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100 Cards in this Set
- Front
- Back
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Nucleus
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Contains all DNA in an animal cell (except for small amount in mitochondria)
Distinguishes eukaryotes (nucleus) from prokaryotes (no nucleus) |
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Nuclear envelope (membrane)
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Double phospholipid bilayer that wraps the nucleus
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Nuclear pores
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Large holes that perforate the nucleus
RNA exits nucleus through these pores, but not DNA |
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Nucleolus
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Area within nucleus where rRNA is transcribed and subunits of ribosomes are assembled
Not separated from nucleus by a membrane |
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Endocytosis
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Way in which cells can acquire substances from extracellular environment
Several types |
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Types of endocytosis
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1. Phagocytosis
2. Pinocytosis 3. Receptor mediated endocytosis |
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Phagocytosis
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Cell membrane protrudes outward to envelope and engulf particulate matter
Only a few specialized cells are capable of this Antibodies or complement proteins bind to particulate matter, which then bind to protein receptor on phagocytotic cell and initiate phagocytosis Macrophages and neutrophils |
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Pinocytosis
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Extracellular fluid is engulfed by small invaginations of the cell membrane
Performed by most cells in random fashion (nonselective) |
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Receptor mediated endocytosis
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Specific uptake of macromolecules (hormones and nutrients)
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Exocytosis
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Reverse of endocytosis
Expel material out of cell |
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endoplasmic reticulum (ER)
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Thick maze of membranous walls separating the cytosol from the ER lumen (cisternal space)
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Cytosol
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Aqueous solution inside the cell
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ER lumen (cisternal space)
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Extracellular fluid inside the ER
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Rough (granular) ER
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ER near the nucleus
Flattened sacs Has many ribosomes attached to it on the cytosolic side, giving it a granular appearance Translation on the rough ER propels proteins into the ER lumen as they are created |
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Golgi apparatus (complex)
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Newly synthesized proteins are moved through ER lumen towards golgi
Series of flattened, membrane sacs Organizes and concentrates proteins as they are shuttled by transport vesicles progressively outward from one compartment (cisterna) of golgi to the next |
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Secretory vesicles
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Protein filled vesicles leaving golgi to be expelled from cell
enzymes, growth factors or extracellular matrix components release contents through exocytosis Mechanism to supply cell membrane with integral proteins and lipids Mechanism for membrane expansion |
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Lysosomes
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contain acid hydrolases (hydrolytic enzymes that function best in acidic environment; proteases, lipases, nucleases and glycosidases)
Capable of breaking down every major type of macromolecule within the cell Interior pH of 5 Fuse with endocytic vesicles and digest their contents |
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Smooth (agranular) ER
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ER that lacks ribosomes
Tubular in appearance Contains enzyme to hydrolyze glucose from glycogen Produce triglycerides, which are stored as fat droplets With cytosol, responsible for cholesterol formation Synthesis of phospholipids Oxidizes foreign substances, detoxifying drugs, pesticides, toxins and pollutants |
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Adipocytes
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Cells containing predominantly fat droplets (triglycerides)
Important in energy storage and body temperature regulation With cytosol, responsible for cholesterol formation Synthesis of phospholipids |
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Peroxisomes
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vesicles in cytosol
grow by incorporating lipids and proteins from cytosol self-replicate Production and breakdown of hydrogen peroxide Inactive toxic substances such as alcohol Regulate oxygen concentration Synthesis and breakdown of lipids Metabolizes nitrogenous bases and carbohydrates |
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Cytoskeleton
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network of filaments that determines the structure and motility of a cell
Different types of filaments |
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2 types of filaments of cytoskeleton
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1. microtubules
2. microfilaments |
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Microtubules
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larger than microfilaments
rigid, hollow tubes made from protein called tubulin Have a + end (attaches to MTOC, microtubules grow away from) & - end |
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Tubulin
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globular protein that polymerizes into long straight filaments
13 filaments lie alongside each other to form microtubules 2 different types: 1. alpha tubulin 2. beta tubulin 2 different types gives it spiral appearance |
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Mitotic spindle
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made from microtubules
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Flagella and cilia
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specialized structures made from microtubules
major part called axoneme flagella wiggle causing fluid to move directly away from cell cilia whip causing fluid to move laterally (found only in fallopian tubes and respiratory tract) |
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Axoneme
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major part of flagella and cilia
contains 9 pairs of microtubules forming a circle around 2 lone microtubules in an arrangement known as 9+2 Cross-bridges made from dynein connect each outer pair of microtubules to their neighbor Cross-bridges cases the microtubule pairs to slide along their neighbors creating movement of cilia or flagella |
