Control of Involuntary Muscle

Cardiac muscle and smooth muscle function involuntarily-beyond our conscious control. There is smooth muscle in organs of the digestive, respiratory, circulatory and urinogenital systems, while cardiac muscle is found exclusively in the heart. These muscles are controlled by the autonomic nervous system, which is composed of two opposing divisions, the sympathetic, shown in red, and the parasympathetic, shown in blue. Sympathetic nerves leaving the spinal cord lead first to nearby nerve chains before connecting the body organs, where they stimulate muscle activity. In the parasympathetic division, nerves pass from the spinal cord directly to the organs and have the opposite effect-decreasing muscle activity. This dual mechanism provides a method for maintaining the activity of the muscles within controlled limits. The sympathetic system is dominant in situations requiring rapid action. When, for example, danger threatens there is an increase in heart rate, respiration rate, blood pressure and sweat gland activity. The parasympathetic system is dominant while the body is resting-usually during sleep, when the heart rate is slower and respiration is deeper and more regular.[By dizzo95 August 03, 2007]

Nervous System, spinal cord,neurons,membrance potential,action potential ,Neuromuscular Junction and drugs effect.

Nervous system
How thThe nervous system is a complex network of nerve cells and nerve fibers spread throughout the body. Its function is to interpret, store, and respond to information received from inside and outside. The central nervous system or CNS, consists of the brain and spinal cord and is responsible for processing information gathered from the rest of the nerves and transmitting instructions to the body. Messages passing to and from the CNS are carried by the nerves of the peripheral nervous system. This system includes twelve pairs of cranial nerves and thirty-one pairs of spinal nerves. The cranial nerves and the spinal nerves control voluntary movements and sensations. The autonomic nervous system, consisting of sympathetic and parasympathetic nerve fibers, controls such involuntary body functions as the heartbeat. e Body Works : The Anatomy of the Central Nervous Syst
Spinal Cord xs1 - Reflex Pathway

Amazing Brain!

Neurons-How they work-Human Brain

Action potential
Membrane Potential
Function of the Neuromuscular Junction
Calcium, Myosin, Muscle Contraction
Actin/Myosin Movie 1
Actin/Myosin Movie 2

ANATOMY OF A NERVE,NEUROTRANSMITTERS AND NEURONS

More than ten thousand million nerve cells and their fibers, or axons, make up the nervous system. The axons are grouped together in nerve trunks containing sensory fibers, which conduct information from the sensory organs to the central nervous system, and motor fibers, which carry information to the central nervous system of the body. The nerve fibers which carry information quickly are enclosed in a thick sheath made of the fatty substance myelin. They are called myelinated nerve fibers. The myelinated sheath has regular indentations along its length called the nodes of Ranvier. The nonmyelinated nerve fibers, which carry information slowly, are grouped together and enclosed in a single sheath.

The anatomy of a nerve includes: the cell body, which is composed of cytoplasm and contains the cell nucleus; the nucleus, which contains the information needed to control the activity of the neuron; the dendrites, outgrowths of the cell body to which and from which they conduct impulses; the epineurium, a fibrous sheath that surrounds the whole nerve; the perineurium, the connective tissue sheath that surrounds bundles of nerve fibers; the endoneurium, the fine sheath of connective tissue around each nerve bundle; the axon, the extended fiber of the nerve cell which carries impulses to and from the cell body; the fatty myelin sheath, the insulating coat that separates the axon in a nerve bundle; the Schwann cell nucleus, the mechanism responsible for the production and maintenance of the myelin sheath and the Nodes of Ranvier, constrictions in the myelin sheath. .[By dizzo95 August 03, 2007]
NEUROTRANSMITTERS AND NEURONS