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physio #2
test number two information
| Question | Answer |
|---|---|
| How do drugs act on synaptic transmission? | by interfering with or stimulating normal processes in the neuron involved in: 1. neurotransmitter synthesis 2. storage 3. release 4. receptor activation |
| What are neuromodulators? | 1. they modify both the presynaptic and posynaptic cell's response to specific neurotransmitters amplifying or dampening the effectiveness of ongoing synaptic activity |
| What do receptors for neurotransmitters affect? | ion channels that directly affect excitation or inhibition of the postsynaptic cell within milliseconds. |
| What do receptors for neuromodulators do? | bring changes in metabolic processes in neurons over min, hours, or days |
| what are the alterations that take place during metabolic processes when neuromodulators are affected by receptors? | 1. alterations in enzyme activity 2. influences on DNA transcription 3. protein synthesis |
| ______ are involved in rapid communitcation, and _______ tend to be associated with slower events | neurotransmitters; neuromodulators |
| what events do neuromodulators tend to be associated with? | 1. learning 2. development 3. motivational states 4. some types of sensory or motor activities |
| What are the six classes of some of the chemicals known or presumed to be neurotransmitters or neuromodulators? | 1. acetylcholine 2. biogenic amines 3. amino acids 4. neuropeptides 5. gases 6. purines |
| Where is acetylcholine found? | 1. peripheral nervous system 2. central nervous system |
| what are cholinergic neurons? | neurons that use acetylcholine as the primary neurotransmitter |
| what does aceytlcholine act as? | 1. muscarinic receptors/g protein coupled 2. nicotinin receptors/ion channels |
| when and where is acetylcholine produced? | produced in the presynaptic axon by the enzyme choline acetyl transferase |
| what is the equation for the creation of aceytlcholine? | Acetyl CoA + choline --> acetylcholine + CoA |
| when and where does degradation of aceytlcholine occur? | occurs in the synaptic cleft and is done by the enzyme acetylcholinesterase |
| what is the equation for the degradation of acetylcholine? | acetylcholine --> acetate + choline |
| what are the causes of alzheimer's disease? | because of degeneration of the cholinergic neurons, this disease is associated with a decreased amount of acetylcholine in certain areas of the brain and even the loss of the postsynaptic neurons that would have responded to it. |
| what are the side affects of alzheimer's disease? | 1. declining language and perceptual abilities 2. confusion 3. memory loss |
| what are biogenic amines? | small, charged molecules that are synthesized from amino acids and contain an amino group |
| what amino acids are used to make neurotransmitters? | 1. made from tyrosine - catecholamines 2. made form tryptophan 3. made from histidine |
| what three biogenic amine neurotransmitters are made from tyrosine? | 1. dopamine 2. norepinephrine 3. epinephrine |
| what biogenic amine neurotransmitter is made from tryptophan? | serotonin |
| what biogenic amine neurotransmitter is made from histidine? | histamine |
| what are adrenergic receptors? | g protein coupled that are generally linged to second messenger signal transduction pathways |
| what are adrenergic receptors utilized by? | 1. norepinephrine 2. epinephrine |
| where is norepinephrine found in the body? | 1. central nervous system 2. peripheral nervous system |
| where is epinephrine found in the body? | peripheral nervous system |
| what is serotonin? | 1. aka 5-HT 2. central nervous system neurotransmitter 3. mainly located in the brain stem |
| what are the functions of serotonin? | 1. regulating sleep 2. emotions 3. regulates cell growth 4. vascular smooth muscle cell contraction 5. affects mood and axiety |
| what is histamine most commonly known for? | paracrine actions |
| where is histamine located? | 1. hypothalamus 2. peripheral nervous system |
| what is histamine involved in? | 1. allergic reactions 2. nerve sensitization 3. acid production in the stomach |
| what amino acid neurotransmitters are at excitatory synapses? | 1. aspartate 2. glutamate |
| what amino acid neurotransmitters are at inhibitory synapses? | 1. glycine 2. GABA (gamma amino butyric acid) |
| what is glutamate? | estimated to be the primary neurotransmitter at 50% of the excitatory synapses in the central nervous system. |
| what are neuropeptides? | short chains of amino acids with peptide bonds. |
| what are some examples of neropeptides? | -endogenous opioids 1. enkephalins 2. endorphins 3. morphine 4. codeine |
| what are morphine and codeine used for? | they are synthetic opioids that are used as analgesics, or pain reducers |
| how are gas neurotransmitters produced? | by enzymes in axon terminals that simply diffuse from their sites of origin in one cell into the intracellular fluid of other neurons or effector cells, where they bind to and activate protiens |
| what are examples of gas neurotransmitters? | 1. nitric oxide 2. carbon monoxide 3. hydrogen sulfide |
| what are the receptors on the effector cell known as? | ionotropic or metabotropic |
