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Kinesiology Exam One - Flashcards

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Class:KINE 304 - Human Physiology
Subject:Kinesiology & Hlth Sciences
University:William and Mary
Term:Spring 2010
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3 types of biological units eukariotic cell, prokaryotic cell, virus
eukaryotic cell has nucleus (sometimes >1), and membrane bound organelles
prokaryotic cell have no true nucleus, or organelles, typically unicellular primitive organisms (algae, bacteria)
virus simplest structure, contains only DNA and protein envelope
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2 major compartments of cell nucleus, cytoplasm
cytoplasm contains cytosol and non-nuclear organelles
protoplasm substances making up the cell, main constituents are water, electrolytes, proteins, lipids, CHOs
4 basic types of cells in body muscle, nerve, epithelial, connective tissue cells
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muscle produce force and enable movement
nerve designed to initiate and coduct electrical signals
epithelial specialized for secretion and absorption of ions and other molecules
connective tissue cells connect, anchor and support structures of body, typically have higher amounts of extracellular matirx (fat cells, bone cells)
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Plasma membrane acts to 1. provide structure to cell; 2. control movement of substances in and out of cell; 3. detect presence of chemical messengers; 4. link adjacent cells together (tissue); 5. anchor ariety of cell proteins (channels, receptors) to cell surface
composition of cellular membrane mainly lipids, proteins and cholesterol; phospholipids have hydrophobic (tails) and hydrophillic (heads) regions (phospate + lipid)
2 types of proteins in lipid bilayer integral proteins (travers entire membrane; form channels or act as carrier proteins); peripheral proteins (typically attached to inner surface of membrane in connection w/ integral proteins. act as enzymes and catalyze many reactions necessary to cells function
3 ways plasma membrane joins cells desmosomes; tight junctions; gap junctions
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desmosomes hold cells together in tissue subject to stretch (little arms sticking out and holding hands)
tight junctions in dense, rigid tissues these hold cells firmly together (capillaries in brain) (part of cell membranes sticking together)
gap junctions allows communication between cells (parts of cell membranes joining and opening up)
Nucleus contains genetic material, chromatin. chromatin becomes more dense and forms chromosomes. nucleus surrounded by porous membrane called nuclear envelope. contains protein and RNA. forms ribosome precursors. all DNA for entire body is in each cell nucleus
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ribosomes found in cytoplasm; function is to synthesize proteins; can be found in association with endoplasmic reticulum or alone in cytoplasm.
Endoplasmic reticulum network of vesicular structures whose walls are made of lipid bilayers. 2 kinds: rough and smooth
rough (granular) ER has ribosomes attached; proteins produced by ribosomes released into ER
Smooth (agranular) ER free of ribosomes; involved in synthesis of lipids and contains calcium which, when released regulates many cellular enzymatic activities
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Golgi Apparatus closely related to ER functions to process and package proteins as they exit ER; proteins placed in vesicles which are transported to various parts of the cell or released from cell. (pinches off own membrane to wrap up protein)
Mitochondria produce ATP (energy). contains 2 lipid bilayer membranes; inner contains many infoldings called cristae where oxidative enzymes are found. releases ATP into cytoplasm
Lysosomes vesicular organnelles formed by golgi apparatus and dispersed throughout cytoplasm. contain acid hydrolases that destroy/digest unwanted substances and damaged organelles (in 2 ways)
peroxisomes use oxygen but not to produce ATP, instead they activate H2O2 which is harmful to cell (hydrogen peroxide)--to destroy infectious cells in scrapes etc
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cytoskeleton filamentous structure that gives shape and stability to cell
4 types of filaments microfilaments (actin); thick filaments (myosin); intermediate (help reduce mechanical stress); microtubules (hollow tube of tubulin, most rigid of filaments, found in elongated neural processes)
diffusion net movement of molecules from one area of higher concentration to area of lower concentration
what affects net flux (of diffusion) 1. temperature (hotter=faster); 2. mass of molecule (larger=slower); medium (gas=fastest, liquid=middle, solid=slowest); surface area (more space=faster); *diffusion time increases by the square of the distance that must be travelled
