Term
| major components of sensory system |
|
Definition
1. receptors: detect environmental changes
2. neural pathways: carry info receptor --> brain
3. brain: interpret sensory info |
|
|
Term
|
Definition
1. mechanoreceptors: mechanical deformation
2. thermoreceptors: temperature changes
3. nociceptors: pain, tissue damage
4. electromagnetic: light
5. chemoreceptors: taste, smell, oxygen, osmolariy |
|
|
Term
|
Definition
| stimulus changed to electrical energy at receptor, "receptor potential" = local graded potential, if sufficient when gets to node of ranvier AP results |
|
|
Term
|
Definition
| area of body covered by receptors from single afferent neuron |
|
|
Term
|
Definition
| single afferent neuron and all of its receptors |
|
|
Term
|
Definition
| proportional to strength of response, more response potential exceeds threshold so greater AP frequency |
|
|
Term
|
Definition
| at constant stimulus intensity receptors gradually desensitized (decreased AP firing) |
|
|
Term
|
Definition
| fast adapting, more sensitive to changes in stimulus intensity |
|
|
Term
|
Definition
| slow adapting, send prolonged signals (posture) |
|
|
Term
| neural ascending pathways |
|
Definition
| afferent neurons carry info to specific brain regions, several classes of afferent neurons based on size/speed of conduction, 1st order (primary) neurons synapse with interneurons in spinal cord, info transmitted along interneurons til reaches brain |
|
|
Term
|
Definition
| info from single afferent neuron synapses with many interneurons |
|
|
Term
|
Definition
| information from many afferent neurons arrive at the same interneuron (summation) |
|
|
Term
| 1st classification of neural pathway scheme |
|
Definition
- specific ascending pathways: carry info about single stimulus type
- nonspecific ascending pathways: carry info about different types of stimuli
3. sensory info crossed over to opposite side of spinal cord in both |
|
|
Term
| 2nd classification of neural pathway scheme |
|
Definition
- dorsal column lemniscal system: carries info in dorsal spinal cord column (white matter), crosses to opposite side in medulla, through brainstem --> thalamus via lemniscus, large myelinated nerve fibers, increased degree of spatial orientation (phasic/position info, touch using spatial accuracy)
- anterolateral system: carries info in dorsal horns of cord's gray matter, info crosses to opposite side immediately, transmits to brain stem and thalamus, small unmyelinated fibers |
|
|
Term
| interpretation of sensory info |
|
Definition
by the brain
-from thalamus and brain stem, info delivered to specific parts of cerebral cortex
-results in perception (seeing roommate makes me happy), not sensation (see a person) |
|
|
Term
|
Definition
1. type
2. intensity
3. location
4. duration |
|
|
Term
| type (modality) detected by sensory system |
|
Definition
chemical, taste, smell, somatosensory, muscle, balance, hearing, vision
- submodalities (sweet, sour, salty) |
|
|
Term
| intesity detected by sensory system |
|
Definition
| determined by frequency of AP firing and number of receptors stimulated |
|
|
Term
| location detected by sensory system |
|
Definition
acuity of stimulus location
- smaller receptor field = greater acuity
- greater degree of convergence in ascending pathway = lower acuity |
|
|
Term
| duration detected by sensory system |
|
Definition
| receptors have different rates of adaption, rapid vs. slow (phasic vs. tonic) |
|
|
Term
|
Definition
1. nervous system
2. hormonal (endocrine) system: primarily metabolic |
|
|
Term
|
Definition
- effects occur in seconds or last for weeks
- produced/released by endocrine glands (2+ work together as axis), carried by blood, affect target cells |
|
|
Term
|
Definition
- can perform other physiological functions (heart, pancreas, hypothalamus)
- single gland can secrete 1+ hormones, but single cell type secretes on 1 type |
|
|
Term
|
Definition
1. amine: derived from tyrosine (thyroid hormones, chatecholamines)
2. peptide: processed before secretion
3. steroid: derived from cholesterol |
|
|
Term
|
Definition
