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Showing posts with label Organ. Show all posts
Showing posts with label Organ. Show all posts

Monday, February 15, 2021

ACUTE LUNG INJURY

ACUTE LUNG INJURY

ACUTE LUNG INJURY

The syndrome now referred to as acute lung injury (ALI) is a condition defined by noncardiogenic pulmonary edema, originally described almost 50 years ago as Da Nang lung and subsequently as acute or adult respiratory distress syndrome (ARDS). The commonly used definition of ALI includes four elements: acute onset of symptoms, bilateral alveolar infiltrates on chest radiography, a PaO2 (partial pressure of oxygen)/FIO2 (fraction of inspired oxygen) ratio below 300 (200 defines the more severe subset of the patients as ARDS), and no evidence of left atrial hypertension. Histologically, the syndrome is identified by the classic finding of diffuse alveolar damage, but few patients undergo lung biopsy during the course of their clinical illness.

SUPPORT OF PELVIC VISCERA

SUPPORT OF PELVIC VISCERA

SUPPORT OF PELVIC VISCERA

To clarify the relationships of muscles and fasciae in supporting the pelvis, with particular reference to the vagina and internal female genitalia, the uterus, in the accompanying picture, has been elevated upward and backward.  The plane chosen for the section (small upper diagram) runs from a point anterior to the body of the uterus down through the anterior vaginal fornix and along the longitudinal axis of the vagina to the perineum. At this level, the large iliac vessels run close to the superior pubic rami which form the lateral pelvic walls. These pubic rami are connected to the ischiopubic rami across the obturator foramen by the obturator membrane, the obturator internus muscle, and the obturator fascia. The broad ligaments begin at the lateral pelvic walls as double reflections of the parietal peritoneum, forming large wings, which divide to include the uterus and separate the pelvic cavity into anterior and posterior compartments. They are continuous with the peritoneum of the bladder anteriorly and the rectosigmoid posteriorly. The broad ligaments contain fatty areolar tissue, blood vessels, and nerves, and at their apices invest the round ligaments, which are condensations of smooth muscle and fibrous tissue holding the uterus forward and inserting below and anterior to the fallopian tubes. The left ovary has been lifted up to demonstrate the uteroovarian and infundibulopelvic ligaments, the latter containing the ovarian blood supply. The bladder peritoneal reflection has been detached from the uterus, revealing the endopelvic or uterovaginal fascia, which runs laterally to the pelvic wall as the cardinal ligament, and with the associated blood vessels, nerves, and fat forms the parametrium. The uterine arteries and veins extend medially from their origins in the hypogastric vessels to the lateral vaginal fornices. The ureters (cross-sectioned) at this point pass beneath the uterine vessels and then continue in the uterovaginal fascia medially and anteriorly across the upper vagina into the bladder. The close proximity of the ureters to the uterine blood supply and vagina explains why they may easily be injured during hysterectomy and in operations to repair lacerations of the endopelvic fascia.

PELVIC DIAPHRAGM II—FROM ABOVE

PELVIC DIAPHRAGM II—FROM ABOVE

PELVIC DIAPHRAGM II—FROM ABOVE

The pelvic diaphragm forms a musculotendinous, funnel-shaped partition between the pelvic cavity and the perineum and serves as one of the principal supports of the urethra, vagina, rectum, and pelvic viscera. It is composed of the levator ani and coccygeus muscles, sheathed in a superior and inferior layer of fascia. The muscles of the pelvic diaphragm extend from the lateral pelvic walls downward and medially to fuse with each other and are inserted into the terminal portions of the urethra, vagina, and anus. Anteriorly, they fail to meet in the midline just behind the pubic symphysis, exposing a gap in the pelvic floor, which is completed by the urogenital diaphragm. This gap is partially filled by the subpubic ligament that is pierced by the dorsal vein of the clitoris. In this area, the inferior fascia of the pelvic diaphragm fuses with the superior fascia of the urogenital diaphragm.

PELVIC DIAPHRAGM I—FROM BELOW

PELVIC DIAPHRAGM I—FROM BELOW

PELVIC DIAPHRAGM I—FROM BELOW

Removing the superficial muscles and fasciae of the pelvic floor, the pelvic diaphragm, viewed from below, forms a hammock of muscle from the pelvic brim, investing the urethra, vagina, and rectum and attaching posteriorly to the sacrum and coccyx. The principal muscles of this group are the levatores ani, consisting of both medial and lateral components on each side and supplied by the pudendal nerve. The larger medial component, the pubococcygeus, arises from the posterior surface of the superior ramus of the pubis adjacent to the symphysis, whence the fibers pass downward and backward around the lateral walls of the vagina, with some fibers reaching the coccyx, some terminating in the fascia forming the central tendinous point of the perineum, and others blending with the longitudinal muscle coats of the rectum. The pubococcygei are separated medially by the interlevator cleft through which pass the dorsal vein of the clitoris, the urethra, vagina, and rectum. These organs are supported by musculofascial extensions from the pubococcygei, their inferior fascia being continuous with the superior fascia of the urogenital diaphragm.