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how do poloar and charged molecules cross membrane 1. channels; 2. mediated transport; 3. osmosis; 4. endo/exocytosis
Channels (for molecules to cross membrane) integral proteins open and close *movement of ions dictated by electrochemical difference--not just based on concentration
mediated transport (for molecules to cross membrane) used with charged or polar molecules that have no channels; 2 types: (a) facilitated and (b) active transport
facilitated diffusion kind of mediated transport; higher concentration to lower concentration--no energy
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active transport kind of mediated transport (pumps); move molecules against concentration gradient--uses energy. primary--uses ATP, secondary--hitches a ride with either cotransport (same direction) or countertransport (different directions)
Osmosis diffusion of water from higher concentration to lower concentration. (water follows solute) attracted by solutes (#, not size); if membrane permeable to solute in water, equilibrium will be reached, if not, will still reach equilibrium, but there will be a change in volume
osmolarity concentration of solute of a solution; # of mols in 1 L of solution; osmotic pressure
osmolality # of mols of solute in one kg of water
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hypertonic solution extracellular solution > intracellular solution; water leaves; cell shrinks
hypotonic extracellular solution < intracellular solution; water enters; cell swells (and bursts=lysis)
isotonic extracellular solution=intracellular solution
endo/exocytosis endocytosis: membrane invaginates to trap and ingest water or other particles.........................................exocytosis: intracellular vesicles fuse with cell membrane and extrudes particles
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Generalizations about Homeostasis 1. input = output; 2. dependent upon balance of input and output, not magnitude; 3. control systems cannot maintain complete constancy; 4. each variable has normal range of values; *steady state requires energy unlike equilibrium *virtually all homeostatic control systems use neg. feedback (offset disturbance), pos. feedback exacerbates original disturbance
Major Functional Homeostatic Systems 1. Circulatory; 2. Respiratory; 3. Gastrointestinal (digestive); 4. Hepatic (liver); 5. Renal (kidneys); 6. Nervous (fast acting); 7. Endocrine (slower responding)
Flexibility of Homeostasis 1. Establishment of new set points (fever); 2. Natural homeostatic cycles (circadian--daily, circannual--yearly)
Homeostatic Reflex System stimulus-->receptor-->afferent pathway-->integrating center-->efferent pathway-->effector-->response
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Intercellular messengers neurotransmitters (released by neuron to exert influence on effector cell); hormones (typically secreted by glands)
3 kinds of hormones 1. endocrine: released from gland into blood to be carried to activate other organs at some distance (goes through whole body, cells that need it recept its); 2. paracrine: released by some cells/tissue and diffuse into extracellular fluid and interacts via receptors with neighboring cells/tissue; 3. autocrine: released by cells tissue and have impact on same cells/tissue by interacting with membrane bound receptors
receptors binding site occupied by intercellular messenger; made of proteins; 2 broad categories: steroid (intracellular, when bound they act directly w/ DNA), protein/peptide (bound to cell membrane; *increasing # of receptors increases chance of hormone hitting one
Signal Transduction Mechanisms 1. receptor complex incorporating ion channel; 2. protein kinase phosporylates enzymes, affecting cells activities; G proteins (receptor activation-->exchange of GDP for GTP-->activated G proteins interact with effector protein (ion channel or other enzyme))--receptor kicks off a GDP to get a GTP *messengers have unique/specific receptors with unique/specific pathway causing unique/specific response
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Second Messengers 4. G-proteins (inside cytosol; converts ATP to cAMP which activates cAMP dependent kinases)-each step magnifies the effect, can be Gi (inhibatory) or Gs (stimulatory); 5. G-proteins can activate ion channels of membranes of organelles (Ca++); 6. Membrane bound phospholipids
Nervous System can be categorized as: 1.voluntary, 2.autonomic; also as 1.central, 2.peripheral
"Typical" neuron consists of: 1. dendrites (receive info); 2. cell body (soma--carries out normal cellular activities); 3. axon (nerve fiber--carries info toward other cells); 4. axon terminals (transmit message to other cells)
3 basic types of neurons 1. afferent (sensory) conveys impulses to CNS--no dendrites, only bipolar axon, soma lies outside of CNS; 2. efferent (motor) conveys impulses toward PNS, dendrites, soma in CNS; 3. interneurons--only in CNS, connect afferent and efferent neurons
