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Physiology - Test 2 study guide


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converts one kind of stimulation to another
Transmits info from A to B
Impulses will be interpreted
cells found in Nervous System
Neurons & Glial Cells
Kinds of neurons
1. Anaxonic
2. Bi-Polar
3. Unipolar
4. Multipolar
Anaxonic Neuron
- not well understood
- connecting neurons in the CNS
- no axon
Bi-Polar Neuron
- 1 axon
- 1 dendrite
- sensory (special senses - taste, vision)
Unipolar Neuron
- sensory (hot, cold, touch)
- axon a little shorter than dendrite
- Ex. Dorsal Root Ganglion
Multipolar Neuron
- motor neuron
- connecting neurons
- peripherial nervous system
Types of Glial Cells (Neuroglia)
1. Ependymal
2. Astrocytes
3. Microglia
4. Oligodendrocytes

1. Satellite cells
2. Schwann Cells
2 glial cells that work together to form BBBarrier
Ependymal and Astrocytes
Ependymal cells
- behave as epithelial
- lines and covers tissues
- multi processes
- connective tissue of CNS
- structural support
- work with Ependymal cells for BBB
Microglia cells
- wandering phagocytes of CNS
- ingest potential pathogens
- clean up debris
- myelination of fibers in CNS
Satellite Cells
In PNS - similar to Epindymal and Astrocytes
Schwann Cells (aka neurolemmacyte)

- surround axons in PNS
- myelination in PNS
Bundle of axons and/or dendrites.
Membrane potential
Difference in charge between inside and outside of cell.
All membranes have 3 types of ion channels
1. leak channels
2. Sodium Potassium Exchange pump
3. Gated - chemical, mechanical, voltage
Leak channels
- aka passive channels
- always open
- tend to be more permeable to K than Na
3 forms of gated channels
- chemically regulated
- voltage-regulated
- mechanically regulated
3 states of gated channels
- closed, but capable of opening
- open
- closed, incapable of opening
Sodium Potassium Exchange Pump
- maintains resting potential at -70mV
- used ATP to pump out Na+ and pump in K+
3 Na to 2 K
What initiates an action potential?
Opening and closing of gated channels.
Action Potentials
Propagated changes in the transmembrane potential that, once initiated, affect an entire excitable membrane.
Absolute refractory period
Does not matter how many other stimuli, cannot get another action potential.
Relative refractory peoriod
possible to get another action potential generated, but takes greater stimuli
addition of stimuli
temporal summation
addition of stimuli occurring in rapid succession.
Occurs at a single synapse
spatial summation
simultaneous stimuli at different locations have a cumulative effect on the transmembrane potential.
EPSP creates?
Excitatory Post synaptic potential

- depolarization (move toward threshhold)
IPSP creates?
Inhibitory Post Synaptic Potential
- hyperpolarize - move away from threshold.
Saltatory conduction (propagation)
Action potential "jumps" from node to node rather than moving along the axon in a series of tiny steps.
3 types of fibers & describe
Type A - largest, myelinated, 300 mph
Type B - intermediate, myelinated, 40-45 mph
Type C - smallest, unmyelinated, continuous propagation, 2 mph
2 forms of synapses
Electric or Chemical
Electric synapse
- rarest
- the pre & post synaptic membranes are locked together at gap junctions
- known advantage - quicker response due to connection at gap junctions.
2 types of Chemical synapse & describe
- may or may not propagate the postsynaptic cell - depends on the NT

Cholinergic - synapses that release AcH

Adrenergic - uses a variety of NT
- not necessarily a NT
- alters the rate of release of NT or alters the affect the NT has on the post synaptic membrane.
- can effect pre,post or both at the same time
- can operate on thei own or in conj with NT's.
NM effects
Direct effect - Ionotropic - causes change in ion concentrations between inside and outside of receptor cells.

Indirect effect - Metabotropic - causes metabolic ahnges of the post synaptic cell. Overall change in the cells metabolism. G-protein GTP enzymes linked to them.
What affects nerve inpulses?
concentration of Na+, K+, Ca+, Temperature
if conc of Na+ & K+ are to high or low, affect resting potential, if temp high, ion movement faster through leak channels.

H+ in extracellular fluid - effect of depolarizing membrane

Buffers very important in cellular physiology
Types of reflexes
- learned/acquired - trained response
- somatic - control skeletal muscle contractions
- visceral - autonomic - cardiac muscle
- monosynaptic - one synapse
- polysynaptic - more than one synapse
- cranial - processing in brain
- spinal - processing in the spinal cord
4 types of neural pathways
- Linear pathway (serial processing)
- Diverging pathway (one -- to many) comon - motor
- Converging pathway (many -- to one) common - sensory - less convergence
- Reverberating (Linear -- loop) will continue to cycle stimulate until circuit fatigues or run out of NT's
5 sensory receptors
1. thermoreceptors (free nerve endings)
2. chemoreceptors (respond to chemical changes)
3. photoreceptors (respond to light)
4. mechanoreceptors (respond to mechanicl stimulus)
5. nociceptors (pain receptors)
break down Mechanoreceptors
1. baroreceptor - blood pressure
2. tactile receptors - touch receptors
a. tactile disc (merkels discs) free nerve endings with padlike structures.
b. lamellated corpuscle (deep touch - vibratory receptors)
c. organ of ruffini (deep touch - do not adapt quickly)
Site of sharpest vision
Blind spot?
Optic disc
react to all wave lengths of visible, low intensity light.
respond to certain wavelengths - color vision.
Organ of Corti
organ of hearing
how many hair cels are being stimulated at a given time.
dynamic equilibrium
semi circular ducts filled with endolymph

detect rotational movements of the head.
static equilibrium
Utricle and Saccule

Provide equilibrium sensations, whether the body is moving or is stationary.
incomplete tetany
muscle fiber contract, begin to relax but restimulated
complete tetany
stimulation so close together - no chance to relax. muscle will fatigue.
tension rises in stages - like warming up
types of muscle contractions
Isotonic - as muscle contracts - tension remains stable - muscle gets shorter. (to move)

Isometric - as muscle contracts - tension increases - muscle does not change much (maintaining posture)
Kinds of muscle fibers
1. slow twitch (lg # of mitochondria, high conc of myoglobin, slower to react, slower to fatigue)

2. intermediate (middle # of mitoch & myoglobin,)

3. fast twitch (few mitochondria, myoglobin, anerobic resp, react quick, fatigue rapidly)
Charactics of Cardiac muscle
- intercallated discs (gap junctions between cells)
- striated, pacemaker cells,
- deep nuclei
2 subgroups of smooth muscle
single unit & multi unit

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