Exam 4 Study Guide Flashcards
(130 cards)
How are stimuli communicated to the central nervous system?
Sensory stimuli is turned into electrical signals that are passed along by neurons within the PNS and travel to the CNS
How are responses sent to effectors in the body?
the CNS makes a decision and the motor neurons transmit the information to the designated area of the body to carry out a response
What is the threshold for production of an action potential?
-55mV
Why is -55mV the threshold?
When depolarization reaches threshold, it becomes self generating, urged on by positive feedback. As more Na enters, the membrane depolarizes further and opens more ion channels until all Na channels are open.
Name the five essential components of the reflex arc.
- receptor
- sensory neuron
- integration center
- motor neuron
- effector
Describe the process of the reflex arc.
The receptor picks up a stimulus then sends it down the sensory neuron. The sensory neuron then sends it into the integration center where a decision is made on what to do. The decision is then sent down the motor neuron, which sends it to the effector. The effector carries out the decision.
Describe the retina
-the innermost layer of the eyeball that develops from extension of the brain
-delicate two layer membrane
-absorbs light and keeps it from scattering
-composed of photoreceptors, bipolar cells, and ganglion cells
-contains the optic disc and quarter billion photoreceptors
Describe rods
-dim light and peripheral vision receptors
-no color vision or sharp images
-more numerous and sensitive to light than cones
Describe cones
-vision receptors for bright light
-high resolution color vision
-fovea centralis is a tiny pit in center or macula w all cones; best vision
Describe ganglion cells
-generate AP’s transmitted in optic nerve to brain
-ganglion cell axons exit eye as optic nerve
Describe graded potentials
-the more neurotransmitters, the more graded potentials
-the longer they stick around, the more graded potentials
-short lived, localized changes in membrane potential
-can either be depolarizations or hyperpolarizations
-are triggered by changes in the neuron’s environment that opens gated ion channels
-the more GP there are, the closer you are to an AP
Describe excitatory postsynaptic potentials(EPSP)
EPSPs move closer to the threshold
Describe inhibitory postsynaptic potentials(IPSP)
IPSP’s move away from the threshold
What is an action potential?
a brief change in membrane potential in a patch of membrane that is depolarized by local currents
Describe the optic nerve
-only consists of sensory function(vision), not motor function
Describe the visual cortex
-located in the occipital lobe
-receives visual information that originates on the retina of the eye
-the largest cortical sensory area
Describe gray matter
consists of short, nonmyelinated neurons and neuron cell bodies
Describe white matter
consists mostly of myelinated axons with some nonmyelinated axons, primarily in fiber tracts; the dense coating of fatty myelin is what gives white matter its color
Describe the cerebral cortex
the “executive suite” of the nervous system where the conscious mind is found; enables us to be aware, communicate, remember, and understand; composed of grey matter
The brain stem consists of:
the midbrain, pons, and medulla oblongata
Brain centers produce the rigidly programmed:
automatic behaviors necessary for survival
The brain stem is heavily involved with
innervating the head
Describe the cerebellum
ultimate planner and coordinator of complex motor activities; also adjusts motor output, ensuring coordination and balance
What are sulci?
shallow grooves marking the surface of the brain