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Specialized Eukaryotic Cells and Tissues

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icer215's version from 2016-08-17 02:34

Section 1

Question Answer
Specialized Eukaryotic Cells and TissuesBeing complex organisms humans and other eukaryotes have not one multiple cells, but the cells are specialized and vary greatly in size, shape, color, ability and function (like pikmen).
Cell bodyThe cell body is a "normal cell" it has a nucleus, mitochondria and other organelles.
Axonis elongated nerve fiber of the nerve cell that extends from the cell body to the terminal branches.Most neurons have only one.Conducts electrical impulses away from the cell body (soma).Transmit information to different neurons, muscles, and glands.Larger the size, the faster the transmission of information (signals).Some are covered with myelin sheath that works as an insulator which increases the transmission of information
Axon terminalssecretory regions of nerve.
Dendritesare branched extensions of cell body of the nerve cells.Treelike roots.Most neurons have many, some have only one.Increases the surface area of the cell body.Receive information from other neurons and transmit electrical stimulation to the soma (cell body).
Pre-synaptic cell (delivering end)1. Neurotransmitter: chemical messenger that carries signals between neurons and other cells in the body – is synthesized and sent down the axon 2. Action potential causes calcium channels to open and neurotransmitters are released into the synaptic cleft
Post-synaptic cell(receiving end)1. Neurotransmitter from the synaptic cleft binds to the receptors on the post-synaptic cell which either excites or inhibits depending on the information 2. Any left over neurotransmitters is taken back into pre-synaptic cell
Myelin sheathWraps around the axon intermittently (not continuous).Gaps between adjacent Schwann cells are known as nodes of Ranvier.Fatty substance
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Presynaptic cell (delivering end)1. Neurotransmitter.Chemical messenger that carries signals between neurons and other cells in the body.There are various types of neurotransmitters including.Aspartate, Glutamate, Acetylcholine, Dopamine, Norepinephrine, Epinephrine, and more that bind to different receptors.Synthesized and sent down the axon 2. Action potential causes calcium channels to open and neurotransmitters are released into the synaptic cleft
Postsynaptic cell (receiving end)3. Neurotransmitter. From the synaptic cleft binds to the receptors on the postsynaptic cell which either excites or inhibits depending on the information 4. Any left over neurotransmitters is taken back into presynaptic cell or enzymatically broken down
Schwann cellsPart of glial cell.Makes myelin sheath in the peripheral nervous system (PNS) by wrapping around the axons of motor and sensory neurons.Found in PNS
Oligodendrocytesthe central nervous system analogue of Schwann cells, makes myelin sheath around CNS axons.Found in CNS.
Nodes of RanvierGaps where there is no fat on an axon, allowing the electrical signal to travel (since fat/myelin sheaths block the signal).
SynapseA small gap between two neurons cells that allows one neuron to send information to another
Satellite cellsProvide insulation to neurons in the peripheral nervous system (PNS)
MicrogliaDigest parts of dead neurons
AstrocytesStar shaped cell,Provide physical and nutritional support,Clean debris,Transport nutrients to neurons,Hold neurons in place,Digest parts of dead neurons,Regulate content of extracellular space
Intermittent insulation➙ action potential jumps from one node of Ranvier to the next ➙ speed of conduction is faster.Action potential cannot propagate in myelinated segments.Current is carried by node of Ranvier instead
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Section 2

