All the information nurses need to understand about different diagnostic tests and laboratory exams: nursing responsibilities and results.
CARTILAGE Key points: • Cartilage is connective tissue with a semi-solid extracellular matrix that comprises collagen fibers and ground substance, which provides both support and protection for other body tissues. • Three types covered here: hyaline, fibrous, and elastic. Hyaline cartilage • Most abundant type of cartilage in the body. • Hyaline cartilage forms most of the fetal skeleton and is important in endochondral bone growth until the end of adolescence. • In the adult, it persists in the nose, trachea, and larynx, thorax, and also covers the articular surfaces of long bones (where it has no perichondrium). • Degeneration and calcification of hyaline cartilage may either be physiologic or pathologic. It is physiologic in the case of endochondral bone formation but it is pathologic in the case of osteoarthritis, which leads to pain and restricted joint movement. There are other forms of arthritis, such as rheumatoid arthritis, which is an inflammatory form of arthritis in which the immune system aggressively attacks the cartilage, bone, and synovial membranes of the joints • Calcification (the processes by which cartilage is replaced by osseous tissue) is common in hyaline cartilage, but very rare in elastic or fibrous cartilages.Hyaline Cartilage Layers: • Perichondrium, outer surface • MatrixPerichondrium • Comprises inner and outer layers (although in slow-growing or inactive perichondrium, it is not always possible to visually distinguish two separate layers). • Inner layer is the chondrogenic (aka cellular) layer; it comprises chondrogenic cells. • Outer layer it he fibrous layer; it comprises Type I collagen fibers, blood vessels, which supply nutrients to the cartilage below, and, fibroblasts, which are thought to produce collagen fibers and/or chondroblasts (although intertextual variation exists regarding this point).Matrix • Appears glass-like under the microscope. • Is basophilic and stains purple on H & E section • Contains territorial matrixes that comprise the proteoglycan-rich, dark staining area around the lacunae. • Ground substance of the matrix, which is gel-like, comprises the following components: Proteoglycan aggregates, which are bound to collagen fibrils, and which provide a semi-solid structure to cartilage, Chondronectin, which adheres collagen fibers to chondrocytes, and, Itercellular Water, which is 60-80% of net weight of the cartilage (varies by location). • Matrix comprises type II collagen fibers, which are invisible in standard histologic preparations. • Houses lacunae, which are spaces in the matrix. • Inside the lacunae are the chondrocytes, which are mature cartilage cells that generate and maintain the matrix. • Chondroblasts are derived from chondrogenic cells, and eventually mature into chondrocytes. • Clusters of chondrocytes are called isogenous groups. • Interterritorial matrix outside of the isogenic groups; it stains lightly. Elastic Cartilage • Also known as yellow fibrocartilage. • Shares many similarities to hyaline cartilage (for instance, it also has perichondrium and contains invisible type II collagen fibers within the matrix). • Helpful distinguishing feature of elastic cartilage are its interwoven elastic fibers, which provide flexibility. • Elastic cartilage provides flexibility and resistance to permanent deformation. • Present in the external ear, the auditory (Eustachian) tube, and the epiglottis. Fibrous Cartilage • Also shares many similarities with hyaline cartilage • Two helpful distinguishing features are its lack of perichondrium and its rows of chondrocytes that have type I and type II fibers in between them. • The bundles of type 1 and type II collagen fibers provide strength and durability for shock absorption. • The matrix is dense and contains relatively little ground substance. • The type of joint and person's age determine the relative proportions of these two collagen fiber types within the fibrous cartilage. • NO perichondrium is present in fibrous cartilage. • Fibrous cartilage is found, most notably, in intervertebral discs, pubic symphysis, menisci of the knee, and tendons where properties of stress resistance are particularly important. Formation and Growth of Cartilage • Two types of growth: Interstitial and appositional growth; both types occur simultaneously during early development; the relative rate of each type of growth determines the shape and structure of the cartilage. Interstitial growth: • Interstitial growth occurs during early stages of cartilage formation, and in the growth plates and articular cartilages of growing long bones. • Cells divide within matrix to produce daughter cells that secrete their own matrix. Appositional growth • New matrix forms at the periphery of the cartilage. • Chondrogenic cells in perichondrium differentiate to become chondroblasts • Chondroblasts secrete new matrix, eventually become chondrocytes. • Older chondrocytes remain active and maintain matrix. Clincal Correlation: Hyaline cartilage that has been only nominally damaged can slowly repair itself via appositional growth, but severely damaged cartilage is often replaced by tougher, more fibrous connective tissue. Hormones that impact the growth of hyaline cartilage: • Stimulators: thyroxine, testosterone, and somatotropin. • Inhibitors: cortisone, hydrocortisone, and estradiol.Nutritional states affect bone growth: • Hypovitaminosis A diminishes the thickness of epiphyseal plates; decrease in growth rate. • Hypervitaminosis A accelerates ossification of epiphyseal plates; short stature (dwarfism). • Hypovitaminosis C inhibits matrix production and distorts cartilage columns in epiphyseal plates (bones are weak, repair of fractures obstructed; scurvy develops) • Hypovitaminosis D inhibits calcification of matrix, causing softening of the bones (osteomalacia); in children, growing bones become bowed (rickets)
Should you be taking a probiotic? What do probiotics do, anyway? Read to find out all the benefits of these microscopic bacterial friends, including how to get them from food.
