Nervous System
Functions of Nervous System The nervous system is the major controlling, regulatory, and communicating system in the body. It is the center of all mental activity including thought, learning, and memory. Together with the endocrine system, the nervous system is responsible for regulating and maintaining homeostasis. Through its receptors, the nervous system keeps us in touch with our environment, both external and internal.
Central Nervous System (CNS) Includes Brain and Spinal Cord Responsible for integrating motor and sensory information Seat of intelligence memory and emotion
Peripheral Nervous System (PNS) Includes all nerve tissue outside the CNS – Afferent division – brings sensory information TO CNS – Efferent division – sends commands FROM CNS to muscles and glands
Somatic Nervous System (SNS) Part of the efferent system of the PNS Voluntary control over skeletal muscles A.Central nervous system B. Peripheral nervous system B1. Somatic nervous system B2. Autonomic nervous system Diagram :
Autonomic nervous system (ANS) Part of the PNS Automatic regulation of smooth muscle, cardiac muscle and gland activity or secretions
Cellular Organization in Neural Tissue
Neuron with synapse
Classes of Neurons
Neuron transmissionNeuron transmission – sending & receivingsending
Cellular Organization in Neural Tissue Neuroglia – Regulate environment around neuron – Provide support for neural tissue – Act as phagocytes – Aka glial cells – More numerous than neurons
Neuroglia, aka glial cells
Diagram pg 201 (black book) Interaction of neurons and glial cells
Neuroglia- Astrocytes Most numerous Maintain the blood brain barrier Repair damaged neural tissue
Neuroglia- oligodendrocytes Create myelin Improves the speed of impulse conduction on an axon
Neuroglia- microglia Smallest and rarest Phagocytic white blood cells Protect neurons
Neuroglia- ependyma Produce cerebral spinal fluid (CSF)
Neuroglia- Schwann cells Most important glial cells Also create myelin
Neurotransmitters Chemical that send messages from neuron to neuron or from neuron to other tissues – Ach – stimulates muscle contraction – Norepinephrine – creates an excited state in the organism – Dopamine and serotonin – effects are inhibitory
Dopamine and Cocaine Cocaine is a mood- altering drug that interferes with normal transport of the neurotransmitter dopamine, which carries messages from neuron to neuron. When cocaine molecules block dopamine receptors, too much dopamine remains active in the synaptic gaps between neurons, creating feelings of excitement and euphoria.
Blood Brain Barrier Maintained by astrocytes Cause capillaries of CNS to become impermeable to many compounds Example: some antibiotics can not help heal brain infections because they can’t cross the barrier
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