front 1 Nervous system: definition | back 1 master controlling and communicating system of the body -- cells communicate with each other and other systems by electrical (similar to action potential) and chemical (like AChl) signals
--rapid and specific
Made of CNS and PNS
**Endocrine system is the other |
front 2 Nervous system: functions | back 2 1. Sensory input - receives stimuli; mostly brain but sometimes in the spinal column (Afferent pathway)
2. Integration - interprets stimuli and makes decisions (Control Center)
3. Motor output - responds to stimuli; activates effector organ (Effector pathway) |
front 3 Central nervous system (CNS) | back 3 - brain and spinal cord
- integration and command center |
front 4 Peripheral nervous system (PNS) | back 4 - nerves outside brain and spinal cord <--any structure outside brain and spinal cord but it is still related to the nervous system
- sensory receptors, cranial nerves, spinal nerves, peripheral nerves
- Carries messages to and from CNS |
front 5 Sensory (afferent) Division of the PNS | back 5 - carries nerve impulses from sensory organs to CNS
- from skin, skeletal muscles (lactic acid accumulation makes muscles hurt), and visceral organs (stomach, bladder, etc...) |
front 6 Motor (efferent) Division of PNS | back 6 - carries nerve impulses from CNS to effector organs
- 2 parts: Somatic (voluntary) and Autonomic (involuntary) |
| back 7 - VOLUNTARY nervous system
- controls skeletal muscles |
| back 8 - INVOLUNTARY nervous system
- regulates smooth and cardiac muscles and glands
includes sympathetic and parasympathetic divisions - have opposite effects on organs |
| back 9 where your body is in relation to itself
- the tiny little adjustments that prevent you from falling on your facy |
front 10 What cell types make up nervous tissue? | |
| back 11 - transmit nerve impulses
- large, complex cells
- comprised of cell body and processes
- long lived and amiotic (don't divide)
- High metabolic rate - can't survive long without O2 |
| back 12 - has a nucleus and usual organelles
- active in synthesis or neurotransmitters
- well developed rough ER, ribosome, and Golgi apparatus
- Focus point for outgrowth of processes
* Most cell bodies are located in the CNS
* Most cell processes (AXONS) are located in the PNS |
| back 13 DENDRITES
- numerous, short, and branched processes
- receptive regions of the neuron
- Convey incoming messages toward cell body via GRADED POTENTIALS
AXONS
- singular long processes
- secrete neurotransmitters from axon terminals
- generate and transmit ACTION POTENTIALS (exactly the same as in muscle) along axon and away from cell body |
| back 14 - structural classification
- one axon and many dendrites
- 99% of neurons - most of them are in CNS |
| back 15 - structural classification
- one axon and one dendrite
- cell body is found in the middle
- rare, found in eyes and ears |
| back 16 - structural classification
- One axon only - cell body is disassociated from the neuron (one, short process extends and attaches the cell body to a long process)
- rare, function as sensory receptors |
| back 17 - AFFERENT
- functional classification
- transmit ACTION POTENTIAL from skin, muscle, or internal organs toward CNS
- mostly unipolar and bipolar nuerons |
| back 18 - EFFERENT
- functional classification
- carry ACTION POTENTIAL from CNS to muscles and glands <-- tells muscle to contract
- mostly multipolar neurons |
| back 19 - within CNS; between sensory and motor neurons
- mostly multipolar neurons
- most common function of neurons
** Do NOT convery message in/out of CNS, because they are already IN the CNS. |
front 20 What is the difference between nuclei and ganglia | back 20 cell body clusters in CNS versus PNS |
front 21 What is the difference between fiber tracts and nerves | back 21 cell body clusters in CNS versus PNS |
| back 22 1. Astrocytes
2. Microglia
3. Ependymal cells
4. Oligodendrocytes
5. Satellite Cells
6. Schwann Cells |
| back 23 "STAR CELL"
- most abundant and versatile glial cells
- support, and anchor neurons to capillaries
- guide migration of young neurons
- control chemical environment by cleaning up released neurotransmitters <-- control them (if they're in the wrong place) by enzymes
