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Medical Student Forums => Basic Medical Science => Topic started by: Miina on October 23, 2009, 02:44:47 AM

Title: A physiology question.
Post by: Miina on October 23, 2009, 02:44:47 AM

Asalaamu Caleykum Waraxmatullaahi Wabarakaatuhu.

What is the origin and spread of excitation in the nodal tissue of the heart?

I would be delighted if you could help me with this question....

Kindest regards;

Miina.

Title: Re: A physiology question.
Post by: Dr.Abdul on October 23, 2009, 06:52:12 PM

Quote from: Miina on October 23, 2009, 02:44:47 AM

Asalaamu Caleykum Waraxmatullaahi Wabarakaatuhu.

What is the origin and spread of excitation in the nodal tissue of the heart?

I would be delighted if you could help me with this question....

Kindest regards;

Miina.

Hello, Miina
     
     It originates from the cardiac pacemaker cells and goes through gap junctions from where it  spreads  to whole myocardium.
        The primary pacemaker is SA node which is small tissue on the right atrium specifically between the Superior and Inferior Vena cava. Usually the beats at  SA node is about 90 beats, but it is minimized by vagal activity to about 70 beats, in a healthy person.The other pace maker tissues are slower than SA node and includes AV node, Purkinje and bundle of His.
       The initiated excitations from SA node spread to atrial myocardium where it goes from on atrial cell to the next throughout both atria and towards the AV node. AV node conducts through the fibrous tissue which separates the Atria and Ventricle walls. AV node is slower than  the conduction through Atrial or ventricle by 0.1 sec, and as a result atrial excitation is finished at about the time that ventricular excitation begins.
 
hope this helps,
Abdul

Title: Re: A physiology question.
Post by: Miina on October 23, 2009, 10:22:37 PM

Asalaamu Caleykum.

Thank you so very much Dr Abdul, may Allah reward you with so much
kheyr and xasanaad.

Miina.

Title: Re: A physiology question.
Post by: Dr.Abdul on October 24, 2009, 02:11:21 AM

Quote from: Miina on October 23, 2009, 10:22:37 PM

Asalaamu Caleykum.

Thank you so very much Dr Abdul, may Allah reward you with so much
kheyr and xasanaad.

Miina.

Salam

You are welcome any time Miina, am glad to help, keep up the good job!

Title: Re: A physiology question.
Post by: Miina on October 28, 2009, 08:59:42 AM

Asalaamu caleykum!

Insha'allah I will do my very best!

Miina.