| where do many neurons synapse take place? | muscle and gland cells |
| what are the two parts of the central nervous system? | 1. brain 2. spinal cord |
| what are the two divisions of the peripheral nervous system? | 1. afferent division 2. efferent division |
| what are the three parts of the afferent division of the peripheral nervous system? | 1. somatic sensory 2. visceral sensory 3. special sensory |
| what are the two parts of the efferent division of the peripheral nervous system? | 1. somatic motor 2. autonomic motor |
| what are the three parts of the autonomic motor system? | 1. sympathetic 2. parasympathetic 3. enteric |
| what does the cerebrum consist of? | 1. right cerebral hemisphere 2. left cerebral hemisphere 3. other structures on the underside of the brain |
| what is the central core of the forebrain formed by? | the diencephalon |
| what is the cerebral cortex? | 1. an outer shell of gray matter composed primarily of cell bodies that give the area a gray appearance 2. an inner layer of white matter, composed primarily of myelinated fiber tracts 3. integrating area of the nervous system |
| the cerebral hempisheres consist of what? | the cerebral cortex |
| what is the subcortical nuclei? | cell clusters which are also gray matter |
| what does the fiber tract consist of? | nerve fibers that: 1. bring info into the cerebrum 2. carry info out 3. connect different areas within a hemisphere |
| what is the massive bundle of nerve fibers that connect the cortex layers of the left and right cerebral hemispheres? | corpus callosum |
| the cortex of each cerebral hemisphere is divided into what? | four lobes: 1. frontal 2. parietal 3. occipital 4. temporal |
| how thick is the cortex? | 3mm |
| the folding of the cortex results in the characteristic external appearance of the human cerebrum, which has what two things? | 1. sinuous ridges aka gyri 2. separated by grooves aka sulci |
| the cells of the human cerebral cortex are organized into what? | six distinct layers |
| what are the two basic types of cells that make up the human cerebral cortex? | 1. pyramidal cells 2. nonpyramidal cells |
| what are pyramidal cells? | they form the major output cells of the cortex, and send their axons to other parts of the cortex and to other parts of the CNS |
| what are nonpyramidal cells? | cells that are mostly involved in recieving inputs into the cortex and in local processing of info |
| what is contained in the diencephalon? | 1. thalamus 2. hypothalamus 3. epithalamus |
| what is the diencephalon divided by? | third cerebral ventricle |
| what is the thalamus? | a collection of several large nuclei |
| what are the functions of the thalamus? | 1. synaptic relay station 2. integrating center for most inputs to the cortex 3. plays a key role in general arousal 4. involved in focusing attention |
| the thalamus is responsible for filtering out what? | extraneous sensory information |
| what are the functions of the hypothalamus? | 1. contains different cell groups and pathways that form the master command center for neural and endocrine coordination 2. preservation of the individual 3. preservation of the species |
| what is an important endocrine structure that the hypothalamus regulates? | pituitary glad |
| what is the epithalamus? | a small mass of tissue that includes the pineal gland |
| what is the pineal gland? | gland that has a role in regulating biological rhythms |
| what is the limbic system? | some of the forebrain areas, consisting of both gray and white matter that are classified together |
| what are structures with the limbic system associated with? | 1. learning 2. emotional experience 3. behavior 4. visceral functions 5. endocrine functions |
| what is the cerebellum? | important center for coordinating movements and for controlling posture and balance |
| what are the functions of the cerebellum? | receives info from: 1. muscles 2. joints 3. skin 4. eyes 5. ears 6. viscera 7. parts of the brain involved in control of movement 8. some forms of learning |
| what is the brainstem? | part of the body that all nerve fibers relay signals between the: 1. forebrain 2. cerebellum 3. spinal cord |
| what is the reticular formation of the brain? | running through the core of the brainstem and consisting of loosely arranged neuron cell bodies intermingled with bundles of axons |
| what are the functions of the brainstem? | 1. receives and integrates input from all regions of the CNS 2. processes neural info |
| what are the functions of the reticular formation? | 1. motor functions 2. cardiovascular control 3. respiratory control 4. mechanisms that regulate sleep, wakefulness, and focus of attention |
| which cranial nerves have ONLY afferent fibers? | 1. olfactory 2. optic 3. vestibulocochlear |
| which cranial nerves have ONLY efferent fibers? | 1. accessory 2. hypoglossal |
| which cranial nerves have BOTH afferent and efferent fibers? | 1. oculomotor 2. trochlear 3. trigeminal 4. abducens 5. facial 6. glossopharyngeal 7. vagus |
| what is the spinal cord and where is it located? | lies within the bony vertebral column and is a slender cylinder of soft tissue about as big around as the little finger |
| what is the central butterfly-shaped area of gray matter composed of? | 1. interneurons 2. cell bodies and dendrites of efferent neurons 3. entering axons of afferent neurons 4. glial cells |
