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Click on a lesson name to select. Chapter 33 Nervous System Section 1: Structure of the Nervous System Section 2: Organization of the Nervous System Section 3: The Senses Section 4: Effects of Drugs
Transcript of Chapter 33 Nervous System - mscaron - home€¦ · · 2012-05-07Chapter 33 Nervous System Section...
Click on a lesson name to select.
Chapter 33 Nervous System
Section 1: Structure of the Nervous System
Section 2: Organization of the Nervous System
Section 3: The Senses
Section 4: Effects of Drugs
Neurons
Neurons are specialized nerve cells that help you gather information about your environment, interpret the information, and react to it.
33.1 Structure of the Nervous System Nervous System
Neurons consist of three main regions: the dendrites, a cell body, and an axon.
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Dendrites pass signals they receive on to the cell body in electrical impulses.
Nervous System
The axon passes those impulses on to the other neurons or muscles.
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There are three kinds of neurons: sensory neurons, interneurons, and motor neurons.
Nervous System
Sensory neurons send impulses from receptors in the skin and sense organs to the brain and spinal cord.
Interneurons carry impulses to motor organs.
33.1 Structure of the Nervous System Chapter 33
Nervous System
33.1 Structure of the Nervous System
Motor neurons carry impulses away from the brain and spinal cord to a gland or muscles, resulting in a secretion or movement.
The nerve impulse completes a reflex arc, or a nerve pathway that consists of a sensory neuron, an interneuron, and a motor neuron.
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A Nerve Impulse
Nervous System
Neurons at rest do not conduct impulses.
Sodium ions (Na+) collect on the outside of the cell membrane.
33.1 Structure of the Nervous System Chapter 33
Potassium ions (K+) collect on the inside of the cell membrane.
Nervous System
33.1 Structure of the Nervous System
Negatively charged proteins actively transport sodium ions out of the cell and potassium ions into the cell.
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An Action Potential
Nervous System
A nerve impulse is also known as an action potential.
The minimum stimulus to cause an action potential to be produced is called a threshold.
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The small gap between the axon of one neuron and the dendrite of another neuron is called a synapse.
Nervous System
An action potential is carried across these gaps by neurotransmitters.
The Synapse
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The nervous system consists of two major divisions: the central nervous system and the peripheral nervous system.
33.2 Organization of the Nervous System Nervous System Chapter 33
The Central Nervous System
Nervous System
The central nervous system (CNS) is made up mostly of interneurons.
Coordinates all of the body’s activities
Relays messages, processes information, and analyzes responses
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The Brain
Nervous System
The brain is sometimes called the control center of the entire body.
Divided into the cerebrum, the cerebellum, and the brain stem.
33.2 Organization of the Nervous System Chapter 33
The cerebrum is divided into two halves called the left and right hemispheres.
Nervous System
The functions of the brain include thought processes (learning), memory, language, speech, voluntary body movements, and sensory perception.
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The cerebellum controls balance, posture, and coordination.
Nervous System
The skeletal muscles are controlled to make your motor skills coordinated and smooth.
33.2 Organization of the Nervous System Chapter 33
The brain stem connects the brain and spinal cord and is composed of the medulla oblongata and the pons.
Nervous System
The medulla oblongata helps control breathing rate, heart rate, and blood pressure.
The pons also aids in breathing.
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The hypothalamus, located between the brain stem and the cerebrum, is essential for homeostasis.
Nervous System
Regulates body temperature, thirst, appetite, and water balance.
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The Spinal Cord
Nervous System
Nerve column that extends from the brain to the lower back.
Protected by the vertebrae
Processes reflexes
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The Peripheral Nervous System
Nervous System
A nerve is a bundle of axons and may contain sensory and motor neurons.
The peripheral nervous system (PNS) contains all the neurons that are not part of the central nervous system.
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The Somatic Nervous System
Nervous System
Nerves in the somatic nervous system relay information from external sensory receptors to the central nervous system, and motor nerves relay information from the central nervous system to skeletal muscles.