- preprohormone (ribosome) --> prohormone (ER) --> hormone (Golgi) --> vesicle --> exocytosis
- readily soluble in plasma
- insulin, GH, glucagon, ACTH |
|
|
Term
|
Definition
- derived from cholesterol
- steroidogenic enzymes in cell determine which steroids produced
- diffuse across cell membrane, enter blood stream (no intracellular storage)
- insoluble in plasma, in circulation combine with binding proteins
- small fraction of free steroid is biologically active
- glucocrticoids (cortisol, corticosterone), androgens (testerone, androstenedione), estrogens |
|
|
Term
|
Definition
- catecholamines, peptide hormones
- receptors on cell membrane
- intracellular second messenger activated upon binding
- cAMP usually 2nd messenger (bind -> G protein -> increase in adenylate cyclase -> ATP to cAMP -> protein kinase activation -> enzyme phosphorylation)
- fast response |
|
|
Term
| steroid/thyroid receptors |
|
Definition
- found within cells (cytosol or nucleus)
- hormone/receptor complex interacts with DNA as transcription regulation factor
- slower response |
|
|
Term
| adjusting to hormonal response |
|
Definition
- up/downregulate receptor number (alters probability of hormone binding)
- change receptor affinity |
|
|
Term
| features of hormonal action |
|
Definition
1. actions amplified at target cells
2. regulat rates of existing reactions, don't initiate new ones
3. actions slow/prolonged (esp. steroids)
4. biological effect of hormone proportional to circulating concentration of hormone |
|
|
Term
| determinants of circulating levels of hormone |
|
Definition
1. rate of secretion: pulsatile release, circadian rhythm (moderated by external cues but not driven by them)
2. rate of removal: metabolism, clearance |
|
|
Term
| types of input affecting hormonal release |
|
Definition
1. change in plasma concentration of mineral ions
2. change in plasma concentration of nutrients
c. neurotransmitters released from neurons
4. other hormones/paracrine agents |
|
|
Term
|
Definition
- liver/kidneys, some in target cells
- peptide hormones broken down by specific peptidases
- steroids undergo series of reduction reactions that make them water soluble
- urine = main excretion route, small amount intact hormone excreted in urine |
|
|
Term
| hypothalamic-pituitary pathway |
|
Definition
- hypothalamus stimulated by neurons
- pituitary at base of brain (master gland)
- hypo conveys info to pituitary via neurons/blood vessels
- hypophysis = 2 sections of pituitary (posterior and anterior) |
|
|
Term
| posterior pituitary (neuropophysis) |
|
Definition
- receives direct neural input form hypothalamus
- releases ADH (vasopressin) and oxytocin into bloodstream
- ADH: renal system, controls water excretion
- oxytocin: uterine contractions, milk ejection |
|
|
Term
| anterior pituitary (adenohypophysis) |
|
Definition
- receives input from hypothalamus from portal blood vessels carrying hypophysiotropic hormones controlling secretion of hormones from anterior pituitary
- hypothalamic-pituitary axis
1. thyrotropin release hormone (TRH)
2. corticotropin releasing hormone (CRH)
3. growth hormone releasing hormone (GHRH)
4. somatostatin (SS)
5. gonadotropin releasing hormone (GnRH)
6. dopamine (prolactin release inhibiting hormone, PIH)
7. FSH
8. LH
9. prolactin
10. GH
11. ACTH
12. TSH |
|
|
Term
|
Definition
| - thryotropin releasing hormone - anterior pituitary - stimulates release of thyroid stimulating hormone (TSH) and prolactin |
|
|
Term
|
Definition
| - corticotropin releasing hormone - anterior pituitary - stimulates secretion of adrenocorticotropin (ACTH) |
|
|
Term
|
Definition
- growth hormone releasing hormone
- anterior pituitary
- stimulates release of growth hormone (GH) |
|
|
Term
|
Definition
- somatostatin
- anterior pituitary
- inhibits GH secretion |
|
|
Term
|
Definition
- gonadotropin releasing hormone
- anterior pituitary
- stimulates secretion of luteinizing hormone (LH) and follicle stimulating hormone (FSH) |
|
|
Term
|
Definition
- prolactin release inhibiting hormone
- anterior pituitary
- inhibits secretion of prolactin |
|
|
Term
|
Definition
- follicle stimulating hormone
- anterior pituitary