| what are the dorsal horns? | regions of gray matter projecting toward the back of the body |
| what are the ventral horns? | regions of gray matter oriented toward the front of the body |
| what is the gray matter surrounded by? | white matter, which consists of groups of myelinated axons |
| what kind of pathway is the ventral root of the spinal cord? | motor/efferent |
| what kind of pathway is the dorsal root of the spinal cord? | sensory/afferent |
| what is the peripheral nervous system? | neurons transmit signals between: 1. the CNS 2. receptors and effectors in all other parts of the body |
| what is the PNS composed of? | 43 pairs of nerves: 1. 12 pairs of cranial nerves 2. 31 pairs that connect with the spinal cord and spinal nerves |
| how are the 31 pairs of spinal nerves designated? | by the vertebral levels from which they exit: 1. cervical (8) 2. thoracic (12) 3. lumbar (5) 4. sacral (5) 5. coccygeal (1) |
| efferent neurons carry signals out from the CNS to what? | muscles or glands |
| the efferent division of the PNS is subdivided into what? | 1. somatic nervous system 2. autonomic nervous system |
| what are the functions of the somatic nervous system? | 1. consists of a single neuron between CNS and skeletal muscle cells 2. innervates skeletal muscle 3. can lead only to muscle excitation |
| what are the functions of the autonomic nervous system? | 1. has two-neuron chain between CNS and effector organ 2. innervates smooth and cardiac muscle, glands and GI neurons 3. can be either excitatory or inhibitory |
| what is the enteric nervous system and where is it located? | located in the GI tract and is classified as a subdivision of the autonomic efferent nervous system. also includes sensory neurons and interneurons |
| what are the subdivisions of the autonomic nervous system? | 1. sympathetic 2. parasympathteic |
| what is the basis for the autonomic nervous systems further subdivision? | anatomical and physiological differences |
| where do the sympathetic fibers leave the CNS from? | 1. thoracic (chest) region of the spinal cord 2. lumbar region of the spinal cord |
| where do the parasympathetic fibers leave the CNS from? | 1. brainstem 2. sacral portion of the spinal cord |
| sympathetic division is also known as... | thoracolumbar division |
| what kind of synapses does sympathetic division have? | 1. short pre-ganglionic 2. long post-ganglionic |
| what are the major neurotransmitters of sympathetic division? | 1. ACh at the pre-ganglionic synapse 2. NE and Epi at the post-ganglionic |
| parasympathetic division is also known as... | craniosacral division |
| what kind of synapses does parasympathetic division? | 1. long pre-ganglionic 2. short post-ganglionic |
| what are the major neurotransmitters of the parasympathetic division? | ACh at both pre- and post-ganglionic synapses |
| one set of postganglionic neurons in the sympathetic division never develops axons, instead they form what? | adrenal medulla |
| what are catecholamines? | hormones rather than neurotransmitters |
| how are catecholamines transported? | via the blood to effort cells having receptors sensitive to them |
| what is dual innervation? | innervated by both sympathetic and parasympathetic fibers |
| what body parts receive dual innervation? | 1. heart 2. glands 3. smooth muscles |
| what supports and protects the structures of the CNS and PNS? | bone |
| what are the structures of the CNS and PNS? | 1. cranium 2. vertebrae |
| what are meninges? | membranes that line the structures and add additional support and protections |
| what are the three layers of the meninges from external to internal? | 1. dura mater 2. arachnoid matar 3. pia matar |
| what does the cerebrospinal fluid do? | protects and cushions the structures |
| what are the jobs of the meninges? | 1. cover and protect the CNS 2. protect blood vessels and enclose the venous sinuses 3. contain cerebrospinal fluid 4. form partitions in the skull |
| what is meningitis? | inflammation of the meninges and is a serious threat to the brain since bacterial or viral meningitis can spread to the CNS |
| what is encephalitis? | when the brain itself is inflamed |
| what is cerebrospinal fluid? | the extracellular fluid of the CNS and it is secreted by ependymal cells of the choroid plexus |
| what is the total volume of CSP present at any given time? | 125-150 mL |
| the choroid plexus produces how many mL of CSF every day? | 400-500 mL/day |
| how many times does the entire contents of CSF get recycled everyday? | 3 times |
| the recycling of CSF is important because why? | maintains a stable and optimal environment |
| what is hydrocephalus? | an accumulation of CSF in the brain that is often caused by tumors |
| what is the blood-brain barrier? | a protective mechanism that helps maintain a stable environment for the brain |
| what is a stroke? | decreased blood supply or a hemorrhage |
| what is an ischemic stroke? | a blood blot that blocks and artery or the rupture of an aterosclerotic plaque |
| what is a hemorragic stroke? | where the blood vessel has ruptured |
| what is a contustion? | bruising of the brain |
| what are sensory receptors? | specialized cells that generate receptor potentials in response to a stimulus |