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Microfilaments
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Smaller than microtubules
Squeeze membrane together in phagocytosis or cytokinesis Contractile force in microvilli and muscle active in cytoplasmic streaming (amoeba-like movement) formed by polymerized actin |
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Centrosome
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major MTOC (microtubule-organizing-center) in cell
Microtubules grow away from attached to + end of microtubules |
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Centrioles
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Function in production of flagella and cilia
not necessary for microtubule production |
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3 types of junctions that connect cells
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1. tight junctions
2. desmosomes 3. gap junctions |
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Tight junctions
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form a watertight seal from cell to cell
can block water, ions and other molecules from moving around and past cells fluid barriers (bladder, intestines, kidneys) barrier to protein movement between apical (lumen of cavity) and basolateral surface of cell |
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Desmosomes
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join 2 cells at a single point
attache directly to cytoskeleton of each cell do not prevent fluid from circulating around all sides of the a cell found in tissues that experience stress (skin, intestines) often accompany tight junctions |
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Gap junctions
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small tunnels connecting cells
allow small molecules and ions to move between cells in cardiac muscles, they provide the spread of action potential from cell to cell |
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Mitochondria
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powerhouses of eukaryotic cells
where Krebs cycle takes place may have evolved from symbiotic relationship between ancient prokaryotes and eukaryotes (endosymbiont theory) have their own circular DNA (no histones or nucleosomes) that replicates independently from cell (like prokaryotes) mitochondrial DNA is passes maternally surrounded by 2 phospholipid bilayers made up of outermembrane, intermembrane space, matrix, crista and inner membrane |
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Inner membrane
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invaginates to form cristae
holds the electron transport chain |
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Extracellular matrix
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molecular network that holds tissue cells in place
can be most of tissue (bone) or small part of tissue can have different consistancy (bone and blood) provide structural support, help determine cell shape and motility and affect cell growth made by cell itself |
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3 classes of molecules that make up cell matrices
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1. glycosaminoglycans and proteoglycans (pliability)
2. structural proteins (strength) 3. adhesive proteins (stickiness) |
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4 types of tissue
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1. epithelial tissue (separates free body surfaces surroundings)
2. muscle tissue 3. connective tissue (extensive matrix; blood, lymph, bone, cartilage, tendons, ligaments) 4. nervous tissue |
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3 types of communication molecules
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1. neurotransmitters (nervous system, short intercellular gaps)
2. local mediators (paracrine system, interstitial fluid) 3. hormones (endocrine system, throughout organism via blood) |
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Neural communication
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neurotransmitters
short distance between intercellular gaps released by neurons rapid, direct and specific |
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Hormonal communication
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slower, spread throughout body, affect many cells and tissues in different ways
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Interstitial fluid
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fluid between cells
area in which local mediators are released |
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local mediators
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released into interstitial fluid
act on neighboring cells may be proteins, other amino acid derivatives, fatty acids |
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Nervous system
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Made up of:
1. Central nervous system (CNS) 2. Peripheral nervous system (PNS) Includes: Brain, spinal cord, nerves, neural support cells, sensory organs (eyes and ears) |
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Neuron
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Functional unit of the nervous system
Highly specialized cell capable of transmitting an electrical signal from one cell to another via electrical or chemical means Does not divide (in Go) Depends entirely on glucose for its chemical energy do not depend upon insulin to obtain glucose Consists of: dendrites, single cell body, axon and small branches |
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Dendrites
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receive the signal to be transmitted
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Axon hillock
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cytosol of cell body is highly conductive and any electrical stimulus creates a disturbance in the electric field that is transferred immediately to axon hillock
if stimulus is great enough, it generates an action potential in all directions, including down the axon does not have enough ion channels to sustain an action potential |
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Axon
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carries the action potential from axon hillock to synapse, which passes signal to another cell
has enough ion channels to sustain an action potential |
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Possible neural cell structures
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1. unipolar (sensory only)
2. bipolar (retina, inner ear, olfactory area of brain) 3. multipolar (most neurons in brain) |
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Action potential
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a disturbance in the electric field across the membrane of a neuron
-70mV 1. Membrane is at rest. Na+ and K+ channels are closed 2. Na+ channels open and cell depolarizes 3. K+ channels open as Na+ channels being to inactivate 4. Na+ channels inactivate. Open K+ channels repolarize membrane 5. K+ channels close and membrane equilibrates to resting potential |
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Resting potential
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potential difference (voltage) between inside of membrane and oustide