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synapse interface between one excitable cell and another; *signal transducted from pre-synaptic neuron to post-synaptic neuron by neurotransmitter
Glial Cells comprise about 90% of CNS; functions: form myelin sheaths (allow action potential to conduct rapidly), provide metabolic substrates, remove metabolic wastes, provide structure/support for neurons, guide migration of neurons to target cells, may be involved in intercellular communication
resting membrane potential natural electrochemical potential acros neurons membrane (about -75 mV) *within cells there is a higher concentration of nucleic acids, proteins, phosphates, sulfates and K+; outside of cell there is a higher concentration of cations such as Na+ and Ca++ **magnitude determined by: 1.intra- vs extracellular conc. difference of ions, 2.permeability of membrane to specific ions--each ion has its own equilibrium potential across membrane (electrochemical in nature) which is driving force. 2 major ions involved in determining membrane potential are Na+ and K+
Nernst equation determines equilibrium potential for each ion: equilibrium potential (mV) = 61 log (external/internal)
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graded potential caused by ligand-gated channels; slow change in membrane potential; change in potential restricted to small area; intensity=intensity of stimulus; as current diffuses away from site of initiation, its intensity decreases
action potential initiated by voltage-gated ion channels; changes in membrane potential are fast (quick flooding of ions in); self propogating (intensity does not decrease)
hillock between soma and axon; where action potential starts
Nodes of Ranvier gaps on axon not covered by myelin sheath where new action potentials are generated
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Saltatory conduction How action potential jumps from Node of Ranvier to Node of Ranvier; carries impulse to nerve terminals
Synapse structure/space that permits a neuron to pas a signal to another cell. Two tyes: 1.electrical (cell membranes of two excitable cells joined together by gap junctions (uncommon in nervous system); 2.chemical (substance-neurotransmitter-released from terminal of pre-synaptice neuron and binds to post-synaptic receptors)
Mechanism of Synapse AP reaches axon terminal and opens Ca++ channels; Ca++ enters terminal; neurotransmitter bound in vesicles released via exocytosis; neurotransmitter crosses synaptic cleft and binds with receptors on post-synaptic neuron; causes local graded potential of post-synaptic membrane (post synaptic potential)
2 kinds of post-synaptic potential 1. excitory (depolarizing effect) (EPSP); 2. inhibatory (hyperpolarizing effect) (IPSP) *typically one EPSP not strong enough to evoke AP (subthreshold intensity), but additive effects of several are: 1.temporal summation (several EPSPs in quick succession), 2.spatial summation (several EPSPs, from different pre-synaptic neurons, arrive simultaneously)
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Pacemaker Potential some excitable cells (such as cardiac muscle, smooth muscle, some neurons) are able to spontaneously and rhythmically generate AP. *due to greater permeability (leakiness) of those membranes. **resting potential of these cells is less than that of other neurons (about -55mV)
Smooth Muscle (a pacemaker) some voltage gated Ca++ channels open at "resting potential"; Ca++ enters causing depolarization; K+ channels then open; efflux of K+ causes repolarization. think of sine curve
Myocardium (a pacemaker) HEART! resting membrane potential is -55 mV. this membrane leakier to Na+ than other cells. influx of Na+ depolarizes membrane to -40mV (threshold voltage). voltage gated Na+ channels open (fast channels); causes voltage gated Ca++ channels to open (slow phase) ie plateau. ***Na+ quick; Ca++ slow; K+ efflux to repolarize
Three Major Levels of CNS (related to evolutionary development) 1. Spinal Cord Level; 2. Lower Brain Level; 3. Higher Brain (Cortical) Level
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Spinal Cord Level (1st level of CNS) not simply conduit for signals delivered from and arriving at brain; neuronal cicuits in cord control: (A)walking movements (B)reflexes to withdraw limbs from noxious stimuli (C)reflexes to maintain upright posture (D)reflexes that control local blood vessels (E)relfexes that control GI movements ** mostly reflexes
Lower Brain Level (2nd level of CNS) medulla, pons, cerebelllum, hypothalamus, thalamus; controls subconscious bodily functions; arterial pressure and respiration controlled by medulla and pons; equilibrium and balance controlled by cerebellum and medulla; feeding reflexes controlled by medulla, pons, and hypothalamus; lower brain also site of emotions ** mostly basic needs and emotions
Higher Brain (Cortical) Level (3rd level Of CNS) NEVER Functions Alone, always in conjunction w/ lower centers of CNS; fine tunes functions of lower brain; acts as memory storehouse; center of higher thought processes and imagination/creativity; limbic system (unites emotions or other sensations with memories **fine tuning, memory, imagination, higher thinking
