Spermatogenesis is the process in which spermatozoa are produced from spermatogonial stem cells by way of mitosis and meiosis. The initial cells in this pathway are called spermatogonia, which yield primary spermatocytes by mitosis.

The heart is the body's engine room, responsible for pumping life-sustaining blood via a 60,000-mile-long (97,000-kilometer-long) network of vessels. The organ works ceaselessly, beating 100,000 times a day, 40 million times a year—in total clocking up three billion heartbeats over an average lifetime. It keeps the body freshly supplied with oxygen and nutrients, while clearing away harmful waste matter.

Knee replacement, also called arthroplasty, is a surgical procedure to resurface a knee damaged by arthritis. Metal and plastic parts are used to cap the ends of the bones that form the knee joint, along with the kneecap. This surgery may be considered for someone who has severe arthritis or a severe knee injury.

Coronary artery bypass grafting (CABG) is a type of surgery that improves blood flow to the heart. Surgeons use CABG to treat people who have severe coronary heart disease (CHD). CHD is a disease in which a waxy substance called plaque (plak) builds up inside the coronary arteries.

Diseases and Disorders of the Nails

Four-Step Guide to ABG Analysis Is the pH normal, acidotic or alkalotic? Are the pCO2 or HCO3 abnormal? Which one appears to influence the pH? If both the pCO2 and HCO3 are abnormal, the one which deviates most from the norm is most likely causing an abnormal pH. Check the pO2. Is the patient hypoxic?

The external jugular vein receives the greater part of the blood from the exterior of the cranium and the deep parts of the face, being formed by the junction of the posterior division of the retromandibular vein with the posterior auricular vein.

wound clean from pus

Dacryocystorhinostomy (DCR) is a procedure performed for the treatment of tearing (epiphora) due to blockage of the nasolacrimal duct. Tears originate in the lacrimal gland, located at the upper outer margin of the eye. As tears cross the eye with each blink, they are directed into small openings in the eyelids called puncta. From this point, tears travel through a pathway known as the canalicular system into the lacrimal sac. The lacrimal sac is located between the eye and the nose, and funnels tears into the nasal cavity through the nasolacrimal duct (Figure 1). As this is quite a long path for tears to travel, there can be many causes of excessive tearing. Blockage of the nasolacrimal duct is one common cause, and can be treated by creating a direct opening from the lacrimal sac into the nasal cavity in a procedure known as DCR. The evaluation and management of tearing may involve both an ophthalmologist and an otolaryngologist.

As the liver becomes more severely damaged, more obvious and serious symptoms can develop, such as: yellowing of the skin and whites of the eyes (jaundice) swelling in the legs, ankles and feet, due to a build-up of fluid (oedema)

Initially, lead poisoning can be hard to detect — even people who seem healthy can have high blood levels of lead. Signs and symptoms usually don't appear until dangerous amounts have accumulated. Lead poisoning symptoms in children Signs and symptoms of lead poisoning in children include: Developmental delay Learning difficulties Irritability Loss of appetite Weight loss Sluggishness and fatigue Abdominal pain Vomiting Constipation Hearing loss Seizures Eating things, such as paint chips, that aren't food (pica) Lead poisoning symptoms in newborns Babies exposed to lead before birth might: Be born prematurely Have lower birth weight Have slowed growth Lead poisoning symptoms in adults Although children are primarily at risk, lead poisoning is also dangerous for adults. Signs and symptoms in adults might include: High blood pressure Joint and muscle pain Difficulties with memory or concentration Headache Abdominal pain Mood disorders Reduced sperm count and abnormal sperm Miscarriage, stillbirth or premature birth in pregnant women Causes Lead is a metal that occurs naturally in the earth's crust, but human activity — mining, burning fossil fuels and manufacturing — has caused it to become more widespread. Lead was also once used in paint and gasoline and is still used in batteries, solder, pipes, pottery, roofing materials and some cosmetics. Lead in paint Lead-based paints for homes, children's toys and household furniture have been banned in the United States since 1978. But lead-based paint is still on walls and woodwork in many older homes and apartments. Most lead poisoning in children results from eating chips of deteriorating lead-based paint. Water pipes and imported canned goods Lead pipes, brass plumbing fixtures and copper pipes soldered with lead can release lead particles into tap water. Lead solder in food cans, banned in the United States, is still used in some countries. Other sources of lead exposure Lead sometimes can also be found in: Soil. Lead particles from leaded gasoline or paint settle on soil and can last years. Lead-contaminated soil is still a major problem around highways and in some urban settings. Some soil close to walls of older houses contains lead. Household dust. Household dust can contain lead from lead paint chips or from contaminated soil brought in from outside. Pottery. Glazes found on some ceramics, china and porcelain can contain lead that can leach into food served or stored in the pottery. Toys. Lead is sometimes found in toys and other products produced abroad. Cosmetics. Tiro, an eye cosmetic from Nigeria, has been linked to lead poisoning. Herbal or folk remedies. Lead poisoning has been linked to greta and azarcon, traditional Hispanic medicines, as well as some from India, China and other countries. Mexican candy. Tamarind, an ingredient used in some candies made in Mexico, might contain lead. Lead bullets. Time spent at firing ranges can lead to exposure. Occupations. People are exposed to lead and can bring it home on their clothes when they work in auto repair, mining, pipe fitting, battery manufacturing, painting, construction and certain other fields

