Exam 3 - Nervous System Flashcards
What are the main functions of the nervous system?
- sensory input
- integration
- motor output
What is involved in sensory input?
- receptors respond to external/internal stimuli
- relay message to brain and spinal cord
What is involved in integration?
brain and spinal cord integrate data and send nerve pulses back out
What is involved in motor output?
impulses go to effectors, such as the muscles and glands
What are the characteristics of the central nervous system?
- consists of brain and spinal cord enclosed in boy coverings
- serves as an integration center
What are the characteristics of the peripheral nervous system?
- consists of nerves and ganglions
- serves to deliver and send information to and from CNS
What are the characteristics of afferent/sensory neurons?
- specialized neurons to detect stimuli
- starts in PNS and travels to CNS
- functions to deliver information about environment or condition of the body to the CNS
What are the characteristics of interneurons?
- located in CNS
- functions to receive and integrate information
What are the characteristics of efferent/motor neurons?
-send signals from the CNS to effectors of the PNS, such as muscles, organs, and glands
What are the two types of motor neurons, and when do they predominate?
- sympathetic neurons: during fight or flight
- parasympathetic neurons: during relaxtation
How do hormones and neurons control the post-absorptive state?
- sympathetic nervous system interacts with several hormones to control events of post-absorptive state
- post-absorptive state is triggered by reduced insulin release as blood glucose levels drop
Why is the lipid bilayer membrane surrounding a neuron impermeable to ions?
- ions must pass through channels to enter or exit the neuron
- some channels require activation to open and allow passage of ions
- these ion channels are sensitive to the environment and can change their shape
What are the characteristics of voltage-gated ion channels?
- ion channels that change their structure in response to voltage changes
- structural changes in protein allow or prevent ion movement
What are the characteristics of ligand-gated ion channels?
- ion channels that change structure in response to a chemical binding to a receptor
- typical ligands include neurotransmitters
What are the characteristics of leak channels?
- generally open, but may open and close at random
- no actual event that opens the channel; rather, an intrinsic rate of switching between the open and closed states
What is the resting membrane potential of a neuron?
approximately -70 millivolts
What is depolarization?
when the charges inside and outside the cell become less separated
What is hyperpolarization?
when the charges inside and outside the cell become more separated
What repolarization?
when charges begin to move, leading neurons from a depolarized to a polarized state
What structure is needed to return neuron cells to the original ionic conditions?
Na+/K+ pump
How do Na+ and K+ concentrations look for a typical cell at resting membrane potential?
- Na+ conc. is higher outside the cell than inside
- K+ conc. is higher inside the cell than outside
Which ion has more leak channels - K+ or Na+?
K+
What are local/action potentials?
changes in RMP created by the movement of ions
How do local potentials and action potentials differ?
- local potentials occur when changes in RMP allow ions to move at the dendrites
- action potentials occur when local potentials are large enough for ion movement to occur along the axons
