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what are the levels of organization in the body
cell, tissue, organ
composed of two or more tissues that act in such a way as to perform a specific function
what are the shapes of the epithelial tissues?
squamous (flat), cuboidal and columnar
permeability barrier that prevents the transport of protein from lumenal to basolateral side of the cell. Helps also hold neighboring cells together.
hold epithelial cells together
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)
actin bands that can encircle a cell, helping to create a strong attachment between the cells.
exocrine vs. endocrine glands
exocrine is when cells secrete a substance intot he lumen, endocrine into the blood.
what are the three layers of skin
epidermis, dermis and subcutaneous tissue
describe the structure of the skin
stratified squamous epithelial cells->outer cells are dead and contain keratin
which straighten the hair shaft that surrounds hair follicles, innervated by nerves which cause them to contract at specific times
fibroblasts secrete many types of cells, which are they
- structural cells include collagen, reticulin, and elastin.
- -bond and cartilage are also structural connective tissue.
what are bone and cartilage secreted by?
- collagen in bone is secreted by osteoblasts
- cartilage is secreted by chondrocyte
what releases histamine in response to allergic reaction, infection or injury?
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.
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.
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.
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)
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)
how and where is ACh synthesized?
ACh synthesized in the cytosol of the neuron from acetyl CoA and choline
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.
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.
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
what are the levels of muscle cells?
muscle cells, myofribrils, actin/myosin.
what is a sarcomere
each contractile unit of muscle, bounded by Z-line. Each sarcomere contains actin and myosin.
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.
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.
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.
what is the sarcoplasmic reticulum?
membrane surrounding myofibril (Calcium is sequestered there)
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
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.
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.
what is the ultimate determinant of muscle contraction?
concentration of ATP
what is ganglion?
is a grouping of nerve cells. Groupings of neurons in higher animal lead to more elaborate sense organs.
what are the three divisions of the brain?
what are the components of forebrain?
cerebrum (left and right cerebral hemispheres), thalamus, and hypothalamus
what is the pituitary gland?
master endocrine gland; receives info from the hypothalamus and sends out info to regulate different parts of the body.
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.
what is the difference between afferent and efferent systems?
afferent: if neuron carries info into spinal cord and brain
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.
synapse that is inhibitory; synapse with motor neuron that innervates the bicep. when bicep muscle contracts, lower portion of the leg bends or flexes
- 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.
what are the sympathetic division?
- has nerve fibers branching from the thoracic and lumbar regions of the spinal cord.
- preganglionic nerve fibers are short
one that releases hormones
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.
what is a receptive field?
end of neuron divided into many branches, which can end at a receptor.
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.
secondary active transport
do not use ATP directly but use the energy stored in a concentration gradient est. across a cellular membrane.
what is the electrochemical gradient?
difference between the membrane potential and the equilibrium potentials for the ion in question.