BPK 105 Study Guide - Midterm Guide: Axon Hillock, Autonomic Nervous System, Sensory System
27 Apr 2018
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Module 4 - Study Guide
Divisions and Functions of the Nervous System
- The PNS collects sensory information (sensory division) from throughout the body and
sends it to the CNS for integration (decision-making based on a large number of inputs).
Some decisions such as spinal reflexes are made in the spinal cord, while other, more
complex decisions are made in the brain.
- The CNS also sends signals out to the periphery to affect the activity of muscles
(somatic motor division) and other organs and glands (autonomic nervous system).
- The sensory division detects our internal and external environments, the signals are
processed in central NS and various systems are stimulated or inhibited through the
autonomic and somatic divisions in an effort to achieve homeostasis.
Neurons and Glial Cells
- Neurons = the smallest functional unit of the nervous system, they receive stimuli,
integrate it, conduct action potentials and send signals to other neurons and effectors
organs.
- multi-polar and bipolar neurons: several dendrites, cytoplasm extensions that receive
information, associated with each cell. Multiple dendrites allow communication with many
other neurons at once.
- Communication from other neurons, through neurotransmitters, can be stimulatory or
inhibitory by opening or closing of chemically gated ion channels.
- When these local currents reach the axon hillock, the site where the axon leaves cell
body, the excitations (+) and inhibitions (-) are added together.
- If there is a net depolarization above threshold, many sodium channels will open and an
action potential will start down the single axon. An action potential will eventually reach a
new synapse, furthering the communication between neurons or stimulating an effector
cell such as a muscle cell or glandular cell.
- several support cells in the Nervous System that offer protection in the from physical
blood brain barrier (Astrocytes) and immunity (Microglia). Other glial cells form myelin
sheaths to increase the speed of signal conduction in axons (Oligodendrocytes (CNS)
and Schwann cells (PNS)).
Electrical Signals
Resting Membrane Potential
- Unstimulated cells have a resting membrane potential (charge) that results from a higher
concentration of K+ (potassium) ions inside the cell and a higher concentration of
Na+(sodium) ions outside the cell.
Document Summary
The pns collects sensory information (sensory division) from throughout the body and sends it to the cns for integration (decision-making based on a large number of inputs). Some decisions such as spinal reflexes are made in the spinal cord, while other, more complex decisions are made in the brain. The cns also sends signals out to the periphery to affect the activity of muscles (somatic motor division) and other organs and glands (autonomic nervous system). The sensory division detects our internal and external environments, the signals are processed in central ns and various systems are stimulated or inhibited through the autonomic and somatic divisions in an effort to achieve homeostasis. Neurons = the smallest functional unit of the nervous system, they receive stimuli, integrate it, conduct action potentials and send signals to other neurons and effectors organs. Multi-polar and bipolar neurons: several dendrites, cytoplasm extensions that receive information, associated with each cell.
