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Physiology (Guyton)
Physiology - Guyton Text
| Question | Answer |
|---|---|
| synapse | junction point from one neuron to the next; signal passes in forward direct; almost all synapses are CHEMICAL in CNS |
| sensory information | 99% is discarded as irrelevant and unimportant |
| memory | storage in cerebral cortex (largest memory storehouse) |
| spinal cord level of CNS | controls walking mvmts & reflexes |
| lower levels of CNS | controls most of subconscious activities of body |
| neurotransmitters | chemical substance secreted by neurons; NOREPINEPHRINE -> excitatory/inhibitory; ACETYLCHOLINE -> excitatory but can inhibit some parasympath. fibres; DOPAMINE & SERATONIN -> inhibitory |
| chemical synapses | ideal for nerve transmission due to unidirectional signal |
| spatial summation | summing postsynaptic potentials by activating multiple terminals on widely spaced areas of membrane; increased signal strength trasmitted by using progressively GREATER NUMBERS of fibres |
| temporal summation | successive discharge from SINGLE presynaptic terminal can summate if they occur rapidly enough; increased signal strength transmitted by increasing FREQUENCY of nerve impulses in each fibre |
| mechanical sensory receptors | detects compression or stretching |
| thermal sensory receptors | detects temperature changes; located under skin in discrete & separate spots |
| nociceptor sensory receptors | detects tissue damage |
| electro sensory receptors | detects light |
| all receptors | are non-responsive to other types of stimuli but a special characteristic is that they adapt to a constant stimulus after a period of time |
| reciprocal inhibition circuit | neurol circuit which controls all antagonistic pairs of muscles, involves output excitatory signal in one direction & at same time w/ inhibitory signal going elsewhere |
| after discharge | signal entering neuronal pool causing prolonged output, lasting after incoming signal is over |
| somatic senses | collect sensory info. from body (ie. mechano, thermo, pain) |
| special senses | vision, hearing, smell, taste & equilibrium |
| mechano senses | type of somatic sense; stimulated by mechanical displacement of tissues |
| thermo sense | type of somatic sense stimulated by heat & cold sensations |
| pain | type of somatic sense stimulated by any factor that damages tissues; cenrtain tactile receptors can depress transmission of pain signals |
| positional sense | detects static position & rate of mvmt |
| proprioception | sense that have to do w/ physical state of body (ie. position, tendon, muscle, equilibrium) |
| (blank) | touch, pressure & vibration are detected by same types of receptors |
| free nerve endings | tactile receptor located in skin & other tissues that detect touch & pressure; pain receptors |
| Meissner's Corpuscles | nerve endings in non-hairy parts of skin (LIPS & FINGERTIPS) that adapt quickly & are sensitive to mvmt of objects against skin |
| Merkle's Disc | expanded tip receptors grouped into units [Iggo Dome] located in hairy & non-hairy parts of skin, slow to adapt, detects steady state signals about continual touch against skin |
| hair end organ | receptor that incl. hair & nerve fibre entwined at bad that adapts readily & detects mvmt of & initial contact of objects on surface of skin |
| Ruffini's End Organ | nerve fibres found in deep layers of skin & jt capsulles that adapt slowly & signal continuous states of deformation of skin/deeper tissues & degree of jt rotation |
| Pacinian Corpuscle | nerve fibres located immediately underneath skin of deep tissue, adapts quickly, are stimulated by rapid mvmt of tissues & are important for detecting tissue vibration |
| vibration | involves detection of ALL different tactile receptors |
| tickle & itch | detected by very sensitive rapidly adapting mechanoreceptive nerve endings found almost exclusively in superficial layers of skin |
| dorsal column-medial lemniscal (DC-ML) pathway | sensory pthwy transmits info w/ temporal & spatial fidelity, mainly transmits discrete types of mechanoreceptive sensations |
| Anterolater pathway | sensory pthwy transmits broad spectrum of snesory modalities (pain, temp., crude tactile, tickle/itch) slower & w/o spatial fidelity |