- stimulates growth and development of ovarian follicles, controls spermatogenesis |
|
|
Term
|
Definition
- luteinizing hormone
- anterior pituitary
- regulate steroidogenesis of gonads |
|
|
Term
|
Definition
- anterior pituitary
- enhances breast development, milk production |
|
|
Term
|
Definition
- anterior pituitary
- stimulates postnatal growth, affects all tissue
- increases lypolysis, decreases glucose uptake by tissue, increases protein synthesis |
|
|
Term
|
Definition
- adrenocorticotropic hormone
- anterior pituitary
- stimulates adrenal cortex to release cortisol |
|
|
Term
|
Definition
- thyroid stimulating hormone
- anterior pituitary
- stimulates thyroid gland to release thyroid hormone |
|
|
Term
|
Definition
- male sexual characteristics
- anabolic effect on tissue |
|
|
Term
|
Definition
| - female sexual characteristics |
|
|
Term
|
Definition
- important during pregnancy
- regulates menstrual cycle
- increases body temperature |
|
|
Term
|
Definition
- T3 and T4
- increase metabolic activity of all tissue
- increases intestinal glucose absorption
- increases lipolysis |
|
|
Term
| cortisol (glucocorticoid) |
|
Definition
- facilitates response to stress
- catabolic effect on protein/fat
- stimulates gluconeogenesis |
|
|
Term
| aldosterone (mineralocorticoid) |
|
Definition
| - controls rate of Na+ loss in renal system |
|
|
Term
|
Definition
- endocrine gland
- islets of Langerhans = endocrine units
- alpha cells: produce/secrete glucagon
- beta cells: produce/secrete insulin |
|
|
Term
|
Definition
- affects 80% cells, esp. muscle/adipose/liver
- decreases blood glucose levels
- increases cellular uptake of glucose/FA's/AA's
- glucose taken in, enzymes that control glycogen synthesis are stimulated (insulin inhibits glycolysis/gluconeogenesis)
- FA's transported to/taken in by adipose cells, converted to triglycerides (insulin inhibits lipase activity)
- AA's transported to/taken in by several cell types (muscle), insulin increases protein synthesis via increase in rate of transcription/translation
- decreases rate of proteolysis
- potent anabolic hormone |
|
|
Term
|
Definition
- opposite effects of insulin
- increases blood glucose levels
1. stimulates glycogenolysis (liver, increases)
2. stimulates gluconeogenesis (liver)
- stimulates lipolysis/release of FA's
- glucagon/insulin regulate each other |
|
|
Term
|
Definition
- innermost portion of adrenal cortex
- synthesizes/secretes catecholamines (affect all tissue) |
|
|
Term
|
Definition
- epinephrine, norepinephrine, dopamine
- same biosynthetic production (tyrosine -> DOPA -> dopamine -> norepinephrine -> epinephrine)
- stored in gland, released upon synpathetic nervous system stimulation/hypoglycemia/exercise
- mediate fight or flight response |
|
|
Term
|
Definition
- mediated by catecholamines
- increase blood glucose (stimulate glycogenolysis/gluconeogenesis)
- increase lipolysis
- increase heart rate/stroke volume
- dilate coronary blood vessels/skeletal muscles |
|
|
Term
|
Definition
1. skeletal (striated)
2. smooth
3. cardiac (striated) |
|
|
Term
|
Definition
- composed of individual muscle fibers
- fibers developed from mononucleated myoblasts
- fiber surrounded by endomysium
- bundle of fibers form fascicle encased by perimysium
- many faciculi = whole muscle, encased by epimysium
- fiber contaitns several hudnred-thousand myofibrils made of myofilaments |
|
|
Term
|
Definition
1. thin: actin (contractile), troponin and tropomyosin (regulatory), 2 double helix chains, within groove is tropomyosin w/ troponin complexes
2. thick: myosin (contractile), 6 chains (2 heavy, 4 light), heavy = double helix, end of each chain MHC forms globular head (cross-bridge) |
|
|
Term
|
Definition
- thin and thick filaments arranged in structured pattern, dark A bands and light I bands
- sarcomere = single contractile unit |
|
|
Term
|
Definition
- caused by filaments sliding
- myosin cross-bridges as ATPase
- when ATP cleaved to ADP and Pi, myosin energized
1. binding of cross bridge to binding site on actin
2. release of ADP and Pi, allows power stroke (pulls toward M line)
3. new ATP binds to cross-bridge, dissociates cross-bridge from actin (relaxation)
