Physiology

Blockers of Acetylcholine: 1/Competitive nicotinic blockers: _Curare. _Hexamethonium. 2/Depolarizing nicotinic blocker: Large amount of nicotine 3/Competitive muscarinic blockers: _Atropine. _Scopolamine. 4/Depolarizing muscarinic blocker: _large amount muscarine

Autonomic Blockers: 1/ competitive blockers 2/ Depolymerizing blockers

⭕️ Epinephrine acts better on beta-receptors whereas, norepinephrine acts better on alpha-recpeptors.

N.B: Certain organs are not supplied by the parasympathetic (although they supplied by the sympathetic); and therefore, they are do not have muscarinic receptors. These include ventricles of the heart, radial muscle of the iris & some blood vessels (of the skin, abdominal viscera and the kidney).

Noradrenaline receptors: 1/ Alpha receptors (a) Have many subtypes (a1& a2). Alpha 1 receptors (a1 Rs): a1 Rs are found in smooth muscle of many organs (e..g., blood vessels. urethral sphincter & dilator pupillae muscle). They induce induce smooth muscle contraction resulting in many effects (e…

Acetylcholine receptors: 1- Nicotinic receptors (N1 & N2) - Described as nicotinic because they can be stimulated by small amount enicotine (the chemical substance found in tobacco). - They act as ion channels (their stimulation results in Na+ influx & K+ efflux) - They are found at the followi…

Other neurotransmitter: Substance P: released by some GIT postganglionic parasympathetic neurons. Nitric oxide (NO); released by some GlT postganglionic parasympathetice. Dopamine: Released by some interneurons in sympathetic ganglial. GnRH: Released by some preganglionic neurons. Co-transmi…

Hydrolysed by : 1/Monoamine oxidase MAO 2/Catechol_O_methyl_transferase COMT Metabolites of catecholamines → vanillylmandelic acid VMA (urine )+ Metaepinephrine + Metanephrine High excretion of VMA indicates hyper production of catecholamines due to pheochromocytoma (tumor in adrenal medulla)

Post = noradrenaline except: Sweet glads arterioles of skeletal muscles Pilo_erector muscles

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The oxygen debt mechanism : Is extra amount of oxygen consumed after exercise. 1/ It takes oxygen from myoglobin. 2/ It metabolizes glucose anaerobically to lactic acid to synthesize ATP. 3/ It uses phosphorylcreatine to synthesize. ⭕️ After exercise extra amount of oxygen (oxygen debt) is provide…

TYPES OF CONTRACTION: 1/ Isometric ("same measure" or length): Contraction without an appreciable decrease in the length of the whole muscle. In isometric contraction there is Increasing tone. Isometric = No change in length + Increased tension 2/ Isotonic ("same tension"). Contraction against …

Muscle fatigue - It is the reduction in muscle ability to generate force. - It usually follows high intensity or prolonged low/ moderate intensity exercise. It also occurs easily when there is an interruption of the muscle blood flow. - It can be explained by: ■ Depletion of energy stores in th…