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2 organ systems dedicated to maintaining internal coordination
- 1. Endocrine System
- 2. Nervous System
Function of the Endocrine System
Communicates by means of chemical messengers (hormones) secreted in the blood
Function of the Nervous System
employs electricsl and chemical means to send messages very quickly from cell to cell
What are the 2 systems associated with the nervous System?
- 1. Central nervous System
- 2. Peripheral Nervous System
What does the CNS consists of?
Brain and Spinal Cord
What does the PNS consist of
all the Nervos system except the CNS components.
What is the PNS copmposed of
abundle of nerve fibers (axons) wrapped in fibrous connective tissue
Where do nerves emerge from?
the foramina of the skull a nd vertebral column
What is the function of a nerve?
To carry signals to and from other organs of the body
a knotlike swelling in a nerve where the cell bodies of neurons are concentrated
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
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
What are effectors?
Cells and organs that respond to commands from the nervous system
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
What are the responses of the autonomic nervous system and its effectors
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
The communicative role of the nervous system is carried out by???
Nerve cells or neurons
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
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