| sensory input | posterior areas of cerebral cortecx |
| motor control | anterior areas of cerebral cortex |
| lips | represent by largeest areas in somatic cortex |
| muscle spindle | detection of mid-range jt angulation; proprioceptive sensory receptor located in muscle belly regarding length & rate of change of length |
| pacinian-ruffini | detection of EXTREME jt angulation |
| pacini & muscle spindle | detects rate of mvmt |
| dermotome | spinal nerve that carries info. from segmental field of skin |
| fast pain | sharp, prickling, acute, electric; not felt in deep tissues; elicited by thermal or mechanical stimuli |
| slow pain | slow, burning, aching, throbbing, nauseous, chronic & can lead to prolonged unbearable suffering; is associated w/ tissue destruction; can occur in skin & deep tissues; elicited by mechanical, thermal & chemical stimuli |
| pain receptors | adapt very little & sometimes not at all |
| hyperalgesia | increased sensitvity of pain receptors (keeps person apprised of tissue damage) |
| intensity of pain | correlated w/ rate of tissue damage |
| muscle spasm | can cause pain, possibly due to direct stimulation of pain receptors or indirect effects (ie. ischemia) |
| fast-sharp pain | apprises person rapidly of damaging influence for reaction of immediate removal of stimulus |
| slow-chronic pain | gets greater over time, person continues to relieve cause of pain |
| analgesia | capability of brain to suppress input of pain signals; morphine suppress pain signals entering from peripheral nrv |
| referred pain | felt in body part considerably remote from tissue causing pain; occurs because some signals from viscera conducted thru same neurons that conduct pain signals from skin |
| headache | pain referred to head from deep head structures; can be caused by emotional tension which causes spasm of head/neck muscles |
| migraine | special type of headache result from abnormal vascular phenomena |
| anterior motor neurons | (specifically alpha motor neurons) leave spinal cord & innervate skeletal muscles |
| proper control of muscle fx | requires continuous sensory feedback from each muscle |
| Golgi tendon organ (GTO) | proprioceptive sensory receptor located in muscle tendon, detects tendon tension & rate of change of tension; causes inhibition of motor neurons; neutralizes contractile force on separate muscle fibres |
| contraction | trigger involving muscle stretch reflex involves stretch of muscle (by muscle spindles) |
| stretch reflex | prevents oscillation or jerkiness of body mvmt providing DAMPENING effect or smoothing fx |
| voluntary movements | initiated by cerebral cortex by activating PATTERN of fx stored in lower centres which signal muscles |
| primary motor area | topographical representation of muscles in body w/ more than 1/2 concerned w/ control of hands & speech; excitation of single neuron excites specific mvmt (not single muscle) |
| anterior part of premotor cortex | generates MOTOR IMAGE for muscle mvmt, then excites complex patterns of mvmt |
| supplementary motor cortex | stimulate BILATERAL mvmt |
| corticospinal tract | most import pthwy, aka DIRECT PYRAMIDAL PTHWY, carries motor signals directly from primary motor cortex down sp. cord |
| direct pathways | aka corticospinal tract; controls discrete & detailed mvmts esp. of distal segments of limb |
| extra pyramidal system | include all motor pthwys in brain that are NOT part of pyramidal system |
| brain stem | provides special control fx (ie. respiration, arterila pressure, cardiovasc., equilibrium & stereotyped mvmts of body); acts w/ cerebellum to control mvmts & maintain equilibrium |
| vestibular apparatus | sensory organ detects sensation of equilibrium |
| semicircular ducts | detect rate & direction of rotation of head in all 3 planes of space |
| utricle & sacculae | responsible for informing brain of position of head w/ respect to gravity |
| cerebellum | major role in timing of motor activities & in rapid smooth progression of mvmts |
| basal ganglia | works with corticosp. syst. to plan & control complex patterns of muscle mvmts |
| spinal level of motor cortex | programmed local patterns of mvmt |
| hind brain | maintenance & axial body tome for standing & maintaining equilibrium |