The central nervous system controls most functions of the body and mind. It consists of two parts: the brain & the spinal cord. Read about the spinal cord.
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Filoviruses like Ebola “edit” genetic material as they invade their hosts, according to a study published this week in mBio®, the online open-access journal of the American Society for Microbiology. The work, by researchers at the Icahn School of Medicine at Mount Sinai, the Galveston National Laboratory, and the J. Craig Venter Institute, could lead
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Basal Ganglia Anatomy • Brain Atlas: Basal Ganglia NomenclatureCorpus striatum • Caudate • Putamen • Globus pallidusCaudate nucleus • Head • Body • TailGlobus pallidus • External (lateral) • Internal (medial) segments.Striatum Collective term for the: • Caudate • Putamen Derived from the striations that connect them.Lentiform nucleus Collective term for the: • Globus pallidus • Putamen Given their lens-shaped appearance. This is an important term to know because it makes sense of the syndrome of hepato-lenticular degeneration.Pallidum • Descriptor for the globus pallidus because bundles of myelinated fibers traverse the globus pallidus, giving it a pale appearance. • The pallidum is sometimes referred to as the paleostriatum because the globus pallidus is derived from the phylogenetically older portion of the brain — the diencephalon. • The neostriatum refers to the caudate and putamen, which are derived from the phylogenetically newer part of the brain — the telencephalon.Fiber pathways • The corpus striatum also encompasses several fiber pathways that pass between the globus pallidus and the subthalamic nucleus and thalamus: the ansa lenticularis, lenticular fasciculus, subthalamic fasciculus, and thalamic fasciculus. These fibers comprise a considerable portion of the white matter region inferolateral to the thalamus, which is called the fields of Forel (aka prerubral fields or Forel's Field H).Basal nuclei vs Basal ganglia • Basal ganglia is more correctly referred to as the basal nuclei because a ganglion is a neuronal aggregation within the peripheral nervous system and the basal nuclei lie within the central nervous system, but the term basal ganglia is the common parlance, so we use it here. AnatomyAxial view Key landmarks: the frontal horn and body of the lateral ventricles, thalamus, and the claustrum, and insulaAnatomical Structures • Caudate head in the wall of the frontal horn • Caudate tail at the posterolateral tip of the thalamus (the body is not visible in this section) • Lens-shaped lentiform nucleus, which subdivides into the putamen, laterally, and the globus pallidus, mediallyEarly in development, the globus pallidus migrates into the medial wall of the putamen... • Thus, we can envision the lentiform nucleus as a globus pallidus core surrounded by a putaminal shell. • The internal capsule lies in between the lentiform nucleus and the head of the caudate and thalamus. • The external capsule lies in between the putamen and the claustrum. • The extreme capsule lies in between the claustrum and the insula.Coronal view: Anterior Key landmarks: optic chiasm, frontal horn of lateral ventricle, corpus callosum, and the basal forebrainAnatomical Structures • The combined putamen and head of the caudate. • The nucleus accumbens, which is the bridge that persists between the head of the caudate and putamen after the anterior limb of the internal capsule separates the head of the caudate from the putamen. - It is important in rewarding behavior.Coronal view: Posterior Key landmarks: • Optic tract • Frontal horn of lateral ventricle • 3rd ventricle • Corpus callosumAnatomical Structures - Caudate Head in the wall of the frontal horn - Putamen - Globus pallidus • The lateral medullary lamina separates the putamen and globus pallidus. • The medial medullary lamina subdivides the globus pallidus into an internal (or medial) segment and an external (or lateral) segment. • The internal capsule lies in between the lentiform nucleus and the caudate. • Beneath the globus pallidus, lies the basal forebrain and the horizontally-oriented anterior commissure in between them. - Note that the globus pallidus actually extends beneath the anterior commissure as the ventral pallidumsagittal view Key landmarks: • corpus callosum • & the subjacent lateral ventricular system: - frontal horn - atrium - temporal hornAnatomical Structures • Caudate: head and body (the tail is not visible in this section) • Putamen (anteriorly) • Thalamus (posteriorly) The internal capsule funnels inferiorly into the cerebral peduncle. Basal Ganglia Ischemic & Hemorrhagic Strokes • Basal Ganglia Ischemic Stroke • Basal Ganglia Hemorrhage Basal Ganglia