BiologyCoachOnlineBlog

Your hyoid bone is a small U-shaped bone in your neck--between your mandible (or lower jaw bone) and larynx (or Adam's apple)--that does not articulate with (is not connected to) any other bone in your body. The hyoid bone is suspended in your neck by ligaments and it is positioned such that it provides attachment for muscles of the floor of the mouth, the tongue, the larynx, the pharynx, and the epiglottis. The hyoid bone is important in speech, swallowing, and breathing. In fact it is your hyoid bone that helps maintain an open airway while you sleep.

Last week's #MysteryCreature was the Okapi (Okapia johnstoni).

The okapi is endemic to the tropical forests of the Democratic Republic of the Congo (in Central Africa). Okapi (with their stripes) resemble zebras. However, they are most closely related to the giraffe. In fact, the okapi and the giraffe are the only extent members of the family Giraffidae. The okapi stands nearly five-feet (1.5 m) at the shoulder. Average body length of about eight-feet (2.5 m) and average weight ranges from 450 to 750 popunds. Okapi have relatively long necks. Their coats are chocolate to reddish brown and they have white horizontal stripes and rings on their legs and white ankles. Okapis are sexually dimorphic. Males possess short horns (called ossicones) while females have hair whorls. Ossicones are absent on females as well. Breeding for okapis is not season dependent. That is, breeding may occur anytime of the year. A single calf is born after a gestation of around 450 days.

The International Union for the Conservation of Nature and Natural Resources (IUCN) classifies the okapi as Endangered. Major threats include habitat loss, hunting (for bushmeat and skin), and illegal mining. The Okapi Conservation Project was established in 1987 to protect okapi populations.

Last week's #MysteryCreature was the Frilled-neck Lizard (Chlamydosaurus kingii).

Chlamydosaurus kingii is the only member of the genus Chlamydosaurus and is found mainly in northern Australia and southern New Guinea. C. kingii is a relatively large lizard with an average length of about 32-inches (85cm). As its common name suggests, the frilled-neck lizard has a large frill around its neck (which the lizard usually keeps folded and against its body). C. kingii is predominantly arboreal and it feeds on insects and small vertebrates. Frilled-neck lizards are sexually dimorphic with adult males being larger than adult females. Breeding occurs in September and October (the rainy season in that part of the #biosphere) with males fighting for females. [Male lizards display their frills in order to look bigger as a way to intimidate competitors as well as predators.] Females lay their clutches of 6-25 eggs in a nest as much as 8-inches below ground. Incubation takes two or three months.

The spinal cord is a long, thin, tubular bundle of nervous tissue that extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column. [The vertebral column (i.e. "backbone") surrounds and protects the spinal cord.] The brain and spinal cord together make up the central nervous system (CNS).

The spinal cord functions primarily in the transmission of neural signals between the brain and the rest of the body. That is, the spinal cord carries sensory impulses from the body to the brain and reversely, motor impulses from the brain to the body. Spinal cord injuries can be caused by trauma to the spinal column (e.g. bruising, severing, laceration) or or shattering of the bones of the vertebral column. In the latter scenario, the spinal cord can be punctured by fragments of bone. Victims of spinal cord injuries may suffer numbness in certain parts of their body. Severe injuries of the spinal cord may result in paraplegia, quadriplegia, or full body paralysis below the site of injury to the spinal cord.

Last week's #MysteryCreature was the Greater Blue-ringed Octopus (Hapalochlaena lunulata).

Despite its common name Hapalochlaena lunulata is a comparatively diminutive mollusk: 4-inches (10cm) from arm to arm. [The term "greater" refers to the diameter of its rings: around 8-millimeters, much larger than those of other species in the genus.] The greater blue-ringed octopus abundant in the warm tropical and subtropical waters of the Indo-West Pacific. H. lunulata can be observed from Sri Lanka to the Philippines and from Australia to the shallows of southern Japan. H. lunulata inhabits mixed seabed environs and shelters in burrows. H. lunulata feeds primarily on crustaceans bivavles. H. lunulata is a solitary mollusk (except, of course, during breeding). Females lay 60 to 100 eggs which they protect under their arms during incubation (approximately one month).

The greater blue-ringed octopus has two different venom glands: the first it uses to subdue and kill its prey; the second, a neurotoxin, is used for defense. Abite from the greater blue-ringed octopus can be fatal to even humans. While the bite itself is painless, the effects of the toxin may be anything but. The first phase of poisoning - which usually occurs within the first 30-minutes after contact - is characterized by facial paresthesia, hypersalivation, and cyanosis. The second phase - which generally occurs after about 8-hours - is characterized by hypotension and systemic spastic muscle weekness. Death from respiratory paralysis usually occurs about 20-minutes after phase two symptoms appear.

