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SCI221-2
| Question | Answer |
|---|---|
| Membrane potential | Difference in electrical charge between inside and outside of the plasma membrane |
| Resting membrane potential (RMP) | Membrane voltage when the neuron is not excited and not conducting an impulse |
| Sodium-potassium pump | Active transport pump that operates in the plasma membrane of all human cells; transports both sodium ions and potassium ions but in opposite directions and in a 3:2 ratio, thereby maintaining a gradient across the plasma membrane |
| Local potential | Temporary fluctuation in a local region of the membrane in response to a sensory or nerve stimulus; may be an upward or downward fluctuation in voltage; loses amplitude as it spreads along membrane |
| Stimulus-gated channels | Type of cell-membrane channel for the transport of molecules that is controlled by a gate that responds to a stimulus such as a sensory stimulus or chemical (neurotransmitter) stimulus |
| Ligand-gated channels | Membrane channel that opens or closes in response to the binding of a chemical signal (ligand) to a receptor; also called a stimulus-gated channel |
| Depolarization | Electrical activity that triggers a contraction of the heart muscle |
| Hyperpolarization | Increase in electrical charges separated by the cell membrane; causes change further below 0 mV |
| Action potential | Temporary maximum depolarization of membrane voltage that travels to end of axon without losing amplitude |
| Threshold potential | Minimum local depolarization needed to trigger voltage-gated channels that produce the action potential |
| Steps of the Mechanism That Produces an Action Potential | A stimulus triggers stimulus-gated Na channels to open and allow inward Na diffusion. This causes the membrane to depolarize. As the threshold potential is reached, voltage-gated Na channels open. As more Na enters the cell through voltage-gated Nachann |
| Absolute refractory period | Time during which the local area of the membrane has surpassed the threshold potential and will not respond to any stimulus |
| Relative refractory period | In muscle cell contraction, the few milliseconds after the absolute refractory period; time during which the membrane is repolarizing and restoring the resting membrane potential |
| Saltatory conduction | Process in which a nerve impulse travels along a myelinated fiber by jumping from one node of Ranvier to the next |
| Synapse | Membrane-to-membrane junction between a neuron and another neuron, effector cell, or sensory cell; functions to propagate nerve impulses |
| Electrical synapse | A mechanical and electrically conductive link between two neighboring neurons that is formed at a narrow gap between the pre- and postsynaptic neurons known as a gap junction |
| Chemical synapse | Specialized junctions through which cells of the nervous system signal to one another and to non-neuronal cells such as muscles or glands |
| Synaptic cleft | Space between a synaptic knob and the plasma membrane of a postsynaptic neuron |
| Postsynaptic potential | Local potential produced by opening of ion channels in the postsynaptic membrane |
| Excitatory postsynaptic potential | Temporary depolarization of postsynaptic membrane following stimulation |
| Inhibitory postsynaptic potential (IPSP) | Temporary hyperpolarization that makes the inside of the membrane even more negative than at the resting potential |
| Spatial summation | Ability of the postsynaptic neuron to add together the inhibitory and stimulatory input received from numerous different presynaptic neurons and produce an action potential based on that collation of information |
| Temporal summation | When synaptic knobs stimulate a postsynaptic neuron in rapid succession and the effects add up over time to produce an action potential (also spatial summation) |
| Neurotransmitters | Chemicals by which neurons communicate; the substance is released by a neuron, diffuses across the synapse, and binds to the postsynaptic neuron |
| Ionotropic receptors | Membrane receptor that includes a ion channel that opens or closes in response to stimulation (binding) of the receptor site |
| Metabotropic receptors | A G protein–coupled receptor (GPCR) that triggers cell metabolic pathways when stimulated, rather than directly opening a membrane channel |
| G protein–coupled receptors (GPCRs) | Receptor mechanism embedded in plasma membranes of cells that receives chemical messengers (such as neurotransmitters and nonsteroid hormones) and initiates signal transduction to the cell by way of a G protein, which triggers the resulting changes in the |
| Acetylcholine (ACh) | Type of neurotransmitter used by motor neurons at neuromuscular junctions to stimulate muscle contraction at or in some autonomic synapses |
| Catecholamines | Dopamine, epinephrine, norepinephrine |
| Amines | Serotonin, histamine |
| Amino Acids | Glutamiate, gamma-aminobutyric, glycine |
| Other small molecules | Nitric oxide, adenosine triphosphate (ATP), adenosine |
| Large molecule transmitters | Vasoactive intestinal peptide, cholecystokinin, substance P, enkephalins, endorphins, dynorphins, neuropeptide Y |
| Neural networks | A network of interconnected neurons in nervous tissue, forming a web of pathways to process information [ |
| Convergence | A coming together, as in movement of the two eyeballs inward so that their visual axes come together at the same point on the object viewed; also, when more than one presynaptic axon syn-apses with a single postsynaptic neuron |
| Divergence | When a single presynaptic axon synapses with more than one different postsynaptic neuron [ |
