The Gross Human Body

Gross: adjective, 1. indecent, obscene, horrifying. 2. the bulk or whole, e.g., gross anatomy

Are you interested in unique, weird, and fascinating facts about the human body? The Gross Human Body is a biweekly newsletter offering everything you didn't want to know.

On Mondays you have the word of the week (this week's is flatus!). On Thursdays is an informative post about some aspect of the human body - usually some sort of oddity or secretion. Occasionally there will be bonus posts of a news item of interest or factoid.

You can subscribe via Substack for free at grosshumanbody.com. 

Congenital Anomalies of the Female Reproductive System

Congenital anomalies occur for a number of reasons. Approximately every 1 in 33 babies is born with some form of birth defect, ranging from mild and asymptomatic to life-threatening, and they can be either preventable (i.e. influenced by the mother and her environment) or heritable (i.e. genetic). The female reproductive system isn't spared from this possible outcome during fetal development, and there are several types of congenital anomalies that are seen in this biological system.

Birth defects

The differences between birth defects in males and females are most discernible in regards to the external genitalia by which we designate the baby's sex. Female is defined genetically based on the presence of two X chromosomes (genotype 46XX as opposed to male, 46XY), but the absence of male genitalia is considered an indicator of a female at birth. However, abnormal levels of male sex hormones during fetal development due to congenital adrenal hyperplasia, maternal treatment with progesterone, or a maternal hormone-producing tumor can caused alterations to occur in the external female genitalia (e.g., enlarged clitoris). Truly ambiguous external genitalia is referred to as pseudohemaphroditism or virilization. The physical condition is often corrected by surgery after genetic confirmation of sex.

Mullerian duct development. CC By-SA 4.0 Devinka98. Source

Mullerian anomalies

Defects of the vagina and uterus are called Mullerian anomalies based on their embryonic development from the Mullerian duct. The defects are usually not detected until puberty, when they cause pelvic pain, irregular menstruation, or other reproductive issues, because the ovaries and external genitalia are not affected. The most common defects are agenesis and hypoplasia, in which the tract or part of the tract (such as the vagina) does not form. Whether fertility is affected depends on the exact type and extent of the defect. Some can be surgically remedied to alleviate painful menstruation.

• Unicornuate uterus: only half the uterus forms (banana-shaped). The condition is rare and often accompanied by kidney agenesis.
• Uterus didelphys: double uterus, potentially including duplication of the vagina and cervix.
• Bicornuate uterus: misshaped womb.
• Septate uterus: a wall of tissue divides the uterus.
• Diethylstilbestrol (DES)-related uterus: T-shaped uterus in the child due to maternal exposure to the drug DES; also increases risk of vaginal cancer.
  
• Arcuate uterus: slight variation in the shape of the uterus, considered simply as a variation of the norm.

Other female reproductive tract defects

• Cloacal abnormalities: The cloaca is the initial tube from which the rectum, urinary tract, and vagina form. Persisting late into development can result in a lack of the appropriate orifices, resulting in severe pain and gastrointestinal disruption, as well as the appearance of male genitalia.
• Imperforate hymen: The vaginal opening is completely blocked, which is discovered when menstruation begins.
• Abnormal ovaries: An extra ovary or extra tissue on the ovaries can occur, as well as ovotestes (presence of both male and female tissues).

Chromosomal abnormalities

When a baby is born with only one sex chromosome it is known as monosomy. X monosomy is referred to as Turner syndrome, or gonadal dysgenesis, and occurs in an estimated 1 of every 2000 live births. Sometimes the second X chromosome is only partially missing. Children born with this condition have swollen hands and feet, and sometimes a wide webbed neck. Puberty doesn't occur and the adolescent lacks secondary sex characteristics unless treated with estrogen. Children may also have a short stature unless treated with growth hormone. Menstruation is absent and an adult with Turner’s is infertile. The condition has a number of complications, including heart defects, autoimmune disorders (e.g., hashimoto’s thyroiditis and diabetes), arthritis, and cataracts.

 

Heart and Cardiovascular Learning Guides

Human heart. Gray's Anatomy, 1918

 

Here is an outline and links to the current heart and cardiovascular system-related learning guides currently available at Just Facts-Long-lasting Curriculum.

• Vocabulary lists
• Congenital heart defects
• Stroke
• Heart disease
• Secondary heart disease
• Primary heart disease
  
• Endocarditis
• Heart failure

 

The basics on the circulatory system are in this other post.

Platelets and Clotting

Now we come to the end of Blood week and I hope I've shared something with you. This final post is about platelets - sometimes considered a cell and sometimes not.

Blood cells - The middle is a thrombocyte

Platelets are known scientifically as thrombocytes. Thrombocytes break off from large cells called megakaryocytes, so they aren't actually cells, but a piece of a cell. Platelets circulate in the blood, on the ready for use in clotting.

