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Anatomy Exam 2
The Nervous System
| Term | Definition |
|---|---|
| 3 main processes the nervous system is involved in | 1. receives information, 2. stores/processes information, 3. effects interactions and maintains homeostasis |
| cell body | receives and processes information, makes a decision |
| axon hillock | part of cell body of a neuron that connects to axon |
| initial segment | part of an axon where action potentials are initiated |
| axon | all or nothing, send a signal through axon to synaptic cell |
| axon terminal | releases the electrical impulse of the presynaptic cell |
| synaptic knob | Neurotransmitter is released into the synapse from vesicles as a neuron reaches the synaptic knob |
| myelin sheath | a fatty white substance that forms an electrical insulating layer and surrounds the axon, increases speed of electrical signal |
| synapse (noun) definition | a junction between 2 nerve cell bodies, consisting of a minute gap across which impulses pass by diffusion of a Neurotransmitter |
| unipolar neurons | one process is attached to the nerve cell body (in our sensory neurons) |
| bipolar neurons | two processes are coming out of the soma |
| multipolar neurons | more than two processes are coming out of the soma, common in our body (motor neurons) |
| 2 major components of nervous system WITHIN the Central Nervous System | spinal cord and brain |
| a bundle of axons in the CNS are called... | fiber tracts |
| a bundle of axons in the PNS are called... | nerves |
| a group of nerve cell bodies in the CNS is called... | nuclei |
| a collection of nerve cell bodies in the PNS is called... | gaglia |
| astrocytes (location and function) | location: wrapped around blood vessels, function: help maintain extracellular enviornment |
| ependymal cells (location and function) | location: lines cavities, function: cilia circulates fluid |
| microglial cells (location and function) | location: brain and spinal cord, function, digest things that dont belong, disposal system |
| oligodendrocytes (location and function) | location: around axons, function: speed up signal down axon |
| satellite cells (location and function) | location: PNS function: support and nuture neurons, supply nutrients |
| schwann cells (location and function) | location: PNS, function: produce a lipid substance that wraps around an axon, create myelinate sheath |
| formal name for the sensory nervous system | afferent, bringing information toward central nervous system |
| formal name for the motor nervous system | efferent, bringing information away from central nervous system |
| what kind of signal passes down the length of the axon? | electrical signal |
| what is meant by the term 'potential' in terms of cells? | the result of charge differences across membranes, measured in voltage |
| is the charge inside a cell more or less negative than outside the cell? | more negative inside the cell |
| name of large molecules that stay inside the cell and dont leave. what effect do they have on membrane potential? | DNA and cell protein, make inside the cell negative |
| in the sodium potassium pump, what direction does each ion travel? | NA+ pumped out, K+ pumped in |
| is ATP required for the sodium potassium pump to work? what kind of transport is used? | yes ATP, active transport |
| what is the ratio of sodium and potassium ions pumped across the membrane? | 2 K+ and 3 Na+ |
| sodium and potassium ions are both positive. Why does pumping them influence the membrane potential? | because pumping them makes it more negative since its going against the concentration gradient. |
| Do leak channels require ATP? What kind of transport is used? | no ATP, Facilitated diffusion because need help of protein channel |
| Na+ and K+ leak channels | allow K+ to leak back out, and Na+ to leak back in |
| what is the value of the typical resting potential? (Vr) | -70 mV |
| resting membrane potential | difference in charges inside vs outside (-70 mV) |
| what is the equilibrium potential for K+? | -90 mV |
| what is the equilibrium potential for Na+? | +66 mV |
| K+ equilibrium potential | chemically K+ wants to go out, electrically K+ wants to stay in |
| Na+ equilibrium potential | chemically Na+ wants to leak in, electrically Na+ also wants to leak in |
| why is Vr so much closer to the equilibrium potential of K+ and not Na+? Vr = -70 | because cell membrane is a lot leakier to potassium, and membrane with leak channels is permeable to potassium |
| 3 kinds of gated channels | mechanically, chemically, voltage |
| mechanically gated channels (what causes it to open and does it require ATP) | No ATP, opens by membrane stretch by physical distortion |
| chemically gated channels (what causes it to open and does it require ATP) | No ATP, opens by chemical ligands - molecule binds with channel |
| voltage gated channels (what causes it to open and does it require ATP) | No ATP, opens by threshold voltage |
| Graded Potential (definition, and where in neuron is it located?) | getting more positive, but not reaching threshold. located in dendrites and NCB's |
| what machinery allows for graded potentials? | ligand-gated ion channel proteins |
| when threshold is reached, what opens to begin the action potential? | the sodium channels open when voltage reaches threshold |
| what is threshold and what happens when it is reached? | threshold is the limit at which the neuron needs to exceed/hit in order for an action potential to be initiated |
| refractory period | a period immediately following stimulation during which a nerve or muscle is unresponsive to further stimulation |
| absolute refractory period | point at which action potentials cant come through again |
| relative refractory period | point at which action potentials can come through, but it is difficult |
| what 3 factors can influence speed of an action potential? | diameter, temperature, myelination |
| what structure surrounds the axon of some neurons? what name is given to this kind of movement of the action potential? | myelinated sheath, satitory propagation = movement from node to node |
| saltatory propagation | action potentials down myelinated axons jump from node to node |
| continuous propagation | unmyelinated axons |
| synapse | communication space between the 2 neurons |
| what kind of cell junction allows for an electrical synapse? | gap junction , because there is a direct travel of ions through a tube between two cells |
| what is one advantage of an electrical synapse? | fast and bidirectional |