**lots of processes make this cell look like a star
**some are attached to neurons and others are attached to capillaries
**brings blood vessels and neurons closer together - vascularizes neurons |
| back 24 **specialized macrophage, only for the brain
- small cells with long spiny processes
- turn into macrophage when microorganisms are present - immune function <-- become more rounded with fewer processes
- responsible for monitoring and maintaining health of neurons |
| back 25 **look like epithelial cells
- squamous or columnar shape, some have cilia
- line cranial and spinal cavities to form a permeable barrier for cerebrospinal fluid
- beating of cilia helps circulate cerebrospinal fluid |
| back 26 **a cell with just a few processes
- wrap around thick CNS nerve fibers
- Produce insulating covering myelin sheaths around large axons in CNS |
| back 27 a type of glial cell that surrounds cell bodies of the neuron in the PNS
- function unknown |
| back 28 a type of glial cell that forms myelin sheaths around larger axons
- function similar to oligodendrocytes |
| back 29 the fluid within the cranial cavity that provides nutrients and cushioning for the brain. |
front 30 How can you tell the difference between axon and dendrite? | back 30 axons usually have a myelin sheath
*dendrites and cell bodies are ALWAYS unmyelinated |
front 31 Myelin sheaths: Definition and function | back 31 **produced in multiples (up to 60 segments) by oligodendrocytes in the CNS
Definition:
- whitish, fatty segments made of phospholipids that surround only the larger axons
Function:
- protects the axon
- insulates axons from one another <-- like live wires
- increase nerve impulse conduction speed <-- you can feel touch quickly |
front 32 Form Myelin sheaths take in CNS | back 32 - formed by oligodendrocytes
- occur in multiple segments
- wrap concentric layers of plasma membrance and cytoplasm around axon (like roll cake) |
| back 33 gaps between segments of myelin sheaths
- where axon branches emerge
- where action potentials land |
front 34 Form Myelin sheaths take in PNS | back 34 - Formed by Schwann cells
- Each Schwann cell makes up one segment
- Attach themselves to the axon and then roll out (like dough) to wrap around it.
**Segments are fatter on longer atoms |
| back 35 **Neurons behave a bit like skeletal muscle - receive stimuli and respond (muscle responds by contracting)
- Neurons are highly excitable
- Ability to receive stimuli and respond
- When neurons are adequately stimulated* (GRADED POTENTIAL on dendrites and cell bodies), nerve impulses (ACTION POTENTIALS on axon) are generated
- regardless of stimulus, neuron type and location
*adequately because not all stimuli are created equal; some are too weak to stimulate the neurons |
| back 36 **similar to ACTION POTENTIAL but much simpler
- resting neuron membrane is polarized at -70mV
- Changes due to electrolyte distribution
- Depolarization - inside becomes less negative
- Repolarization - inside returns to resting potential/neutral
- Hyperpolarization - inside becomes more negative |
| back 37 short lived, local changes in membrane potential
- initial intensity varies
- intensity decreases with distance (from the beginning of dendrite to the cell body)
- occur only in dendrites and cell bodies (because axons deal with action potentials)
- not all stimuli are created equal; many are weak and die down before reaching axon and stimulating the neurons
- if the stimuli is strong enough it can initiate action potentials in axons. |
| back 38 - the principal means of neural communication
- occurs when GRADED POTENTIAL is strong enough
- occurs only in axons - aka nervous impulses
- do not decrease in strength over distance
- no change in intensity
*pretty much the same as in skeletal |
front 39 Which is more important, action potential or graded potential? | back 39 They are equally important because you need graded to get action and you need action to talk to other cells. |
front 40 How is Action Potential Conducted? | back 40 In unmyelinated axons - continous but slow. Electrical current moves forward and depolarizes next region.
In myelinated axons current is only conducted at nodes of Ranvier - fewer places for ions to enter through therefore they have to make bigger jumps.
**myelinated is 30 times faster than unmyelinated. |