| motor cortex | complex patterns of mvmt & can bypass programmed patterns |
| cord patterns | determined at birth, "hard-wired" |
| cerebral cortex | all areas have extensive to-&-fro connections w/ deeper structures of brain; two halves of brain have INDEPENDANT capabilities for consciousness, memory storage, communcation & motor activity control |
| thalamus | excitation of thalamus is necessary for almost all cortical activity; almost all pthwys from sensory organs pass thru thalmus to cortex |
| association areas of cerebral cortex | receives & analyzes signals from multiple regions of brain |
| Wernicke's | an association area responsible for language comprehension |
| pre-frontal | association area helps plan complex patterns & sequences of motor mvmt |
| working memory | ability of brain to store many pieces of info on short term basis, used to analyze new thoughts entering brain |
| Broca's | association area responsible for motor patterns for word formation by exciting larynx, resp. syst & mouth muscles |
| limbic system | association area concerned w/ behaviour, emotions & motivation |
| corpus callosum AND anterior commisure | makes info stored in cortex of one hemisphere available to corresponding cortical areas of opposite hemisphere |
| corpus callosum | required for boh sides of brain to operate |
| anterior commisure | important role in unifying EMOTIONAL responses of 2 sides of brain |
| holistic theory | a thought results from "pattern" of stimulation of many parts of nerv. syst. at the same time |
| consciousness | continuing stream of awareness of either our surroundings or our sequential thoughts |
| memory traces | memories caused by changes in sensitivity of synaptic tranmission <-> neurons as a result of prev. neural activity, forms new or facilitated pthwy; once established, can activate "thinking" to reproduce memories |
| short-term memory | caused by continual neuronal activity resulting from nerve signals travelling around temporary memory trace thru circuit of reverberating neurons |
| intermediate memory | temporary chemical &/or physical changes |
| long-term memory | result of actual structural changes instead of only chemical changes |
| short- term to long-term memory | must be consolidated for conversion; consolidation happens when actively repeating something, initiating chemical, physical & anatomical changes in synapes |
| reticular area of brain stem | main part of nerv. syst. which controls excitation of cerebral cortex |
| positive feedback loop | activation of cerebrum excites brain stem which activates cerebrum more leading "awake mind" |
| hypothalamus | major part of limbic syst for its ability to control vegetative fx of brain closely related to behaviour |
| autonomic nervous system (ANS) | activated by centres of spinal cord, brain stem & hypothalamus |
| sympathetic nerve fibres | originate <-> T1 to L2 of sp. cord |
| parasympathetic nerve fibres | originate from cranial & sacral nerves of sp. cord; 75% originate from CN X (vagus) |
| norepinephrine | neurotransmitter released by most SNS fibres that supply blood vessels; vasoconstrictor |
| acetylcholine | neurotransmitter released by most PNS fibres; stimulates all types of gastric glands to release secretions |
| sympathetic nervous system (SNS) | pupil dilation, increased heart activity, blood vessel constriction |
| parasympathetic nervous system (PNS) | pupil constriction, increased peristalsis, decreased heart rate |
| adrenal medulla | releases epineph. & norepineph. into blood upon sympathetic stimulation; effects last 5-10x longer than direct sympathetic stimulation |
| mass discharge | all portions of SNS discharge simultaneously; aka STRESS RESPONSE, allows person to perform greater stenuous physical act. otherwise possible |
| right side of heart | pumps blood to lungs |
| left side of heart | pumps blood to all body except lungs |
| ventricles | supplies main forces of contraction |
| heart | composed of atrial & ventricular muscle tissues & specialized excitatory & conductive fibres; cardiac muscle contraction lasts 15x longer than skeletal |
| intercalated discs | cell membranes separating individual cardiac muscle cells |
| gap junction | diffusion of ions from one cardiac muscle cell to the next |
