By I. Topork. Northern Michigan University. 2018.
The caudate is a long nucleus that follows the basic C-shape of the cerebrum from the frontal lobe purchase 100 mcg levothroid with visa thyroid cancer high blood pressure, through the parietal and occipital lobes, into the temporal lobe. The globus pallidus is a layered 560 Chapter 13 | Anatomy of the Nervous System nucleus that lies just medial to the putamen; they are called the lenticular nuclei because they look like curved pieces fitting together like lenses. The globus pallidus has two subdivisions, the external and internal segments, which are lateral and medial, respectively. The basal nuclei in the cerebrum are connected with a few more nuclei in the brain stem that together act as a functional group that forms a motor pathway. The direct pathway causes the disinhibition of the thalamus (inhibition of one cell on a target cell that then inhibits the first cell), whereas the indirect pathway causes, or reinforces, the normal inhibition of the thalamus. The thalamus then can either excite the cortex (as a result of the direct pathway) or fail to excite the cortex (as a result of the indirect pathway). The switch between the two pathways is the substantia nigra pars compacta, which projects to the striatum and releases the neurotransmitter dopamine. When the substantia nigra pars compacta is firing, it signals to the basal nuclei that the body is in an active state, and movement will be more likely. When the substantia nigra pars compacta is silent, the body is in a passive state, and movement is inhibited. To illustrate this situation, while a student is sitting listening to a lecture, the substantia nigra pars compacta would be silent and the student less likely to get up and walk around. Likewise, while the professor is lecturing, and walking around at the front of the classroom, the professor’s substantia nigra pars compacta would be active, in keeping with his or her activity level. As shown in this video, the direct pathway is the shorter pathway through the system that results in increased activity in the cerebral cortex and increased motor activity. As shown in this video, the indirect pathway is the longer pathway through the system that results in decreased activity in the cerebral cortex, and therefore less motor activity. The indirect pathway has an extra couple of connections in it, including disinhibition of the subthalamic nucleus. The Myth of Left Brain/Right Brain There is a persistent myth that people are “right-brained” or “left-brained,” which is an oversimplification of an important concept about the cerebral hemispheres. There is some lateralization of function, in which the left side of the brain is devoted to language function and the right side is devoted to spatial and nonverbal reasoning. Whereas these functions are predominantly associated with those sides of the brain, there is no monopoly by either side on these functions. A drastic way to deal with a rare and devastating neurological condition (intractable epilepsy) is to separate the two hemispheres of the brain.
If both nerves are damaged but not • Cricothyroid joint: a small synovial joint between the inferior horn completely divided the cords are adducted since the abductors are of the thyroid cartilage and the cricoid buy levothroid 200mcg with visa thyroid symptoms similar to pregnancy, permitting a hinge-like move- more affected than the adductors (Semon’s law). The pharynx and larynx 139 63 The root of the neck Middle cervical ganglion Scalenus medius Vertebral artery Scalenus anterior Sympathetic trunk Phrenic nerve Inferior thyroid artery Upper trunk of brachial plexus Superficial cervical artery Vagus Suprascapular artery, nerve Subclavian artery Dorsal scapular artery Subclavian vein Carotid sheath Internal thoracic artery Inferior cervical ganglion Thoracic duct Fig. The curved arrow on the right side of the diagram indicates the course of the thoracic duct Scalenus posterior Sympathetic trunk Superior intercostal artery Attachment of scalenus medius 1st thoracic nerve Serratus anterior 8th cervical nerve (first digitation) Lower trunk of brachial plexus Scalene tubercle, Subclavian artery for attachment of Subclavian vein scalenus anterior Subclavius Costoclavicular ligament Fig. The subclavian artery and the Through this relatively conﬁned space pass the trachea and oesopha- trunks of the brachial plexus are between the two muscles and the sub- gus, the carotid and subclavian arteries and the corresponding large clavian vein is in front of scalenus anterior. At the outer border of the 1st rib it becomes the axillary scalenus anterior before crossing the subclavian artery and entering the artery. The The veins middle cervical ganglion is close to the entry of the artery into the fora- • The subclavian vein: begins at the outer border of the 1st rib and lies men transversarium of C6 and the inferior cervical ganglion is near the in a shallow groove on the upper surface of the rib in front of scalenus neck of the 1st rib behind the origin of the vertebral artery. At the medial border of this muscle it is joined by the internal fused with the 1st thoracic ganglion to form the stellate ganglion. The internal jugular vein is enclosed in the carotid sheath, along with the common carotid artery The thoracic duct (Fig. The duct ascends out of the thorax between