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Physiology 335

Exam I

physiology mechanisms of body function from cells to the whole body;separately and integrated.
cells Functional units;samllest unit of body that still meets criteria of life.Have unique problems within the body(get food/oxygen with all other cells around and get rid of waste other cells bathe it in. Solution is cell specializaton.
cell types 1.epithelial-selective excretion/absorption and protection 2.connective tissue-anchor and support 3.nerve-communication 4.muscle-generate mechanical forces=movement *200 different cell types in these four groups
body fluid compartments Extracellular fluid(14L)=plasma(3L)+interstitial fluid(11L)/Intracellular fluid(28L)=blood cells in capillaries(2L)+body cells(26L)/ECF is homogeneous except more proteins in plasma/ICF helps maintain differences and regulate cell activity.
homeostasis(Ex.of regulated things=Na+,K+,Ca2+,pH,[Glu],O2,CO2,temp.,[blood pressure] Common physiological variables are maintained within a predicatble range;Mechanisms detect deviation from set-point and respond in opposite direction;Has dynamic constancy-Levels change over short periods but remain constant over long periods of time.
negative feedback Most common way to maintain condition of ECF;changes variable to move in opposite direction of original change.Controls compensatory responses to contain homeostasis.
Afferent and efferent pathways in homeostasis (circle) Ex.temperature Change from norm(stimulus),receptor(sensory neuron detects change),afferent pathway(nerves),integratin center(set-point value housed here, compare and if different=response),efferent pathway(blood vessel),effector(organ),response(reverse),neg.feedback
Positive feedback (only three instances in human body 1.childbirth 2.breast feeding 3.ovulation) Accelates process and leads to explosion; needs to have a terminating event to stop(Ex.baby coming out)
Feedfoward Anticipates changes in regulated variables=speeds up homeostatic responses=less deviation from the set-point.Result of learning.Ex.intestine activity increases before a meal(stomach rumbling)
plasma membranes selective barrier;signals can alter;confines products of chemical rxn;phospholipid bilayer and amphipathic(hydrophilic/polar head group and hydrophobic/np tails);fluid mosaic;has proteins to assist movement of ions/molec.s,carbohydrates, and cholesterol.
transmembrane proteins proteins that go all the way through the p.mem. and transport chemicals,ions,water across. Combo of phospholipids/proteins makes it selectively permeable.
integral membrane proteins closely assoc. with membrane, if removed=disruption. Can be either transmembrane or not.
peripheral membrane proteins On membrane surface bound to polar regions of integral mem. proteins;not amphipathic.
nucleus storage/transmission of genetic info. to next cell generation.
nuclear envelope barrier;has nuclear pores for RNA to come in; double membrane
chromatin DNA;becomes chromosomes during division.
nucleolus no membrane;regions of DNA that have genes to form RNA;RNA and protein assembled here
ribosomes make proteins from amino acids;composed of proteins and RNA
endoplasmic reticulum smooth-no ribosomes;branched,tubular stucture;symthesis of lipids, stores/releases Ca2+. rough-has ribosomes attacthed;flattened appearance;involved in protein packaging and secretion
golgi aparatus proteins from ER undergo series of changes, sorted and secreted
endosomes membrane-bound vesicular structures that pinch off
mitochondria produces energy from chemical bonds to ATP;cellular respiration;inner layer(folded cristae) and outer layer mem.(smooth)
lysosomes break down bacteria/debris;important to defense
peroxisomes consumes molecular oxygen to remove hydrogen from lipids,alcohol;product=H2O2;break down fatty acids
vaults important for molecular transport b/w cytosol and nucleus;drug sensitivity
cytoskeleton protein filaments in cytoplasm that maintain shape and produce movement;3 types:1.microfilaments(Mj.portion)2.intermediate filaments(less readily disassembled)3.microtubules
cytoplasm vs cytosol cytoplasm=everything b/w nucleus and p.mem. and cytosol=only the fluid
"life" ability to locally violate the 2nd law of thermodynamics(universe tends towards disorder);cells maintain the nonrandom distribution of molec.s across the mem.=homeostasis maintains life.
diffusion over time, molecules placed in solvent will equally distribute themselves because of thermal motion/random collisions of molec.s.Diffusion equillibrium=concentrations of each compartment are equal so NET flux=0.Useful for cell dimensions,bigger= too LONG
thermal motion all molec.s in continuous state of movement/vibration because of constant collisions.warmer=faster,bigger=slower,more molecs=faster,more surface area=faster,medium matters too(Ex.air is slower than water); move from high conc. to low
net flux difference b/w two one-way fluxes; therefore, always 3 different fluxes for every surface.Increases with bigger gradient and surface area.