Voluntary movements and reflexes are a part of the somatic nervous system.
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The Autonomic Nervous System
Nervous System
The autonomic nervous system carries impulses from the central nervous system to the heart and other internal organs.
The body responds involuntarily, not under conscious control.
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There are two branches of the autonomic nervous system.
Nervous System
The sympathetic nervous system is most active in times of emergency or stress when the heart rate and breathing rate increase.
The parasympathetic nervous system is most active when the body is relaxed.
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Taste and Smell
Specialized neurons in your body enable you to taste, smell, hear, see, and touch, and to detect motion and temperature.
33.3 The Senses Nervous System
Taste buds detect combinations of chemicals that we identify as sweet, sour, salty, and bitter.
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Receptors associated with taste and smell are located in the mouth and nasal cavity.
Nervous System
33.3 The Senses
Signals from these receptors work together to create a combined effect in the brain.
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Sight
Light travels through the cornea and the pupil to the lens.
Nervous System
The lens focuses the image on the retina.
33.3 The Senses
Rods and cones in the retina provide light-sensitivity and information about color.
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Hearing
Nervous System
33.3 The Senses
Sound waves enter the auditory canal and cause a membrane, called the tympanum, at the end of the ear canal to vibrate.
These vibrations cause the cochlea to generate nerve impulses that are interpreted by the brain.
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Balance The semicircular canals, located in the
inner ear, transmit information about body position and balance to the brain.
Nervous System
33.3 The Senses Chapter 33
Touch
Many types of sensory receptors that respond to temperature, pressure, and pain are found in the epidermis and dermis layers of the skin.
Nervous System
33.3 The Senses Chapter 33
Which is not one of the main parts of a neuron?
A. axon B. cell body C. dendrites D. nucleus
Nervous System
Chapter Diagnostic Questions
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Another name for a nerve impulse is _______.
A. synapse B. threshold C. reflex arc D. action potential
Nervous System
Chapter Diagnostic Questions
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What occurs when a motor neuron synapses with a muscle cell?
A. muscle contracts B. muscle relaxes C. pain D. numbness
Nervous System
Chapter Diagnostic Questions
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What type of neuron begins a reflex arc?
A. interneuron B. motor neuron C. sensory neuron D. transmitter neuron
Nervous System
33.1 Formative Questions
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What is another name for nerve impulse?
A. synapsis B. threshold C. action potential D. neurotransmitter
Nervous System
33.1 Formative Questions
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Nervous System
Which is not part of the central nervous system?
A. brain B. spinal cord C. interneurons D. sensory neurons
33.2 Formative Questions
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Nervous System
What does the cerebrum regulate?
A. breathing and heart rates B. complex motor skills C. sleep, aggression, and fear D. voluntary body movements
33.2 Formative Questions
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Nervous System
True or False Some reflexes are processed only in the spinal cord and do not need input from the brain.
33.2 Formative Questions
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Nervous System
What is a nerve?
A. a bundle of axons B. a chain of neurons C. a sensory synapse D. a series of impulses
33.2 Formative Questions
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Nervous System
What part of the nervous system is usually under voluntary control?
A. autonomic nervous system B. somatic nervous system C. sympathetic nervous system D. parasympathetic nervous system
33.2 Formative Questions
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Nervous System
What are sensory receptors?
33.3 Formative Questions
A. cells that create action potentials and thresholds
B. localized areas of the central nervous system
C. chemicals that cross a synapse between two nerve cells
D. specialized neurons for detecting the world around you
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Nervous System
What is the function of the optic nerve?
A. It forms a visual image. B. It controls the muscles of the iris. C. It interprets light intensity and colors. D. It sends action potentials to the brain.
33.3 Formative Questions
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What carries signals from the axon of one neuron to the dendrite of another neuron?
Nervous System
A. interneurons B. ion channels C. neural nodes D. neurotransmitters
Standardized Test Practice
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