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Questions and Answers
Nerves are stringlike bundles of axons and dendrites that come from the spinal cord and are held together by ______.
connective tissue
The Central Nervous System is made up of neurons located in the ______ and spinal cord.
brain
The resting membrane potential of a neuron is approximately ______ millivolts (mV).
-70
If the depolarization is strong enough to raise the membrane potential to around ______ mV, the threshold is reached.
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During depolarization, sodium ions rush into the neuron, causing rapid ______ of the membrane potential.
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After sodium channels close, ______ channels open, allowing potassium ions to flow out of the neuron.
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In some cases, potassium channels remain open briefly, causing hyperpolarization before returning to ______.
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Neurotransmitters are chemicals used for communication between neurons during mental or physical ______.
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Genes are chains of chemicals arranged like rungs on a twisting ______.
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A human brain weighs about ______ grams.
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Glial cells are the most numerous brain cells, about ______ billion.
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A neuron is a brain cell with two specialized ______ for receiving and transmitting signals.
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Dendrites are branchlike ______ that receive signals from other neurons.
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The axon is a single threadlike structure that carries signals ______ from the cell body.
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Presynaptic terminals look like tiny ______ that store neurotransmitters.
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The Peripheral Nervous System (PNS) consists of nerves located throughout the body except in the brain and ______.
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Study Notes
Overview of the Human Brain
- Genes consist of chemical chains that influence the development of the brain and body, with 20,000 to 25,000 identified.
- The mature human brain weighs approximately 1,350 grams and has a pinkish-white color, resembling firm JELL-O.
- Contains about 1 trillion cells and has three major divisions.
Key Cell Types in the Brain
- Glial Cells: Approximately 900 billion; provide structural support, insulation for neurons, and release chemicals that affect neuron growth.
- Neurons: About 100 billion; specialized cells designed for receiving and transmitting electrical signals.
Neuron Structure and Function
- Dendrites: Branched extensions from the cell body that receive signals from other cells.
- Soma (Cell Body): Egg-shaped structure that maintains neuron function and produces necessary chemicals.
- Axon: Long structure that transmits signals away from the cell body.
- Presynaptic Terminals (End Bulbs): Store neurotransmitters for communication with adjacent cells.
- Synapse: Microscopic gap (20-30 billionths of a meter) between neurons where signal transmission occurs.
Nervous System Components
- Peripheral Nervous System (PNS): Comprises nerves outside the brain and spinal cord, composed of bundled axons and dendrites; nerves can regenerate if damaged.
- Central Nervous System (CNS): Composed of neurons located in the brain and spinal cord.
Information Transmission in Neurons
- Resting Potential: Neurons maintain a stable membrane potential of about -70 mV; the inside is negatively charged due to potassium ions and negatively charged proteins.
- Threshold: If membrane potential reaches -55 mV, voltage-gated sodium channels open, initiating an action potential.
- Depolarization: Sodium ions influx leads to rapid membrane potential change, reaching +30 mV.
- Repolarization: Sodium channels close, potassium channels open to restore the negative potential.
- Hyperpolarization: Potassium efflux may overshoot, temporarily decreasing membrane potential below baseline.
- Refractory Period: A brief pause after neuron firing during which new action potentials cannot occur.
Neurotransmitters
- Approximately a dozen different chemicals vital for neuron communication that facilitate mental and physical activities.
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Description
Explore the fascinating structure and function of the human brain. This quiz covers essential concepts such as the types of cells in the brain, their roles, and the anatomy of neurons. Dive into the complexities of glial cells and neurons to enhance your understanding of brain development and operation.