THE VAGINA

THE VAGINA

THE VAGINA

The vagina (from Latin, literally “sheath” or “scabbard”) serves as the portal to the internal female reproductive tract and a route of egress for the fetus during delivery. The viscera contained within the female pelvis minor include the pelvic colon, urinary bladder and urethra, uterus, uterine tubes, ovaries, and vagina. These structures surround the vagina and interact with it in the clinical setting. Therefore, the vagina also provides a convenient portal to understanding the female pelvic viscera.

FEMALE CIRCUMCISION

FEMALE CIRCUMCISION

FEMALE CIRCUMCISION

Female circumcision is a culturally determined practice of ritually cutting a female’s external genitals that results in removal of part or all of the external genitalia including the labia majora, labia minora, and/or the clitoris. This activity is illegal in many locations. Female circumcision (female genital mutilation, infibulation) is generally performed as a ritual process, often without benefit of anesthesia and frequently under unsterile conditions, generally near the time of puberty or soon after. The resulting scarring may preclude intromission or normal vaginal delivery should pregnancy be achieved. In rare cases, scarring and deformity may be sufficient to result in amenorrhea or dysmenorrhea. The ritual is often performed to reinforce a woman’s place in her society, to establish eligibility for marriage and entry into womanhood. It is sometimes also performed to safeguard virginity or to paradoxically improve fertility. Although the ritual can have devastating effects on the woman’s sexual pleasure, it is some- times performed to enhance the husband’s pleasure.

Sunday, February 14, 2021

MALIGNANT TUMORS

MALIGNANT TUMORS

MALIGNANT TUMORS

About 5% of the malignant tumors of the female genital organs originate on the vulva. (The incidence of vulvar cancer rose by approximately 20% between 1973 and 2000, likely related to increased exposure to human papillomavirus [HPV].) Primary carcinoma is almost always seen in elderly women with an average age for in situ tumors being 40 to 49 years, and 65 to 70 for invasive lesions. The vast majority of these tumors are of the squamous cell variety. Histologic types include squamous cell (90%), melanoma (5%), basaloid, warty, verrucous, giant cell, spindle cell, acantholytic squamous cell (adenoid squamous), lymphoepithelioma-like, basal cell, and Merkel cell. Sarcoma accounts for approximately 2% of vulvar cancers. Metastatic tumors from other sources are rare but do occur.

BENIGN TUMORS

BENIGN TUMORS

BENIGN TUMORS

Benign tumors of the vulva include the fibroma, fibromyoma, lipoma, papilloma, condyloma acuminatum, urethral caruncle, hidradenoma, angioma, myxoma, neuroma, and rarely endometrioid growths.

Friday, February 12, 2021

SUMMATION OF EXCITATION AND INHIBITION

SUMMATION OF EXCITATION AND INHIBITION

SUMMATION OF EXCITATION AND INHIBITION

Summation of excitation and inhibition is the vital principle on which the functioning of the CNS is based. The illustration shows the various intracellular potential changes observed during temporal and spatial summation of excitation and inhibition, as voltage- versus-time tracings similar to those produced by an oscilloscope.

CHEMICAL SYNAPTIC TRANSMISSION

CHEMICAL SYNAPTIC TRANSMISSION

CHEMICAL SYNAPTIC TRANSMISSION

Chemical synaptic transmission proceeds in three steps: (1) The release of the transmitter substance from the bouton in response to the arrival of an action potential, (2) The change in the ionic permeabilities of the post-synaptic membrane caused by the transmitter, and  (3) the removal of the transmitter from the synaptic cleft. Depending on the type of permeability changes produced in the second step, synaptic activation may have either an excitatory or an inhibitory effect on the post-synaptic cell.

NEURONAL STRUCTURE AND SYNAPSES

NEURONAL STRUCTURE AND SYNAPSES

NEURONAL STRUCTURE AND SYNAPSES

NEURONAL STRUCTURE

A typical neuron of the central nervous system consists of three parts: dendritic tree, cell body (soma), and axon. The highly branched dendritic tree has a much greater surface area than the remainder of the neuron and is the receptive part of the cell. Incoming synaptic terminals make contact directly with the dendritic surface or with the small spines (gemmules) that protrude from it. The membrane potential induced in the dendrites spreads passively onto the cell soma, which allows all inputs acting on the neuron to summate in controlling the rate of neuronal discharge through the axon.

THALAMOCORTICAL RADIATIONS

THALAMOCORTICAL RADIATIONS

THALAMOCORTICAL RADIATIONS

All pathways carrying information from the periphery or the brainstem to the neocortex relay in the nuclei of the posterior thalamus. These nuclei can be divided into two groups on the basis of their structure, connections, and function.

