Among these discount 8 mg reminyl with mastercard, ex- tities purchase reminyl 8mg with visa, such as pressure buy reminyl 4mg on-line, sound waves, and other vibrations; teroceptors detect stimuli from outside the body; entero- and chemical qualities, such as acidity and molecular shape ceptors detect internal stimuli; proprioceptors (receptors of and size. Common to all these types of stimuli is the prop- “one’s own”) provide information about the positions of erty of intensity, a measure of the energy content (or con- joints and about muscle activity and the orientation of the centration, in the case of chemical stimuli) available to in- body in space. Nociceptors (pain receptors) detect noxious teract with the sensory receptor. Most sensory re- The central nervous pathway over which sensory infor- ceptors respond preferentially to a single kind of environ- mation travels is also important in determining the nature mental stimulus. The usual stimulus for the eye is light; that of the perception; information arriving by way of the optic for the ear is sound. This specificity is due to several features nerve, for example, is always perceived as light and never as that match a receptor to its preferred stimulus. Stimuli Into Biological Information Often these accessory structures are a control system that adjusts their sensitivity according to the information being This section focuses on the actual function of the sensory received (Fig. The usual and appropriate stimulus for a receptor in translating environmental energy into action receptor is called its adequate stimulus. For the adequate potentials, the fundamental units of information in the stimulus, the receptor has the lowest threshold, the lowest nervous system. A device that performs such a translation is stimulus intensity that can be reliably detected. A threshold called a transducer; sensory receptors are biological trans- is often difficult to measure because it can vary over time ducers. The sequence of electrical events in the sensory and with the presence of interfering stimuli or the action of transduction process is shown in Figure 4.
The Brain: Gross Views buy 4mg reminyl free shipping, Vasculature cheap reminyl 8mg on-line, and MRI 27 Fornix Choroid plexus quality 8 mg reminyl, third ventricle Optic tract Posterior choroidal arteries Thalamogeniculate artery Lateral geniculate body Dorsal thalamus Posterior cerebral artery Mammillary body Medial geniculate body Quadrigeminal artery Superior colliculus Posterior communicating artery Crus cerebri Internal carotid artery Brachium of inferior colliculus Oculomotor nerve Inferior colliculus Superior cerebellar artery Trochlear nerve Trigeminal nerve Motor root Sensory root Superior cerebellar peduncle Anterior medullary velum Basilar artery Middle cerebellar peduncle Anterior inferior cerebellar artery Vestibulocochlear nerve Labyrinthine artery Facial nerve Abducens nerve Posterior inferior cerebellar artery Glossopharyngeal nerve Choroid plexus, Vagus nerve fourth ventricle Hypoglossal nerve Restiform body Accessory nerve Cuneate tubercle Gracile tubercle Posterior inferior cerebellar artery Posterior spinal artery Anterior spinal artery Vertebral artery 2-24 Lateral view of the brainstem and thalamus showing the rela- tively, are shown as dashed lines. Compare with Figure 2-22 on the fac- tionship of structures and cranial nerves to arteries. Compare to Figure 28 External Morphology of the Central Nervous System Anterior paracentral gyrus (APGy) Central sulcus (CSul) Paracentral sulcus (ParCSul) Posterior paracentral gyrus (PPGy) Precentral sulcus (PrCSul) Marginal sulcus (MarSul) Precuneus (PrCun) Cingulate gyrus (CinGy) Superior frontal gyrus (SFGy) Parieto-occipital sulcus (POSul) Cingulate sulcus (CinSul) Cuneus (Cun) Calcarine sulcus (CalSul) Lingual gyrus (LinGy) Sulcus of corpus callosum (SulCC) Isthmus of cingulate gyrus Paraterminal gyri Occipitotemporal gyri Parolfactory gyri (ParolfGy) Parahippocampal gyrus Temporal pole Uncus Rhinal sulcus APGy PrCSul CSul PPGy ParCSul MarSul SulCC CinGy PrCun CinSul POSul ParolfGy Cun CalSul LinGy SFGy MarSul Corpus callosum POSul CalSul Colloid cyst Internal cerebral vein 2-26 Midsagittal view of the right cerebral hemisphere and dien- A colloid cyst (colloid tumor) is a congenital growth usually dis- cephalon, with brainstem removed, showing the main gyri and sulci covered in adult life once the ﬂow of CSF through the interventricular and two MRI (both T1-weighted images) showing these structures foramina is compromised (obstructive hydrocephalus). The lower MRI is from a patient with a may have headache, unsteady gait, weakness of the lower extremities, small colloid cyst in the interventricular foramen. When compared to visual or somatosensory disorders, and/or personality changes or con- the upper MRI, note the enlarged lateral ventricle with resultant thin- fusion. The Brain: Gross Views, Vasculature, and MRI 29 Internal frontal branches Paracentral branches Callosomarginal branch of ACA Internal parietal branches Parietooccipital Pericallosal branch branches of PCA of ACA Frontopolar branches of ACA Orbital branches of ACA Anterior cerebral