| syncytium | when one cell is excited, the action potential spreads to all |
| calcium | unique to cardiac muscles for prolonged contractions |
| diastole | period of relaxation when heart fills w/ blood; 75% of blood flows from atria to ventricles; AV valves open, during atrial systole they open, during ventricular systole they close |
| systole | period of contraction when heart expels blood; 25% of blood pushed into ventricle when atria contracts; semilunar (SL) valves closed, atrial diastole they close, ventricular diastole they open |
| atrioventricular (AV) valves | tricuspid & mitral valves; 1st heart sound which sounds low & long |
| semilunar (SL) valves | pulmonary & aortic valves; edges of SL valves subject to greater mechanical stress than AV valves; 2nd heart sound which sounds short snap due to closing |
| papillary muscles & chordae tendinae | prevent AV valves from bulging back into atrium during ventricular systole |
| Frank-Starling Mechanism | the greater the stretch of heart during filling, the greater the contraction |
| ventricle relaxed | AV open, SL closed |
| ventricle contracted | AV closed, SL open |
| sinus node | located in superior posterolateral wall of right atrium; sets rhythm of heart because it emits new impulses FASTER than AV or Purkinje; aka pacemaker |
| internodal pathways | bundles of specialized fibres that connect sinus node & AV node |
| cardiac impulse delay | delayed @ AV node due to fewer gap junctions <-> cells; also allows atria to contract & finish filling ventricles before ventric. contraction |
| atrialventricular (AV) bundles | fibres that conduct impulse from AV node to ventricles |
| Purkinje fibres | conduct impulse from AV bundle to all parts of ventricles 6x faster & 150x faster than AV node |
| cardiac output | quantity of blood pumped into aorta per minute; mainly controlled by venous return |
| venous return | quantity of blood flowing from veins into right atrium per minute; sum of all local blood flow from individual tissue segments of peripheral circulation |
| heart less efficient | factors that increase total peripheral resistance increases cardiac output |
| heart more efficient | factors that decrease total peripheral resistance would increase cardiac output; nerv. stimulation & hypertrophy of heart muscles -> better pump |
| systemic circulation | supplies blood to all tissues except lungs |
| arteries | transport blood under high pressure to tissues; contains 13% of total blood volume; control of pressure independant of local bl. flow & cardiac output |
| arterioles | act as control conduits that release blood into capillaries |
| capillaries | exchange of substances <-> blood & interstitial fluids |
| venules | have pores only permeable to H2O & small molecular substances; collects blood directly from capillaries |
| veins | transport blood from tissues back to heart; major reservoir of blood (64%) |
| pulmonary circulatory system | contains 9% of total blood vol.; 25/8 mmHg (sys/dia) |
| blood pressure | force exerted by blood against any unit area of vessel wall |
| resistance | impediment to blood flow in vessel |
| total peripheral resistance | resistance of entire systemic circulation |
| viscosity of blood | determined by red blood cells |
| hematocrit | %age of blood composed of cells |
| arterial compliance | pulse pressure of heart affected by stroke volume output |
| spleen | specific blood reservoir & destroys old blood red blood cells |
| red pulp | area of spleen where RBC stored |
| microcirculation | transport of nutrients to tissues & removal of cellular excreta |
| metaarterioles | structure <-> arteriole & capillary |
| precapillary sphincter | smooth muscle fibre around metaarteriole to control entrance of blood into capillary |
| intercellular cleft | thin passageway <-> adjacent endothelial cells of capillaries |
| vasomotion | on/off flow of blood thru capillaries; controlled by oxygen |
| diffusion | means of substance transport in/out of capillaries |
| water | smallest substance passes thru capill. pores |
| plasma proteins | larger than capillary pores |
| interstitium | spaces <-> cells of body; low concentrations of proteins |
| interstitial fluid | fluid that fills spaces <-> cells of body |
| collagen | long, strong structures in interstitium, provides tensional strength to tissues |
