcholinesterase inhibitor?

Answer 47

M u s c a r i n ic r e c e p t o r a n t a g o n is t s , e . g . a t r o p in e

Question 48

most arteries and veins have α1 adrenocepters – --------and ----------muscle vasculature also have β2

Answer 48

Coronory and skeletal muscle

Question 49

Give 2 examples of β-adrenoreceptor antagonists

Answer 49

-propranolol Non selective b1/b2 antagonist Slows HR, reduce force of contraction, acts on bronchiol smooth muscle (b2)-brinchocomstriction ``` -atenolol Selective b1 (selective β1 (cardio-selective) - less risk of bronchoconstriction ```