Created by Ayman Barghout
over 8 years ago
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Question | Answer |
In-vivo preparations | 1. Anesthetized cat blood pressure. 2. Cat nictitating membrane |
Anesthetized cat blood pressure preparation | Animals are cannulated at 3 sites: 1. Tracheal cannulation. 2. Femoral vein cannulation. 3. Femoral artery cannulation |
1. Tracheal cannulation | Polyethylene cannula is introduced into the trachea, cannula is connected to respirometer (artificial ventilator) to overcome respiratory pralysis produced by skeletal muscles relaxants. |
2. Femoral vein cannulation | Through a small cut in the vein connected to a syringe for IV adminstration of drugs |
3. Femoral artery cannulation | The femoral artery is connected to a blood pressure transducer for blood pressure measurement which converts blood pressure to electronic signals which are recorded on a multi-channel system |
Tetrad system | 1. Electrical vagal stimulation. 2. IV administration of acetylcholine. 3. Bilateral Carotid Occlusion (OCB). 4. IV administration of epinephrine or norepinephrine. |
Vagus nerve | The parasympathetic nerve supplying the heart & GIT. |
Vagus nerve origin | It originates from 2 nuclei in the meddula oblongata 1. Dorsal motor nucleus of vagus (DMV) 2. Nucleus ambiguous (NA) |
1. Electrical vagal stimulation | 1. The neck area is opened and one of the two vagi is dissected. 2. Vagus nerve is stimulated electrically (preganglionic stimulation) |
Effect of electrical vagal stimulation | 1. Release of endogenous Acetylcholine which affects \[M_2\] receptor in heart. 2. Bradycardia → decreased cardiac output → hypotension. |
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