innervating the heart Flashcards
VAGUS HAS AFFERENTS AS WELL AS EFFERENTS.
Yas
if u denervate the heart, will it beat in a faster or slower rate and why?
faster, bc parasympathetic is dominated at rest.
***METABOLITES play a major role in making sure the skelteal muscle amd cornory muscle get adequate perfusion
More important than the act of B2 recepters
BP=COx TPR
Ok
during shock, u wanna give a shot of Adrenaline, why?
to cause vasoconstriction
An asmatic patient came with a problem in heart condition & u adminstered propanol, he developed an asmatic attack, why is this so?
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.
describe sympathetic activity of vessels
symp. activates a1 for vasoconstriction
symapthetic
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)
Effect of administering atenolol?
Its a SELECTIVE b1»_space; therefore causing less risk of bronchocomstriction
explain what the vasomotor tone is? what allows this arise?
Bv must always remain PARTIALLY contracted in order to maintain a stable arterial pressure!!
via the vasconstrictor area in the vasomotor centre.
We want to examine the eyes of a patient, what do we administer and why?
Atropine» dilates the eyes
Muscuranic antagnoist
What r some drugs that work on the ANS
Sympathomimetics
- a adrenorecepters agonists
- b adrenorecepters agonists
adrenorecepter ANTAGONISTS
Cholinergics
- List the probable physiological effects of giving an individual a drug which antagonises the action of noradrenaline at a- adrenoreceptors.
Arteriolar vasodilation, reduces blood pressure and may cause postural
hypotension
Initial increase in heart rate mediated by baroreceptor reflex Relaxes GI and urinary sphincters
During excersize, what increases BF to the tissues?
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.
What organ is responsible for controlling plasma volume and
how does it do so?
Kidneys, by increased na reabsorbtion
Why are baroreceptors not able to control longer term changes
in blood pressure?
Baroreceptors can re-set to higher levels with persistent increases in blood
pressure
where r baroreceptors located? what do they do?
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
barorecepters in the carotid sinus send sensory signal via_________ nerve
barorecepters in the aortic arch send sensory signal via_________ nerve
glossopharyngeal
Vagus
TPR=______________
Bp/Co