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goodrich exam 2
human phys test 2 important terms
| Question | Answer |
|---|---|
| absolute refractory period | refers to the amount of time that another action potential cannot fire and represents the time required for the Na+ channel gates to reset to their resting potentials. |
| action potential | large, constant strength depolarization that can travel long distances though a neuron without losing their strength |
| conduction | represents the flow of electrical energy from one part of the cell to another in a process that constantly replenishes lost energy |
| frequency coding of action potentials | frequency of action potentials encodes the intensity of a stimulus |
| motor unit | group of skeletal muscle fibers and the somatic motor neuron that controls them |
| relative refractory period | follows the absolute refractory period; a stronger-than-normal depolarizing graded potential is needed to bring the cell up to threshold, and the action potential will be smaller than normal |
| α (alpha) motor neuron | neurons that innervate extrafusal muscle fibers and cause muscle contraction |
| central pattern generator | networks of CNS neurons that function spontaneously to control certain rhythmic muscle movements |
| extrafusal | the normal contractile fibers of a muscle |
| flexion reflex (pain) | a polysynaptic reflex that causes an arm or leg to be pulled away from a painful stimulus |
| γ (gamma) motor neuron | small neuron that innervates intrafusal fibers within the muscle spindle |
| Golgi tendon organ | receptors are found at the junction of the tendons and muscle fibers that respond to both stretch and contraction of the muscle |
| intrafusal | modified muscle fibers of the muscle spindle that lack myofibrils in their central portions |
| proprioception | awareness of body position in space and of the relative location of body parts to eachother |
| stretch reflex | a reflex pathway in which muscle stretch initiates a contraction response |
| vestibular apparatus | portion of the inner ear that contains sensory receptors for balance and equilibrium. provides information about head position with respect to gravity, as well as acceleration. |
| vestibular nuclei | neurons send axons to the ventral horn of the spinal cord (to α and γ motor neurons). |
| telokinetic movements | xample: “paradoxical reversal phenomenon” - forearm/hand movements from the same stimulus “reverse” depending on the starting position, but produce the same final position in space |
| kinesthetic sensation | “movement” sensing |
| statokinetic | basic body position and locomotion (spinal cord + brain stem CPG’s) |
| length control reflex | increased stretch leads to an increase in the spindle afferent AP frequency, innervated by muscle spindles |
| tension control reflex | maintains constant tension, innervated by Gtos |
| Babinski sign | abnormal extensor response of foot |
| paradoxical reversal phenomenon | phenomenon indicated some of the special nature of this pyramidal pathway: stimulate just a few cortical neurons in the primary motor cortex of monkeys; movements from the same stimulus “reverse”, depending on starting position |
| primary motor area (pyramidal system) | This is a relatively thin strip of cortex, neighboring the primary sensory area |
| servomechanism | a powered mechanism producing motion or forces at a higher level of energy than the input level, |
| DA (dopamine) neurons | neurons that administer dopamine across the blood-brain barrier |
| Parkinson's disease | Substantia nigra damage; Symptoms: resting tremor (variable; possibly cerebellar?) & some degree of rigidity & lack of spontaneous movement (“akinesia”) |
| active hyperemia | Active tissues increase their own blood flow. This takes place through relaxation of arteriolar smooth muscle. |
| chronotropic action of NE, Epi, ACh | increased heart rate caused by sympathetic innervation; caused by increased pacemaker depolarization |
| end diastolic volume (EDV) | the volume of blood in a ventricle at the end of filling. EDV is often used synonymously with preload. An increase in EDV increase the preload on the heart and, through the Frank-Starling mechanism of the heart, increases the amount of blood ejected from |
| end systolic volume (ESV) | End-systolic volume (ESV) is the volume of blood in the left ventricle at the end of contraction, or systole, and the beginning of filling, or diastole. End systolic volume can be used clinically as a measurement of the adequacy of cardiac emptying, relat |
| inotropic action of NE, Epi | increased force of contraction; sympathetic effect of increased amount of calcium |
| myogenic autoregulation | Vascular smooth muscle responds to stretch by contracting.Negative feeback. |
| reactive hyperemia | flow is restored. If blood flow is severely limited or temporarily shut down, then metabolites build up. |
| ventricular fibrillation | is a condition in which there is uncoordinated contraction of the cardiac muscle of the ventricles in the heart, making them tremble rather than contract properly. Ventricular fibrillation is a medical emergency. If the arrhythmia continues for more than |
| baroreceptor reflex | This relatively simple negative feedback loop provides homeostatic control of BP. Increase in BP leads to increase in firing of baroreceptors which in turn leads to increased parasympathetic activity and decrease in sympathetic activity. |
| baroreceptors | located in aortic arch and carotid sinus. These are arranged as stretch receptors and are therefore sensitive to BP |
| hydrostatic pressure | this is the pressure due to position, gravity; affects all vessels |
| mitral stenosis | damage to the left A-V valve, preventing normal closure during systole. This has major effects on adjustment to exercise. |
| orthostatic (postural) reflexes | moving to a standing position leads to a hydrostatic change which needs baroreceptor to maintain which gives you a constant pressure |
| aneurism | erosion of the vessel wall |
| atherosclerosis | vessels lose elasticity, vessels narrowed by accumulating plaque, plaques can initiate clotting |
| primary hypertension | Arterial BP is normally distributed in populations; no obvious “cut-off” points to identify “hypertension”. Clinical definition: chronic BP elevation > 130 mm Hg systolic and/or > 85 mm Hg diastolic; cause unknown |
| secondary hypertension | Caused by another condition – often abnormal hormone secretion: renal causes vascular obstruction to kidneys renal disease abnormality of descending aorta hormonal pregnancy |
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