Biology Final Exam (100)

Biology Final Exam (100) - The sex organs produce sperm or...

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The sex organs produce sperm or eggs, but they are also important endocrine glands. The testes secrete several steroid hormones, including testosterone. Ovaries secrete two types of steroid hormones: estrogen and progesterone. The sex organs play a key role in puberty. Puberty is a phase in life during which the reproductive systems of both sexes become mature and functional. CH. 38 The Nervous System and the Senses Information is transmitted through the nervous system in the form of nerve impulses or action potentials. These are all or nothing events. The ability to distinguish any type of stimulus depends on the part of the brain that receives the signal. What matters is where impulses go, not what triggers them. Action potentials that reach the brain via sensory neurons are called sensations. Once the brain is aware of sensations, it interprets them, giving us the perception of the stimuli. Perceptions such as colors, smells, sounds, and tastes, are constructions of the brain and do not exist outside of it. (different animals perceive the world differently than we do). Neurons are nerve cells. Each one must perform four specialized functions: 1. Receive information from the internal or external environment or from other neurons. (Dendrite the site where information is received) 2. Integrate the information it receives and produce an appropriate output signal. (Takes place inside cell body) 3. Conduct the signal to its terminal ending, which may be some distance away. 4. Transmit the signal to other nerve cells or to glands or muscles. (Happens between the synaptic terminals and the dendrites) Typical vertebrate neurons have four structural regions that carry out the various functions. They are: dendrites, the cell body, the axon, and the synaptic terminals. Dendrites receive signals. They can respond to chemical neurotransmitters released by other neurons. Electrical signals travel down the dendrites and converge on the neuron’s cell body, which serves as an integration center. If the signal is important enough, the neuron will produce an action potential. An action potential is an electrical output signal.
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Axons are long, thin fibers that extend out from the neuron. They can extend from the spinal cord to the toes, making neurons the longest cells in the body. They conduct the electrical signal. Axons are usually bundled together into nerves. The transmission of the signal to other cells occurs at synaptic terminals. Synaptic terminals are swellings at the branched endings of axons. Most synaptic terminals contain a neurotransmitter, which is a specific chemical released in response to an action potential reaching the terminal. The synaptic terminals of one neuron may communicate with a gland, a muscle cell, or the dendrites or cell body of a second neuron. The output of the first cell becomes the input to the second cell. The site at which
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This note was uploaded on 06/11/2008 for the course BIOL 1103 taught by Professor Armstrong during the Spring '07 term at University of Georgia Athens.

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Biology Final Exam (100) - The sex organs produce sperm or...

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