| what are the 5 major divisions of sensory receptors based on stimuli that they respond to? | 1. mechanoreceptors - touch 2. thermoreceptors - temp 3. photoreceptors - light 4. chemoreceptors - chemicals 5. nociceptors - pain |
| what is primary sensory coding? | conversion of a stimulus into a signal that is conveyed to the CNS |
| who is info conveyed to the CNS by primary sensory coding? | by both the frequency and the amplitude of the resulting signals |
| what are examples of stimulus type, aka stimulus modality? | 1. temp 2. pressure 3. sound 4. light |
| what are labeled lines? | info about the location of a stimuli which is determined by the site of the stimuli and because signals from different locations travel along separate pathways to a specific region of the brain |
| what are specific ascending pathways | pathways that carry info about one type of stimuli and enters the brainstem and thalamus then to specific sensory areas of the cerebral cortex |
| what are nonspecific pathways? | activated by several different types of stimuli and just indicate that 'something is happening' |
| what are the 4 types of primary cortical areas? | 1. somatosensory cortex 2. visual cortex 3. auditory cortex 4. olfactory cortex |
| what are the factors that affect perception? | 1. receptor adaptation and afferent processing 2. emotions and experiences 3. not all stimuli give rise to a conscious sensation 4. lack of receptors for certain stimuli 5. damaged neural pathways 6. drugs |
| what is somatic sensation? | sensation from: 1. skin 2. muscles 3. bones 4. tendons and joints |
| how is somatic senstaion initiated? | by a variety of sensory receptors collectively called somatic receptors |
| what do somatic receptors respond to? | 1. touch and pressure 2. sense of posture and movement 3. temperature 4. pain |
| what are the eyes composed of? | 1. optical component 2. neural component |
| what does the optical component of the eye do? | focuses the visual image on the receptor cells |
| what does the neural component of the eye do? | transforms the visual image into a patter of graded and action potentials |
| how are light signals converted into action potentials? | through the interaction of photoreceptors with bipolar cells and ganglion cells |
| why do photoreceptor and bipolar cells undergo graded responses? | they lack the voltage-gated channels that mediate action potentials in other type of neurons |
| what are the first cells in the pathway where action potentials can be initiated? | ganglion cells |
| what does like striking the photoreceptors of either pathway do? | hyperpolarizes the photoreceptors |
| what is the result of hyperpolarization of photoreceptors? | a decrease in gluatmate release onto bipolar cells |
| what are the two differences in the pathways? | 1. bipolar : on-pathway = depolarize and off-pathway = hyperpolarize 2. glutamate : on-pathway = inhibitory and off-pathway = excitatory |
| how do we have color vision? | we perceive the colors related to the wavelengths of light that the pigments in the objects of our visual world reflect, absorb or transmit. |
| in brightly lit conditions what in our vision allows for good color? | the response of cones |
| in dim light, what in our vision allows for good color? | highly sensitive rods |
| what is the sense of hearing based off of? | the physics of sound and the physiology of the exernal, middle and inner ear, the nerves to the brain, and the brain regions involved in processing acoustic info |
| how is sound energy transmitted? | through gaseous, liquid, or solid medium by setting up a vibration of the medium's molecules |
| what is the most common medium? | air |
| can there be sound if there are no molecules? | no |
| what do chochlear nerver fibers synapse with? | interneurons in the brainstem |
| how is vestibular info used? | 1. control eye movement 2. to maintain posture and balance 3. to provide awareness of body position and acceleration |
| how do vestibular nerve fibers transmit info? | through the brainstem and thalamus to the vestibular centers in the parietal lobe |
| how is vestibular info integrated? | with info from proprioceptors |
| what are chemicals binding to specific chemoreceptors responsible for? | detection of taste and smell |
| what are taste buds? | small groups of cells arranged like orange slices around a hollow pore |
| what are microvilli? | increase the surface area of taste receptor cells and contain integral membrane proteins and transduce the presence of a given chemical into a receptor potential |
| what are at the bottom of taste buds? | basal cells |
| what do basal cells do? | divide and differentiate to continually replace taste receptor cells damaged in the occasionally harsh environment of the mouth |
| what are the basic types of taste receptors? | 1. sweet 2. sour 3. salty 4. bitter 5. umami |
| what is umami? | taste associated with the taste of glutamate and similar amino acids and is sometimes described as conveying the sense of savoryness or flavorfulness |
| what signals salt taste? | sodium ions |
| what signals sour taste? | hydrogen ions |
| what signals sweet taste? | glucose |
