Female Urethra

The female urethra is much shorter than the male counterpart. This is the reason women are prone to suffer from urinary infection, much more often than men. It has an average length of only 3.5 cm, while in male this fibromuscular tube is 22 cm long. However, its lumen is one and half times wider than the male urethra. This is the reason why women do not have problems in releasing the urine from the vesical bladder in older age as men usually have (because of its length and prostate inflammation), unless they have cystitis.

The female urethra arises from the internal urethral opening in the bladder wall. Then it goes through the urogenital diaphragm and it opens by means of the external orifice of urethra in the vestibule of the vagina. During its short course, it runs parallel to the vagina on the anterior wall, to which it fuses. Then it extends downwards and forwards as it passes under the pubic symphysis. Like in the male, the female urethra is composed of a muscular coat and mucous coat. The muscular layer consists of smooth muscle fibers, while the mucous coat is made up of stratified squamous endothelial cells.

Blood Supply and Innervation

The female urethra is supplied by the internal and external pudendal arteries. It is innervated by nerve fibers originating from the hypogastric, pudendal, and lumber plexuses.

In the schematic drawing of the urogenital apparatus below, you can see the female urethra at the end of this system. You can also see the difference between the ureter and the urethra.

Fallopian Tube

The Fallopian tube is a paired organ of the female reproductive system. It is a long duct which lies horizontally on each side of the fundus of uterus. It carries the ovum from the ovary to the cavity of body of uterus, where it is fertilized by the sperm. It is also called uterine tube. It is innervated by branches of the inferior hypogastric and the uterovaginal plexuses and it is supplied by the ovarian artery.

Anatomical Description

Each of the Fallopian tube is a cylindrical canal, which is internally lined with a mucous membrane. It measures between 10 and 12 cm in length, with an average of 0.5 cm in diameter. The left and right tube slightly differ in length. Its lateral end is open and it is known as the infundibulum, which bears the abdominal opening and is fringed by a great number of pointed processes called fimbriae. Each one of the fimbria has small notches on its ends, with the longest one being the ovarian fimbria.

For an anatomical description, the Fallopian tube is divided into three portions; the isthmus, the ampulla, and the infundibulum. The isthmus is the medial part, and it is the thinnest segment of the duct, with only 3 mm in diameter and its lumen being very narrow, continuing with the uterine opening, which measures only 1 mm in diameter. The ampulla is the longest portion, with a tortuous course, measuring 8 mm in diameter. The infundibulum, as mentioned above, is the lateral end of the uterine tube, which fans out into a funnel-like shape bordered by the fimbriae.

Structurally, the Fallopian tube is composed of three layers; the serous coat, which contains the tunica adventitia, containing loose connective tissue; the muscular coat, which is made up of an external longitudinal and an internal circular smooth muscle fibers; and the mucous membrane, which consists of a simple, ciliated epithelium.

Below, a schematic drawing of the female organs, showing the right Fallopian tube and the ovary.

 

Human Ovary

The human ovary (ovarium) is the female gonad, which is a paired, reproductive organ where the ovum develops and matures. Each one of the ovaries is located transversely on the lateral wall of the true pelvis, to the side of the fundus of uterus.

The ovary is attached by the mesentery (peritoneum fold) to the posterior layer of the uterus broad ligament, right below the Fallopian tube. It is surrounded superiorly and laterally by the lateral portion of the uterine (Fallopian) tube, which curves downwards. It is supplied by the ovarian artery, which arises straight from the abdominal aorta.

Anatomical Description

The ovary of a mature female measures between 2.5 and 5 cm in length, and approximately 2 cm in width. Being bluish-white in color, it has a flattened oval shape, with its surface being slightly uneven. It has a medial and a lateral surface. It also features a straight mesovarian border and a convex free border. Both its size and weight varies greatly, depending on the age and the general condition and health of the female body.

Microscopically, the ovary has a heterogenous structure. Although it is an intraperitoneal organ, it is not directly covered by the peritoneum, with its free surface consisting of cuboidal single-layer inactive germinal epithelium, which lies on a connective tissue capsule. Within the capsule, the ovary is composed of a superficial dense cortical substance (the ovary cortex), glandular tissue, and a medullary substance. This medullary substance is rich in blood vessels and loose connective tissue, which forms the stroma of the ovary.

The cortical substance contains the follicles, which are vesicular spherical sacs going through various stages of development. Each follicle is a cavity lined with cells and wrapped in a connective tissue capsule. The ovum develops in the follicle, being the female reproductive cell.

An endocrine gland, called the corpus luteum of menstruation is formed to replace the ruptured follicle, transforming into the corpus albicans, which disappears subsequently.

Drawing of the human female reproductive organs, exhibiting the ovary right below the Fallopian tube (anterior aspect).

 

Branches of Femoral Artery

The branches of femoral artery have a complex course, running, twisting and curving around the muscles of thigh. This is so, because they must supply the largest skeletal muscles of the human body. Being the continuation of the external iliac, the femoral is the main, oxygen-rich blood vessel that supplies the whole human lower limb (thigh, leg, and foot). In order to do that, it gives off important branches along its downward course. Once it has gone down beyond the inguinal ligament, the femoral artery begins to give off important branches that supply the muscles, bone, and tendons of the thigh.

