The nervous system regulates most body systems using direct connections called nerves. It enables you to sense and respond to stimuli The basic function of nervous system are: Receive sensory input internal or external Integrate the input Responding to internal and external stimuli Nervous System
The nervous system is composed of the following organs and tissues: 1. Brain 2. Spinal cord 3. Sense organs (eyes, ears, etc.) 4. nerves
Neuron Nervous tissue is composed of 2 main cell types: neuron & glial cells The neuron is the functional unit of the nervous system All neurons have three parts: Dendrites receive information from another cell and transmit the message to the cell body cell body contains the nucleus, mitochondria and other organelles typical of eukaryotic cells Axon conducts messages away from the cell body
Three types of neurons : Sensory neurons -long dendrite, short axon and carry messages from sensory receptors to the central nervous system Motor neuron -long axon, short dendrite and transmit messages from the central nervous system to the muscles (or to glands) Interneuron -found only in the central nervous system where they connect neuron to neuron
Schwann cells Serve as supportive, nutritive, and service facilities for neurons The gap between Schwann cells is known as the node of Ranvier (serve as point along the neuron for generating a signal) Signal jumping from node to node travel hundreds of times faster than signals traveling along the surface of the axon
The Nerve Message An unequal distribution of ions and electrical charges between the two sides of the membrane. Outside-positive, inside-negative charge. Passage of ions across the cell membrane passed the electrical charge along the cell. The action potential begins at one spot on the membrane, but spread to adjacent area of the membrane, propagating the message along the length of the cell membrane.
Synapses The junction between a nerve cell and another cell is called a synapse The space between two cell is known as the synaptic cleft To cross the synaptic cleft requires the action of neurotransmitters Neurotransmitters are stored in small synaptic vesicles clustered at the tip of the axon Arrival of the action potential causes some of the vesicles to move to the end of the axon and discharge their content into the synaptic cleft Bind to receptor molecules on the next cell, prompting transmission of the message along the cell membrane
Nervous system can be divided into two system; 1. Central Nervous System (CNS) Brain Spinal cord 2. Peripheral Nervous System (PNS) The somatic nervous system The autonomic nervous system Sympathetic systems Parasympathetic systems
A) CNS: Brain Main control center - homeostasis, thoughts, emotions. Cerebrum-conscious activity, memory, language and senses are processed here Cerebellum-balance, posture, and coordination Brain stem which has the following parts and functions: medulla oblongata -controls involuntary activities Pons -pathway connecting upper functions of the brain with the rest of the spinal cord Midbrain -location of: Thalamus-receives all sensory information Hypothalamus-the seat of homeostasis and control over the endocrine system.
A) CNS: Spinal cord Connects the brain to the rest of the body, sending and receiving messages. Runs along the dorsal side of the body and links the body to the rest of the body Vertebrates have their spinal cord encased in a series of (usually) bony vertebrae that comprise the vertebral column The gray matter -cells bodies and dendrites The white matter -bundles of interneuronal axons
B)PNS:Somatic Nervous System Consists of bundles of sensory and motor neurons relaying information between the central nervous system and muscles or sensory organs.
B)PNS:Autonomic Nervous System regulates unconscious bodily functions such as: movement of food through your intestines secretion of hormones and digestive enzymes breathing and heart rate reflexes Has 2 subsystems: Sympathetic Parasympathetic
1. The sympathetic nervous system It produces heightened alertness -- increase in heart rate, blood flow is directed to arms and legs and away from the body core and digestion. 2. The parasympathetic reduces heart rate and increases blood to internal organs such as digestion.
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