the ies but the inferior thyroid veins are solitary and run down from the trachea and oesophagus and arches laterally between the carotid sheath lower border of the thyroid gland, in front of the trachea, to reach the in front and the vertebral artery behind. The nerves • The upper, middle and lower trunks of the brachial plexus: emerge from between the scalenus anterior and medius and pass down The root of the neck 141 64 The oesophagus and trachea and the thyroid gland Thyrohyoid Superior thyroid artery Sternothyroid Cricothyroid Common carotid artery Inferior thyroid artery Inferior thyroid artery Right recurrent laryngeal nerve Inferior thyroid veins Left brachiocephalic vein Fig. A large part of the right lobe has been removed The oesophagus These infrahyoid muscles are all supplied by the ansa cervicalis (C1, The oesophagus begins at the level of the cricoid cartilage and runs 2 and 3). Their function is to ﬁx the hyoid bone so that the suprahyoid down behind and slightly to the left of the trachea. Their main importance lies in their close laryngeal nerve is in the groove between the oesophagus and trachea relation to the thyroid gland. The thyroid gland The trachea The thyroid is an endocrine gland with an extremely rich blood supply The trachea begins at the level of the cricoid cartilage and ends by (Fig. Its isthmus lies across the 3rd, 4th and 5th rings of the tra- dividing into left and right bronchi at the level of the manubriosternal chea and the lobes lie on either side, reaching up as far as the ‘pocket’ joint. The trachea can be palpated in the midline just above the sup- under the attachment of sternothyroid to the thyroid cartilage. The upper enclosed in the thin pretracheal fascia and also has its own ﬁbrous part of the trachea is crossed by the isthmus of the thyroid. When the gland is enlarged, the strap muscles are stretched bronchi and lungs develop from a groove in the ﬂoor of the embryonic tightly over it and the carotid sheath is displaced laterally. It divides into two branches which run down the posterior border and The infrahyoid (‘strap’) muscles along the upper border. It is thus possible to tie all four arteries during subtotal • Sternohyoid: is superﬁcial to the other two and runs from the thyroidectomy and still leave an adequate blood supply to the manubrium to the lower border of the hyoid.
Skeletal Muscle Pump In many body regions levothroid 200 mcg low cost thyroid symptoms underactive, the pressure within the veins can be increased by the contraction of the surrounding skeletal muscle. As leg muscles contract, for example during walking or running, they exert pressure on nearby veins with their numerous one-way valves. This increased pressure causes blood to flow upward, opening valves superior to the contracting muscles so blood flows through. Simultaneously, valves inferior to the contracting muscles close; thus, blood should not seep back downward toward the feet. Military recruits are trained to flex their legs slightly while standing at attention for prolonged periods. Consequently, the brain will not receive enough oxygenated blood, and the individual may lose consciousness. During inhalation, the volume of the thorax increases, largely through the contraction of the diaphragm, which moves downward and compresses the abdominal cavity. The elevation of the chest caused by the contraction of the external intercostal muscles also contributes to the increased volume of the thorax. Additionally, as air pressure within the thorax drops, blood pressure in the thoracic veins also decreases, falling below the pressure in the abdominal veins. This causes blood to flow along its pressure gradient from veins outside the thorax, where pressure is higher, into the thoracic region, where pressure is now lower. During exhalation, when air pressure increases within the thoracic cavity, pressure in the thoracic veins increases, speeding blood flow into the heart while valves in the veins prevent blood from flowing backward from the thoracic and abdominal veins. Pressure Relationships in the Venous System Although vessel diameter increases from the smaller venules to the larger veins and eventually to the venae cavae (singular = vena cava), the total cross-sectional area actually decreases (see Figure 20. The individual veins are larger in diameter than the venules, but their total number is much lower, so their total cross-sectional area is also lower. Also notice that, as blood moves from venules to veins, the average blood pressure drops (see Figure 20. Again, the presence of one-way valves and the skeletal muscle and respiratory pumps contribute to this increased flow. Since approximately 64 percent of the total blood volume resides in systemic veins, any action that increases the flow of blood through the veins will increase venous return to the heart. Maintaining vascular tone within the veins prevents the veins from merely distending, dampening the flow of blood, and as you will see, vasoconstriction actually enhances the flow. The Role of Venoconstriction in Resistance, Blood Pressure, and Flow As previously discussed, vasoconstriction of an artery or arteriole decreases the radius, increasing resistance and pressure, but decreasing flow. The walls of veins are thin but irregular; thus, when the smooth muscle in those walls constricts, the lumen becomes more rounded.