Peripheral Nervous System 1. Afferent Division; 2. Efferent Division: (A)Somatic; (B)Autonomic: (I)Sympathetic branch; (II)Parasympathetic branch
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Afferent Division (of PNS) conveys info from peripheral receptors to CNS
Efferent Division (of PNS) carries signals from CNS to muscles or glands; two kinds: somatic and autonomic
Somatic Voluntary; neurons leading from CNS to skeletal muscle (motor neurons), carrying only excitatory signals (Ach); cell body within CNS
Autonomic Involuntary; neurons leading from CNS to all other types of cells (besides skeletal muscle) (glands smooth muscle, cardiac muscle); involves 2 neurons and synapse at autonomic ganglion; outside of CNS *neurotransmitter of pre-ganglionic neuron is Ach; Two kinds: Sympathetic branch and Parasympathetic branch
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Sympathetic Branch STIMULATES; nerves leave spinal cord from thoracic and lumbar regions; post-ganglionic neurotransmitter is norepinephrine; stimulates "fight or flight" response; generally had excitatory effect on organism *adrenal medulla-has specialized autonomic ganglion
Parasympathetic branch CALMS; nerves leave spinal cord from servical and sacral regions; most of this neural info passed along 2 vagus nerves to thoracic and abdominal regions; post ganglionic neurotransmitter is Ach; generally has calming/soothing effect on body
Differences between Somatic and Autonomic Nervous System SOMATIC: 1.consists of a single neuron between cns and effector organ, innvervates skeletal muscle, can lead only to muscle excitation; AUTONOMIC: 1.has two-neuron chain (connected by synapse) between cns and effector organ, innervates smooth and caridac muscle, glands and GI neurons, can lead to excitation or inhibition of effector cells
Blood-Brain Barrier capillaries of brain much less permeable than those to other organs; endothelial cells joined together by tight junctions; anything crossing capillary walls must do so through the cells; must be permeable to cell membrane or use transport protein
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Cerebrospinal-Fluid produced within and fills ventricles of brain; leaves ventricles and bathes exterior of brain and spinal cord (cushions and protects); hydrocephalus: accumulation of CSF
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 3 types of biological unitseukariotic cell, prokaryotic cell, virus
 eukaryotic cellhas nucleus (sometimes >1), and membrane bound organelles
 prokaryotic cellhave no true nucleus, or organelles, typically unicellular primitive organisms (algae, bacteria)
 virussimplest structure, contains only DNA and protein envelope
 2 major compartments of cellnucleus, cytoplasm
 cytoplasmcontains cytosol and non-nuclear organelles
 protoplasmsubstances making up the cell, main constituents are water, electrolytes, proteins, lipids, CHOs
 4 basic types of cells in bodymuscle, nerve, epithelial, connective tissue cells
 muscleproduce force and enable movement
 nervedesigned to initiate and coduct electrical signals
 epithelialspecialized for secretion and absorption of ions and other molecules
 connective tissue cellsconnect, anchor and support structures of body, typically have higher amounts of extracellular matirx (fat cells, bone cells)
 Plasma membrane acts to1. provide structure to cell; 2. control movement of substances in and out of cell; 3. detect presence of chemical messengers; 4. link adjacent cells together (tissue); 5. anchor ariety of cell proteins (channels, receptors) to cell surface
 composition of cellular membranemainly lipids, proteins and cholesterol; phospholipids have hydrophobic (tails) and hydrophillic (heads) regions (phospate + lipid)
 2 types of proteins in lipid bilayerintegral proteins (travers entire membrane; form channels or act as carrier proteins); peripheral proteins (typically attached to inner surface of membrane in connection w/ integral proteins. act as enzymes and catalyze many reactions necessary to cells function
 3 ways plasma membrane joins cellsdesmosomes; tight junctions; gap junctions
 desmosomeshold cells together in tissue subject to stretch (little arms sticking out and holding hands)
 tight junctionsin dense, rigid tissues these hold cells firmly together (capillaries in brain) (part of cell membranes sticking together)
 gap junctionsallows communication between cells (parts of cell membranes joining and opening up)
 Nucleuscontains genetic material, chromatin. chromatin becomes more dense and forms chromosomes. nucleus surrounded by porous membrane called nuclear envelope. contains protein and RNA. forms ribosome precursors. all DNA for entire body is in each cell nucleus
 ribosomesfound in cytoplasm; function is to synthesize proteins; can be found in association with endoplasmic reticulum or alone in cytoplasm.