Branches of the femoral

1- Superficial epigastric artery. It arises from the anterior side of the femoral artery, right below the inguinal ligament line. Extending upwards and medially, it supplies the abdominal wall region near the umbilicus (navel).

2- Superficial circumflex iliac artery. It originates from the lateral aspect of the femoral. Running laterally along the inguinal ligament, it supplies the muscles, skin, and the inguinal lymph glands.

3- External pudendal arteries. They are two small branches which originate from the medial side of femoral. Traveling medially, one of them irrigates the external region above the pubic; the other runs obliquely to supply the scrotum (labia majora in female).

4- Inguinal arteries. These are three small arterial blood vessels that arise just where the femoral artery begins. It supplies the skin and the lympth nodes of the inguinal region.

5- Profunda femoris artery. Being its largest branch, it originates from the posterior aspect of the main femoral, 4 cm below the inguinal ligament. Then it runs laterally and downwards, stretching across the iliopsoas and the pectineus muscles. It gives off the lateral circumflex femoral and the medial circumflex femoral artery.

6- Descending genicular artery. It arise from the anterior side of femoral. Then it forked into two branches to supply the knee-joint and tissues of nearby areas.

7- Popliteal Artery. It is the continuation of the femoral artery, lying on the posterior aspect of knee. Having run down beyond the popliteal region, it divides into the anterior and the posterior tibial arteries.

Below, diagram of the branches of femoral artery.

Medial Superior Genicular Artery

The medial superior genicular artery is one of several blood vessels that supply the knee-joint region. It springs directly from the popliteal artery. Then it travels medially and forwards under the tendon of the semimembranosus and adductor magnum muscle right above the medial condyle of femur.

It curves around the medial surface of this bone, sending smaller branches as it goes. There, the medial superior genicular artery anastomoses with other secondary arterial branches, such as the middle genicular and the sural arteries, thus contributing to the formation of the network of arteries that supply the knee (muscles, tendons, ligament, and bones).

Below a schematic drawing portraying the arteries of the knee-joint region, posterior aspect. The medial superior genicular is marked on the left side of image, right below the popliteal a.

Viperidae Family

The Viperidae family, commonly known as vipers, constitute a large family of venomous snakes, which are found in all continents. The vipers belong to the order Squamata (scaled reptiles). They are also grouped in the suborder Serpentes. All vipers have one common physiological trait; they all secrete cytotoxic/hemotoxic venom, which is different from the neurotoxic venom produced by the secretory glands of the Elapidae family.

The Viperidae family includes 11 major genera: Agkistrodons (moccasins), Azemiops, Bitis, Bothrops (lanceheads), Crotalus (rattlesnakes), Gloydius, Lachesis (muta), Ovophis, Porthidium (hognoses), Trimeresurus, and the Viperinae (viperines). However, some serpentologists group all the azemiops and viperines as two separate subfamilies. Nevertheless, the majority of them assort these snakes into two genera of the Viperidae family.

The vipers of the genus Agkistrodons are found only in North America. The Bothrops and Lachesis snakes are common in Central and South America, while the different species of genus Crotalus, the rattlesnakes, are found throughout the whole American continent, from Canada to Argentina. The Bitis inhabit Africa, and the snakes from the genera Azemiops, Gloydius, and Ovophis are found only in Asia, from the Ural region of Russia, to Vietnam and Japan.

Common Characteristics

All the vipers are venomous snakes, injecting cytotoxic/hemotoxic venom, which breaks down body tissues, causing areas of necrosis and sometimes clots in the bloodstream. When their venom gets into the bloodstream, it becomes systemic and affects the organs, causing kidney failure, for example. This is due to the proteases it contains. In other words, the venom is a powerful enzyme that aids the vipers to digest the prey they catch.

They have a pair of long, curved, hollow fangs, which are not retractable, as is the case with the Elapids's fangs. Their venom sacs (glands) lie at the rear of the upper jaw, right behind their eyes. Their maxillary (upper jaw) is unhinged from the lower jaw, making it possible for the snake to swallow large prey. Most of snakes of this family have vertical, slit-shaped eye pupil.

Below, a a diamond-back rattlesnake, very common in North America, a member of the genus Crotalus.

 

Diet and Human Evolution

Diet and human evolution go hand in hand, especially the evolution of the human brain and its internal wiring. Having hands, with four fingers and an opposing thumb, a bipedal upright gait, an a foramen magnum located at the center of the base of the head favored greatly the evolution of the human brain. However, it would never have happened without the right kind of food to boost it. And in terms of cerebral cortex evolution, the right food simply means the right fuel, the kind of stuff that provides you with enough calories for a demanding organ such as the brain, which uses up to 27% of the total fuel you have in your body in the form of glucose, ketone bodies, and fatty acids. But the question is what was the richest source of calories hundreds of thousands of years ago? At a time when there was no agricultural products and, therefore, carbohydrates, such as starches (flour) and sucrose (table sugar)?