| what signals bitter taste? | many poisonous substances such as plant alkaloids like sstrychnine and arsenic |
| what signals umami taste | umami receptor cells |
| what are olfactory receptors and where are they located? | they life in the olfactory epithelium, in the upper part of the nasal cavity and they only last for about two months which means they are constantly being replaced by new cells produced from stem cells |
| what does the cilia contain? | the receptor proteins that provide the binding sites for odor molecules |
| what do proteins in mucus do? | may interact with odorant molecules, transport them to the receptors, and facilitate their biding to the receptors |
| olfactory discrimination varies with what things? | 1. attentiveness 2. hunger 3. gender 4. smoking 5. age 6. state of the olfactory mucosa |
| what is anosmia? | total lack of the ability to smell |
| how is muscle classified? | 1. skeletal muscle 2. smooth muscle 3. cardiac muscle |
| what are the characteristics of skeletal muscle fiber? | 1. multinucleated 2. contains many mitochondria 3. has T tubules 4. has myofibrils and sarcomeres 5. sarcolemma 6. sarcoplasma 7. sarcoplasmic reticulum |
| what is the sarcolemma of skeletal muscle fiber? | plasma membrane |
| what is the sarcoplasm of the skeletal muscle fiber? | cytoplasm |
| what is the sarcoplasmic reticulum of the skeletal muscle fiber? | smooth ER |
| what are myofibrils? | structures that give skeletal and cardiac muscle their characteristic striated appearance |
| how are myofibrils arranged? | 1. actin (thin filament) 2. myosin (thick filament) |
| what is muscle contraction? | activation of the force-generating sites within muscle fibers aka the cross-bridges |
| what is the sliding filament mechanism? | produces shortening of a skeletal muscle fiber, the overlapping thick and thin filaments in each sarcomere move past each other, propelled by movements of the cross-bridges |
| what are the aspects of actin? | 1. contractile protein 2. each G actin has a binding site for myosin |
| what are the aspects of tropomyosin? | 1. regulatory protein 2. overlaps binding sites on actin for myosin and inhibits interaction when in the relaxed state |
| what are the aspects of troponin? | 1. regulatory protein 2. forms a complex with the other proteins of the thin filament 3. binds CA2+ and once bound changes conformation to pull tropomyosin away from the myosin interaction sites |
| what does ca2+ binding to troponin regulate? | skeletal muscle contraction becuase it moves the tropomyosin away and allows myosin to interact with the actin |
| what is the sarcoplasmic reticulum? | where ca2+ is store and release following membrane excitatation |
| how are t-tubules and SR connected? | with junctions that involve two integral membrane proteins |
| what is the t-tuble protein? | a modified voltage-sensitive ca2+ channel known as the DHP receptor which acts as a voltage sensor |
| what protein is embedded in the SR membrane? | ryanodine receptor which forms a ca2+ channel |
| what is a motor unit? | the motor neuron and the skeletal muscle fibers it innervates |
| are there many motor units within a whole muscle? | yes |
| what is the only mechanism by which action potentials are initiated in skeletal muscle? | stimulation of the nerve fibers to a skeletal muscle |
| what are the nerve cells whose axons innervate skeletal muscle fibers known as? | motor neurons aka somatic efferent neurons |
| where are motor neurons cell bodies located? | in either the brainstem or the spinal cord |
| the axons of motor neurons are what? | 1. myelinated 2. largest-diameter axons in the body |
| what do axons of motor neurons do? | propagate action potentials at high velocities which allow signals from the CNS to travel to skeletal muscle fibers with minimal delay |
| what do the axon terminals of a motor neuron contain? | vesicles |
| what neurotransmitter do vesicles contain? | ACh |
| what is the region of the muscle fiber plasma membrane that lies directly under the terminal portion of the axon? | motor end plate |
| what is the junction of an axon terminal with the motor end plate? | neuromuscular junction |
| are all neuromuscular junctions excitatory? | yes |
| what does the synaptic junction contain? | 1. receptors for ACh 2. enzyme acetylcholinesterase |
| what does acetylcholinesterase do? | breaks down ACh, just as it does at ACh-mediated synapses in the nervous system |
| what does a muscle fiber do? | generates force called tension |
| what is tension? | opposes a force called the load |
| what is the load? | force exerted on the muscle by an object |
| what is the mechanical response of a muscle fiber to a single action potential known as? | twitch |
| what are the three phases of a twitch contraction? | 1. latent 2. contraction 3. relaxation |
| what is the latent period of a twitch contraction? | period of time from the action potential to the onset of contraction |
| what is the time delay in the latent period due to? | the excitation-contraction coupling |
| what is the contraction phase of a twitch contraction? | time that tension is developing due to cross-bridge cycling |
| what is the relaxation phase of a twitch contraction? | time that the tension is decreasing and is longer than the contraction phase |