 Endoplasmic reticulumnetwork of vesicular structures whose walls are made of lipid bilayers. 2 kinds: rough and smooth
 rough (granular) ERhas ribosomes attached; proteins produced by ribosomes released into ER
 Smooth (agranular) ERfree of ribosomes; involved in synthesis of lipids and contains calcium which, when released regulates many cellular enzymatic activities
 Golgi Apparatusclosely related to ER functions to process and package proteins as they exit ER; proteins placed in vesicles which are transported to various parts of the cell or released from cell. (pinches off own membrane to wrap up protein)
 Mitochondriaproduce ATP (energy). contains 2 lipid bilayer membranes; inner contains many infoldings called cristae where oxidative enzymes are found. releases ATP into cytoplasm
 Lysosomesvesicular organnelles formed by golgi apparatus and dispersed throughout cytoplasm. contain acid hydrolases that destroy/digest unwanted substances and damaged organelles (in 2 ways)
 peroxisomesuse oxygen but not to produce ATP, instead they activate H2O2 which is harmful to cell (hydrogen peroxide)--to destroy infectious cells in scrapes etc
 cytoskeletonfilamentous structure that gives shape and stability to cell
 4 types of filamentsmicrofilaments (actin); thick filaments (myosin); intermediate (help reduce mechanical stress); microtubules (hollow tube of tubulin, most rigid of filaments, found in elongated neural processes)
 diffusionnet movement of molecules from one area of higher concentration to area of lower concentration
 what affects net flux (of diffusion)1. temperature (hotter=faster); 2. mass of molecule (larger=slower); medium (gas=fastest, liquid=middle, solid=slowest); surface area (more space=faster);
*diffusion time increases by the square of the distance that must be travelled
 how do poloar and charged molecules cross membrane1. channels; 2. mediated transport; 3. osmosis; 4. endo/exocytosis
 Channels (for molecules to cross membrane)integral proteins open and close *movement of ions dictated by electrochemical difference--not just based on concentration
 mediated transport (for molecules to cross membrane)used with charged or polar molecules that have no channels; 2 types: (a) facilitated and (b) active transport
 facilitated diffusionkind of mediated transport; higher concentration to lower concentration--no energy
 active transportkind of mediated transport (pumps); move molecules against concentration gradient--uses energy. primary--uses ATP, secondary--hitches a ride with either cotransport (same direction) or countertransport (different directions)
 Osmosisdiffusion of water from higher concentration to lower concentration. (water follows solute) attracted by solutes (#, not size); if membrane permeable to solute in water, equilibrium will be reached, if not, will still reach equilibrium, but there will be a change in volume
 osmolarityconcentration of solute of a solution; # of mols in 1 L of solution; osmotic pressure
 osmolality# of mols of solute in one kg of water
 hypertonic solutionextracellular solution > intracellular solution; water leaves; cell shrinks
 hypotonicextracellular solution < intracellular solution; water enters; cell swells (and bursts=lysis)
 isotonic extracellular solution=intracellular solution
 endo/exocytosisendocytosis: membrane invaginates to trap and ingest water or other particles.........................................exocytosis: intracellular vesicles fuse with cell membrane and extrudes particles
 Generalizations about Homeostasis1. input = output; 2. dependent upon balance of input and output, not magnitude; 3. control systems cannot maintain complete constancy; 4. each variable has normal range of values; *steady state requires energy unlike equilibrium *virtually all homeostatic control systems use neg. feedback (offset disturbance), pos. feedback exacerbates original disturbance
 Major Functional Homeostatic Systems1. Circulatory; 2. Respiratory; 3. Gastrointestinal (digestive); 4. Hepatic (liver); 5. Renal (kidneys); 6. Nervous (fast acting); 7. Endocrine (slower responding)
 Flexibility of Homeostasis1. Establishment of new set points (fever); 2. Natural homeostatic cycles (circadian--daily, circannual--yearly)
 Homeostatic Reflex Systemstimulus-->receptor-->afferent pathway-->integrating center-->efferent pathway-->effector-->response
 Intercellular messengersneurotransmitters (released by neuron to exert influence on effector cell); hormones (typically secreted by glands)