Trisomy 18, also called Edwards syndrome, is a chromosomal condition associated with abnormalities in many parts of the body. Individuals with trisomy 18 often have slow growth before birth (intrauterine growth retardation) and a low birth weight. Affected individuals may have heart defects and abnormalities of other organs that develop before birth. Other features of trisomy 18 include a small, abnormally shaped head; a small jaw and mouth; and clenched fists with overlapping fingers. Due to the presence of several life-threatening medical problems, many individuals with trisomy 18 die before birth or within their first month. Five to 10 percent of children with this condition live past their first year, and these children often have severe intellectual disability.

Rheum is made up of mucus, skin cells, oils and dust. The rheum that comes from the eyes and forms eye boogers is called gound, which you may know as eye sand, eye gunk, sleep dust, sleep sand, sleep in your eyes, or eye shnooters. When you're awake, gound doesn't cause any problems.

The examination consists of three portions: Inspection, Palpation, and Synthesis of data from these techniques In addition to palpating for size, also note the gland texture, mobility, tenderness and the presence of nodules. Inspection Inspection: Anterior Approach The patient should be seated or standing in a comfortable position with the neck in a neutral or slightly extended position. Cross-lighting increases shadows, improving the detection of masses. To enhance visualization of the thyroid, you can: Extending the neck, which stretches overlying tissues Have the patient swallow a sip of water, watching for the upward movement of the thyroid gland. quicktime video 251KB video demo from Return to the Bedside Inspection: Lateral Approach After completing anterior inspection of the thyroid, observe the neck from the side. Estimate the smooth, straight contour from the cricoid cartilage to the suprasternal notch. Measure any prominence beyond this imagined contour, using a ruler placed in the area of prominence. Palpation Note: There is no data comparing palpation using the anterior approach to the posterior approach so examiners should use the approach that they find most comfortable. Palpation: Anterior Approach placement of hands for palpatation of thyroid in anterior approach The patient is examined in the seated or standing position. Attempt to locate the thyroid isthmus by palpating between the cricoid cartilage and the suprasternal notch. Use one hand to slightly retract the sternocleidomastoid muscle while using the other to palpate the thyroid. Have the patient swallow a sip of water as you palpate, feeling for the upward movement of the thyroid gland. quicktime video 454KB video demo from Return to the Bedside. Palpation: Posterior Approach placement of hands for palpatation of thyroid in posterior approach The patient is examined in the seated or standing position. Standing behind the patient, attempt to locate the thyroid isthmus by palpating between the cricoid cartilage and the suprasternal notch. Move your hands laterally to try to feel under the sternocleidomstoids for the fullness of the thyroid. Have the patient swallow a sip of water as you palpate, feeling for the upward movement of the thyroid gland.

What's helping me become a better doctor

Endometriosis (en-doe-me-tree-O-sis) is an often painful disorder in which tissue that normally lines the inside of your uterus — the endometrium — grows outside your uterus. Endometriosis most commonly involves your ovaries, fallopian tubes and the tissue lining your pelvis. Rarely, endometrial tissue may spread beyond pelvic organs.

Myelodysplastic syndromes are a group of cancers in which immature blood cells in the bone marrow do not mature or become healthy blood cells. In a healthy person, the bone marrow makes blood stem cells (immature cells) that become mature blood cells over time.Aug 12, 2015

Cushing's disease is a serious condition of an excess of the steroid hormone cortisol in the blood level caused by a pituitary tumor secreting adrenocorticotropic hormone (ACTH). ACTH is a hormone produced by the normal pituitary gland. ACTH stimulates the adrenal glands (located on top of the kidneys) to produce cortisol, commonly referred to as the stress hormone.

The cell cycle or cell-division cycle is the series of events that take place in a cell leading to its division and duplication of its DNA (DNA replication) to produce two daughter cells.

If you look at someone’s back, you’ll see that the spine runs straight down the middle. When a person has scoliosis, their backbone curves to the side. The angle of the curve may be small, large or somewhere in between. But anything that measures more than 10 degrees is considered scoliosis. Doctors may use the letters “C” and “S” to describe the curve of the backbone. You probably don’t look directly at too many spines, but what you might notice about someone with scoliosis is the way they stand. They may lean a little or have shoulders or hips that look uneven. What Causes Scoliosis? In as many as 80% of cases, doctors don’t find the exact reason for a curved spine. Scoliosis without a known cause is what doctors call “idiopathic.” Some kinds of scoliosis do have clear causes. Doctors divide those curves into two types -- structural and nonstructural. In nonstructural scoliosis, the spine works normally, but looks curved. Why does this happen? There are a number of reasons, such as one leg’s being longer than the other, muscle spasms, and inflammations like appendicitis. When these problems are treated, this type of scoliosis often goes away.