| why is the relaxation phase longer than the contraction phase? | it is due to the amount of time it takes to get all the ca2+ sequestered |
| what is an isometric twitch? | generates tension but do not shorten the muscle |
| what is an isotonic twitch? | shorten the muscle |
| what is tetanus? | a maintained contraction in response to repetitive stimulation |
| what is summation? | the increase in muscle tension from successive action potentials occurring during the phase of mechanical activity |
| what happens when a stimulus is applied before a fiber has completely relaxed from a twitch? | it induces a contractile response with a peak tension greater than that produced in a single twitch |
| how long does a single action potential in a skeletal muscle fiber last? | 1 to 2 ms |
| is it possible for a second action potential to be initiated during the period of mechanical activity? | yes |
| what are the three ways a muscle fiber can form ATP? | 1. phosphorylation of ADP by creatine phosphate 2. oxidavtive phosphorylation of ADP in the mitochondria 3. phosphorylation of ADP by the glycolytic pathway in the cytosol |
| what happens when a skeletal muscle fiber is repeatedly stimulated? | the tension the fiber develops eventually decreases though the stimulation continues |
| what is the decline in muscle tension a result of previous contractile activity known as? | muscle fatigue |
| what does the onset of fatigue and its rate of development depend on? | 1. type of skeletal muscle fiber that is active 2. the intensity and duration of contractile activity 3. degree of an individual's fitness |
| what three things cause muscle fatigue? | 1. conduction failure 2. lactic acid buildup 3. inhibition of cross-bridge cycling 4. central command fatigue |
| what is conduction failure? | when the muscle action can fial to be conducted into the fiber along the t-tubules, which halts the release of ca2+ from the SR |
| what is lactic acid buildup? | 1. elevated hydrogen ion concentration alters protein conformation and activity 2. acidification of a muscle by lactic acid may alter a number of muscle proteins 3. function of ca2+ - ATPase pumps of the SR is affected = impaired relaxation |
| what is inhibition of cross-bridge cycling? | 1. buildup of ADP and Pi within muscle fibers during intense activity 2. slowing the rate delays cross-bridge detachment from actin, thus slowing the over all rate of the cross-bridge cycling 3. reduced shortening velocity and impaired relaxation |
| what is central command fatigue? | 1. occurs when the appropriate regions of the cerebral cortex fail to send excitatory signals to the motor neurons 2. can cause a person to stop exercising even though muscles are not fatigued |
| what does an increase in the amount of contractile activity do to muscle fibers? | 1. increase their size 2. increase their capacity for ATP production |
| what are the two types of muscle atrophy? | 1. disuse atrophy (arm in a cast) 2. denervation atrophy (nerve damage = loss of function) |
| what produces muscle cramps? | involuntary tetanic contraction of skeletal muscles |
| what happens to action potentials during muscle cramping? | action potentials fire at abnormally high rates |
| what is the cause of muscle cramps? | uncertain, but probably related to electrolyte imbalances in the extracellular fluid surrounding both the muscle and nerve fibers |
| how do electrolyte imbalances occur? | 1. overexercise 2. persistent dehydration |
| what are the aspects of the structure of smooth muscle? | 1. spindle-shaped 2. diameter between 2-10 um 3. length ranging from 50-400 um |
| how wide and long are skeletal muscle fibers? | 1. 10-100 um wide 2 tens of centimeters long |
| what are the aspects of smooth muscle cells? | 1. single nucleus 2. capacity to divide throughout the life of an individual 3. thick myosin-containing filaments 4. thin actin-containing filaments 5. tropomyosin NO troponin |
| where are the thin filaments of smooth muscle cells anchored? | either to the plasma membrane or to cytoplasmic structures aka dense bodies |
| are thick and thin filaments organized into myofibrils on smooth muscles? | no |
| are there sarcomeres on smooth muscles? | no |
| what does the lack of sarcomeres on smooth muscles account for? | the absence of the banding pattern |
| how does smooth muscle contraction occur? | by a sliding-filament mechanism |
| what do smooth muscles surround? | hollow structures and organs that undergo changes in volume with accompanying changes in the lengths of the smooth muscle fibers in their walls. |
| what are the two sources of ca2+ that contribute to the rise in cytosolic ca2+ that initiates smooth muscle contraction? | 1. the SR 2. extracellular ca2+ enter the cell through plasma-membrane ca2+ channels |
| what happens to relax a smooth muscle contraction? | the ca2+ has to be removed either to the SR or back to the extracellular fluid |
| can smooth muscle responses be graded? | yes |
| can input to smooth muscle contraction be either excitatory or inhibitory? | yes |
| how is the contractile activity of smooth muscles influenced? | by neurotransmitters released by autonomic neuron endings |
| do smooth muscle cells have a specialized motor end-plate region? | no |
