BiologyCoachOnlineBlog

Last Week's #MysteryCreature was the Satanic Leaf-tailed Gecko (Uroplatus phantasticus).

First described in 1888, U. phantasticus is the smallest of the Uroplatus geckos. Adults range in length from about 2.5 to 6 inches (66 to 152 mm). Leaf-tailed geckos may have notches in their flattened tails (to mimic decaying leaves). However, this particular trait is seen predominantly in males and many experts have posited that such is a form of sexual dimorphism. Its dry-leaf appearance helps this particular species blend into its surroundings during the day and provides camouflage at night while hunting. Leaf-tailed geckos feeds on insects and the adhesive scales on their fingers and toes enable them to move easily through the trees.

Leaf-tailed geckos are oviparous (laying clutches of two spherical eggs under leaf litter). Endemic to the island of Madagascar, habitat destruction, deforestation, and the pet trade all threaten the leaf-tailed gecko's existence. This species is intolerant of even small environmental changes making the satanic leaf-tailed gecko vulnerable to habitat degradation and harvesting. All Uroplatus species are listed on the World Wide Fund for Nature's Top Ten Most Wanted Species List of animals threatened by illegal wildlife trade.

Last week's #MysteryAnatomy structure was the Common Carotid Artery.

The common carotid arteries supply the head and neck with oxygenated blood. The common carotid arteries are present on the left and right sides of the body. They subsequently divide into the external and internal carotid arteries. [The external branches supply blood to the face and scalp while the internal branches service the left and right sides of the brain.] The average diameters of the common carotids in adult males and females are 6.5 mm and 6.1 mm respectively. The common carotid artery is often used in measuring the pulse in patients who are in shock. [The pulse is taken by palpating the artery just deep to the anterior border of the sternocleidomastoid muscle at the level of the superior border of the thyroid cartilage.]

Carotid stenosis is a narrowing or constriction of the carotid artery. Carotid stenosis is often the result of atherosclerosis.

Atherosclerosis - or "hardening of the arteries" - is caused by an inflammatory response due to the chronic presence of low-density lipoproteins - or LDLs - that carry cholesterol and triglycerides. These LDLs promote an accumulation of white blood cells (WBCs) which, in turn, build-up as plaques on the inner walls of the arteries. The plaques reduce the flexibility of the arteries and, over time, may lead to a restriction in blood flow (which can trigger an increase in blood pressure and eventually - if left untreated - complete blockage of blood flow).

Last week's #MysteryCreature was Wallace's Flying Frog (Rhacophorus nigropalmatus).

A flying frog - sometimes referred to as a "gliding frog" - is a frog that has the ability to achieve gliding flight. That is, it can descend at an angle of less than 45° relative to horizontal. [Non-flying frogs descend vertically and only at angles greater than 45-degrees (which is referred to as parachuting)]. Gliding flight evolved as an adaptation to a life high above the ground in trees. Characteristics of the Rhacophoridae include enlarged hands and feet with full webbing between all fingers and toes, lateral skin flaps on the arms and legs, and reduced body weight. All of these characteristics help make the flying frog more aerodynamic. Alfred Russel Wallace - 19th and early 20th century British naturalist, explorer, and biologist - made one of the earliest observations of flying frogs. The species he observed (from whom Wallace's Flying Frog gets its common name) was later described by George Albert Boulenger as Rhacophorus nigropalmatus.

CYBER-SPECIAL: Get my course "Anatomy of a Pandemic" at 60% off the published price for a limited time. This course examines the progression of the 2014-15 EBOLA Virus Disease outbreak from a local epidemic to a worldwide pandemic. This course is a great primer for nursing or pre-med students, science majors, or anyone interested in learning more about disease, disease transmission, or the Natural World. Also makes a great gift. Receive my CYBER SPECIAL price by enrolling TODAY only @ https://www.udemy.com/anatomy-of-a-pandemic-ebola-disease…/…;

Last week's #MysteryAnatomy structure was Hyaline Cartilage.

Hyaline cartilage is a translucent glassy (hyaline) soft tissue found on many joint surfaces throughout the body. Hyaline cartilage is firm in consistency and it contains a considerable amount of collagen. Hyaline cartilage contains no nerves or blood vessels.