| proteoglycan filaments | aka "brush pile", thin, coiled & form a mat of fine filaments |
| tissue gel | combination of solid structures of interstitium & trapped fluid |
| collotid osmotic pressure | osmotic pressure caused by plasma proteins |
| lymphatic system | accessory route from interstitial space into blood & carries proteins & large particulate matter away from tissue spaces; 1/10 fluid filters into interstitium from capilliaries NOT reabsorbed & is returned to circulation |
| thoracic duct | lymph flow from lower body, left head, left arm & chest |
| right lymph duct | lymph flow from right neck & head, right arm & thorax |
| lymphatic endothelial cells | overlap & act like valves pushed open by pressure & pushed closed by backflow |
| oxygen-lack theory of local blood flow | inadequate levels of oxygen & nutrients cause blood vessels to relax & dilate |
| reactive hyperemia | increased blood flow to tissues recently suffered of blood supply deprivation |
| active hyperemia | increased blood flow to tissues highly active |
| nitric oxide | vasodilating substance due to shear stress from increased blood flow |
| angiogenic | vascular growth factors involved in reconstructing tissue vascularity in response to long-term changes in blood flow |
| angiotensin | powerfully constricts all arterioles & mainly involved in arterial pressure regulation |
| vasopressin | an antidiuretic hormone secreted by hypothalamus & acts to increase reabsorption of water by kidneys |
| histamine | vasodilater substance released when tissues are damaged or inflamed but also involved in allergic reactions; causes bronchiolar constriction; secreted by gastric glands |
| increased arterial pressure | constriction of arterioles & veins & increase cardiac pumping when occuring simultaneously |
| baroreptor | nervous reflex initiated by stretch receptors which then send signals to CNS about changes in arterial pressure; when person stands after lying down baroreceptor maintains arterial pressure in upper body; located in large systemic arteries |
| chemoreceptors | nerv. reflex involve receptos sensitive to oxygen lack, carbon dioxide & hydrogen ion excess; located in large systemic arteries; involved in maintaining arterial pressure at pressure lower than normal range |
| fx of red blood cells | transports hemoglobin to deliver oxygen to tissues; do not rupture when squeezed thru capillaries due to excess of cell membrane |
| red blood cells (RBC) | produced in bone marrow; matures from proerythroblast to reticulocyte stage gains hemoglobin & lose their nucleus; excess may impede blood flow; survives 120 days in bl. stream |
| RBC formation | rate not controlled by concentration in blood stream but by their ability to transport oxygen |
| erythropoietin | released from kidneys & liver triggered by low oxygen levels to produce more RBC |
| Vit B12 & Folic Acid | critical for RBC maturatoin |
| interaction between hemoglobin & oxygen | loose & reversible; hemoglobin helps to maintain oxygen pressure in tissues regardless of fluctuations of O2 concentration in alveoli (Buffer System) |
| iron | important for formation of hemoglobin; free iron in blood -> "transferrin"; iron stored in cells -> "ferratin"; iron lost during blood loss; when RBC bursts iron release for storage in liver |
| hemoglobin | transported by RBCs for delivery of oxygen; is broken down & converted into bilirubin when RBC cells burst; enhances transport of oxygen 30-100x |
| anemia | deficiency of hemoglobin |
| white blood cells (WBC) | combats infectious & toxic agents, specifically transported to areas of infection; recruited during inflammation |
| granulocytes | are neutrophils, eosinophils & basophils; formed in bone marrow |
| phagocytosis | are granulocytes & monocytes which help protect body & cellular ingests foreign invaders |
| lymphogenous tissues | where lymphocytes & plasma cells are formed |
| neutrophils | WBC capable of phagocytosing bacteria in circulating blood; already mature when it enters tissues, can only ingest small # of bacteria before dying; 2nd line of defence few hrs after inflammation (enters tissue via diapedesis) |
| monocytes | inactive while in blood steam, only become activated once they enter tissues; formed in bone marrow |
