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The Nervous System
Transcript of The Nervous System
-When a neuron is at rest (its resting potential), it is polarized, with a negative charge inside the cell membrane and a positive charge outside.
-When a neuron is stimulated by another neuron, its cell membrane is either depolarized or hyperpolarized.
-The spreading voltage changes along the cell membrane that occur as one neuron is excited by other neurons are called graded potentials.
-If the cell membrane is depolarized by enough graded potentials, the neuron will fire. This process is called an action potential, or nerve impulse.
-neurotransmitters are chemicals that transmit information from one neuron to another
-receptors are protein molecules in the postsynaptic membrane that pick up neurotransmitters
Neuroscience and Psychology
-Neuro-reductionism: are you your brain?
-What about the body?
-hindbrain: above the spinal cord; the most primitive but essential part of our nervous system. Sustains life by controlling the supply of air and blood to cells in the body, regulates arousal level.
-midbrain: above the hindbrain involved in some auditory and visual functions, movement, and conscious arousal and activation
-the subcortical forebrain helps regulate a wide range of behaviors, including eating, sleeping, sexual activity, and emotional experience. Processes incoming sensory information and transmits this information to higher brain centers.
-the cerebral cortex includes primary areas, which usually process raw sensory data (except in the frontal lobes), and association areas, which are involved in complex mental processes such as perception and thinking. The cortex consists of two hemispheres, each of which has four lobes.
-The occipital lobes are involved in vision.
-The parietal lobes are involved in the sense of touch, perception of movement, and location of objects in space.
-The frontal lobes serve a variety of functions, such as coordinating and initiating movement, attention, planning, social skills, abstract thinking, memory, and aspects of personality.
-The temporal lobes are important in hearing, language, and recognizing objects by sight.
-some psychological functions are lateralized, or processed primarily by one hemisphere: in general, the left hemisphere is more verbal and analytic, and the right is specialized for nonlinguistic functions.
The nervous system is the interacting network of nerve cells that underlies all psychological activity
The fundamental unit of the nervous system is the nerve cell or neuron,85bn, specialized for electrical and chemical communication
-sensory neurons- transmit information from sensory cells in the body, called receptors, to the brain; also called afferent neurons
-motor neurons- transmit commands from the brain to the glands or musculature of the body, typically through the spinal
cord; also called efferent neurons
-interneurons connect other neurons to each other; found only in the brain and spinal cord
Central and Peripheral
-central nervous system (CNS): directs psychological and basic life processes; responds to stimuli.
-the brain: directs psychological activity; processes information; maintains life supports.
-spinal cord: receives sensory input; sends information to the brain; responds with motor output.
-peripheral nervous system (PNS): a
component of the nervous system that includes neurons that travel to and from the central nervous system; includes
-the somatic nervous system: conveys sensory information to the central nervous system and
sends motor messages to muscles.
-the autonomic nervous system: serves basic life functions, such as beating of the heart and
response to stress.
-sympathetic nervous system: readies the body in response to threat; activates the organism.
-parasympathetic nervous system: calms the body down; maintains energy.
The Nervous System
The Anatomy of a Neuron
-dendrites: branchlike extensions of the neuron that receive information from other cells
-cell body: the part of the neuron that includes a nucleus containing the genetic material of the cell (the chromosomes) as well as other microstructures vital to cell functioning
-axon: the long extension from the cell body of a neuron through which electrical impulses pass
-myelin sheath: a tight coat of cells composed primarily of lipids, which serves to isolate the axon from chemical or physical stimuli that might interfere with the transmission of nerve impulses and speeds neural transmission
-terminal buttons: structures at the end of the neuron that receive nerve impulses from the axon and transmit signals to adjacent cells
-synapse: the place at which the transmission of information between neurons occurs