Hyaline cartilage can be found in the larynx, trachea, and bronchi as well as on the articulating surfaces of bones. The collagen fibers of hyaline cartilage make structures and joints strong. However the collagen fibers make those same structures less elastic and movable. Hyaline is the most prevalent form of cartilage in the body. Hyaline cartilage consists of cells (chondrocytes) occurring generally in groups of two in an almost homogeneous matrix. It's simple structure makes hyaline cartilage relatively easy to identify for histology and anatomy students.

"In a bid to stop the killing of elephants for their tusks, world governments voted at a major conservation conference to urge the closure of all domestic ivory markets.

After fierce debate -- including opposition from governments like Namibia and Japan -- the motion was adopted on the final day of the International Union for Conservation of Nature World Conservation Congress, a 10-day meeting that drew 9,000 people to Honolulu, Hawaii this month." Read more @ https://www.yahoo.com/…/world-governments-urge-end-domestic…;

The Mary River turtle is a short-necked, fresh-water turtle that is endemic to the Mary River in south-east Queensland, Australia. It is one of Australia's largest turtles. In fact, specimens with a carapace length of more than 20-inches (50 cm) have been recorded.

Adult Mary River turtles have an elongated carapace that may be plain-colored or intricately patterned. Color can vary from rusty red to brown and almost black. The plastron may be cream to pale pink. Skin coloration is generally similar to the shell and may have salmon- pink blotches on the tail and limbs. These highly endangered turtles may also have blue eyes.

Mary River turtles use bimodal respiration. That is, they are capable of absorbing oxygen through their cloacas (while under water) as well as breathing air at the surface. Unique to Australian turtles is their comparatively long tails (which can measure almost two-thirds of the carapace length). Also unique to to Mary River turtles are the long barbels under their chins. Proportionately, the Mary River turtle has the smallest head and largest hind feet of all the species within the genera. In fact, their large hind feet contribute to this turtles' distinction of being the fastest swimmer. Mary River turtles inhabit well-oxygenated sections of streams in the Mary River basin. Like all acquatic turtles they nest on land. They are omnivorous: they feed on plant matter (e.g. algae) as well as bivalves and other small prey animals.

Finally, Mary River turtles are unique as well as they often are seen sporting vast "gardens" of algae growing on their shells and even their heads. The latter often gives these turtles the appearance of having wild and unkempt green "hairdos."

Cardiac muscle is one of three types of muscles tissues found throughout the body. [The other two are skeletal muscle and smooth muscle.] Cardiac muscle (a.k.a. "heart muscle") composes the thick, middle layer - or myocardium - (between the endocardium and the epicardium) of tissue that forms the walls of the heart. The cells that make up cardiac muscle are called myocardiocytes.

Like all muscle tissue, cardiac muscle contracts. It is the serial contractions of cardiac muscle that forces deoxygenated blood from the right ventricle to the lungs (via the pulmonary circulation) and oxygenated blood from the left ventricle to the other tissues of the body (via the systemic circulation). [By the way, the contraction of heart (i.e. cardiac muscle) registers as the systolic blood pressure while relaxation of the heart registers as the diastolic blood pressure.]

Morphologically, myocardiocytes are very often branched (unlike the cells of smooth and skeletal muscle which are both linear). [Branching is easily seen microscopically and is one of the distinguishing characteristics of cardiac tissue.] Like skeletal muscle, cardiac muscle is striated. Striations are the pattern of light and dark banding representing the alternating segments of thick (myosin) and thin (actin) protein filaments that make up myocardiocytes. Most generally, cardiomyocytes have a single nucleus (while the myocytes of skeletal muscle are multinucleated).

Finally, unique to cardiac muscle are the numerous "intercallated discs" which, again, are clearly visible on the microscopic specimen and are useful when identifying cardiac muscle. Intercallated discs (at arrows below) are structures which connect the ends of cardiomyocytes to one another and which form the cardiac "syncytium." The cardiac syncytium enables the rapid transmission of electrical impulses through the cardiac network yielding a coordinated contraction of the heart.