| macrophage | derived from monocytes; able to ingest many & large particles, can survive many months; actions of macrophages can injure healthy living tissues around injured area; responsible for presenting antigens to B & T cells |
| diapedesis | cell squeezing thru small opening by sliding only a small portion of itself thru |
| chemotaxis | mvmt of cells towards source of chemical sign; draws neutrophils & monocytes towards tissues in inflamed state |
| tissue macrophage | first line of defence of tissue injury; phagocytic cells attached to tissues & remain after inflammation subsides |
| sinusoids of liver | macrophage lined structure where inaders entering via GI tract enters portal blood & must pass thru |
| inflammation | dramatic 2ndary changes observed after injury to tissue |
| margination | sticking of cells to capillary walls near areas of inflammation |
| pus | mixture of necrotic tissues, dead phagocytes, tissue fluids, etc found in areas of inflammation |
| eosinophils | involved in specifically targeting parasitic invaders |
| basophils | involved in allergic reactions & are similar to mast cells by liberating heparin (anticoagulant) & histamine (vasodilator) into blood |
| immunity | ability to resist different types of organisms & toxins |
| acquired immunity | doesn't develop until after body first attacked by disease/toxin; B & T cells basic types activated when exposed & reacts w/ specific antigens |
| innate immunity | general processes for killing invaders |
| humoral cells | aka B lymphocytes, acquired immunity that secretes antibodies which bind attacking agent; formed in bone marrow; secrete antibodies which bind antigen |
| cell-mediated cells | T lymphocytes, type of acquired immunity that directly attack & destroy foreign agents; formed in thymus; directly bind to antigens using receptors |
| antigens | specific chemical compounds that makes organism different from all others |
| lymph nodes | contains majority of lymphocytes |
| spleen & bone marrow | 2 types of lymph tissues that play important role in intercepting agents in circulating blood |
| helper T cells | contributes to activation of B cells; most numerous type of T cells; regulates all immune fxs, destroyed/inactivated by AIDS virus |
| plasma | activated B cells that have differentiated & producing antibodies |
| memory cells | activated B & T cells circulated to & remain dormant in various lymph tissues to provide faster & potent response if body exposed to same antigen again |
| antibodies | immunoglobin compounds that bind specific antigens |
| IgG | most common immunoglobin |
| IgE | immunoglobin primarily involved in allergic response |
| complement system | grp of proteins that aid in destruction of antigens by promoting opsonization, phagocytosis, agglutination& activation of basophils & inflam. response |
| cytotoxic T cells | directly attacks & kills microorganisms |
| suppressor T cells | suppresses fx of other T cells |
| immunization | process which acquired immunity is induced by injecting dead/attenuated organisms &/or altered toxins |
| goals of respiration | to provide oxygen to & to remove carbon dioxide, from tissues |
| pulmonary pressure | inflow/outflow of air <-> atmosphere & lung alveoli |
| lungs expansion/contraction | 2 ways: upward & downward, elevation & depression |
| abdominal muscles | provides additional force for expiration during heavy breathing |
| exernal intercostals | muscles that raise rib cage (inspiration) |
| internal intercostals | muscles that pull down on rib cage (expiration) |
| muscles of inspiration | external intercostals, SCM, serratus anter., scalenes |
| muscles of expiration | internal intercostals, abdom. recti |
| pleura | fluid w/in which lungs "float" & provides lubrication for mvmts of lungs |
| pleural pressure | pressure of fluid in space <-> lung & chest wall normally maintained at slightly negative value |
| lveolar pressure | pressure of air inside alveoli of lung; alv. pres. of O2 & CO2 determined by rate they pass in/out of blood & alveoli (alveolare ventilation) |
| air to flow INTO lungs | pressue inside alveoli need to be less than atmospheric pressure |
| transpulmonary | pressure difference <-> alveolar pressure & pleural pressure |
