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Nervous system
Nerves
| Question | Answer |
|---|---|
| nerves and ganglia | Nerves: bindles of axons and their sheaths which extends from the CNS Ganglia: collections of neuron cell bodies which are outside the CNS |
| CNS and PNS | The central nervous system: - brain - spinal cord The peripheral nervous system: - nerves - ganglia (bundle of nerves) |
| 2 types of nerves | 2 types of nerves: Spinal (originate from the spinal cord) Cranial (originate from the brain) |
| PNS divided in 2 sections? | afferent and efferent |
| afferent - PNS | Afferent (sensory) - transmit action potentials from he sensory organs to the CNS for processing (body to brian) |
| efferent - PNS | Efferent (motor) - transmit action potentials from the CNS to the effecter organs (glands and muscles) (brain to something) |
| PNS efferent decided into 2 sections? | Somatic motor nervous system (transmits A.P. from CNS to skeletal muscles) SMNS controls muscles 2. Automatic motor Nervous System (transmits A.P. from the CNS to smooth and cardiac muscles and glands) ANS controls involuntary muscles |
| PNS--> efferent ---> ANS divided into 2 sections | sympathetic and parasympathetic |
| ANS - Sympathetic? | Sympathetic (prepares the body for physical activity) Increases heart rate and raise blood pressure is responsible for the flight or fight response when we;re scared or angry this supplies the body with the energy (glucose) to fight or run away |
| ANS - Parasympathetic? | 2. Parasympathetic (regulates resting and nutrition-related functions such as digestion and urination) Slows the heart rate and lowers blood pressure controls smooth muscles in the stomach to digest foods we eat and controls tear and salivary glaw |
| 2 types of cells in nervous system? | Neurons - (made up of 3 basic units: cell body, axons, and dendrites) Neuroglia (gliad cells) - non-neural cells that maintain homeostasis, form myelin, and provide support and protection for the brain's neurons. |
| Soma | Soma - house mitochondria Neurons have a lot of energy Body has a lot of GA (golgi apparatus)- lots of secretions (neurotransmitters) |
| dendrites | Dendrites: typically shorter brings messages into the cell body signals travel down the dendrites |
| axons | Axons: AP begins at axon hillock (the end of the cell body and beginning of axon) Can be less that a cm long or longer than a meter are wrapped in a myelin sheath (a fatty wrapping that insulates and speeds up the transmission of the AP down the axon) |
| myelin (schwann cells) | Myelin is produced by neuroglia (called Schwann cells in PNS and oligodendrocytes in the CNS) |
| Nodes of Ranvier | THe gaps in the myelin sheath are called Nodes of Ranvier |
| can neurons undergo mitosis? | Neurons cannot undergo mitosis. we have all the neurons we need form birth. |
| what can ill neurons? | Excess alcohol consumption and drug use can kill neurons. |
| unipolar | 1. unipolar: only one process - the cell body "hangs" off that process. has pseudo dendrites (still sends signals to the cell body but sends it the way an axon does) afferent neurons are usually unipolar. soma separated form the axon |
| bipolar | 2. Bipolar: 2 processes- an axon and a single dendrite split into many benches. many specialized afferent neurons (eyes to brain) are bipolar. (soma in the middle) |
| mulitpolar | 3. Multipolar: may processes - several dendrites but only one axon. no matter how many processes a neuron had, it will have only one axon. usually wither motor neurons or association neurons |
| list 3 functions of neuroglia . | maintain homeostasis, form myelin, and provide support and protection for the brain's neurons |
| what are the 3 main parts of a neuron | cell body, axons, and dendrites |
| what is the function and definition of the myelin sheath | a fatty wrapping that insulates and speeds up the transmission of the AP down the axon |
| what produces myelin | neuroglia |
| An axon has a myelin sheath produced by Schwann cells. is this neuron in the PNS or CNS? | pns |
| Neuroglia = ___? | natural glue |
| 5 types of Neuroglia? | oilgodendrocytes, Schwann Cells, Microglia, Astrocytes, Ependymal Cells -(unciliated, ciliated) |
| Oligodendrocytes? Schwann cells? | Oligodendrocytes are found in the CNS, and the have 2 jobs: bind neurons together, insulate the axons. In the PNS, Schwann Cells are the cells that insulate axons -- one distinction is that while one oligodendrocyte may wrap around several axons, several |
| Miicroglia and Astrocytes? | Microglia - engage in phagocytosis to fight infections.;;;form the blood-brain barrier. we need this barrier bc we have capillaries in our brain that may release substance that are toxic to the neurons but are necessary to other parts of our bodies. |