Last week's ‪#‎MysteryCreature‬ was the Naked Mole-rat (Heterocephalus glaber).

The Naked Mole-rat, also known as the sand puppy, is a burrowing mammal native to parts of East Africa. It is the only species classified in the genus Heterocephalus. The naked mole-rat averages between about three- and four-inches (8-10 cm) in length. They may weigh up to just over an ounce (35-grams). The naked mole-rat is the first mammal discovered to exhibit eusociality (similar to that found in ants, termites, bees, and wasps. A naked mole-rat colony consists of a single female (the queen) and one to three breeding males. The remaining members of the colony are (sterile) workers. Worker members gather food, maintain tunnels, and protect the colony. Workers also care for the pups by keeping them from straying, grooming them, and keeping them warm. Naked mole-rats feed primarily on large tubers that they find through their mining operations. They eat the inside of the tuber while allowing the outside to regenerate. This practice provides the colony with a long-term source of food.

The naked mole-rat is quite well-adapted to life in its underground labyrinthe. Its lungs are very small and its blood has a very strong affinity for oxygen (thereby increasing the efficiency of oxygen uptake). It has a very low respiration and metabolic rate for an animal of its size as well. In fact, the naked mole-rat can reduce its metabolic rate by as much as 25-percent (in response to longer periods sans food).

Unlike a typical mammal (which is a thermoregulator), naked mole-rats are thermoconformers. That is, they adjust their body temperatures according to local ambient temperatures. In other words, as local ambient temperature decreases, the naked mole-rat's effective body temperature likewise decreases. As local ambient temperature rises, the animal's effective body temperature concurrently rises.

The skin of the naked mole-rat lacks the neurotransmitter (i.e. Substance-P) that is responsible for sending pain signals to the brain. As a result, naked mole-rats feel no pain (even when exposed to acid). [It has been posited that this is an adaptation to living in their poorly-ventilated, underground lairs (where high levels of carbon dioxide would cause acid to build up in their body tissues).]

Finally, the naked mole-rat can live up to 30-years (an extraordinarily long lifespan for a rodent of its size). Their unusual longevity is thought to be related to their ability to reduce their metabolism thereby preventing age-inducing damage from oxidative stress.

L

Last week's ‪#‎MysteryAnatomy‬ structure was the pancreas.

The pancreas is a glandular organ that is located in the abdominal cavity and just posterior to the stomach. The pancreas, which is about six-inches (15-cm) long, is an organ with dual functions. That is, it functions as both an endocrine and a digestive organ. As an organ of the endocrine system, the pancreas makes and secretes the hormones glucagon and insulin via its pancreatic islets (i.e. Islets of Langerhans). Insulin is secreted into the circulating blood as blood glucose levels rise (as happens after eating a meal). Conversely, glucagon is secreted into the bloodstream when blood glucose levels drop (as happens during sleep or fasting).

As an organ of the digestive system, the pancreas makes and excretes "pancreatic juice." Pancreatic juice is a solution of digestive enzymes excreted into the duodenum (of the small intestine) via the pancreatic duct. The digestive enzymes include proteases, lipases, and amylases which assist in the chemical digestion of proteins, fats, and starches (respectively). [These digestive enzymes are produced in clusters of cells called ascini.]

Inflammation of the pancreas, known as pancreatitis, is most often associated with recurrent gallstones or chronic alcohol. Pancreatic cancer (which usually does not occur in those younger than 40) can result from excessive smoking, obesity, diabetes, and some genetic conditions. The most common condition associated with the pancreas is diabetes. Diabetes mellitus type-1 is a chronic autoimmune disorder in which the immune system attacks the pancreatic islets. As a result, insulin cannot be synthesized. Treatment for severe Type-1 diabetes includes insulin injections. Diabetes mellitus type-2 is the most common form of diabetes. Insulin resistance and impaired insulin secretion lead to chronic high levels of blood glucose in Type-2 diabetes. Maintenance of Type-2 diabetes includes changes in diet and physical activity levels. These are usually enough to reduce blood sugar levels and increase insulin sensitivity.