Ch. 31
collects information about the body’s internal and external environment processes and responds Messages allow organs to act together and react to conditions in the environment.
Brain and spinal cord Processes information Creates a response (that is delivered to the appropriate part of the body through the Peripheral Nervous System (PNS))
Draw and label the brain. Frontal lobe emotion touch, pressure vision Temporal lobe interpreting sounds coordination balance equilibrium Brain stem breathing, heartbeat, blood pressure
Nerves and supporting cells Collects information about the body’s internal and external environment
Impulses : messages carried by the nervous system Impulses are transmitted by cells called neurons.
Sensory neurons: carry impulses from the sense organs, ears/eyes, to the spinal cord and brain.
Motor neurons: carry impulses from the brain and spinal cord to muscles and glands.
Interneurons: process information from sensory neurons and send commands to other interneurons/motor neurons.
Cell body: largest part of a neuron that contains the nucleus and cytoplasm
Dendrites: short, branched, receive impulses from other neurons
Axon: long fiber that carries impulses away from the cell body
Myelin Sheath: insulating membrane that surrounds the axon
What roll does the myelin sheath serve? Myelin surrounds the axon, but it has gaps called nodes. When an impulse travels along an axon it jumps from node to node which allows it to travel faster. The myelin is like insulation.
Membrane Potential Slight difference in charge across membrane 1. Resting Potential Membrane potential is at rest 2. Action Potential Nerve impulse
Neurotransmitters Signal molecules Produced by neurons Many types with different actions ***nerve impulses cannot cross the synaptic cleft without neurotransmitters.
Connections between neurons Dendrite Axon Impulse Synapse Impulse Dendrite Axon
1. Neurotransmitters are released in vesicles through exocytosis. 2. They can either excite or inhibit the activity of the postsynaptic cell it binds too. 3. They do not remain in the synaptic cleft. They are either cleared or reabsorbed.
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Threshold: the minimum level of a stimulus that is required to cause an impulse in a neuron. Synapse: the point at which a neuron transfers an impulse to another cell. Neurotransmitters: chemicals that transmit an impulse across a synapse to another cell.
a. The axon terminals has vesicles containing chemicals called neurotransmitters. b. The chemicals are secreted into the gap between the two neurons.
The Central Nervous System
The brain is the control point of the CNS The 3 major areas of the brain are responsible for processing and relaying information: Cerebrum Cerebellum Brain stem
The brain’s main task is to process information. The spinal cord is the main communication link between the brain and the rest of body.
One of the neurotransmitters playing a major role in addiction is dopamine. Dopamine affects brain processes that control movement, emotional response, and ability to experience pleasure and pain.
Cocaine and other drugs of abuse can alter dopamine function. Drugs such as cocaine and amphetamine produce their effects by changing the flow of neurotransmitters.
Nearly every addictive substance affect brain synapses. The synapses use dopamine (neurotransmitter) The brain reacts to excessive dopamine levels by reducing the number of receptors for the neurotransmitter. Normal activities don’t produce the same response they once did.
Addicts feel depressed and sick without drugs. Because of fewer receptors, larger amounts of a certain substance are needed to produce the same high.
The Peripheral Nervous System
The PNS consists of all the nerves and associated cells that are NOT part of the brain/spinal cord The sensory division transmits impulses from sense organs to the CNS. The motor division transmits impulses from the CNS to the muscles and glands. mM