Chapter 35 - Nervous System Flashcards
What is homeostasis?
the process by which organisms keep internal conditions relatively constant despite changes in the external environments
What are neurons?
cells that transmit electrical signals (impulse)
What is the charge inside a neuron when it’s resting?
negative (K+)
What is the charge outside a neuron when it’s resting?
positive (Na+)
What happens during action potential?
At the front of the impulse, gates of the sodium (Na+) channels open, allowing Na+ to enter the neuron. The Na+ makes the neuron positive. As the impulse passes, gates within the potassium channels open, allowing K+ ions to flow out. This restores the negative charge of the neuron after the impulse.
What is threshold?
the minimum level of a stimulus that is required to activate a neuron (all or nothing)
How is homeostasis maintained?
feedback loops or inhibition
What is feedback inhibition?
process in which a stimulus produces a response that opposes the original stimulus (negative feedback) [heating system]
What are neurons?
cells that transmit electrical signals (impulse)
What is resting potential?
the electrical charge across the cell membrane of a neuron inits resting state
What is action potential?
a nerve impulse; reversal of charges from negative to positive
What happens during action potential?
At the front of the impulse, gates of the sodium (Na+) channels open, allowing Na+ to enter the neuron. The Na+ makes the neuron positive. As the impulse passes, gates within the potassium channels open, allowing K+ ions to flow out. This restores the negative charge of the neuron after the impulse.
What is threshold?
the minimum level of a stimulus that is required to activate a neuron (all or nothing)
What is synapse?
the location at which a neuron can transfer an impulse to another cell
What happens in a synapse?
When an impulse arrives at an axon terminal, the vesicles release the neurotransmitters into the synaptic cleft. The neurotransmitter molecules diffuse across the synaptic cleft and attach themselves to receptors on the membrane of the neighboring cell. If the stimulation exceeds the cell’s threshold, a new impulse begins
What are meninges?
3 layers of connective tissue that wrap the brain and spinal cord
What is cerebrospinal fluid?
bathes the brain and spinal cord and acts as a shock absorber that protects the central nervous system
What is the cerebrum?
- largest & most prominent part of brain
- responsible for voluntary activities
- site of intelligence, learning, and judgment