 3 kinds of hormones1. endocrine: released from gland into blood to be carried to activate other organs at some distance (goes through whole body, cells that need it recept its); 2. paracrine: released by some cells/tissue and diffuse into extracellular fluid and interacts via receptors with neighboring cells/tissue; 3. autocrine: released by cells tissue and have impact on same cells/tissue by interacting with membrane bound receptors
 receptorsbinding site occupied by intercellular messenger; made of proteins; 2 broad categories: steroid (intracellular, when bound they act directly w/ DNA), protein/peptide (bound to cell membrane; *increasing # of receptors increases chance of hormone hitting one
 Signal Transduction Mechanisms1. receptor complex incorporating ion channel; 2. protein kinase phosporylates enzymes, affecting cells activities; G proteins (receptor activation-->exchange of GDP for GTP-->activated G proteins interact with effector protein (ion channel or other enzyme))--receptor kicks off a GDP to get a GTP *messengers have unique/specific receptors with unique/specific pathway causing unique/specific response
 Second Messengers4. G-proteins (inside cytosol; converts ATP to cAMP which activates cAMP dependent kinases)-each step magnifies the effect, can be Gi (inhibatory) or Gs (stimulatory); 5. G-proteins can activate ion channels of membranes of organelles (Ca++); 6. Membrane bound phospholipids
 Nervous Systemcan be categorized as: 1.voluntary, 2.autonomic; also as 1.central, 2.peripheral
 "Typical" neuron consists of:1. dendrites (receive info); 2. cell body (soma--carries out normal cellular activities); 3. axon (nerve fiber--carries info toward other cells); 4. axon terminals (transmit message to other cells)
 3 basic types of neurons1. afferent (sensory) conveys impulses to CNS--no dendrites, only bipolar axon, soma lies outside of CNS; 2. efferent (motor) conveys impulses toward PNS, dendrites, soma in CNS; 3. interneurons--only in CNS, connect afferent and efferent neurons
 synapseinterface between one excitable cell and another; *signal transducted from pre-synaptic neuron to post-synaptic neuron by neurotransmitter
 Glial Cellscomprise about 90% of CNS; functions: form myelin sheaths (allow action potential to conduct rapidly), provide metabolic substrates, remove metabolic wastes, provide structure/support for neurons, guide migration of neurons to target cells, may be involved in intercellular communication
 resting membrane potentialnatural electrochemical potential acros neurons membrane (about -75 mV) *within cells there is a higher concentration of nucleic acids, proteins, phosphates, sulfates and K+; outside of cell there is a higher concentration of cations such as Na+ and Ca++ **magnitude determined by: 1.intra- vs extracellular conc. difference of ions, 2.permeability of membrane to specific ions--each ion has its own equilibrium potential across membrane (electrochemical in nature) which is driving force. 2 major ions involved in determining membrane potential are Na+ and K+
 Nernst equationdetermines equilibrium potential for each ion: equilibrium potential (mV) = 61 log (external/internal)
 graded potentialcaused by ligand-gated channels; slow change in membrane potential; change in potential restricted to small area; intensity=intensity of stimulus; as current diffuses away from site of initiation, its intensity decreases
 action potentialinitiated by voltage-gated ion channels; changes in membrane potential are fast (quick flooding of ions in); self propogating (intensity does not decrease)
 hillockbetween soma and axon; where action potential starts
 Nodes of Ranviergaps on axon not covered by myelin sheath where new action potentials are generated
 Saltatory conductionHow action potential jumps from Node of Ranvier to Node of Ranvier; carries impulse to nerve terminals
 Synapsestructure/space that permits a neuron to pas a signal to another cell. Two tyes: 1.electrical (cell membranes of two excitable cells joined together by gap junctions (uncommon in nervous system); 2.chemical (substance-neurotransmitter-released from terminal of pre-synaptice neuron and binds to post-synaptic receptors)
 Mechanism of SynapseAP reaches axon terminal and opens Ca++ channels; Ca++ enters terminal; neurotransmitter bound in vesicles released via exocytosis; neurotransmitter crosses synaptic cleft and binds with receptors on post-synaptic neuron; causes local graded potential of post-synaptic membrane (post synaptic potential)