permeabilty of membrane dependent on: ion channels and hydrophobic(lipid soluble[O2,CO2,steroids,fatty acids]) and hydrophilic(large polar molecs and ions)
Channel types opening of channles results from conformational changes in integral proteins.Channels selective for certain ions and/or gated by electrical(accumulation of charger),chemical(NTs),mechanical(touch,pressure)events
electrochemical gradient Membranes can be charged and charge AND gradient influences flux of ion.
carrier-mediated transport three types:1.facilitated(flux in same direction as predicted by gradient) 2.primary active transport 3.secondary active transport(2and3 have flux opposite of predicted by gradient)
faciliated diffusion down concetration gradient;NO energy required.Molec binds, protein clicks then molec diffuses out to other side. Ex. glucose entry into cells
primary active transport (Ex. Na+/K+-ATP-ase pump!) against gradient(creates one) and uses energy by DIRECTLY splitting ATP.3Na+ and ATP bind, ADP ripped off and P left=conformational change so Na not comfy and released on other side,2 K+ come in P leaves=conformational change and K leaves on other side.
secondary active transport against concentration gradient and energy provided by another molecs'gradient(usually Na[binds to create affinity for solute to attatch).Cotransport:ion and second solute cross mem. in same direction vs countertransport. Needs primaryAT near for gradient
Factors that influence flux in diffusion, only limited by gradient(=HIGH flux rate). In carrier-mediated limited by # of transport proteins,extent of saturation, of binding sites, and comformational change in transport protein.
osmosis net diffiusion of water across a mem. facilitated by aquaporins so faster.Movement of water equalizes the solute.More solute=less water.Ions lower water conc in proportion to # of ions.(Ex. NaCl=1molNa,1molCl=2mol solute=lower water 2x as much.
osmole vs moles all particles to be counted vs Avogadro's number of specific particle.
osmolarity total solute concentration of all solutes;more osmolarity= less water conc.If only permeable to water same conc will be reached but only water will move= diff amount of water on each side.usually 285-300 mOsm in ECF/ICF.
osmotic pressure pressure that must be applied to soln. to prevent net flow of water into it. more osmolarity=more osmotic pressure needed.
isotonic solution(only nonpenetrating solute) solution that does NOT cause change in cell size; solute conc inside=outside
hypotonic solution (only nonpenetrating solutes) Solute is lower in ECF than usual=water moves into cell=swells
hypertonic soution (only nonpenetrating solutes) Solute is higher in ECF than usual=water moves out of cell=shrinks
isoosmotic(300mOsm/L),hypoosmotic(less than 300),hyperosmotic(greater than 300) solutions tells of osmolarity of solution regardless of whether or not the solution is penetrating or nonpenetrating.
endocytosis entry into cell;process to move large particles, use vesicles;require ATP and membrane proteins.1.phagocytosis 2.pinocytosis-cell drinking 3.receptor-mediated
phagocytosis/pinocytosis "cell-eating"Engulf bacteria, fuse into vesicles, migrate and fuse to lysosomes.Only special cells have like immune system.Pinocytosis same but with liquid-like particles.
receptor-mediated specific molecs bind to specific receptors=conformtional change.Clathrin protein goes to p.mem. and forms clathrin-coated pit=pinch off=form vesicle.Localize receptors=more concentrated=don't have to engulf so much ECF;Clathrins recycled. Ex.cholesterol
potocytosis receptor-mediated type restricted by ligands to small molecs.Tiny caveolae pinch off and deliver contents to the cytosol.Help in cell signaling and transport.
exocytosis exit from cell;usually through ER,golgi,vesicle,fuse w/ p.mem. and out.Replaces p.mem. so stays constant.
central nervous system brain and spinal cord
peripheral nervous system nerves that connect CNS to muscles,glands,organs,sensory organs.Divided into 1.somatic and 2.autonomic. and 2 divided into parasympathetic and sympathetic.Helps homeostasis cuz receives info from external environ/ECF,integrates,directs cell activities.
afferent division of PNS somatic sensory(sensing your body),visceral sensory(sensations of organs),special sensory(five sense).Towards CNS.
efferent division of PNS somatic motor(conscious use of skeletal muscles),automoic motor(mostly unconscious;sympathetic[fight or flight],parasympathetic[rest and digest],enteric).Exiting CNS.
neurons individual nerve cell;basic unit of NS;generate electrical signals=NTs to release and communicate with other cells.
neuronal structure dendrites/soma=receive info(graded pot.),initial segment(axon hillock)=info integrated/decide if fire,axon collateral=branching(More=bigger influence),axon=carry info(AP)away,axon terminal=(tons of processes)communicate w/ dendrites of neighboring neuron.
glial cells 90% of NS cells;surround soma,axon,dendrites and provide physical/metabolic support.