| what are varicosities? | swollen regions that contain many vesicles filled with neurotransmitter, some of which are released when an action potential passes it |
| what neurotransmitter can produce opposite effects in different smooth muscle tissues? | NEpi |
| what is norepinephrine? | neurotransmitter released from most post-ganglionic sympathetic neurons, enhances contraction of most vascular smooth muscle by acting on alpha-adrenergic receptors but produces relaxation of airway smooth muscle by acting on beta-2 adrenergic receptors |
| what does the type of response (excitatory or inhibitory) depend on? | 1. the chemical messenger 2. the receptors the chemical messenger binds to in the membrane and on the intracellular signaling mechanisms those receptors activate |
| what are the local factors that can alter smooth muscle tension? | 1. paracrine signals 2. acidity 3. o2 and co2 levels 4. osmolarity 5. ion composition of the extracellular fluid |
| what local factor induces smooth muscle relaxation? | nitric oxide in a paracrine manner |
| that does stretching do? | opens mechanosensitive ion channels, leading to membrane depolarization |
| what is a pacemaker potential? | the membrane potential change occurring during the spontaneous depolarization to the threshold |
| what are slow waves? | periodic fluctuations in ion flux across the membrane |
| where are pacemaker cells found? | 1. GI tract 2. some cardiac muscle fibers 3. few neurons in the CNS |
| what are inputs that influence smooth muscle contractile activity? | 1. spontaneous electrical activity in the plasma membrane of the muscle cell 2. neurotransmitters released by autonomic neurons 3. hormones 4. locally induced changes in the chemical composition of the extracellular fluid surrounding the cell 5. stre |
| what are the aspects of cardiac muscles? | 1. two nuclei centrally located 2. striated 3. use sliding filament mechanism to contract 4. branching cells with intercalated discs with desmosomes and gap junctions 5. large mitochondria |
| what are gap junctions? | critical to the heart's ability to be electrically coupled |
| what are the mitochondria in cardiac muscle responsible for? | 1. produce energy needed 2. prevent the heart from fatiguing |
| what is automaticity or autorhythmicity? | the ability of node cells to stimulate their own action potentials in cardiac muscle |
| what is the absolute refractory period of cardiac muscle? | 1. about 250 ms 2. prevents tetanic contractions |
| what would tetanic contractions do to cardiac muscle? | interfere with the heart's ability to pump |
| what are the different chemical classes of hormones? | 1. amine hormones 2. peptide and protein hormones 3. steroid hormones |
| what are amine hormones? | 1. derivatives of tyrosine 2. include thyroid hormones 3. epi and noepi |
| what are most hormones? | peptide and protein hormones |
| what are steroid hormones? | 1. derivatives of cholesterol 2. produced by adrenal cortex 3. gonads |
| what are adrenal cortex hormones? | 1. aldosterone 2. cortisol 3. affect metabolism of glucose and other nutrients 4. dehydroepiandrosterone and androstenedione |
| what is aldosterone? | 1. controlled by angiotensin II 2. affect na+, k+, and h+ |
| what is dyhydroepiandrosterone and androstenedione? | androgen's aka male sex organs |
| what are the gonads? | 1. testes 2. ovaries |
| what are the hormones of the testes? | androgens |
| what are the hormones of the ovaries? | 1. estrogen 2. progesterone |
| what is an example of androgens? | testosterone |
| what is an example of estrogen? | estradiol |
| what is progesterone responsible for? | menstrual cycle and preganancy |
| how are peptides and catecholamines transported in blood? | 1. free (unbound) in plasma 2. receptors located in plasma membrane 3. most common signaling mechanisms: second messengers, enzymes activation by receptor, and intrinsic enzymatic activity of receptor 4. fast (min.) rate of excretion/metabolism |
| how are steroids and thyroid hormones transported? | 1. protein-bound in plasma 2. receptors located in intracellular fluid 3. most common signaling mechanism: intracellular receptors directly alter gene transcription 4. slow (hours to days) rate of excretion/metabolism |
| what does hormone concentration depend on? | 1. rate of secretion 2. rate of uptake from blood |
| how can hormones be cleared? | 1. excretion in urine 2. breakdown by liver, in blood or tissues 3. metabolism by target cells |
| are protein bound hormones protected from excretion or metabolism? | yes |
| where are the receptors for peptides and catecholamines located? | cell membrane |
| where are the receptors for steroids and thyroid hormones located? | inside target cells |
| can hormones regulate the presence of their receptors? | yes, and they may regulate receptors for hormones too |
| what does the ability of a cell to respond to a hormone depend on? | the presence of receptors for that hormone on or in the target cell |
| what is up-regulation? | an increase in the number of receptors for a hormone |
| what is down-regulation? | a decrease in the number of receptors for a hormone |
| what are the effects of peptide hormones and catecholamines? | 1. influence enzyme activity of the receptor 2. influence activity of enzymes or ion channels associated with the receptor 3. signal transduction may lead to gene activation or inhibition |
