Qualification > Sciences
ALL CIE BIOLOGY DOUBTS HERE !!!
Amelia:
--- Quote from: ~~!$!HUSH!$!~~ on April 06, 2011, 10:23:52 am ---can anyone explain MJ 2002 P1 Q21 please?
--- End quote ---
Can you post the question? I cant find that paper.
**RoRo**:
I have a doubt in the circulatory system.
The heart's cardiac muscles are described as myogenic, right?
Myogenic means that the contraction of the muscles is initiated from the muscles itself and the term neurogenic means that the contraction of the muscles is initated from the nerves.
When we learnt the cardiac cycle, it was the SAN that received the impulse from the Cardiac Acceleratory/Inhibitory Center in the medulla oblongata of the brain which was transmitted through the vagus nerve till it reachs the SAN which sends the impulse to the walls of the atria to contract and the impulse is transmitted to the apex of the heart through the Purkinje fibres and the muscles contract, so as you see, it's contraction initiated by an impulse, so why is the cardiac muscle described as myogenic!
Deadly_king:
--- Quote from: The Secret on April 07, 2011, 08:03:02 pm ---I have a doubt in the circulatory system.
The heart's cardiac muscles are described as myogenic, right?
Myogenic means that the contraction of the muscles is initiated from the muscles itself and the term neurogenic means that the contraction of the muscles is initated from the nerves.
When we learnt the cardiac cycle, it was the SAN that received the impulse from the Cardiac Acceleratory/Inhibitory Center in the medulla oblongata of the brain which was transmitted through the vagus nerve till it reachs the SAN which sends the impulse to the walls of the atria to contract and the impulse is transmitted to the apex of the heart through the Purkinje fibres and the muscles contract, so as you see, it's contraction initiated by an impulse, so why is the cardiac muscle described as myogenic!
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AM sorry I can't summarize it for you now since am pretty busy myselft......................but do read the first part of this ;)
http://www.tutorvista.com/biology/physiology-of-the-human-heart
It is said that SAN is only partly controlled by sympathetic nerve. ;)
Do not read everything koz I don't think it is in the \A-lvel syllabus :P
**RoRo**:
--- Quote from: Deadly_king on April 07, 2011, 08:08:05 pm ---AM sorry I can't summarize it for you now since am pretty busy myselft......................but do read the first part of this ;)
http://www.tutorvista.com/biology/physiology-of-the-human-heart
It is said that SAN is only partly controlled by sympathetic nerve. ;)
Do not read everything koz I don't think it is in the \A-lvel syllabus :P
--- End quote ---
Thanks a lot, actually my teacher had taught us the entire thing, it's pretty interesting.
& I got it, the contraction of the cardiac muscle starts from SAN which is a muscle by itself.
**RoRo**:
Guys, someone make my day and reply with a 'no' to this question, do we need to know the structure of the trachea, cartilage and smooth muscle with all those amazing terms 'mucosa', 'chondrocytes', 'lacuna', 'cell nest', 'squamous pnemocyte type (1)' and 'secretory pnemocyte type (2)'?
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