Blood clotting is important because any breach in a blood vessel, even capillaries (as happens when you cut yourself) can result in loss of blood. Too much blood loss and the body can't function, leading to shock and death. Normal clotting response is about 8 minutes if you go by my medical textbooks. The actual process involves chemical signals and varying proteins and pathways all interacting with one another, but the main thing that happens is that platelets stick together to act like a wall between the blood flow and the outside world (technically, the world outside the blood vessel - internal bleeding a serious complication of trauma and any blood loss outside the circulatory system is a problem).

Some people are born with clotting, or bleeding, disorders - hemophilia. When they are injured their vessels bleed easily or are unable to clot, resulting in the need for transfusions and exposure to various risks due to this.

So the platelets are important, as is the plasma that carries them. The water and nutrients in the plasma are used in various signaling processes in the bodies, like hormones that control heart rate and fertility, and the vitamins used in electrical signaling in the muscles. As well as the wastes, like carbon dioxide (produced by cells) and urea (nitrogen waste from protein metabolism) - the build up of which can cause disease.

White blood cells - Immunity

White blood cells come in a number of varieties, each with specialized functions in the body. I mentioned before that they start out as lymphocytes - but really there are other specialized leukocytes (i.e. white blood cells) that aren't lymphocytes as well - specifically monocytes and the phils (neutrophils, eosinophils, basophils). Hematology (the study of the blood) is a field in its own right because of this complexity.

Scanning electron micrograph of blood

White blood cells are responsible for fighting infection and preventing invasion by foreign particles. They are constantly tasting the components in the blood to determine whether they belong to the body, and they do this through receptors on the cell surfaces. What happens if they find something that they don't recognize? An immune response.

Allergies are fast and severe immune responses to something the body doesn't recognize. This is why food intolerance can develop - slowly over time the immune cells become sensitive and then, bam, they're ready to attack and do. Allergies may also be due to the genetics of the proteins on the cell surfaces, which recognize certain food proteins as needing to react.

When the body lacks white blood cells, as in the case of HIV infection (the virus destroys the cells), immunodeficiency occurs. This makes the person susceptible to common infections. Normally we co-exist with bacteria, viruses, and fungi, like cytomegalovirus and strains of staph on our skin, but without the white blood cells to keep these pathogens in their place, they invade. Something as simple as the common cold can be deadly to a person with compromised immunity. And some people are born lacking the immunity they need - resulting in cases like that of the 'bubble boy' syndrome.

So now that we know the cell components of blood are important, what's the purpose of plasma? Read about that tomorrow.

Circulation

Circulatory System, Source: LadyofHats, Wikimedia

The circulatory system is a circular and contained vessel system that allows blood to flow to every tissue of the body. The blood vessels vary from large to very small, with the smallest being the capillaries - a single red blood cell wide connection between the arterial and venous systems.

The arteries carry blood away from the heart. They start out large and muscular (the aorta) and branch out into medium muscular arteries and smaller elastic arterioles. The veins start at the capillaries, carrying blood to the heart. They are not muscular, allowing blood to flow based on pressure and skeletal muscle squeezing. They end as the vena cava, emptying into the heart.

Arteries carry oxygenated blood because blood flows between the heart and lungs, where hemoglobin binds oxygen. And veins carry deoxygenated blood, because the oxygen is transferred to the tissues in the capillaries (exchanged for carbon dioxide which dissolves in the blood and is released in the lungs out to the world). The exception to this is the pulmonary system.

The pulmonary circulation is the opposite of the general circulation. The pulmonary artery carries deoxygenated blood because the blood just returned to the heart via the veins, it goes to the lungs for oxygen. The pulmonary vein carries that newly oxygenated blood to the heart to be pumped through the arteries.

What happens when the red blood cells are not working properly? Read on tomorrow.

Blood is life

This week is "Blood" week at Maeflowers - each day will be a post on something blood related. Today - what is blood?

It's almost a cliche - "blood is life". But it's true. Blood carries the components necessary for cell function, and thus life, to every tissue of the body.

Red blood cells

Blood is actually a milieu - it has many components all mixed together but not combined (it's not like a chemical reaction where two substances mix to become one - blood components are separable and act on their own). Blood is made mostly of plasma, a water-based substance containing dissolved proteins, gases, and other molecules, like vitamins. The cells in blood come in two varieties - white and red. Red blood cells are what we think of when we think blood, because we see their coloration. Known scientifically as erythrocytes, red blood cells contain a protein (hemoglobin) that binds oxygen. White blood cells start out as lymphocytes - these become T cells, B cells, macrophages - the immune cells and maids of the body, cleaning up dead and broken cells and foreign material from the bloodstream and tissues.

Blood is capable of providing life because of the circulatory system - which you'll be able to read about tomorrow.

Sex polysomies

Normal human karyotype

 

Some people have genetic differences they don't even know about, and it could be a sex polysomy. Sex polysomies are the presence of more than two sex chromosomes in an individual’s genome. The normal genotypes are 46XX, female and 46XY, male. The number refers to the number of chromosomes in the genome, with X and Y as the sex chromosomes (Y is the traditional male sex chromosome). Individuals with polysomy can have genotypes of 47XXY, 47XXX, 47XYY, or even 48XXXY, 48XYYY or 49XXXXY. Just like with other chromosomes, the presence of extra sex chromosomes results in anatomical abnormalities, such as abnormalities in the genitalia and secondary sex characteristics, mental deficiencies, and cardiac or skeletal anomalies, though some may be so subtle they are not noticed.