| what three things can act on an endocrine cell altering the rate of hormone secretion/ | 1. ions and nutrients 2. neurotransmitters 3. hormones |
| an increase in plasma glucose concentration results in what reaction? | 1. increase in insulin secretion 2. increase in plasma insulin concentration 3. increase in actions of insulin/transport of glucose from extracellular to intracellular fluid |
| what is a tropic hormone? | a hormone that controls the secretion of another horomone |
| what are the three types of endocrine disorders? | 1. hyposecretion 2. hypersecretion 3. hyporesponsiveness and hyperresponsiveness |
| what is hyposecretion? | secretion of too little hormone |
| what is hypersecretion? | secretion of too much hormone |
| what is hyporesponsivenss and hyperrsponsiveness? | occurs when the target cells do not respond properly to a hormone |
| what is an example of hyporesponsiveness and hyperresponsiveness? | type 3 diabetes mellitus |
| what does the posterior pituitary gland do? | secretes hormones that are made in the hypothalamus |
| what is oxytocin? | 1. involved in milk ejection reflex of nursing mothers 2. emotional bonding 3. uterine contractions |
| what is the antidiuretic hormone known as? | vasopressin |
| what is vasopressin involved in? | 1. regulation of water balance 2. osmolarity |
| what are the anterior pituitary hormones? | 1. follicle stimulating hormone (gamete prodcution) 2. luteinizing hormone (sex hormone production) 3. growth hormone (growth and metabolism) 4. thryroid stimulating hormone 5. prolactin 6. adrenocroticotropic hormone |
| how does t4 get converted to t3? | by target cells |
| what are the two thyroid hormones? | 1. thyroxine (t4) = 4 iodines 2. triiodothyronine (t3) = 3 iodines |
| how is thyroid hormone secretion regulated? | by TSH |
| how is TSH regulated? | by thyrotropin releasing hormone |
| what are the actions of thyroid hormones? | 1. receptors for thyroid hormones 2. receptors in the nucleus 3. induce gene transcription 4. stimulate carb absorption from SI 5. keep metabolic rate high 6. stimulate action of Na+/K+ATPase 7. increase glycolysis and produce heat 8. calorigenic a |
| what are the aspects of a goiter? | 1. lack of iodine which causes inability to produce thyroid hormones 2. releases neg. feedback on hypothalamus and pituitary glands 3. increased production of TSH 4. casues increases in cell division in thymus 5. hypertrophy |
| what is hypothyroidism? | 1. caused by autoimmune disease in the us 2. hashimoto's disease 3. t cells attack thyroid tissue |
| what are hypothyroidism symptoms? | 1. cold intolerance 2. weight gain 3. fatigue 4. reduced appetite 5. reduced mental function |
| what is hyperthyroidism? | 1. caused by thyroid tumors 2. autoimmune disease 3. symptoms: heat intolerance, weight loss, increased appetite, anxiety |
| how does the endocrine system respond to stress? | by increasing the release of cortisol from the adrenal cortex and epi form the adrenal medulla |
| what are reason the body stresses? | 1. trauma 2. infection 3. pain 4. sleep deprivation 5. fright 6. other emotional problems |
| what are the aspects of cortisol? | 1. stimulated by ADH and cytokines 2. stimulate stress response during infection |
| what is adrenal insufficiency? | loss of adrenal cortical function, due to infections diseases like tuberculosis infiltrating the adrenal glands |
| what does adrenal insufficiency cause? | 1. weakness 2. lethargy 3. loss of appetite 4. low blood pressure 5. low blood sugar, especially after fasting |
| what is cushing's syndrome? | excess cortisol in the blood, even in the unstressed individual |
| what is hypotension and how could it be caused? | the loss of salt and water balance which could lead to low blood pressure |
| what is addison's disease? | primary adrenal insufficiencey from any oh these causes |
| what is secondary adrenal insufficiency? | deficiency of ACTH which can arise from pituitary disease |
| how is cushings caused? | 1. a cortisol-secreting tumor of the adrenal gland 2. an ACTH-secreting tumor of the pituitary gland |
| what happens in secondary cushing's disease? | increased blood levels of cortisol promote uncontrolled catabolim of bone, muscle, skin, and other organs. |
| what are some treatments for cushing's syndrome? | 1. surgicla removal of the pituitary tumor 2. adreanalectomy |
| what problems occur during cushing's syndrome? | 1. osteoporosis 2. muscle weakness 3. increase in blood sugar level 4. immunosuppression 5. redistribution of fat 6. hypertension (high blood pressure) |
| what is the parathyroid hormone secreted by and why is it important? | secreted by the parathyroid glands (4 glands located in the neck on the thyroid gland) and it is important to regulation of calcium levels |
| is ca2+ homeostasis vital? | yes |
| what are the effector sites for calcium homeostasis? | 1. bone 2. kidneys 3. GI tract |
| what are the two major hormones that regulate plasma calcium concentration? | 1. parathyroid hormone 2. 1, 25-dihydroxyvitamin D |
| what is calitonin? | decreases plasma calcium concentration by inhibiting osteoclasts by being secreted by parafollicular cells |
Created by:
kpmorris