Nervous & Endocrine

Nervous & Endocrine - Nervous system is divided...

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Nervous system is divided into two parts: Central nervous system – brain and spinal cord Peripheral nervous system – afferent (sensory) and efferent neurons Sensory receptors throughout the body continuously monitor conditions in both the internal and external environments - Send information along afferent neurons to the CNS CNS – integrating center for neural reflexes - Assesses input from the PNS to determine whether or not a response is needed - If the CNS does need to respond, it sends output signals that travel through efferent neurons to the effector cells of the body. Motor neuron = efferent neuron - PNS is divided into somatic and autonomic nervous systems; Somatic motor neurons control skeletal muscles, whereas autonomic motor neurons control smooth and cardiac muscles, exocrine glands and some endocrine glands Autonomic neurons are further divided into sympathetic and parasympathetic branches - The ANS often controls the enteric nervous system . The CNS doesn’t necessarily need any input from the PNS to initiate activity - Examples: thinking and dreaming Dendrites receives an input signal from an adjacent neuron, which integrate the information through the cell body (which contains the nucleus ), and then propagates an action potential down the axon . Neuronal transmission is facilitated by the existence of myelin sheaths (because of salutatory conduction ). The output signals originate at the presynaptic axon terminal , where calcium is released into the presynaptic axon terminal and neurotransmitter is induced to assemble in vesicles. The vesicle is released via docking proteins into the synaptic cleft , and the neurotransmitter usually binds to postsynaptic membranes that have receptors for the receptors. It is important for enzymes to selectively reuptake the neurotransmitters so the postsynaptic cell is not constantly innervated. - The cell body is the “control point” of the entire neuron – much loss of sensation, or numbness/tingling is associated with degenerated parts of a neuron closely associated with the cell body - The dendrites serve to increase the surface area of a neuron to allow it to communicate with multiple other neurons . Interneurons – lie entirely within the CNS Efferent neurons usually look like the typical “model neuron” Sensory nerves – nerves carrying afferent signals (i.e. to the CNS) Motor nerves – nerves carrying efferent signals (i.e. away from the CNS)
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Many degenerative diseases are associated with the nervous system - Mental retardation, Alzheimer’s, etc. The axon terminal usually contain a lot of mitochondria - Why? There are many sodium/potassium-ATPase pumps here in order to facilitate signal transduction. We need energy in order for this process to occur.
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