Taste buds are microscopic structures located on the papillae of your tongue. The papillae are the macroscopic structures that give the surface of your tongue its fuzzy appearance. Taste buds contain taste receptor cells (i.e. gustatory cells) that are responsible for your perception of the five primary tastes. Namely salty, sour, bitter, sweet and umami. [Your detection of "flavors" is due to the combination of two or more of these primary tastes.] The five taste-chemicals mix with saliva to form solutions which then enter taste buds via their associated microscopic pores. The solution then makes contact with the receptors of the gustatory cells. The gustatory cells send this chemical information to the gustatory areas of the brain via the seventh, ninth, and tenth cranial nerves. The average human tongue can have as many as 10,000 taste buds (which regenerate about every two weeks).

The uterus (or womb) is a major female reproductive sex of most mammals. The uterus is located within the pelvic region just behind and above the bladder. The uterus is pear-shaped and is about 3.0 inches (7.6 cm) long. The uterus opens into the vagina on one end and is attached (via the fallopian tubes) to the ovaries on the other end. During pregnancy, the developing embryo (the blastocyst) is implanted (attached) to the inner wall (the endometrium) of the uterus. The fetus will develop here until birth.

A hysterectomy is the surgical removal of the uterus. Experimental uterine transplants have been successful in animals such as mice, rats and sheep. In 2012, the world's first uterine transplant was performed on a Turkish woman who was born without a womb (but had her own ovaries). [She received the uterus from a cadaver.] Today she is in good condition and the womb is functional.

The arrector pili muscles are small muscles attached to hair follicles in mammals. Contraction of these muscles causes the hairs to stand on end (i.e. "goose bumps"). Arrector pili muscles are composed of small bundles of smooth muscle fibres. These tiny muscle bundles are innervated by the sympathetic branch of the autonomic nervous system. Thus, the contraction of the muscle is involuntary. Factors such as cold or fear often stimulate the sympathetic nervous system thereby causing contraction of the arrector pili bundles. The primary function of contraction (of the arrector pili muscles) in mammals is to provide insulation. That is, the air trapped between erect hairs helps animals retain heat. [The function of the same process in humans is not understood as humans have comparatively little hair.] In some animals - like the porcupine (its quills are modified hairs), erection of the hair causes the animal to become appear larger - and thus more intimidating towards predators. Finally, contraction of the arrector pili muscles causes sebum (or oil) to be forced along the hair follicle outwards thereby protecting the hair.

The prostate is an exocrine gland of the male reproductive system. The prostate contains smooth muscles that help expel semen during ejaculation. Secretions of the prostate constitute about 30% of the volume of semen. Prostate secretions are slightly alkaline which helps neutralize the acidity of the vaginal tract thus prolonging the lifespan of sperm. The prostatic fluid is expelled in the first ejaculate fractions together with most of the spermatozoa. Sperm expelled in the first ejaculate have better motility, longer survival, and better protection of the genetic material.

Prostatitis is inflammation of the prostate gland. Benign prostatic hyperplasia (BPH), in which the prostate enlarges to the point where urination becomes difficult, often occurs in older men. Symptoms may include the need to urinate often. If the prostate grows too large it may constrict the urethra and impede the flow of urine making urination difficult and painful and, in extreme cases, impossible. BPH is usually treated succssfully with medication.

Prostate cancer is one of the most common cancers affecting older men in developed countries and a significant cause of death for elderly men. Interestingly, the Journal of the American Medical Association reported a connection between vasectomy and an increased risk of prostate cancer. Of 48,000 men who had vasectomies, 66% of them had higher rates of prostate cancer.

The gastrula is the structure resulting from the phase of early embryonic development known as gastrulation. Gastrulation is the process whereby the blastula - which is a hollow "ball" made up of a single layer of cells - folds inward and enlarges forming the elongated structure (open at one end) pictured here. The gastrula is composed of three (germ) cell layers: ectoderm, mesoderm, and endoderm. The opening, known as the blastopore, opens to the archenteron. As the embryo developes, the blastopore becomes the anus while the archenteron becomes the gut.

Gastrulation is followed by organogenesis (when individual organs develop from the germ layers). Each germ layer gives rise to specific tissues and organs in the developing embryo. Thus, from the ectoderm is formed the epidermis (skin) and the nervous system (brain, spinal cord); the mesoderm - the middle germ layer (between the ectoderm and the endoderm) - forms the musculoskeletal system (muscles, bones) and the circulatory system (blood, blood vessels); and the endoderm gives rise to organs of the digestive system (stomach, liver, intestines) and the respiratory system (lungs).