Question

Notes on neural control and coordination nevous system and condyvtion of nerve impluse

Answer 1

In man and other vertebrates, the physiological functions are coordinated by both the nervous and endocrine systems.

The system that receives the stimulus transmits it to other parts of the body and the corresponding effect shown is known as a Nervous System.  The nervous system performs three basic functions; receives stimuli through sensory neurons from internal and external environment and passes to the brain; where the input stimuli is processed and then response is given back to the body parts through motor neurons.

Nervous system in Invertebrates:

Ø  In primitive invertebrates like Sponges lack neurons

Ø  In Hydra, all neurons are linked to one another, forming a nerve net called plexus between the outer epidermis and inner gastrodermis.

Ø  In Planaria, two nerve cords that converge to form a rudimentary brain.

Ø  In Earthworm, has a single ventral nerve cord and paired segmental ganglia. The ganglia give rise to the segmental

Nervous System of Human:

The human nervous system consists of the following two major parts;

Central Nervous System (CNS): It Comprises of Brain and Spinal cord. It is the site of information processing unit.Peripheral Nervous System (PNS):  The nerves which arise from the CNS (brain and spinal cord).a)      Somatic Nervous System (Voluntary): It consists of sensory / afferent neurons which transmit impulse from the receptors to the CNS; and the motor / efferent neurons, which transmit response from the CNS to the effector (skeletal muscles).

b)      Autonomic Nervous System (Involuntary):  It stimulates the glands and the other muscles of the body and responsible for the involuntary actions.
c)       Neuroendocrine System: It consists of a net work of endocrine glands and their hormonal production is controlled by CNS. 
Nuclei:  The cluster / group of neurons in CNS.
Ganglia: The cluster / group of neurons in PNS. 
Nerve tracts: The bundles of nerve fibres in CNS 
Nerves: A bundles of nerve fibres in the PNS.
A typical Nerve:

A typical nerve has a tough outer covering called Epineurium. Inside the epineurium, axons of nerve cells form bundles called fascicle. Each fascicle is wrapped with a layer called perineurium.

Multipolar nerve cells have many short dendrites and one long axon, eg., in cerebral cortex. A bipolar nerve cell has a long axon extending on either side of the cell body, eg.in retina.  Pseudounipolar nerve cells have cell body in a side branch of the main

Synapse:

The functional junction between two neurons, the axon of a neuron and the dendron/dendrite of another neuron.
Types of synapse:

There are mainly two types of synapses based on the nature of transfer of information across the synapse; a) electrical and b) chemical synapses.
a)      In electrical synapses, the cells are separated by a gap of 0.2nm synaptic cleft, so an action potential can sufficiently depolarize the postsynaptic membrane.

b)      In chemical synapses, synaptic cleft gap is greater and neurotransmitter substance responsible for the transmission of nerve impulse across the synapse.

Conduction of Nerve impulse across synapse:

In a synapse, there is a narrow fluid-filled gap of 10-20 nm, called synaptic cleft.  The nerve terminal has a bulbous expansion called synaptic knob or synaptic button.  In the cytoplasm of the synaptic knob, numerous tiny membrane-bound synaptic vesicles are present.  These synaptic vesicles contain as many as 10,000 molecules of the neurotransmitter.  When a nerve impulse reaches the presynaptic membrane, the voltage-gated calcium channels concentrated in the synapse, open.  Calcium ions from the fluid in the synapse diffuse into the synaptic button and stimulate the vesicles to move to the terminal membrane, fuse with it and then rupture to release the neurotransmitter.  The neurotransmitters quickly diffuse to the other side of the gap, combine with specific receptor molecules of the other nerve cell and cause sparking a second electrical current, passing its signal.

Structure of Human Brain:

Human brain is covered by a tough tissue covering called meninges.  The three layers of meninges are the outer most duramater, middle arachnoid membrane and inner pia mater.  A deep cleft called longitudinal fissure divides the brain the subarachnoid space.
Cerebrospinal fluid has the following functions:
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Answer 2

Answer:

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In our body the neural system and the endocrine system jointly coordinate and integrate all the activities of the organs so that they function in a synchronised fashion. The neural system provides an organised network of point-to-point connections for a quick coordination