established by equilibrium between Na+/K+ pump and passive diffusion of ions across membrane Na+/K+ pumps moves 3x Na+ ions out of cell while bringing 2x K+ into cell increases positive charge along membrane outside of cell relative to charge along membrane inside cell rate at which Na+ passively diffuses back into cell increases until it equals rate at which it is being pumped out Same thing happens for potassium When all rates reach equilibrium, the inside of membrane has negative potential difference (voltage) compared to outside |
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Voltage gated sodium channels
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integral proteins in membrane of neuron
change configuration when voltage across membrane is disturbed allow Na+ to flow through membrane (into cell) as they change conformation As Na+ flows into cell, voltage changes more causing more sodium channels to change conformation allowing for Na+ to flow into cell Positive feedback mechanism |
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Depolarization
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Na+ concentration moves toward equilibrium
K+ concentration remains higher inside cell, causing the membrane potential to reverse polarity = positive inside cell and negative outside |
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Voltage gated potassium channels
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integral proteins in neuronal membrane
less sensitive to voltage change, therefore take longer to open By the time K+ channels open, Na+ channels are closing K+ flows out of cell making inside more negative = repolarization |
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Repolarization
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K+ flows out of cell making inside more negative
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Hyperpolarization
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K+ channels are so slow to close, that inside membrane becomes even more negative than resting potential
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All-or-nothing
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membrane completely depolarizes or no action potential is generated
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Threshold stimulus
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In order for action potential to be generated, stimulus has to be greater than the threshold stimulus
any stimulus greater than threshold stimulus creates same size action potential |
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Synapse
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where neural impulses are transmitted from one cell to another chemically or electrically
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Electrical synapse
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uncommon
composed of gap junctions between cells Cardiac muscles, visceral smooth muscles, few neurons in CNS Do not involve diffusion, therefore transmit signals (in both directions) much faster than chemical synapses |
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Chemical synapse
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common, unidirectional (only one direction)
called a motor end plate when connecting a neuron to a muscle small vesicles filled with neurotransmitters rest inside presynaptic membrane membrane contains many Ca+ voltage gated channels action potential activate Ca+ channels allowing Ca+ to flow into cell sudden influx of Ca+ causes neurotransmitter vesicles to be released through exocytosis into synaptic cleft slowest step in transfer of nervous signal |
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Brownian motion
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random motion of molecules
way in which neurotransmitters diffuse across synaptic cleft |
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Neurotransmitter
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attaches to neurotransmitter receptor on postsynaptic membrane, creates influx of ions, transmits signal, released into synaptic cleft
Digested by enzyme in matrix synaptic cleft and its parts recycled by presynaptic cell Directly absorbed by presynaptic cell via active transport Diffuse out of synaptic cleft a single synapse usually releases only one type of neurotransmitter designed to inhibit or excite (not both) |
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Second messenger system
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neurotransmitter attaches to receptor which activates another molecule inside cell to make changes
preferred for prolonged changes (memory) G-proteins (attached to receptor protein along inside of postsynaptic membrane initiate second messenger systems |
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G-proteins
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G-proteins are attached to receptor protein along inside of postsynaptic membrane
commonly initiate second messenger systems when receptor is stimulated by neurotransmitter, part of G-protein (alpha-subunit) break free and: 1. activates separate specific ion channels 2. activates second messenger (cAMP or cGMP) 3. activates intracellular enzymes 4. activates gene transcription |
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Myelin
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electrically insulating sheaths that surround axons in CNS
increase speed with which action potential moves down axon produced by schwann cells in PNS produced by oligodendrocytes in CNS myelinated axons appear white (white matter) while neuronal cell bodies appear gray (gray matter) only vertebrates have myelinated axons |
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Nodes of Ranvier
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tiny gaps between myelin
action potential jumps from one node of ranvier to next (saltatory conduction) |
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3 Functions of neurons
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1. Sensory neurons (afferent)
2. Interneurons 3. Motor neurons (efferent) |
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Sensory neurons (afferent)
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Receive signals from receptor cell that interacts with environment
It is the sensory neuron that transfers this signal to other neurons 99% of sensory input is discarded by brain located dorsally (toward back) from spinal cord |
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Interneurons
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transfer signals from neuron to neuron
90% of all neurons in human body |
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Motor neurons (efferent)
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carry signals to muscle or gland (effector)
located ventrally (toward front or abdomen) |
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Nerves
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bundles of neuron processes (axons and dendrites)
known as tracts in the CNS |
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Reflex Arc
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Receptor --> dorsal root ganglion --> sensory neuron --> interneuron --> motor neuron --> effector
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2 divisions of nervous system
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1. central nervous system (CNS)
2. peripheral nervous system (PNS) |
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Central nervous system (CNS)
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consists of interneurons and support tissue within brain and spinal cord