| Excitotoxins | Glutamate or other substance that has an excessive stimulatory effect on neurons or other cells, thus causing damage or cell death |
| Pulmonary ventilation | Breathing; process that moves air in and out of the lungs |
| Primary principle of ventilation | Movement of air in the pulmonary airways from the area where the pressure is higher to the area where the pressure is lower |
| Boyle's law | Principle of physics that states that the pressure of a gas is proportional to its volume |
| Dalton's law | A gas law that states that the total pressure exerted by a mixture of gases is the sum of the pressure of each individual gas; also called law of partial pressure |
| Henry's law | A gas law that describes how the pressure of a gas relates to the concentration of that gas in a liquid solution |
| Transpulomonary pressure | The pressure difference between the alveolar air pressure in the lungs and the fluid pressure in the intrapleural space, that is, the pressure difference across the wall of the lung |
| Young-LaPlace law | Principle that states that air pressure (P) in a bubble is inversely proportional to the radius (r) and directly proportional to the surface tension (T) summarized by the equation P ⫽ 2T/r |
| Tidal volume | Amount of air breathed in and out with each breath |
| Expiratory reserve volume (ERV) | Amount of air that can be forcibly exhaled after expiring the tidal volume |
| Inspiratory reserve volume (IRV) | Amount of air that can be forcibly inspired over and above a normal inspiration |
| Vital capacity (VC) | Largest amount of air that can be moved in and out of the lungs in one inspiration and expiration |
| Residual volume (RV) | Amount of air that remains in the lungs after the most forceful expiration |
| Anatomical dead space | Air passageways that contain air that does not reach the alveoli |
| Physiological dead space | The anatomical dead space (pulmonary airway volume outside the alveoli) plus any alveolar dead space ( |
| Functional residual capacity (FRC) | Amount of air left in the lungs at the end of a normal expiration |
| Total lung Capacity (TLC) | Total volume of air a lung can hold |
| Forced expiratory volume (FEV) | Maximum volume (mL or L) of air that can be breathed out; also called forced vital capacity (FVC) |
| Central chemoreceptors | Sensory receptor in the brain (central nervous system) that detects changes in chemical concentrations such as oxygen, carbon dioxide, or pH |
| Peripheral chemoreceptors | Sensory receptor in a peripheral nerve that detects changes in chemical concentrations such as oxygen, carbon dioxide, or pH |
| Hering-Breuer reflexes | Stretch reflex to control respirations—especially rate and rhythmicit |
| Rate law | Law of mass action |
| Bohr effect | When increased Pco2 decreases the affinity between hemoglobin and oxygen |
| Haldane effect | A phenomenon that refers to the increased CO2 loading caused by a decrease in Po2 |
| Deglutition | Swallowing |
| Migrating motor complex (MMC) | Wave of rhythmic contractions of the smooth muscle in the gastrointestinal tract during the fasting state [ |
| Propulsion | Continual pushing of chyme in the stomach toward the pyloric sphincter by peristaltic contractions |
| Retropulsion | Process of chyme being forced to move backward behind a closed pyloric sphincter |
| Chief cells | Cells lining the gastric glands of the stomach that secrete pepsinogen and intrinsic factor; also called zymogenic cells |
| H-K pump | Ion pump for hydrogen ions and potassium ions in the plasma membrane of gastric parietal cells |
| Intrinsic factor | Binds to molecules of B12, protecting them from the acids and enzymes of the stomach; secreted by parietal cells |
| Cephalic phase | Sensations of thoughts about food are relayed to the brainstem, where parasympathetic signals to the gastric mucosa are initiated. This directly stimulates gastric juice secretion and also stimulates the release of gastrin, which prolongs and enhances the |
| Gastric phase | The presence of food, specifically the distention it causes, triggers local and parasympathetic nervous reflexes that increase secretion of gastric juice and gastrin (which further amplifies gastric juice secretion). |
| Intestinal phase | As food moves into the duodenum, the presence of fats, carbohydrates, and acid stimulates hormonal and nervous reflexes that inhibit stomach activity. |
| Mouth | Breaks up food particles Assists in producing spoken language |
| Pharynx | Swallows |
| Liver | Breaks down and builds up many biological molecules Stores vitamins and iron Destroys old blood cells Destroys poisons Bile aids in digestion |
| Gallbladder | Stores and concentrates bile |
| Small intestine | Completes digestion Mucus protects gut wall Absorbs nutrients, most water Peptidase digests proteins Sucrases digest sugars Nucleotidases and phosphatases digest nucleotides |
| Anus | Opening for elimination of feces |
| Salivary glands | Saliva moistens and lubricates food Amylase digests polysaccharides |
| Esophagus | Transports food |
| Stomach | Stores and churns food Pepsin digests protein HCI activates enzymes, breaks up food, kills germs Mucus protects stomach wall Limited absorption |
| Pancreas | Hormones regulate blood glucose levels Bicarbonates neutralize stomach acid Trypsin and chymotrypsin digest proteins Amylase digests polysaccharides Lipase digests lipids Small intestine Completes digestion Mucus protects gut wall Absorbs nutrients, most |
| Large intestine | Reabsorbs some water and ions forms and stores feces |
| Rectum | Stores and expels feces |
| Steatorrhea | Foul-smelling stool as a result of impaired fat absorption |
Created by:
JoyceH
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