| Ependymal cells- 2 types? | 1. Cells without cilia secrete cerebrospinal fluid which bathes the brain and spinal cord tissue and provides a protective cushion around the CNS. 2. the ciliated ependymal cells move this fluid around so that it stays homogeneous (or evenly mixed) |
| Nerves? Epineurium? | Nerves are bundles of axons and their sheaths which extend from the CNS ;;;its a shiny collagen layer on top of each nerve. this wrapping g encloses several bundles of axons and each bundle, called a fascicle, is wrapped together in what's a perineurium. |
| perineurium? endoneurium? Sciatic Nerve? | P - wraps smaller bindles but is made of same material as epineurium each indv. axon of the bundle is wrapped by Schwann cells and a endoneurium. Nerves tend to travel near blood vessels. The thickest nerve in our bodies is the Sciatic Nerve. |
| Nerves classification? 3? | sensory (optic nerve); Motor (our eyes); Mixed (most nerves) |
| how do nerves heal? mitosis? | nerves cant go thru mitosis; once dead, it cant be replaces; if nerve in PNS is severed, it sometimes be healed. Spinal cannot be replacedd; Scwann cell can regenerate, but it must still be alive; oligodendrocytes in the CNS can never regenerate. |
| 2 thihngs must happen fo rthe nerve to heal? | Must be in PNS covered by Scwann Cells and must be lined up with the severed end |
| A.P. and Excitablitly | A.P.- electrical signals carried by an axon Excitability- the ability to create an AP in response to a stimulus 2 types of excitable cells and neurons neurons are excitable, not neuroglia |
| Electrical Signal (AP) cause? Potential Difference? | caused by ions and their interactions with other ions; There is a diff in the electrical charge of the membrane as compared to another part of the cell--this is the potential diff;PD-a measure (mV)of the charge diff between the 2 points on the cell. |
| Neuron Memebrane Charge... | - an axon is part of a cells - it has an inside and an outside, separated by the plasma membrane - the outside has a net positive charge and the inside a net negative charge |
| Potential diff? "at rest"? Resting potential? | at rest = there are no action potentials running down the axon.;; - as a result there is a potential diff, and we call that the resting potential of the axon |
| Epineruium covers? perineurium covers? endoneurium covers? Fasicle made up of what? What type of cells make up the Endoneurium? What nerve is most prevalent is our bodies? | nerves, fascicle, axon, axons, schwann cells, mixed nerves |
| whhy is the inside negatively charged? | -- the proteins trapped inside the cell bear a negative charge and are too big to get through the membrane. |
| Who is the plasma membrane 50-100 times more permable to? | potassium ions! |
| What does the exchange pump do? | helps maintain the -85 mV |
| Only ___ cells can produce AP? 2 examples? | excitable --- neurons and muscles |
| What can a change in enviorment reslt in for an action potential? neuotransmitters are used for what in action potentials? | a change in the environment can result in a stimulus (light for cells in h eyes and the moving of cells can stimulate AP) neurotransmitters are used to pass an action potentials from one neuron to another |
| Depolarization? | when a stimulus occurs at axon, sodium channel proteins open up, allowing NA+ o diffuse through the membrane;;; more NA+ outside ;; diffusion will cause the NA+ ions to move into the cel |
| polarization? | means that there was a positive charge outside and a negative charge inside = the charges were separated |
| How does the axon gets back to its resting potential after a stimulus? | Sodium channels close; new potassium channels open; K+ rushes outside of the cell; inside of the cell gets less positive bc its losing positive ions |
| Re-polarization? | The process of the potential difference going from +30 to below -85 mV is called re-polarization After re-polarization, the NA+/K+ pump starts pumping again |
| Whic part of the neuron carries the AP? The inside of the axon is pos or neg? | axon; negatively charged |
| how deos tthe axon maintain resting potential? | there are no action potentials running down the axon; Sodium Potassium exchange pump - pumps out sodium and causes there to be a bigger diff in the charges |
| what determines the strenght of the AP? | frequency, not the amount of the impulse |
| sub-threshold stimuli? | a stimulus that is not large enough to produce an action potential;The intensity of the feeling depends not on the size of the action potential, but on the frequency of action potentials.;More over a time amount determines what the stimulus will be |