Purpose of the module Diabetes mellitus is a diverse group of hyper glycemic disorders with different etiologies and clinical pictures buy discount levothroid 200 mcg thyroid gland sore; there fore timely diagnosis and management based on true laboratory results are crucial. This Satellite Module on Diabetes Mellitus is intended to resolve the critical shortage of clinical chemistry reference materials both for students and for other professionals of the same field working in different health institutions 1. Pre- test questions Instructions: choose the appropriate answer from the alternatives given for each question and write the answers on a separate sheet of paper. Why is there a discrepancy between the whole blood glucose concentration and the plasma glucose concentration? Which one of the following organs uses glucose from digested carbohydrates and stored it as glycogen for later use as a source of immediate energy by the muscles? Learning objectives After studying this satellite module the student will be able to:- Æ Collect, preserve or prepare the correct specimens for diagnosis of diabetes mellitus Æ Perform different clinical chemistry tests in management of diabetes mellitus Æ Practice different quality control procedures in laboratory diagnosis of diabetes mellitus 4. The blood specimen can be collected both from vein or capillary, it depends on the type of sample the test procedure needs, and if serum or plasma is needed Venus blood should be collected with clean, dry, capped test tube, and with or with out anticoagulant. Urine samples are also possible to collect using, a clean, dry, free of any disinfectant, large and wide mouth container so as to do both qualitative and quantitative determination of glucose and others 4. To more completely detect diabetes mellitus, stressing the system with a defined glucose load tests carbohydrate metabolic capacity. To do this, a high- carbohydrate drink or meal is given to the patient, blood is collected 2 hours after ingestion, and the glucose concentration is determined. In the fasting state the arterial (capillary) blood glucose concentration is 5 mg/dl higher than the venous concentration. Preparation and preservation Samples for glucose determination The following factors which affects the stability of glucose in body fluid must be take in to account, such as: • Those glycolytic enzymes found particularly in the red cells, which under goes glycolysis at an average rate of approximately 10 mg/dl/hr in whole blood or 5 mg/dl/hr in sufficiently centrifuged plasma which still contain leukocytes Keeping these considerations in mind, there are several ways to prevent or retard glycolysis in specimen to be analyzed. For example: • Sample for glucose analysis should be delivered to the laboratory as soon as possible after being drowned from the patient. Note When certain enzymatic glucose methods are used, fluoride anticoagulated blood should not be used, as the fluoride might inhibit the enzyme. Use of serum separator gel tubes, processed as quickly as possible with in thirty minutes if possible- is preformed for these methods. For non pregnant adults, the fasting serum or plasma glucose concentration should normally be less than 110 mg/dl and the serum or plasma glucose taken 2 hours 140 mg/dl. Including in the new criteria from the expert committee on the diagnosis and classification of Diabetes Mellitus. A random blood glucose (blood drawn with out considering time since the last meal) equal to or greater than 200 mg/dl, along with symptoms of diabetes (polyuria, polydipsia, and un explained weight loss), 3. A 2- hour post load glucose level equal to or greater than 200 mg/dl during an oral glucose tolerance test. The various methods for the quantitative determination of glucose can be divided in to three general categories. Of these, enzymatic methods using hexokinase or glucose oxidase methodology are most commonly used 76 7.