 2 kinds of post-synaptic potential1. excitory (depolarizing effect) (EPSP); 2. inhibatory (hyperpolarizing effect) (IPSP) *typically one EPSP not strong enough to evoke AP (subthreshold intensity), but additive effects of several are: 1.temporal summation (several EPSPs in quick succession), 2.spatial summation (several EPSPs, from different pre-synaptic neurons, arrive simultaneously)
 Pacemaker Potentialsome excitable cells (such as cardiac muscle, smooth muscle, some neurons) are able to spontaneously and rhythmically generate AP. *due to greater permeability (leakiness) of those membranes. **resting potential of these cells is less than that of other neurons (about -55mV)
 Smooth Muscle (a pacemaker)some voltage gated Ca++ channels open at "resting potential"; Ca++ enters causing depolarization; K+ channels then open; efflux of K+ causes repolarization. think of sine curve
 Myocardium (a pacemaker)HEART! resting membrane potential is -55 mV. this membrane leakier to Na+ than other cells. influx of Na+ depolarizes membrane to -40mV (threshold voltage). voltage gated Na+ channels open (fast channels); causes voltage gated Ca++ channels to open (slow phase) ie plateau. ***Na+ quick; Ca++ slow; K+ efflux to repolarize
 Three Major Levels of CNS (related to evolutionary development)1. Spinal Cord Level; 2. Lower Brain Level; 3. Higher Brain (Cortical) Level
 Spinal Cord Level (1st level of CNS)not simply conduit for signals delivered from and arriving at brain; neuronal cicuits in cord control: (A)walking movements (B)reflexes to withdraw limbs from noxious stimuli (C)reflexes to maintain upright posture (D)reflexes that control local blood vessels (E)relfexes that control GI movements ** mostly reflexes
 Lower Brain Level (2nd level of CNS)medulla, pons, cerebelllum, hypothalamus, thalamus; controls subconscious bodily functions; arterial pressure and respiration controlled by medulla and pons; equilibrium and balance controlled by cerebellum and medulla; feeding reflexes controlled by medulla, pons, and hypothalamus; lower brain also site of emotions ** mostly basic needs and emotions
 Higher Brain (Cortical) Level (3rd level Of CNS)NEVER Functions Alone, always in conjunction w/ lower centers of CNS; fine tunes functions of lower brain; acts as memory storehouse; center of higher thought processes and imagination/creativity; limbic system (unites emotions or other sensations with memories **fine tuning, memory, imagination, higher thinking
 Peripheral Nervous System1. Afferent Division; 2. Efferent Division: (A)Somatic; (B)Autonomic: (I)Sympathetic branch; (II)Parasympathetic branch
 Afferent Division (of PNS)conveys info from peripheral receptors to CNS
 Efferent Division (of PNS)carries signals from CNS to muscles or glands; two kinds: somatic and autonomic
 SomaticVoluntary; neurons leading from CNS to skeletal muscle (motor neurons), carrying only excitatory signals (Ach); cell body within CNS
 AutonomicInvoluntary; neurons leading from CNS to all other types of cells (besides skeletal muscle) (glands smooth muscle, cardiac muscle); involves 2 neurons and synapse at autonomic ganglion; outside of CNS *neurotransmitter of pre-ganglionic neuron is Ach; Two kinds: Sympathetic branch and Parasympathetic branch
 Sympathetic BranchSTIMULATES; nerves leave spinal cord from thoracic and lumbar regions; post-ganglionic neurotransmitter is norepinephrine; stimulates "fight or flight" response; generally had excitatory effect on organism *adrenal medulla-has specialized autonomic ganglion
 Parasympathetic branchCALMS; nerves leave spinal cord from servical and sacral regions; most of this neural info passed along 2 vagus nerves to thoracic and abdominal regions; post ganglionic neurotransmitter is Ach; generally has calming/soothing effect on body
 Differences between Somatic and Autonomic Nervous SystemSOMATIC: 1.consists of a single neuron between cns and effector organ, innvervates skeletal muscle, can lead only to muscle excitation; AUTONOMIC: 1.has two-neuron chain (connected by synapse) between cns and effector organ, innervates smooth and caridac muscle, glands and GI neurons, can lead to excitation or inhibition of effector cells
 Blood-Brain Barriercapillaries of brain much less permeable than those to other organs; endothelial cells joined together by tight junctions; anything crossing capillary walls must do so through the cells; must be permeable to cell membrane or use transport protein
 Cerebrospinal-Fluidproduced within and fills ventricles of brain; leaves ventricles and bathes exterior of brain and spinal cord (cushions and protects); hydrocephalus: accumulation of CSF
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