Question Answer
Axosomatic synpaseaxon terminal of one neuron (presynaptic) → cell body of another neuron (postsynaptic).
Axoaxonic synapse (rare)axon terminal of one neuron (presynaptic) → axon hillock of another (postsynaptic).
Axodendritic synapseaxon terminal of one neuron (presynaptic) → dendrite of another neuron (postsynaptic).
Transmitter Molecules bind to and trigger receptors on the post synaptic molecule. The distance they travel is 20 nm, the width of the synaptic cleft.
Release of neurotransmitterexocytosis of vesicles containing. Triggered by calcium influx when action potential reaches axon terminal.
Neurotransmitter receptionacross the synaptic cleft, binds to receptor, opens up ion channels that causes a change in membrane potential of the postsynaptic neuron
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Neurotransmittersare quickly eliminated (destroyed by enzymes, reuptake by presynaptic terminal, or diffuse away) so that they don't persistently stimulate the postsynaptic neuron.
Neurotransmitter moleculesAcetylcholine (ACh), Norepinephrine (NE), Dopamine , Serotonin , Histamine , & ATP
Synaptic knobThe name of the disk on the end of an axonal branch that borders the cleft on the presynaptic side.
When the transmitters leavethe synaptic knobs (due to calcium influx) and travel 20 nm to the other side they open or close ion channels.
Opening ion channels depolarizes (excitatory transmitters) or repolarizes (inhibitory transmitters) the cell membrane of the post synaptic neuron.
FatigueFatigue is when the transmitters run out, so the presynaptic neuron can not send signals to the postsynaptic neuron until they re-uptake more transmitters.
Propagation Between Cells Without Resistance LossThe potential of one neuron is the same as the next (both all or nothing), so there is no resistance loss between cells.
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Section 3

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Resting potential3Na+ out and 2K+ in, leaves - charge inside, + charge outside. K+ can leak out, but Na+ cannot leak in supporting the - charge inside, + charge outside.
Electrochemical gradientrefers to sodium and negative charge outside the cell, potassium and positive charge inside the cell
Stages of an action potentialResting, Depolarization, Repolarization, Hyperpolarization, & Refractory period
Restingcell at rest, sodium potassium pump on, -70 mV, sodium outside, potassium inside, ion channels are closed.
Depolarizationsodium channels open, positive sodium rushes inside, membrane potential becomes +30 mV, lots of sodium and potassium inside.
Repolarizationpotassium channels open (positive potassium rushes outside), sodium channels close (lots of sodium inside), this is opposite of the resting state.
Hyperpolarizationmembrane potential drops below normal level.
Refractory periodthe sodium potassium pump reestablishes the resting state, the neuron can not generate another action potential until the cell goes back to the normal -70 mV.
threshold, all-or-noneresponse means that if a stimulus meets the minimum threshold it will cause the same response as any greater stimulus.
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Sodium–Potassium Pumpmoves 3 sodium outside and 2 potassium inside keeping the cell negative on the inside (negative membrane potential).
Excitatory nerves cause nerves to send a signal (membrane -)
inhibitory nervefibers prevent the signal (membrane +).
Excitatory synapsereceptor binding causes postsynaptic potential to be more positive (depolarization) = if it gets above threshold, action potential results.
Inhibitory synapse receptor binding causes postsynaptic potential to be more negative (hyperpolarization) = makes it more difficult to reach threshold.
Summation two or more nerves firing at the same time.
Temporal summationMultiple signals near each other in TIME are added together
Spatial summationMultiple signals near each other in SPACE are added together
Glial CellsAlso known as neuroglia,Supportive cells in the central nervous system (CNS),Supportive – do NOT conduct electrical impulses.Instead, surround and provide support for and insulation between neurons.Most abundant cell types in the CNS.
Different types of glial cells includeAstrocytes, Satellite cells, Microglia, Schwann cells, Oligodendrocytes
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Section 4

