DIFFERENCES BETWEEN SKELETAL, CARDIAC & SMOOTH MUSCLES.pptx

DIFFERENCES BETWEEN SKELETAL, CARDIAC & SMOOTH MUSCLES.pptx

1. DIFFERTIATING FEATURES OF SKELETAL, CARDIAC & SMOOTH MUSCLES

2. DIFFERENCES BETWEEN SKELETAL, CARDIAC & SMOOTH MUCLES CHARACTERS SKELETAL CARDIAC SMOOTH Location Fixed to bony skeleton Heart only Hollow viscera, blood vessels, skin piloerector muscles, iris & ciliary muscles of eye Striations striated striated Non striated Size & shape Multinucleated, cylindrical Single nucleus, short cylindrical & branched Spindle shape & single nucleus Syncytium Non syncytial Functional syncytium Syncytial (single unit) & non syncytial (multiunit) Sarcoplasmic reticulum highly developed moderately developed Poorly developed Sarcotubular system Present at A-I junction (2 per cell) Present at Z lines Present but not so characteristic

3. CHARACTERS SKELETAL CARDIAC SMOOTH Resting membrane potential -90 mv -80mv -55mv unstable Action potential Rapid depolarization & repolarization (total duration 30-40 msec) Rapid depolarization & slow repolarization with plateau (total duration 250-300 msec) Variable Absolute refractory period 1-3 msec 180-200 msec Not defined Fatiguability Liable to fatigue Never fatigued Present Excitation contraction coupling Rapid process (10 msec) Rapid (<10 msec) very slow process All or none law Applicable for single fiber Applicable for whole of atria or ventricles Applicable for single fiber Property of plasticity -- -- present

4. CHARACTERS SKELETAL CARDIAC SMOOTH Post synaptic receptors Nicotinic receptors at NMJ Adrenergic & Muscarinic receptors on the cell surface Adrenergic & Muscarinic receptors on the cell surface Neurotransmitters Ach Epi & NE Ach, epi, NE Origin of Ca++ SR(sarcoplasmic reticulum) SR & ECF(extracellular fluid) SR & ECF Blood supply 3-4 ml/100gm/min with moderate oxygen consumption 80ml/100gm/min with high O2 consumption 1.4 ml/100gm/min with less oxygen consumption Nerve supply Somatic nerves Sympathetic & para sympathetic Sympathetic & para sympathetic Control Voluntary Involuntary Involuntary Energy utilization >60% from carbohydrates, 20% from fats & 20% from proteins 60% from fats, 35% from carbohydrates & 5% from ketones & amino acids Mainly provided by fats

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