Three types of glial cells 3 types:1.oligodendroctye-forms myelin sheath around CNS axons(Schwann cells does for PNS)2.astroctye-regulate comp. of ECF/stimulates tight junction formation=blood-brain barrier3.microglia-macrophage-like specialized for CNS.
neuronal communication based on changes in mem. permeability to ions. results in graded potential or action potential.
membrane potentials seperated charges=potential to do work; phospholipid bilayer=high electrical resistance and open ion channels=low resistance=current;cells each have own potential.at rest=negative(-70).most of ECF/ICF is electroneutral(tiny #ions=change in potential)
establishing the resting membrane potential Na+/K+ ATPase pump sets up and maintains concentration gradients;K+ dominated (leak channels)
Nernst Equation E_k = (61/z)(log[Ko]/log[Ki]) ; Nernst potential = how many ions leave to make electrical gradient (K = -90mV Na = +60mV)
Steady State Constant but needs energy vs. equilibrium does not need energy
Chloride Two cases: 1(most common); RMP sets the Cl-, Cl- adjusts to match. 2(minor); Cl- pumping out=less likely to depolarize.
Membrane Potential Changes -70 = polarized. depolarized=towards zero. overshoot=charge reversal. repolarize=back towards resting. hyperpolarize=more negative.
Graded Potential proportional to size of stimulus, decrease with distance from stimulus, can depolarize/hyperpolarize,can summate, short distance signals that rely only on ionic currents
Action Potential ion increases permeability of membrane=AP driven to equilibrium potential of that ion;fast voltage gated depolarization=channel confirmational changes(Na+,ball and chain,open/closed/inactivated).slow depolarization favors open/closed channels(K+)
Action Potential needs stimulus strong enough to = threshold(-55) & cause positive feedback(threshold stimulus);propagation of AP=1-way(absolute refractory period,Na+ open/inactivated);all or none,cannot summate,propagate over long distances(do not decrease with distance)
Action Potential Propagation 1.unmye.=slow 2.mye.=fast(saltatory conduction);Schwann's cells make mye. in PNS & oligodendrocytes make in CNS;no Na+ chanels under mye.=AP jump from nodes of Ranvier;velocity incr. w/ axon diam EX mye.=speed=motor neurons/nonmye.=no hurry=digestive reg
Synaptic Transmission convergence 4:1 vs divergence 1:4 1. elect. EX. gap junctions-conduct electrical signals forom cell to cell(fast),found b/w heart&smooth muscle cells 2. chem;AP propagates to terminal Ca chanels open and flow in=vesicle exocytosis=NTs diffuse across cleft
Post-synaptic excitatory events (chemical) 1. NT binds to receptor 2. ligand gated chanels open 3. cations flow through(Na+) 4. net effect=depolarization(EPSP)
Post-synaptic inhibitory events (chemical) 1. same 2. same 3. either K+ out of Cl- in 4. hyperpolarization/prevent depolarization(Cl-);IPSP
Chemical synaptic transmission post-synaptic potentials=short because 1. NT rapidly binds/unbinds 2. NT reuptake into presynaptic terminal/destruction 3. NT diffuse away from synapse
Temporal summation vs Spatial summation A. 1 synaptic neuron keeps firing=adds if in time(graded potential). B. 2+ input to neuron,effect of 2 neuronal stimulation added up in space. helps reach threshold
IPSP vs EPSP receptor determines if IP or EP,but some NT consistantly one or other EX. acetylcholine=excitatory,NE/Epi=depends,glutamate=excitatory GABA and glycine=inhibitory
Presynaptic inhibition/facilitation facilitation=increase in depolarization and NT release. inhibition decreases depolarization/NT release(axo-axonic neuron;A influences B w/ indirect effect on C)
Neuromodulators (*second messenger systems Ex. signal trasnduction pathway) presynaptic inhibition/facilitation. effects strength of synapse,small peptides released w/ NT,activate 2nd messengers,can interact w/ pre/post-receptors
Chemical Synaptic Transmission 2 1. long-term potentiation(cellular mechanism of learning/memory) 2. persistance of NT=desensitization 3. synapses vulnerable to drug/disease
Drug/Disease Effect on Synaptic Transmission 1. Tetanus toxin disrupts NT release(protease eats SNAREs=no vesicle fusion);alter CNS IPSPs=lockjaw 2. Botulism same cause;notable effects in periphery Ex.face-lift=no wrinkles=no control of face 3. Cocaine prevent NT uptake=keep euphoria going
