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what are the levels of organization in the body
cell, tissue, organ
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composed of two or more tissues that act in such a way as to perform a specific function
organ
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what are the shapes of the epithelial tissues?
squamous (flat), cuboidal and columnar
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tight junction
permeability barrier that prevents the transport of protein from lumenal to basolateral side of the cell. Helps also hold neighboring cells together.
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desmosomes
hold epithelial cells together
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gap junctions
allow water soluble molecules to pass from one cell to another. These allow for equilibrium within the connected cells (allows them to function as a unit)
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adherens
actin bands that can encircle a cell, helping to create a strong attachment between the cells.
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exocrine vs. endocrine glands
exocrine is when cells secrete a substance intot he lumen, endocrine into the blood.
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what are the three layers of skin
epidermis, dermis and subcutaneous tissue
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describe the structure of the skin
stratified squamous epithelial cells->outer cells are dead and contain keratin
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erector muscles
which straighten the hair shaft that surrounds hair follicles, innervated by nerves which cause them to contract at specific times
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fibroblasts secrete many types of cells, which are they
- structural cells include collagen, reticulin, and elastin.
- -bond and cartilage are also structural connective tissue.
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what are bone and cartilage secreted by?
- collagen in bone is secreted by osteoblasts
- cartilage is secreted by chondrocyte
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what releases histamine in response to allergic reaction, infection or injury?
mast cells
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what are the components of neuron?
- cell body (integration of info)
- dendrites (receiving and transmitting info)
- axons (conduct info away from the cell body)
- neurotransmitters (end of synaptic bulbs.
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what are the relative concentrations of K+ and Na+ inside and outside the cells?
- K+ is greater in the cell. Na+ is greater outside the cell. cells have greater permeability to K than Na+. When either atom leaves, it sets up a voltage from the concentration gradient.
- force of diffusion is greater than force of electrical force.
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how does one reduce the plasma membrane potential?
- increase membrane permeability to Na+ by stimulating the nerve (reduction in membrane potential is depolarization)
- when threshold is reached, then a burse of Na ions enter cell and generate an action potential.
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the process of depolarization
- as depolarization happens, its permeability to Na becomes much greater than its permeability to K.
- reaches about 40mV (no more influx of Na into the cell) and ion channels that let Na+into the cells close and become temporarily inactive (refractory period)
- K channels open (repolarization) and membrane potential passes -80mV (hyperpolarization)
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what are myelinated cells composed off?
- glial cells and unmyelinated axons. and nodes of ranvier
- glial cells in the PNS is called Schwann cells, while glial cells int he CNS is called oligodendrocytes
- salutatory conduction (jump from node to node)
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how and where is ACh synthesized?
ACh synthesized in the cytosol of the neuron from acetyl CoA and choline
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what happens when Ca2+ flows into the terminal region of the neuron?
causes synaptic vesicles to fuse with the presynaptic membrane and release their neurotransmitters to the synaptic cleft. Ca2+ release is triggered by action potentials.
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explain process of neuromuscular junction.
- Ca released in response to stimulus, which causes synaptic vesicles to fuse with presynaptic membrane and release the NT.
- NT bind to postsynaptic membrane receptors, that cause receptor to become channel that allows Na+ through. As Na+ enters, the muscle fiber depolarizes and action potential is generated.
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what is the difference between excitatory and inhibitory postsynaptic potential
- excitaotry causes increase in permeability of the postsynamptic membrane to Na+, hence neuron b will depolarize
- inhibitory causes increase in postsynaptic membrane to K+ and Cl-, causing hyperpolarization, which does not generate an action potential
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what are the levels of muscle cells?
muscle cells, myofribrils, actin/myosin.
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what is a sarcomere
each contractile unit of muscle, bounded by Z-line. Each sarcomere contains actin and myosin.
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what is the structure of actin and what are they made up of?
- G actin makes up actin; actin grows by addition of G actin to the ends of already existing filament. Composed of 2 rows of actin monomers in a helix.
- actin are attached to Z lines.
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how do actin and myosin move?
- when muscle is relaxed: ATP is bound to the myosin head
- when ATP is hydrolyzed, the myosin undergoes conformational change that it interacts with actin.
- the interaction with actin and myosin causes release of Pi and ADP->conformational change so that they shift in a direction away from the Z line (rigor state)
- ATP binds to myosin is when myosin is released from actin.
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what is the role of tropomyosin?
- resides in the actin groove, covers up the binding sites for myosin heads
- when calcium is bound to subunit of the troponin complex, it causes the tropomyosin to shift its position and expose the myosin head binding sites.
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what is the sarcoplasmic reticulum?
membrane surrounding myofibril (Calcium is sequestered there)
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what is the t-tubule
- invaginations of the sarcolemma surround each myofibril and follow the Z lines.
- after action potential crosses, it passes down each T-tuble and stimulates release of Ca from the sarcoplasmic reticulum.
- Ca binds to binding site on troponin. Each sarcomere contracts simultaneously
- once contraction is done, Ca2+ in cytosol is pumped back into the sarcoplasmic reticulum by Ca2+ ATPase pump
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what are some ways the strength of the muscle contraction can be varied?
- size of the motor unit (motor neuron and muscle fibers that it innervates)
- number of available motor units (need more units to pick up heavier objects
- amount of action and myosin contained with each cell.
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what are motor neurons?
nerve cells whose cell bodies are located in the CNS (spinal cord or brain stem) and whose myelinated acons innervate skeletal muscle.
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what is the ultimate determinant of muscle contraction?
concentration of ATP
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what is ganglion?
is a grouping of nerve cells. Groupings of neurons in higher animal lead to more elaborate sense organs.
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what are the three divisions of the brain?
- forebrain
- midbrain
- hindbrain
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what are the components of forebrain?
cerebrum (left and right cerebral hemispheres), thalamus, and hypothalamus
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what is the pituitary gland?
master endocrine gland; receives info from the hypothalamus and sends out info to regulate different parts of the body.
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what is the difference between CNS and PNS?
CNS is the brain and the spinal cord, while PNS is where the nerves extend out from the spinal cord.
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what is the difference between afferent and efferent systems?
afferent: if neuron carries info into spinal cord and brain
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monosynaptic reflex arc
is the synapse from a sensory to a motor neuron that immediately leaves the spinal cord and returns to the quadricep muscle.
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interneuron
synapse that is inhibitory; synapse with motor neuron that innervates the bicep. when bicep muscle contracts, lower portion of the leg bends or flexes
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parasympathetic system
- parasympathetic: nerve fibers that leave from the sacral portion (butt end of the spinal cord and from the midbrain and medulla.
- ganglia of the division lie near or in the organs that are to be innervated. preganglionic are long while postganglionic are short.
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what are the sympathetic division?
- has nerve fibers branching from the thoracic and lumbar regions of the spinal cord.
- preganglionic nerve fibers are short
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endocrine gland
one that releases hormones
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difference between somatic and autonomic nervous system
- somatic: once nerve fibers leave CNS, they do not make synapse until they have reached effector organ. it innervates skeletal muscle
- autonomic: leave CNS, synapse with ganglion before effector organ, innervates glands can be excitatory or inhibitory.
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what is a receptive field?
end of neuron divided into many branches, which can end at a receptor.
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what is facilitated diffusion?
molecules that require carriers to help transport. Rate of diffusion will increase until all of the carrier bonding sites on the membrane transport protein are filled.
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secondary active transport
do not use ATP directly but use the energy stored in a concentration gradient est. across a cellular membrane.
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what is the electrochemical gradient?
difference between the membrane potential and the equilibrium potentials for the ion in question.
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