Thousands of years ago, as it is today, it is saturated fat, animal fat, the food that contains the greatest amount of calories; 1 gram of carbohydrate contains only 4 calories, while 1 gram of fat has 9 calories. But where did primitive man find saturated fat? He found it in the skulls and long bones of animals in the form of brains and marrow. Yes, at the very beginning man was a scavenger that ate a lot of bone marrow and brains. Many years later, when he became an accomplished and skillful hunter, he would also find saturated fat in animal livers, entrails, and meat. Not only does fat contain more calories than carbs, but it also gives you, when you do not eat carbs at all, a different metabolic state called ketosis. And this different metabolic state was the key to the evolution of the human brain since it promotes the generation of new nerve cells.

Early hunter diet and brain bundles development

The diet of primitive man consisted of 60% fat, 30% meat, and 10% vegetable fibers, almost the kind of diet Siberian tribes and Inuit people eat. And it is called ketogenic diet, which put you on ketosis, which means that most of your body cells uses ketone bodies, which are a lot more efficient fuel than glucose (sugar).

One molecule of the fat a primitive hunter ate was downgraded in his duodenum by an enzyme called lipase into three smaller molecules: two fatty acids and one molecule of glycerol. These three smaller molecules traveled in his bloodstream through the superior mesenteric vein and portal system into his liver, where they were further downgraded by the hepatocyte mitochondria. Fatty acids were broken down into three types of ketone bodies (beta-hydroxybutyrate, aceto-acetate, and acetone).

Ketone bodies were used by his muscle fibers and brain neurons as fuel to produce ATP instead of glucose. Since beta-hydroxybutyrate leaves no free radicals as glucose does, this ketone body promoted in the primitive hunter brain neurons the neogenesis of new mitochondria, which produced more ATP per minute, accelerating his metabolism. And this reproduction of new mitochondria boosted in turn the neuroneogenesis of the nerve cells, which is the production of new neurons. And the more neurons he had in his cerebral cortex, the thicker his brain fasciculi (bundles) became.

Your food choices have a profound influence on your brain function and health. Fatty acids and ketone bodies stimulate the production of new mitochondria, triggering the division of neurons (video)

African Coral Snake

The African coral snake (Aspidelaps lubricus) is a venomous elapid snake whose habitat is located in the southwestern, coastal land-strip of Africa. Fully grown adults can measure up to 60 cm in length. However, in northern Namibia adults can be longer but drabber. Although it is not among the most lethal serpent, its bite has caused human death. Being a nocturnal hunter of semi-desert areas, it preys on rodents and small lizards.

Physical Characteristics

The body of coral snake of Africa is cylindrical, whose scales color ranges from bright orange to yellowish brown, with incomplete black bands. Its head is round. It can be identified by a large rostral scale on the nose. The female lays from 3 to 11 eggs in the Summer. Like the cobra from India, it belongs to the Elapidae family in the taxonomy of snakes; therefore, it has hollow, permanently erect fangs, with its glands located at the rear of the upper jaw, secreting neurotoxin venom. Although it inhabits isolated areas, it can be aggressive if one runs into its territory and feel cornered.

Below, the African coral snake, whose Latin name is Aspidelaps lubricus.

 

Rinkhals Snake

The rinkhals snake is a sub-species of cobra whose natural habitat is the southern tip of the African continent. It is large and stout, the adult measuring between 80 cm and 1.20 m. Its venom contains neurotoxins, which is usually fatal when it is injected into the bloodstream through its bite. But before it bites, it usually spits the venom up to 3 m when it feels cornered, rearing up and spreading its hood.

The rinkhals cobra belongs to the Elapidae family; genus Hemachatus; species, haemachatus. The young adult is characterized by its keeled body scales, with conspicuously alternating black with yellowish tan bands, which fade with age into darker shades. However, in Zimbabwe and eastern cape, rinkhals with yellowish with orange bands were seen.

This African cobra is mainly nocturnal as it hunts frogs and small rodents in wet grassland. The female viviparous as up to 70 young hatch out of their eggs inside their mother before their born.

Below, the rinkhals snake on the grass near a home in Mozambique.

Many-Horned Adder

The many-horned adder (Bitis cornuta) is a medium-size venomous viper. Its natural habitat area is the coastal regions of western Cape and southern Namibia, Africa. As a member of the Viperidae family, its glands secrete cytotoxic venom, which destroys tissue, causing necrosis. This snake usually seeks shelter under rocks and boulders, lying in wait for its prey, which could be small rodents and lizards.

Physical Description

The many-horned adder can grow up to 50 cm in length. Its body is grey, blotched with black/dark brown irregular marks; on its mouth, it has yellowish white speckles. On top of its head, the Bitis cornuta has between 2 and 4 horn-like scales standing up over each eye. Symmetrical dark markings on the crown may fuse to form an arrow head shape.

During the warm season, it is most active during the early morning and evening. The female can bear up to 10 young in late summer.

Below, a many-horned adder adult curled, lying in the morning sunshine.