Presentation on theme: "What does a Nervous System do for you? Detect (sense) changes in the environment (light, sound, smell, taste, touch, heat) Detect (sense) changes in the."— Presentation transcript:
What does a Nervous System do for you? Detect (sense) changes in the environment (light, sound, smell, taste, touch, heat) Detect (sense) changes in the internal environment (blood pressure, blood chemistry, temperature, etc.) Integrate and evaluate sensory information Plan, problem-solve, predict Store and retrieve information (memory) Control contractions of skeletal muscles (movements / behavior) Control internal glands, muscles (heart rate, hormone secretions, metabolism )
The Nervous System Organization Central Nervous System - completely surrounded by bone - suspended in cerebrospinal fluid - covered by meninges - protected by “blood-brain barrier” Peripheral Nervous System - nerves leaving and entering the CNS - motor nerves = control muscles and glands - sensory nerves = transmit information to the CNS from sensory receptors. - emerge from cranial and spinal nerves
How the Peripheral and Central Nervous Systems Interact
Cells of The Nervous System Neurons - Detect physical and chemical changes in their environment -Transmit electric impulses (action potentials) from one end to the other (one cell may be more than 3 feet long) - Communicates with other neurons, muscles and glands using chemicals called neurotransmitters. Neuroglia (supporting cells) - Provide physical support to neurons - Provide electrical insulation to neurons - May be involved in processes such as memory. Two neurons releasing neurotransmitters that act on a third neuron. The first two neurons could be in the Central Nervous System, and the third might be a motor neuron leading out to a muscle or gland.
Motor neurons have their cell bodies in the spinal cord, but their axons extend outward into the body to stimulate muscles or glands. Spinal cord smear Dendrites Microglia
Terminal of a motor neuron axon - where the neuron stimulates the muscle cell to contract. Muscle cell Axon terminus Axon Neuromuscular junction (motor end plate)
Pyramidal cells (neurons) of the cerebral cortex
Action potentials are tiny electric impulses produced by neurons. They are used for transmitting information away from the cell body and toward the axon terminals. When they reach the axon terminals, the action potentials cause the release of neurotransmitter from the terminals. When a neuron is stimulated, not every stimulus will cause an action potential. The stimulus must be sufficient to cause the neuron to reach threshold. Only then will an action potential be produced.
The Na/K ATPase pumps set up the necessary conditions across the membrane of a neuron so that the neuron will be capable of producing an action potential. A.High Na outside (3 ions pumped out) B.High K inside (2 ions pumped in) C.Produces a transmembrane potential (-70 mV)