Drugs/Diseases Continued 4. Seratonin Reuptake Inhibitors seratonin kept in synapse=alter mood=depression prescription 5. Ethanol reduced glutamate effects and increased GABA effects=inhibitory
Agonists vs Antagonists A. same response as NT B. block response to NT by occupying the receptors
Possible Drug Effects on Synaptic Effectiveness Increased NT release into synapse,prevention of NT release into synapse,reduced reuptake of NT from synapse,reduced degradation of NT in synapse
Central Nervous System Brain=forebrain(cerebrum/diencephalon[thalamus/hypothalamus]);brainstem=midbrain,pons,medulla oblongata;cerebellum;cerebrum(cortex=grey matter,white matter[axons and myelin]);limbic system functions in learning,emotion,apetite,sex
Peripheral Nervous System 1. somatic-single neuron between CNs and muscle cells,enervates skeletal muscle,inly excitation. 2. autonomic-2neuron chain between CNS and effector organ,enervates smooth/cardiac/glands/GI neurons,excitatory or inhibitory depends on receptor
Autonomic Nervous System Parasymp-discrete,long gang(rest&digest),Symp-activates processes facilitating physical exertion,inhibits those that don't help,generalized(divergences in ganglion)(fight or flight).Dual enervation=typical pattern,effects on organs opposite,but both exist
General Sensory Principles (Terminology) Sensory receptor-2 types(axon or separate cell).Stimulus-forms of energy(temp,light,pressure).TRansduction-eergy converted into electrical signal that's sent into CNS.Receptor potentials-graded potentials
Encoding of Sensory Inputs Based on: 1. stimulus type-design of receptor determines its adeuate stimulus. 2. stimulus intensity-AP frequency. 3. stimulus duration-fast adapt(on/off signal,tells change),slow adapt. 4. stimulus location-acuity is the precision of localizing stimulus
Stimulus Location; Acuity A. Size and B. Density of recept fields. A. littler field=more acuity B. more density=more acuity(Ex. lips vs back).overlapping recept fields-enables us to feel 1+ modality form same stimulus&enables CNS to know where stimulus was cuz in center=more dense
Labeled Lines Specific axons from sensory centers into cerebral cortex,goes to same place every time,terminate in regions of brain dedicated to each area/modality.clinical examples-phantom limb
Association Areas In cortex, integrate/process sensation into perception.things can affect perception-receptor adaption,emotions,personality,experience,damaged pathways(Ex. toddlers)
Somatic Sensations Touch, pressure, temp, pain, body position/movement/balance
Pain Naked nerve endings responding to intense deformation and chemical ligands released with tissue damage(histamine, cytokines, prostaglandins).analgesia relieves pain(ex. aspirin block synthesis of prostaglandins)
Referred Pain Labeled lines convergence misinterpret pain(location feel pain=surface)
Pupil Can dilate/contract=opening allows light
Iris Colored part;smooth muscles inside=change pupil
Scelera White part; tough and fibrous; cornea=clear covering over eyes
Lens Focus light rays; behind cornea
Chorid Lines back of eye; dark, absorbs light=prevents reflection from back of eye
Aqueuous Humor/Vitreous Humor Aqueous=between lens and pupil, vitreous=behind
Fovea centralis Highest visual acuity
Optic nerve Collection of axons projecting to brain
Ciliary muscles Controls shape of lens. relazed C. muscles=zonular fibers tense=flat lens=view from distance. contract C. muscles=slackened zonular fibers=ronded lens=view from near
Visual accomodation To see near object, ability to bring into focus
Presbyopia Lens won't snap back and round, as age lens gets stiff/less elastic=lose ability to focus up close
Rods (Photoreceptor cell) Respond in dim light, located in periphery, low acuity but high sensitivity, no color vision
Cones (Photoreceptor cell) Require bright light, dense around fovea, high acuity but less sensitivem color vision
Photo Transduction 1. no light striking photor=cGMP is high=photor depol=inhib NTs released onto bipolar cell=bip hyperpol=no EPSP=no AP to brain. light strikes photor=cGMP levels fall=photor repol=no inhibitory NTs released=bipolar spont depol=EPSP=AP to brain
Created by: snakano