| elastic forces of lungs | 1/3 of total lung elasticity & mainly due to presence of elastin & collagen fibres; 2/3 try to collapse alveoli by surface tension |
| surfactant | fluid lining alveoli greatly reduce surface tension, helps to reduce amount of pressure required to keep lungs expanded |
| respiration | major limitation to intensity of exercise a person can perform |
| tidal volume | volume of air inspired/expired w/ each normal breath (500 mL) |
| total lung capacity | maximum volume which lungs can be expanded w/ greatest possible effort (5800 mL) |
| alveolar ventilation | rate at which new air reaches gas exchange areas of lungs |
| dead air space | air that never reaches gas exchange areas of lungs (air in nose, pharynx, trachea) |
| cartilage rings | structures help keep trachea & bronchi open allowing easy passage of air thru them |
| bronchioles | no cartilage & is composed of smooth muscle, only kept from collapsing by transpulm. pressure |
| mucus | coats resp. passageways helping to keep the moist & trap small particles |
| nasal cavities | part of resp. passageways first to warm, humidify & filter air |
| turbulent precipitation | larger particles in air filtered by hairs located @ entrance of nostrils |
| alveolar macrophages | removes very small particles settled in alveoli |
| partial pressure | rate of diffusion of each resp. gases directly proportional to pressure caused by each gas alone; exerted when gases dissolved in water or body tissues; greater for oxygen in alveoli than pulm. capillaries |
| carbon dioxide | more soluble in water; by-product as a reaction of oxygen w/ foodstuffs; contributes most to acid-based balance of body fluids |
| respiratory membrane | where gas exchange in lungs must pass thru; comprised of capillary, interstitial space & alveoli wall; rate of mvmt of material thru resp. membrane can be affected by changes to membrane itself (increased thickness/decrease surface area) |
| ventilation of perfusion ratio | balance <-> alveolar ventilation & blood flow |
| deoxygenated blood flow | inadequate VENTILATION to area of lungs receiving adquate blood flow |
| inadequate blood flow to lungs receiving adequate ventilation | oxygen will be breathed back out |
| partial pressure of oxygen | greatest in alveoli, less in blood stream, even less in tissue; lower in capillaries because O2 used by cells to create energy |
| partial pressure of carbon dioxide | greatest in tissue, less in blood, even less in alveoli |
| pressure difference | to move carbon dioxide less than those needed to move oxygen |
| interaction of oxygen with hemoglobin | loose & reversible; binding of oxygen to hemoglobin displaces carbon dioxide, CO2 released from blood stream in lungs because binding of O2 makes hemoglobin a stronger acid |
| arterial blood | saturated w/ 97% oxygen |
| venous blood | saturated w/ 75% oxygen |
| Buffer system | fx of hemoglobin helping maintain oxygen pressure in tissues regardless of fluctuations of oxygen concentration in alveoli |
| carbon anhydrase | enzyme present in accelerated conversion of carbon dioxide & water into carbonic acid |
| bicarbonate | form of carbon dioxide (approx 70%) transported in blood; excess CO2 causes kidneys to release bicarbonate to readjust hydrogen ion concentration; also secreted by pancreas to neutralize stomach acid & pH of chyme |
| medulla & pons | areas of brain stem where respiratory centre mainly located |
| dorsal respiratory group of respirator centre | mainly causes inspiration & generates basic rhythm of respiration |
| ventral respiratory group of respiratory centre | mainly causes expiration & inspiration; inactive during normal quiet breathing, is important when high levels of pulm. vent. required (during exercise) |
| pneumotaxic centre of respiratory centre | mainly controls rate & pattern of breathing; switches off inspiration |
| oxygen | does not have direct effect on resp. centre, mainly acts to control resp. thru peripheral chemoreceptors |
| inspiration | controlled by dorsal resp. group of resp. centre; CO2 & hydrogen ions increase strength of inspiration |
| peripheral chemoreceptors | responds rapidly to excess CO2 at onset of exercise |