| What does an AP do for the travel AP? | providea stimuls fo rthe initiation of an AP in the next part of the axon |
| ap- one way stree? | one way street- AP cannot travel in the opposite direction (must go from hillock to other end of axon) bc the refractory period |
| Refractoro period? | Refractory period is the time when no action potential can be generated on the neuron bc no one is already in progress. |
| Absolute refractory period? | While the action potential is being generated, a new stimulus will not produce another action potential = absolute refractory period bc no matter how strong the stimulus, no action potential can occur. |
| Relative refractory period? | Relative Refractory Period: during this time, the neuron is not really ready to creat an action potential but, if the stimulus is strong enough, it will do so |
| 2 ways AP can be conducted down the axon? | entire axon= unmyelinated (CONTINOUS conditioin) ooor hope down the axon = myelinated (called SALTATORY)- much faster |
| myelinated and unmyelinated? | M=when several Schwann cells encase one axon;; UN=hen one or two Schwann encase several axons |
| Pre-synaptic neuron? post-synaptic neuron? | Pre-synaptic neuron - carries signals to the synapse, which is the only place that a neuron can connect with another cell;; When the signal reaches the end of the pre-synaptic neuron's axon, it must jump the synapse to the Post- synaptic neuron |
| When wil an axon transmit info without change in frequency? downside? synapses let important things in. | if we have a very fast frequency of action potentials beginning on the axon hillock of the pre-synaptic neuron, we will have the same frequency of action potentials at the end of the axon; brains wowuld be overloaded withh sensory input; synapses. |
| Change in frequency? | Unlike axons, neuron-to-neuron synapses let some info in, but usually limit it; The frequency of an AP can be altered as it passes through a synapse btw neurons |
| inhabotiry synapses? | Synapses that stop info from passing to the next neuron are called inhibitory synapses, and these make up the majority of neuron-to-neuron synapses in the body |
| excitatory chemical synapses steps? | 1.Ap on axon of pre-sy neuron; 2.calcuim enter teh pre-sy terminal and calcuium is concentrated on outside; 3. calcuium affects the syn vesticles and causes them to release NT into syn cleft; 4.NT travel to receptor on the poet-syn mem --depolarization |
| 2 types of neuron to neuron synapses? | - Which help[ them work as he gatekeeper and created 2 diff responses: excitatory postsynaptic potential (EPSP's) inhibitory postsynaptic potentials (IPSP's) |
| EPSP? | the 1st neuron will excite the 2nd neuron - the signal from the presyn neuron will make the postsyn neuron closer to creating an AP; requires a greater signal in the presynaptic neuron in order to create an action potential in the postsyn neuron |
| 2 ways for and EPSP to occur? | temoral summation and spatial summation. Four AP occurring within a small amount of time (temporal summation) along one presynaptic membrane;;; when many axons all carry an action potential to the dame neuron all at one = spatial summation |
| What is the purpose of ISPS? | we use our synapses as gatekeepers so that our brains can receive important info for processing and ignore the rest, so we can concentrate on what's important;more negative as a result of inhibitory;more away from being an action potential. |
| Difference in ESPS and ISPS? | receptors for the 2nd neuron;;; determines what channels will open --- if K+ it is inhibitory ; if Na+ it is excitatory ;; both use the same neurotransmitters |
| Coovergent arragment? | Convergent - when 2 neurons form one neuron It has more than one pre-synaptic neuron and one final post-synaptic neuron. As a result, the messages all go one way. many inputs are digested down to just one limited output |
| examples of covergent arragment? | moving your arm to grab something requires input from your brain and other inputs that determine the rate of AP |
| Divergent Arragment? | Divergent - one neuron branches into 2 one input that connects to 2 diff, neurons bc it diverges useful when one piece of info needs to reach several places |
| examples of divergent arragment? | this type is useful when you touch something hot, you get a signal sent to the brain so you learn from the experience and to your skeletal muscles to pull your hand away from the heat. |
| Oscillating Arragment? | Oscillating- sends signal along and to itself. a neuron sends a signal along but also send it back to itself it allows the neuron to regenerate the signal again |
| Oscillating examples? | this kind of circuit is what controls the cycle of staying awake and going to sleep |
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