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2 organ systems dedicated to maintaining internal coordination
- 1. Endocrine System
- 2. Nervous System
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Function of the Endocrine System
Communicates by means of chemical messengers (hormones) secreted in the blood
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Function of the Nervous System
employs electricsl and chemical means to send messages very quickly from cell to cell
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What are the 2 systems associated with the nervous System?
- 1. Central nervous System
- 2. Peripheral Nervous System
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What does the CNS consists of?
Brain and Spinal Cord
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What does the PNS consist of
all the Nervos system except the CNS components.
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What is the PNS copmposed of
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Define Nerve
abundle of nerve fibers (axons) wrapped in fibrous connective tissue
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Where do nerves emerge from?
the foramina of the skull a nd vertebral column
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What is the function of a nerve?
To carry signals to and from other organs of the body
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Define Ganglion
a knotlike swelling in a nerve where the cell bodies of neurons are concentrated
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What are the Divisions of the PNS and their functions?
- 1.Sensory (afferent) division- carries sensorgy signals from various receptors (sense organs and sensory nerve endings) to the CNS
- This is the Pathway that informs the CNS of stimuli within and around the body
- 2. Motor (efferent) division-carries signals from the CNS to gland and muscle cells that carry out the bodys responses
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What are the divisions of the Sensory (afferent) divison and their function
1. Somatic sensory division- carries signals from receptors in the skin, muscles, bones, and joints
2. Visceral Sensory Division-carries signals mainly from the viscera of the thoracic and abdominal cavities
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What are effectors?
Cells and organs that respond to commands from the nervous system
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What are the divisions of the Motor (efferent) neurons and their functions?
- 1. Somatic Motor Division-carries signals to the skeletal muscles
- -Produce involuntary muscle contractions called somatic reflexes
- 2.Visceral motor division (autonomic nervous system)-carries signals to glands, caridac musle, and smooth muscle
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What are the responses of the autonomic nervous system and its effectors
Visceral reflexes
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Divisions of the ANS and their functions
- 1.Sympathetic Division- arouse the body for action
- ex. accelerating the heartbeat, inhibiting digestion
- 2.Parasympathetic Division-tends to have a calming effect
- ex. slowing down heartbeat and stimulating digestion
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The communicative role of the nervous system is carried out by???
Nerve cells or neurons
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Nerve Cell Properties
- 1.Excitability (irritability)-all cells are excitable; they respond to enviornmental changes called stimuli
- 2.Conductivity-respond to stimuli by producing electrical signals that are quickly conducted to other cells at distant locations
- 3.Secretion-when the electrical signal reaches the end of nerve fibers, the neuron sercreta a neurotransmitter wtbhat crosses the gap and stimulates the next cell
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What are the Functional classes of neurons
- 1.Sensory (afferent) neuron-specialized to detect stimuli, such as light, heat, pressure, and chemicals, and transmit them to the CNS
- 2.Interneurons (association)neurons-lie within the CNS. Process, store, and retrieve information and "make decisions that determine how the body responds to stimuli
- 3.Moto(efferent) neurons-send signals predominantly to muscle and gland cells
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