artery (ACA) Calcarine branch of PCA Posterior temporal branches of PCA Posterior cerebral artery (PCA) Anterior temporal branches of PCA 2-27 Midsagittal view of the cerebral hemisphere and dien- to serve medial regions of the frontal and parietal lobes, and the same cephalon showing the locations and branching patterns of anterior and relationship is maintained for the occipital and temporal lobes by posterior cerebral arteries. The positions of gyri and sulci can be ex- branches of the posterior cerebral artery. Inferior sagittal sinus Posterior vein of corpus callosum Superior sagittal sinus Internal occipital veins TV Veins of the caudate nucleus Straight sinus Septal veins Sinus confluens Transverse sinus Superior Anterior cerebral vein cerebellar vein Occipital Basal vein sinus Great Internal cerebral vein cerebral vein 2-28 Midsagittal view of the cerebral hemisphere and dien- (facing page). See cephalon that shows the locations and relationships of sinuses Figures 8-2 (p. The MRI (T1- weighted image) shows many brain structures from the same perspec- tive. The Brain: Gross Views, Vasculature, and MRI 31 Body of fornix (For) Dorsal thalamus (DorTh) Septum pellucidum (Sep) Massa intermedia Choroid plexus of third ventricle Interventricular foramen Stria medullaris thalami Column of fornix Habenula Anterior commissure (AC) Suprapineal recess Lamina terminalis Posterior commissure Pineal (P) Supraoptic recess Superior colliculus (SC) Optic chiasm (OpCh) Quadrigeminal HythHyth cistern (QCis) Inferior colliculus (IC) Optic nerve Cerebral aqueduct (CA) Anterior medullary velum (AMV) Fourth ventricle (ForVen) Infundibulum (In) Infundibular recess Mammillary body (MB) Hypothalamic sulcus Posterior inferior Oculomotor nerve cerebellar artery Interpeduncular fossa (IpedFos) Medulla Basilar pons (BP) For DorTh Sep Internal cerebral vein P AC Tentorium cerebelli Hypothalamus QCis OpCh SC In IC Pituitary gland AMV MB ForVen IpedFos BP CA 2-30 A midsagittal view of the right cerebral hemisphere and di- image) shows these brain structures from the same perspective. Hyth encephalon with the brainstem in situ focusing on the details primarily hypothalamus. The MRI (T1-weighted 32 External Morphology of the Central Nervous System A D Midbrain Anterior quadrangular Anterior lobule lobe (AntLb) Posterior quadrangular lobule Posterior Primary superior fissure fissure E Superior semilunar Hemisphere lobule Bpon Vermis (Ver) AntLb SCP B Fourth ventricle Basilar pons (Bpon) Medulla (Med) Flocculus (Fl) Tonsil (Ton) F Biventer lobule Gracile Med lobule Ton Inferior semilunar PostLb lobule Hemisphere Vermis (Ver) Ver C Colliculi: Anterior Superior Cerebellar peduncles: lobe (AntLb) Inferior Superior (SCP) G Middle (MCP) Inferior Primary fissure AntLb Horizontal MCP fissure Fl Flocculus (Fl) Posterior Tonsil (Ton) lobe (PostLb) Nodulus Med PostLb 2-31 Rostral (A, superior surface), caudal (B, inferior surface), with cerebellar structures seen in axial MRIs at comparable levels (D, and an inferior view (C, inferior aspect) of the cerebellum. Structures seen on the inferior surface of the cerebellum, such as in C shows the aspect of the cerebellum that is continuous into the the tonsil (F), correlate closely with an axial MRI at a comparable level. The view in C correlates with su- In G, note the appearance of the margin of the cerebellum, the general perior surface of the brainstem (and middle superior cerebellar pe- appearance and position of the lobes, and the obvious nature of the duncles) as shown in Figure 2-34 on page 34.
We consider first the renal mechanisms in- + volved in Na excretion and then overall Na balance buy discount reminyl 8mg. Angiotensin II Dryness of Monitoring of The Kidneys Excrete Only a Small Percentage mouth and throat water intake of the Filtered Na Load by GI tract Table 24 quality 8 mg reminyl. A plus and excretion of ions and water for a healthy adult man on FIGURE 24 generic 4mg reminyl. The quantity of Na reab- filtered Na , together with the same percentage of filtered sorbed was calculated from the difference between filtered water, is reabsorbed in the proximal convoluted tubule. Only about 1% of the cause ordinarily about 95% of the Na we consume is ex- filtered Na (and water) is usually excreted. Tubular reabsorption of Na nephron (distal convoluted tubule, connecting tubule, and must be finely regulated to keep us in Na balance. Seventy percent of too much Na fails to be reabsorbed in proximal segments. The distal nephron is of critical importance in determining the final excretion of Na. Distal Proximal convoluted 70% tubule 6% Many Factors Affect Renal Na Excretion convoluted tubule Multiple factors affect renal Na excretion; these are dis- 100% cussed below. A factor may promote Na excretion either by increasing the amount of Na filtered by the glomeruli or by decreasing the amount of Na reabsorbed by the kid- ney tubules or, in some cases, by affecting both processes. Na excretion tends to Space of Collecting change in the same direction as GFR. If GFR falls—for example, as a result of blood loss—the tubules can reabsorb the reduced filtered Na load more completely, and Na excretion falls.