4. myosin ATPase cleaves ATP, energizes myosin (cross bridge extends toward new site on actin) |
|
|
Term
| initiation of muscle contraction |
|
Definition
- by increase in cytosolic Ca2+ concentration
1. Ca released from SR
2. Ca binds to troponin complex (T, I, C subunits)
3. conformational change in tropomyosin
4. exposes binding sites on actin |
|
|
Term
|
Definition
- excitation contraction coupling
1. endplate potential generated by motor neuron evokes AP at sarcolemma, spreads from center outward in both directions
2. AP pepentrates into fiber to individual myofibrils via T-tubules
3. membrane of T-tubule abuts that of SR at junctional feet
4. SR stimulated to open Ca channels in membrane
5. increasing amounts of Ca flood in cytosol, contractile activity continues as long as cytosolic Ca increases |
|
|
Term
| stopping muscle contraction |
|
Definition
- Ca pumps located in SR membrane
- without additional electrical stimulation, cytosolic Ca decreases
- Ca binding to troponin decreases and binding sites on actin are "masked"
- Ca pulse lasts 0.05 seconds |
|
|
Term
| single muscle fiber mechanics |
|
Definition
- tension
- load
- isometric/isotonic/isokinetic contraction |
|
|
Term
|
Definition
| force exerted by contracting muscle |
|
|
Term
|
Definition
| force (resistance) exerted by object opposing contracting muscle |
|
|
Term
|
Definition
| tension developed without movement of load |
|
|
Term
|
Definition
constant tension developed accompanied by movement of load
- concentric: shortening of muscle (tension > load)
- eccentric: lengthening of muscle (load > tension) |
|
|
Term
|
Definition
| tension developed with constant rate of movement of load |
|
|
Term
|
Definition
| mechanical response of muscle to single AP |
|
|
Term
|
Definition
| duration between AP and muscle twitch, associated with E-C coupling |
|
|
Term
|
Definition
- period between end of latent period and peak force generation
- different among fiber types |
|
|
Term
|
Definition
- period between peak tension and complete relaxation
- different among fiber types |
|
|
Term
| mechanics of twitch (shortening) |
|
Definition
- depends on load
- increased load = increased latent period/contraction time
- increased load = distance load moved/duration of twitch decreases |
|
|
Term
|
Definition
- duration of twitch (100x greater than AP)
- second twitch generated while first still occurring |
|
|
Term
|
Definition
- repetitive AP's = muscle contraction maintained
- unfused: overall increasing but up/down til get to top
- fused: steadily increases til plateau at top |
|
|
Term
| length-tension relationship |
|
Definition
- tension develoepd by muscle fibers not same throughout range of motion
- optimal length for tension development is length most fibers are at rest |
|
|
Term
| control of whole muscle tension |
|
Definition
- motor unit: single motor neuron + all innervated muscle fibers
1. slow oxidative
2. fast oxidative glycolytic
3. fast glycolytic |
|
|
Term
|
Definition
- few fibers per unit
- slow rate of nervous conduction/contraction
- fatigue resistant
- small type I fibers |
|
|
Term
| fast oxidative glycolytic |
|
Definition
- more fibers per unit
- fairly fatigue resistant
- fast conduction/contraction
- larger type IIA fibers |
|
|
Term
|
Definition
- greatest number of fibers per unit
- fatigue quickly
- fast conduction/contraction
- large type IIB fibers |
|
|
Term
| determinants of tension developed by whole muscle |
|
Definition
1. amount of tension developed by each fiber
2. number of fibers contracting |
|
|
Term
| determinant of force developed |
|
Definition
| number of actomyosin complexes |
|
|
Term
| force-velocity relationship of whole muscle |
|
Definition
| - force generated decreases exponentially as velocity of contraction increases |
|
|
Term
|
Definition
- needed to fuel contractile activity
1. creatine kinase reaction: PC + ADP <-> ATP + C
2. anaerobic metabolism: glycolysis (contributes during more intense exercise)
3. aerobic metabolism: oxidative phosphorylation (used in decreased/moderate exercise intensity level) |
|
|
Term
|
Definition