| strenuous exercise | up to 20x increase in O2 consumption & CO2 formation --> alveolar ventilation increases, arterial PO2, PCO2 & pH remain the same; increase in resp. mainly due to stimulation by higher brain centre & body mvmt eliciting proprioceptive reflexes |
| smooth muscles | found in wall of GI tract |
| GI muscle fibres | are of smooth muscles; less excitable during sympathetic stimulation; excitable by stretching of muscle |
| enteric nervous system (ENS) | intrinsic nervous system of GI |
| myenteric plexus of enteric nerv. syst | controls mvmts in GI system |
| submucosa | plexus of ENS controls secretion & local blood flow in GI system |
| movements in GI tract | propulsive & mixing |
| peristalsis | basic type of propulsive mvmt in GI, involves formation of contractile ring in gut then moves forward which moves material in front, forward; stimulated by distension |
| mixing | formation of intermittent constrictive contraction every few centimeters along the gut |
| splanchnic circulation | supplies gut, spleen, pancreas & liver |
| portal vein | vessel of which blood from gut, spleen & pancreas flow into liver |
| GI bacterial removal | running of venous blood from GI tract thru sinusoids of liver |
| non-fat / water soluble nutrients absorption | absorbed from gut into blood stream & sent to liver for storage/processing; final products of carb digestion from sm. intestine absorbed into portal blood |
| fat based nutrients absorption | absorbed from gut into lymphatic syst., then into bloodstream by-passing liver |
| blood flow of GI | increases when gut becomes active (after meal); decreased to GI by SNS |
| mucous | for lubrication & protection of GI tract; mainly secreted in esophagus to provide lubrication for swallowing; mucous secreted by stomach has alkaline pH which protect underlying wall from acidic & proteolytic stomach secretions; regulated by local nerv sy |
| trigger of GI secretions | mechanical pressure of food, various hormones & nervous reflexes |
| saliva | contains mucous & digests carbs by ptyalin enzyme; also helps maintain health of oral tissue by washing away / destroying bacteria; released by PNS |
| hydrochloride | needed for activation of pepsinogen into pepsin & thus needed for proper protein digestion in stomach |
| intrinsic factor | a gastric secretion essential for vit B12 absorption in small intestine |
| stomach | secretes hydrochloric acid, pepsinogen, intrinsic factor, gastrin & mucous |
| hydrochloric acid | stimulated by gastrin & histamine |
| substances released when meat or protein foods enter stomach | Gastrin -> histamine -> HCl -> pepsin |
| chyme | in duodenum, main stimulus for pancreatic secretions |
| pancreas | secretes digestive enzymes for carbs, protein & fat; also secretes bicarbonate; secretion stimulated by acetylcholine, cholecystokinin & secretin; secretes amylase enzyme after chyme enters duodenum for starch digestion completion (15-30 min) |
| secretin | secreted by upper small intestine in response to presence of stomach acid which causes pancreas to release bicarbonate ions |
| cholecystokinin (CCK) | released in duodenum in presence of fats, protein digestion & long-chain fatty acids in chyme which in turn, triggers release of bile |
| cholesterol | used to make bile salts |
| small intestine | responsible for nutrient absorption |
| cellulose | undigestible form of carbs by humans |
| ptyalin | salivary enzyme involving carb digestion in mouth |
| enterocytes | enzymes splitting various disaccharides (sucrose, lactose, maltose) |
| pepsin | secreted by stomach important for protein digestion |
| protein digestion | must be in di & tri peptides &/or amino acids before being absorbed into enterocytes of sm. intest. |
| pepsidase | digests peptides into amino acids then absorbed into bloodstream |
| emulsification | critical for proper fat digestion, involves fat globules broken into wee sizes; bile is emulsifier |
| sodium absorption | creates electrochemical gradient across intestinal epithelial cells which promotes chloride absorption |
| sodium co-transport | process which most products of protein digestion is absorbed; galactose & glucose require sodium as co-transp.; fructose does not |
| colon bacteria | capable of producing vit B12, thiamine, riboflavin & vit K |
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