Genitalia and secondary sex characteristics

As expected, altered sex chromosome numbers alter the physical manifestation of gender, particularly due to imbalances in hormone levels such as testosterone, estrogen, and gonadotropin. X polysomy in males, called Klinefelter's syndrome, is considered an endocrine abnormality and leads to hypogonadism (inability to produce sperm and small testes). The 47XXY genotype is the most common cause of hypogonadism in males. Males with Klinefelter’s syndrome also have enlarged breasts, infertility, and sparse body hair. In contrast, women with 47XXX (lack of a Y chromosome leads to female phenotype) often have no discerning anatomical changes. However, approximately half of 48XXXX women have abnormal menstruation, though infertility is not a certainty based on a review of reports prior to 1995.

Y polysomy also has effects on male fertility. 47XYY males have been found to have low sperm counts, but are not necessarily infertile. However, some 47XYY males exhibit female phenotypes due to mosaicism in which some cells are 45X and others are 47XYY (instead of all being 46XY).

Mental and cognitive disorders

Individuals with Klinefelter’s syndrome tend to have psychosocial issues. Clinical descriptions have found that as the number of X chromosomes increases, so does the extent of mental involvement in the disorder, with mental retardation and low IQ being characteristic of 48XXXX and 48XXXY. Cognitive and emotional issues also appear to accompany Y polysomy, with criminality being studied for decades in 47XYY males. However, with more certainty, 47XYY syndrome has been associated with delayed development of motor skills. 48XYYY has been rarely reported, but is also accompanied by a low IQ.

Skeletal, cardiac, and other abnormalities

X polysomy in both males and females tends to be associated with taller stature, especially as the number of chromosomes increases. In addition to tall stature, 48XXXX is also associated with abnormal curvature of the pinkie finger (clinodactyly) and radioulnar synostosis (fusion of the bones in the forearm), and it also causes facial abnormalities, including epicanthic folds (extra eyelid skin as seen in Down’s syndrome, a condition caused by trisomy 21), increased space between the eyes (hypertelorism), and uncontrollable eye movements (nystagmus). Y polysomy, particularly 47XYY, has been characterized by congenital hip dislocation at birth, but also tends to cause a taller stature.

Klinefelter’s syndrome has also been associated with cardiac abnormalities and increased risk of autoimmune disorders, such as diabetes, and altered adipose tissue distribution. However, the manifestation of sex polysomies varies from individual to individual and, because they are rare, clinicians have few cases to compare for each genotype.

"Double-jointed"

Everyone at some point in their childhood knows a kid who is "double jointed". Though many outgrow loose joints, some actually have a condition that can leave them in pain and arthritic later in life.

Hypermobility syndrome is a joint condition that allows movement beyond the normal function of the joint. The connections between bones are usually contained within a network of ligaments and connective tissue that support and control the movement of the bones. When these supporting tissues are “loose”, they allow abnormal movements. This stress can cause pain, irritation, and discomfort.

Signs of hypermobility

Signs of hypermobility include:

• ability to place the palms of the hands on the floor with the knees fully extended
  
• hyperextension of the knee or elbow beyond 10 degrees
• ability to touch the thumb to the forearm

Benign hypermobility syndrome often manifests early in life as “growing pains”, but it is not the same condition and the pain continues into adulthood. The joints may swell when used, such as late afternoon, at night, and after exercise, with resolution in a few hours. The swelling is caused by an accumulation of fluid in the joint capsule due to irritation from the loose connective tissues. Pain is more common in the larger joints and lower extremities. Signs of inflammation (redness and heat) are not common. Partial dislocation may occur as well, with visible movement of the joints.

Who is at risk for hypermobility

Ten to fifteen percent of normal children have hypermobile joints. The condition can run in families when it is caused by a defect in collagen genes. Children are naturally more flexible than adults because their skeletons are still growing. Hypermobility often causes little discomfort until adulthood.

Complications of hypermobile joints

Hypermobility syndrome can also be a feature of Ehlers-Danlos syndrome. This generalized syndrome causes weakness of the connective tissue. It is an inherited defect that also causes elastic skin, easy bruising, and damage to blood vessels. Other chronic medical conditions that can cause hypermobility are Marfan syndrome, Marquio syndrome, and Cleidocranial dysostosis.

Hypermobility can lead to arthritis and an increased risk of sprains and strains. Scoliosis is more common in those with “loose joints”.

Treatment of hypermobility

There is generally no treatment for hypermobile joints. Physical fitness is recommended to strengthen muscles, stabilizing the skeleton. However, exercises should be chosen that prevent stress on the joints or any that are particularly affected by the syndrome. Joint pain can be treated with anti-inflammatories, pain relievers, and arthritis drugs as directed by a doctor. Rheumatologists are often consulted when the syndrome causes other health issues with the joints.