1. GI tract function
2. blood flow regulation
3. bladder function |
|
|
Term
|
Definition
- similar to skeletal muscle in some ways, very different in others
- innervated by autonomic (involuntary) nervous system |
|
|
Term
| smooth muscle characteristics |
|
Definition
- contraction via cross bridge formation/sliding filaments (different mechanism/regulation than skeletal)
- fibers spindle shaped, smaller than skeletal, mononucleated
- fibers contain actin and myosin but in different proportions than skeletal, diagonal orientation, fiber shortens/widens during contraction
- maximal tension equal to skeletal muscle, affected by length as well but greater range than skeletal |
|
|
Term
| mechanism of smooth muscle contraction |
|
Definition
1. Ca binds to calmodulin
2. Ca/calmodulin complex binds to MLCK
3. phosphorylates myosin cross bridges
4. phosphorylated cross bridges bind to actin
5. cross bridge cycling: change in myosin (not actin) allows, myosin cross bridge does not have ATPase but less than skeletal muscle) |
|
|
Term
| smooth muscle contraction characteristics |
|
Definition
- initiated by increase in cytosolic Ca (different process)
- actin has no troponin/tropomyosin, instead myosin affected by Ca
- contraction stops when cytosolic Ca decreases + action of myosin phosphatase
- rate of cross bridge cycling much slower than in skeletal
- energetics of cross bridge cycling more efficient than in skeletal
- latch mechanism: once full contraction achieved, degree of activation need only be fraction of that needed to initiate contraction |
|
|
Term
| causes of cytosolic Ca increase in smooth muscle |
|
Definition
1. released from SR
2. influx of extracellular Ca |
|
|
Term
| release of Ca from SR in smooth muscle |
|
Definition
- no T-tubule but membrane of SR close to that of cell membrane
- electrical excitation of cell membrane opens Ca channels of SR
- influx of extracellular Ca then causes Ca channels in SR to open
- hormone binding to cell membrane causes breakdown of PIP2 to IP3 (releases Ca from SR) |
|
|
Term
| influx of extracellular Ca in smooth muscle |
|
Definition
- voltage/ligand gated Ca channels on cell membrane
- depolarization of cell membrane opens voltage gated channels, binding of hormones/cytokines open ligand gated channels
- where most Ca comes from |
|
|
Term
| causes of smooth muscle excitation |
|
Definition
- same fiber can receive stimulation of more than one form (unlike skeletal)
1. spontaneous electrical activity (pacemaker potential)
2. neural stimulation
3. hormones
4. local tissue factors (blood vessels) |
|
|
Term
| spontaneous electrical activity (pacemaker potential) |
|
Definition
- excites smooth muscle
- controls gut contractions
- increases leakiness of cell membrane to Ca gradually causing AP
- stimulation transmitted to other fibers via gap junctions |
|
|
Term
|
Definition
- excites smooth muscle
- controlled by autonomic nervous system
- releases norepinephrine and acetylcholine
- receives both excitatory and inhibitory input
- neuromuscular junction has no specialized endplate region, called diffuse junction
- Ca/Na channels evoke AP
- current travels along cell membrane, eventually abuts membrane of SR |
|
|
Term
|
Definition
- excites virtually all smooth muscle fibers
- epinephrine, norepinephrine, oxytocin, histamine
- binding of hormone can open membrane channels/activate intracellular 2nd messenger |
|
|
Term
|
Definition
- excite smooth muscle (blood vessels)
- decreased oxygen/increased CO2/decreased pH (lactic acid) causes relaxation/vasodilation
- increased K+/adenosine and decreased Ca have same effect |
|
|
Term
|
Definition
1.multiunit: independently functioning fibers
- controlled by neural input mainly (some hormones)
- innervated by single nerve ending
- ciliary muscles/iris of eye, large arteries, pilorector muscles
2. single unit: large groups of fibers that contract as unit (syncytial contraction)
- contract together due to gap junctions
- contraction initiated by few cells in unit that generate pacemaker potentials (altered by hormones/nerves/local factors)
- gut, uterus, small blood vessels, viscera |
|
|