Anatomy & Circuitry: Advanced InformationBasal ganglia topography • The prefrontal cortex acts through innervation of the head and body of the caudate nucleus. • The parietal lobes act through innervation of both the putamen and caudate. • The primary auditory cortex projects to the caudoventral putamen and tail of the caudate. • The visual cortices project primarily to the nearest portion of the caudate nucleus.Fields of Forel Additional fiber pathways pass through Field H and H1 in their ascent into the thalamus they include: • The cerebellothalamic fibers from the corticopontocerebellar pathway, the medial lemniscus, the nigrothalamic fibers, and the spinothalamic fibers of the anterolateral system pathway.The thalamic fasciculus • The term is sometimes broadened to include the cerebellothalamic fibers and it is also sometimes used synonymously with the term Field H1, just as the term lenticular fasciculus is sometimes used synonymously with term Field H2. • The thalamic fasciculus projects to multiple thalamic nuclei, including the ventroanterior nucleus, which most notably communicates with the globus pallidus; the ventrolateral nucleus, which most notably communicates with the cerebellum; the dorsomedial nucleus, which most notably communicates with the prefrontal cortex and basal ganglia; and the centromedian and parafascicular nuclei (the main intralaminar nuclei), which most notably communicate with the striatum and frontal lobes. Basal Ganglia: Advanced NomenclatureAdvanced Nomenclature • The striatum further subdivides into dorsal and ventral divisions. • The dorsal striatum comprises the bulk of the caudate and putamen, whereas the ventral striatum is limited to only the ventromedial caudate and putamen, but the ventral striatum also encompasses the nucleus accumbens and select basal forebrain structures. • The dorsal striatum is involved in a wide array of processes, including the sensorimotor circuits, whereas the ventral striatum associates principally with the limbic system and is primarily involved in emotional and behavioral processes. • Just as the striatum divides dorsally and ventrally, so the pallidum further subdivides into a dorsal pallidum and ventral pallidum. Similar to the striatum, the dorsal pallidum refers to the bulk of the globus pallidus, whereas the ventral pallidum refers to the anteromedial portion of the globus pallidus that lies below the anterior commissure. However, although we consider the ventral striatum and ventral pallidum to be divisions of the striatum and pallidum, here, certain texts distinguish these ventral structures as entirely separate nuclei (ie, they distinguish the ventral pallidum from the pallidum, itself). • The corpus striatum also encompasses several fiber pathways that pass between the globus pallidus and the subthalamic nucleus and thalamus: the ansa lenticularis, lenticular fasciculus, subthalamic fasciculus, and thalamic fasciculus. These fibers comprise a considerable portion of the white matter region inferolateral to the thalamus, which is called the fields of Forel (aka prerubral fields or Forel's Field H). As a final note, the subthalamic nucleus and substantia nigra are functionally but not developmentally associated with the basal ganglia; therefore, although they are variably included as part of the basal ganglia, we do not include them in our definition of the basal ganglia, here, in accordance with the Terminologia Anatomica*.
Microscopic colitis is an inflammatory condition of the large intestine. This beginner's guide explores the best diet for it based on scientific evidence.
This is clipart converted and broken apart that has been released into the public domain because the document says so, and its from NASA, a USA government agency. The publication is called "The Brain in Space:" http:/www.nasa.gov/audience/foreducators/topnav/materials/listbytype/The.Brain.in.Space.html
Staphylococcus bacteria are Gram-positive characterized by irregular clusters, widely distributed in nature and can be found on the skin and mucous membranes.
The increasingly antibiotic-resistant bug is being helped along by outdated treatments.
Music Therapy: From its ceremonial origin to modern medical usage for shifting mood and concentration, music remains the powerful balm for the human soul.
This handout names each part of a microscope and describes the function of each part...
Definition of malaria in the Medical Dictionary by The Free Dictionary
Should you be taking a probiotic? What do probiotics do, anyway? Read to find out all the benefits of these microscopic bacterial friends, including how to get them from food.
How It Works – Our ancient brains evolved the perfect way to keep us safe by controlling the chemicals in our mind to moderate our behaviour. –