Question Answer
Two subthresholdexcitatory nerves firing at the same time can sum to reach the threshold.
A thresholdexcitatory nerve and an inhibitory nerve firing at the same time, and the resultant signal won't reach the threshold.
Frequency Firing, then quickly firing again.
Muscle Cell/ContractileMuscle contraction occurs by the filament sliding past each other and shortening each cell. The cell folds up like an accordion.
Striatedskeletal muscles, voluntary, has stripes, multiple nuclei shared within the same muscle fiber. Strong, but tire easily = shaped like long fibers.
Smoothvisceral, involuntary muscles, no stripes, single nucleus per cell. Weak, but doesn't tire easily = shaped like almonds, tapered on both ends.
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Cardiacheart muscles, involuntary, has stripes, single nucleus per cell, strong and doesn't tire easily = highly branched, shaped like fibers cross-linked to one another.
Red Muscle Cells (ATP Source)is for endurance activities, the color is myoglobin that prevents fatigue in maintaining posture. Abundant mitochondria produce ATP to be used for endurance activities.
White musclehas few mitochondria due to glycolysis being predominant. fast, but fatigue easily.Equipped for short bursts of glycolysis: stores high amounts of glycogen.
Actin filamentthin filament = has troponin and tropomyosin on it.
Myosin filament thick filament = has myosin heads on it.
Cross bridgemyosin head binds to actin.
Sliding filament model the myosin is able to hook onto the actin and then pull it, shortening the cell.
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Section 5

Question Answer
Rigor mortisno ATP after a person dies, myosin heads can't detach after power stroke, muscle remain in contracted position.
Troponin moves tropomyosin out of the way of myosis heads when Ca+ is high allowing cross bridges to form.
Sarcoplasmic reticulum (SR) smooth ER in muscle = stores calcium, releases them in response to AP.
T-tubuleextension of the muscle cell membrane that runs deep into the cell, so that action potential can reach there.
Muscle contractionNerve stimulates muscle. Action potential runs along muscle cell membrane. Goes deep into the muscle cell via T-tubules.
Sarcomeres"I" and "A" bands, "M" and "Z" lines, "H" zone
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I bandthinnest = thin filaments only = sides of the sarcomere.
H zonefattest = thick filaments only = center of the sarcomere, spans the M line.
A bandcontains both thick and thin filaments, center of the sarcomere spans the H zone.
M lineline of myosin in the middle of the sarcomere, linked by accessory proteins.
Z linezigzag line on the sides of the sarcomere, connects the filaments of adjacent sarcomeres.
Tropomyosinlong protein that spirals along actin, blocks myosin head from cross-linking.
Troponin binds tropomyosin, moves it out of the way when calcium is around.
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Section 6

Question Answer
Other specialized cell typesEpithelial cells , Endothelial cells, Connective tissue cells
Epithelial cellsSquamous, Cuboidal, Columnar , Simple epithelium
Squamousflat.
Cuboidalcube.
Columnarcolumn shaped.
Simple epitheliumsingle cell layer = good for absorption, secretion, filtration, diffusion.
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Simple squamousendothelium, capillary wall, alveolar wall.
Simple cuboidalgland ducts, kidney tubules.
Simple columnarstomach and gut.
Stratified epithelium two or more cell layers = good for protection against abrasion.
Stratified squamousskin.
Endothelial cellsLining on the inside of organs and blood vessels, have rapid diffuse to remove waste CO2 and provide O2 for cellular respiration.
Connective tissue holds organs, tissues or cells in place.
Osteoblastsmake bone
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Section 7

Question Answer
Fibroblasts make connective tissue proper (fats, tendons, ligaments, beneath epithelia).
Chondroblasts make cartilage.
Hematopoietic stem cellsmake blood.
Collagenthe most common fiber type. Very strong. Present in large amounts in dense connective tissue.
Elastic fiberscan stretch.
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Reticular fiberscan branch and form nets. Found in loose connective tissue.
loose fibers lots of fluff (ground substance, cells) = anything that you don't associate with being fibrous = fat, paddings around organs.
dense fiberspredominantly collagen = genuinely fibrous, little fluff (ground substance, cells) = tendon, ligament.
Cartilagechondrocytes + matrix = elastic, flexible, used as padding in spinal discs, ends of bones, ear.
Extracellular matrixsecreted by cells = ground substance (glue) and fibers.
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