functions to integrate nervous signals between sensory and motor neurons |
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Peripheral nervous system (PNS)
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everything other than brain and spinal cord
handles sensory and motor function sof nervous system divided into 2 systems: 1. somatic nervous system 2. autonomic nervous system |
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Somatic nervous system
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Part of PNS
responds to external environment contains sensory and motor functions motor neurons innervate only skeletal muscle cell bodies of somatic motor neurons are located in ventral horns of spinal cord and synapse directly on effectors and use acetylcholine as neurotransmitter motor functions can be consciously controlled and voluntary sensory neuron cell bodies are located in dorsal root ganglion |
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Autonomic nervous system (ANS)
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sensory portion receives signals from viscera (organs inside ventral body cavity)
motor portion conducts signals to smooth muscle, cardiac muscle and glands function is involuntary motor portion divided in 2 groups: 1. sympathetic 2. parasympathetic 2 system work antagonistically controlled by hypothalamus |
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Sympathetic nervous system
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part of ANS
deals with fight or flight responses increase heart rate and stroke volume constrict blood vessels around digestive and excretory systems in order to increase blood flow around skeletal muscles signals originate in neurons whose cell bodies are found in spinal cord |
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Parasympathetic nervous system
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part of ANS
deals with rest and digest slows heart rate increases digestive and excretory activity signals originate in neurons whose cell bodies are found in brain and spinal cord |
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Acetylcholine
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neurotransmitter used by preganglionic neurons in ANS and postganglionic neurons of parasympathetic nervous system
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Epinephrine or Norepinephrine
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Adrenaline or noradrenaline
neurotransmitter used by postganglionic neurons of sympathetic nervous system |
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Lower brain
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consists of medulla, pons, mesencephalon, hypothalamus, thalamus, cerebellum and basal ganglia
integrates subconscious activities (respiratory system, arterial pressure, salivation, emotions and react to pain and pleasure) |
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Higher brain (cortical brain)
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consists of cerebrum or cerebral cortex
incapable of functioning without lower brain acts to store memories and process throughts |
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5 Types of sensory receptors
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1. mechanoreceptor (touch)
2. thermoreceptor (temperature) 3. nociceptor (pain) 4. electromagnetic receptor (light) 5. chemoreceptor (taste, smell and blood chemistry) transduce physical stimulus to neural signals |
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Cornea
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First part of eye that receives light
nonvascular made of collagen clear, refractive index of 1.4 (bending of light occurs at interface of air and cornea and not lens) |
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Lens
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light enters lens from anterior cavity
converging lens flattening of eye by relaxing ciliary muscles makes lens less powerful (moves focal point away from lens) curving of eye by contracting ciliary muscles makes lens more powerful (moves focal point toward lens) |
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Ciliary muscles
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connected to stiff suspensory ligaments and tug and flatten lens
circles lens contraction closes opening of circle allowing lens to become more spherical, bringing focal point closer to lens, increasing power of lens when muscles relax the lens flattens, increasing focal distance from lens, lessening power of lens |
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Retina
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covers inside of back (distal potion) of eye
contains light sensitive cells called rods and cones since eye acts as converging lens and object is outside focal distance, imagine on retina is real and inverted |
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Rods
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Sense all photons with wavelengths in visible spectrum (390nm to 700nm)
cannot distinguish colors distinguish blacks, whites and grays |
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Cones
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3 types, each with different pigment that is stimulated by different spectrum of wavelengths
distinguish colors |
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Iris
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colored portion of eye that creates opening called pupil
made from circular and radial muscles in dark environment, sympathetic nervous system contracts iris, dilating the pupil and allowing more light to enter in bright environment, parasympathetic system contracts circular muscles of iris, constricting the pupil and screening out light |
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3 parts of ear
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1. outer ear
2. middle ear 3. inner ear |
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Tympanic membrane
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eardrum
begins in the middle ear wave carried hear by external auditory canal |
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Middle ear
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3 small bones:
1. malleus 2. incus 3. stapes act as lever system (change combination of force and displacement from inforce to outforce) translating wave to oval window |
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Cochlea
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detects sound
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Hair cells
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detects movement of vestibular membrane in and out caused by alternative increases and decreases of pressure in cochlea
part of organ of corti movement is detected and transduced into neural signals which are sent to brain do not actually contain hair, but instead contain specialized microvilli which detect movement |
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Semicircular canals
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detect orientation and movement of head
part of inner ear responsible for balance contains fluid and hair cells canals are orientated at right angles to each other in order to detect movement in all directions |
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4 primary taste sensations
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1. bitter
2. sour 3. salty 4. sweet |
