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49 Cards in this Set
- Front
- Back
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how often does the our blood make a complete circuit thru the body
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q minute
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how fast do nervous electrical signals travel
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up to 120 m/sec = 268 mi/hr
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what are the 3 routes cells communicate with each other
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simple diffusion, circulatory system, nervous system
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homeostasis
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process of maintaining a stable internal environment
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what body systems control homeostasis
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endocrine and nervous
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how many cells in human body
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75 trillion
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what are the 2 types of physiological signals
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electrical and chemical
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what are the cells that receive signals called
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target cells or targets
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what are the 4 basic methods of intercellular communication
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gap junction, contact dependent signals, local communication, long distance comm
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what is a gap junction
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direct cytoplasmic transfer of electrical and chemical signals between adjacent cells
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what's contact dependent signal
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surface molecules on adjacent cells bind
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what's local communication
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via chemicals in ecf
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what's long distance comm
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combo of electrical and chemical signals
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what are the gap channels made out of
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membrane spanning chons = CONNEXINS, that form a channel (CONNEXON) that can open/close
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when channel is open, connected cells function as
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a single cell with multiple nuclei (synchtium)
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how many different variants of connexins are there
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20
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what are variants of one protein called
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subtypes or isoforms
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what are variants of one enzyme called
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isozymes
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where are gap junctions found
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every cell type
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what do contact dependent signals require?
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cell to cell contact
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where does contact dependent comm occur
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in immune system, and during growth and development
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what are CAM's
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cell adhension molecules. membrane spanning chons (like G proteins)
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what is a paracrine and an example
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para = besides. crine = secrete. chemical secreted by ANY cell to act on cells BESIDE it. example - histamine (released by damaged cells)
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what's an autocrine
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auto- self. acts on cell that secreted it.
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how to paracines and autocrines reach their targets
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diffusion thru interstitial fluid, very limited in distance, act on same or very close cells
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groups of molecules that act as paracrines (2)
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cytokines (peptides) & eicosanoids (lipids)
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what cells are targets for hormones
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ONLY those with receptors for that hormone
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which system uses both chemical and electrical signals to communicate, and how does this work
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nervous. elecrical signal travels neuron to the end - translated into chemical signal secreted by neuron (NEUROCRINE)
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neurocrine signals (3)
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neurotransmitter if diffuses to target with rapid response. neuromodulator if acts slowly. neurohormone if diffuses into bloodstream
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what's a cytokine
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paracine regulatory peptide comm molecule, somewhat like hormone. secreted by all eukaryotocytes. act on broad spectrum of targets. made on demand. example erythropoietin
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are cytokines autocrines or paracrines?
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both.
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can cytokines travel through the circulation?
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yes.
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what's a ligand
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a signal molecule, the finger that pushes the elevator button. aka first messenger.
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what activates the receptor
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ligant receptor binding (finger pushing elevator button)
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what does the receptor do once activated
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activates 1+ intercellular signal molecules
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what does the last signal molecules in pathway do
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initiates synthesis of TARGET PROTEIN or modifies existing target chon to create RESPONSE
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signal pathway steps
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signal molecule --> receptor chon --> intercellular signal molecules --> target proteins --> response
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what are the 2 types of chemical signal molecules (hint - membrane permeability)
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lipophobic and lipophilic
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where are target protein cell receptors located?
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plasmalemma, cytosol, nucleus
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what do the lipophilic signal molecules do & what happens next
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diffuse thru p/l bilayer & bind to cytosolic or nuclear receptors. usu this turns on gene & directs nucleus to make new mRNA (transcription)
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what is mRNA
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messenger RNA. gets protein recipe from DNA in nucleus (transcription). leaves nucleus and teaches recipe to cell (translation).
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what do lipophobic signal molecules do?
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they can't get in the cell so they bind to external receptor chons
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why do we care about receptor proteins
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1/2 of pharma drugs act on receptors
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what are the 4 categories of receptors
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ligand-gated channel, receptor enzyme, g-protein linked receptor, integrin
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what's signal transduction
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transmission of info across membrane using chons
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what's the first law of thermodynamics
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energy cannot be created nor destroyed, only changed in form
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what's the 2nd law of thermodynamics
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entropy - things go from order to disorder and randomness
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what are 2 ways animals store energy in their bodies
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glycogen in fat cells and in chemical bonds
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what's potential vs kinetic energy
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kinetic - actual movement, potential - has the potential to be converted into kinetic
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