FOREBRAIN REGIONS ASSOCIATED WITH HYPOTHALAMUS

FOREBRAIN REGIONS ASSOCIATED WITH HYPOTHALAMUS

FOREBRAIN REGIONS ASSOCIATED WITH HYPOTHALAMUS

The cerebral cortex influences the “autonomic” neurovisceral outflow and the neurohumoral output of the endocrine glands, as can be demonstrated experimentally by stimulating the orbitofrontal cortex of the cingulate gyrus to produce respiratory, cardiovascular, and digestive responses, as well as certain emotional reactions. The responses are less marked than those produced by stimulating the hypothalamus but are still striking; some of them, moreover, do not depend upon the integrity of the hypothalamus, a fact that suggests mediation by corticoreticular fibers to lower “centers.” In humans, subjective emotional experiences are associated with autonomic discharges (e.g., tachycardia, increased blood pressure, blushing) and changes in endocrine activity (e.g., stress-induced amenorrhea or anorexia nervosa).

AMYGDALA

AMYGDALA

AMYGDALA

The amygdala is an almond-shaped complex located in the medial temporal lobe, and contains approximately 13 nuclei. The three main regions are the corticomedial nuclei, basolateral nuclei (both receive afferents and project axons to target structures), and central nucleus (which provides mainly efferent projections to the brainstem). Afferent connections to the amygdala originate from cortical and thalamic areas, and hypothalamic and brainstem areas. Its function is to provide emotional relevance to external and internal sensory information and to provide a behavioral and emotional response, particularly a fearful and aversive response, to a sensory input.

Wednesday, February 10, 2021

LYMPHOGRANULOMA VENEREUM

LYMPHOGRANULOMA VENEREUM

LYMPHOGRANULOMA VENEREUM

Lymphogranuloma venereum (LGV) is a sexually transmitted disease (STD) that is produced by infection with Chlamydia trachomatis serotypes L1, L2, and L3. The disease progresses through three distinct phases of transmission. This bacterial disease was once limited to tropical regions, but with the ease of worldwide travel, it can now be seen globally. The skin manifestations are found predominantly in the groin and genital region. This disease is often seen in conjunction with other STDs, and screening for other STDs should be done routinely in patients diagnosed with LGV.

LYME DISEASE

LYME DISEASE

LYME DISEASE

Lyme disease is a tickborne infection caused by the spirochete bacteria, Borrelia burgdorferi. The deer tick, Ixodes scapularis, is the main tick responsible for transmitting the disease to humans. Discovered in 1975 in the Connecticut town of Lyme, this disease has become the most common tickborne disease in the United States. Most cases are reported in the spring, summer, and early fall, correlating with tick activity. The disease not only affects humans but has been reported to affect dogs, horses, and cattle.

LICE

LICE

LICE

Lice are nonflying insects that live off the blood meal from a human host. They have been human pathogens for thousands of years and continue to cause millions of cases of disease annually. Three variants of the louse exist: the head louse, the body louse, and the pubic louse. For the most part, lice cause localized skin disease from the biting they do to secure their blood meal. However, some lice have been known to transmit other diseases to humans. The most important infectious agents transmitted by body lice are the bacteria that cause epidemic typhus, relapsing fever, and trench fever. These infections are uncommon in the United States and North America but are still seen, and one should be aware of their causes and vectors.

LEPROSY (HANSEN’S DISEASE)

LEPROSY (HANSEN’S DISEASE)

LEPROSY (HANSEN’S DISEASE)

Leprosy is a chronic multi system disease with cutaneous findings that is caused by the bacteria, Mycobacterium leprae. It also goes by the name Hansen’s disease. Gerhard Hansen was the Norwegian physician who first described M. leprae as the cause of leprosy in 1873. Leprosy is most prevalent in regions of Africa, South-east Asia, and South America, and it can be seen in isolated regions of North America.

HISTOPLASMOSIS

HISTOPLASMOSIS

HISTOPLASMOSIS

Histoplasmosis is endemic in the Ohio River Valley but exists throughout North America and is also seen in Central and South America. It is a primary pulmonary disease, with the skin being secondarily involved in disseminated disease; however, isolated cutaneous disease can result from direct inoculation. The disease is typically seen in immunocompromised patients. Patients typically breathe in the infective spores, which lodge in the pulmonary tree. Most infections are subclinical.

HERPES SIMPLEX VIRUS

HERPES SIMPLEX VIRUS

HERPES SIMPLEX VIRUS

Herpes simplex virus type 1 (HSV1) and type 2 (HSV2) are the two viruses that are responsible for the production of both mucocutaneous and systemic disease. Mucocutaneous disease is overwhelmingly more common than systemic disease such as HSV encephalitis. HSV infections are ubiquitous in humans, and almost all adults develop antibodies against one of these viruses. Most infections are subclinical or so mild that they are never recognized by the patient. HSV infections are predominantly oral or genital. The virus becomes latent in local nerves and can be reactivated to produce future outbreaks. Currently, there are eight known herpesviruses that infect humans, including HSV1 and HSV2. HSV infections can cause severe, life-threatening central nervous system (CNS) disease in immunocompromised patients and in neonates. Many unique cutaneous forms of HSV have been described with their own clinical characteristics.

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