| what is one disadvantage of an electrical synapse? | signal is diminished |
| what kind of channels open in response to action potential in the synaptic knob, and what happens when it opens? | voltage gated Ca+ channels open, Ca+ flows into the cell and causes synaptic vesicles to migrate down and merge with membrane, then allows release of NT into the synaptic cleft |
| what kind of transport do neurotransmitters use to cross the cell membrane? | vesicular transport - exocytosis (moving out of) |
| excitatory postsynaptic potentials (EPSP's) | opening chemically gated sodium channel, sodium flows in, depolarizes, gets us closer to threshold |
| inhibitory postsynaptic potentials (IPSP's) | opening of chemically gated potassium channels, moves us away from threshold |
| what are 3 mechanisms for removing NT from the synapse? | degrade, diffuse, reuptake |
| Chemically gated potassium channel (location in neuron) | dendrites, NCB's, axon |
| voltage gated calcium channel (location in neuron) | synaptic knob |
| sodium potassium pump (location in neuron) | axon |
| potassium leak channel (location in neuron) | axon |
| action potentials (location in neuron) | axon |
| graded potentials (location in neuron) | dendrites and NCB's |
| voltage gated channels (location in neuron) | axon |
| 3 basic germ layers | extoderm (outside), mesoderm (middle), endoderm (inside) |
| CNS gray and white matter (why gray and white?) | gray = dendrites don't get myelinated so they remain gray, white = myelin sheaths give or axons the white color |
| location of gray and white matter in brain vs spinal cord | in brain, cerebral cortex is gray around outside and the fiber tracts are white on the inside, in spinal cord, all gray matter is deep to the white matter |
| the cerebrum | consciousness awareness of sensations, motor decisions, personality, ability to make decisions |
| cortex (location) | outer layer of the cerebrum |
| basal nuclei (function) | direct activities at the subconscious level (initiation and termination of movement, ex. holding hand steady) |
| gyris and sulci | gyrus are folds, sulci are grooves |
| primary somatosensory cortex | biggest parts = hands, face,lips (facial expressions, speech, sound production) |
| primary motor cortex | fine motor control, part of the brain that starts an action potential that then causes motor events (ex: moving thumb) |
| hippocampus | in cerebrum, involved in memory |
| commissure | connects the left and right hemispheres in brain |
| corpus callosum | allows our left and right hemispheres to communicate |
| diencephalon | made of thalamus, major relay center for sensory information |
| hypothalamus | master control center, involved in homeostasis, emotion, hunger, appetite, signals the pituitary gland |
| epithalamus | contains the pineal gland which produces melatonin - regulates our sleep/wake cycle |
| cerebellum | important in movement, allows smooth movement to occur, minimizes motor errors |
| medulla oblongata | basic life support! centers for cardiovascular and respiratory rhythmicity, homeostasis |
| pons | bridge,ascending and descending tracts, sending information from nerves and spinal cord up to our brain, our brain sends decisions down |
| how do we protect our CNS (brain and spinal cord) | meninges! layer of CT (dense irregular) that surrounds the brain and spinal cord |
| the Autonomic nervous system (ANS) has only WHAT TYPE OF NEURONS | visceral motor neurons |
| somatic motor system | voluntary, nuclei are located in anterior gray horn of spinal cord, 1 neuron per circuit, NT released at end of axon is always acetylcholine |
| autonomic nervous system | involuntary, nuclei are located in spinal for in lateral gray horn, 2 neurons per circuit, includes ganglia, |
| 2 types of autonomic divisions (how body maintains homeostasis) | sympathetic division, parasympathetic division |
| sympathetic division | prepares for action, coming out of spinal cord |
| parasympathetic division | promotes a restful state (except digestion), craniosacral - coming out of the brain |
| 4 types of spinal nerve plexuses | cervical plexus, brachial plexus, lumbar plexus, sacral plexus |
| plexus definition | way of safely getting axons from one nerve to another nerve |
| sensory receptors | take information/energy and change the stimulus into an action potential |
| why do people not realize they smell? | sensory adaptation! they stop perceiving some sort of stimulus |
| mechanoreceptors | gives us our lightest touch, discriminating touches, vibration and deep pressure, can feel hair follicles move |
| receptive fields on finger tips | have many sensory receptors, easy to tell 1 touch from 2 |
| baroreceptors | (type of mechanoreceptor), respond to pressure changes in arteries and veins |
| proprioreceptors | respond to muscle/tendon stretch |
| nocireceptors | pain receptors |
| thermoreceptors | temperature receptors |
| general chemoreceptors | respond to chemicals |
| the special senses: olfaction | sense of smell, olfactory neurons are embedded in our nostrils |
| the special senses: gustation | the tongue and taste buds, chemicals dissolve in our saliva and then encounter our taste buds where there are receptors |
| lacrimal gland | what creates tears and constant moisture, protects from bacteria |
| 3 layers of the eye | fibrous layer (outermost), vascular layer (middle), neural layer (innermost) |
| fibrous layer (includes what structures?) | outermost layer of eye, scream cornea |
| vascular layer (includes what structures?) | middle layer of eye, iris, choroid, cilliary body |
| neural layer (includes what structures?) | innermost layer of eye, retina |
| what is the area of best vision? | fovea |
| lens | does the focusing for us |
| rods and cones | rods are in our peripheral vision and are nighttime receptors, cones are in our central vision and allow us to see colors |
| 2 types of eye muscles | dialater muscles and constrictor muscles |
| rhodopsin | pigment in rods |
| how can we adapt to different light levels? | rhodopsin molecule breaks down when lint hits it because it is bombarded with photons, can be slowly rebuilt with ATP |
| do we adapt to light or dark faster? why? | light. because in order to see in lower light levels, more rhodopsin is needed which takes awhile to regenerate |
| pitch: __________, volume: ____________ | pitch: frequency, volume: amplitude |
| color vision 3 cone types | red cones, blue cones, green cones |
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loladell
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