The largest cell in the human body is the egg cell, while the smallest is the sperm cell. Find out their dimensions and what makes up their structure.
Road traffic crashes can be fatal leading to death or disabilities among people. Did you know that each year, 1.2 million people die and more people are injured or disabled as a result of road traffic crashes? According to WHO, road crashes are the leading cause of death among young people between ages 15-29 years, killing 1000 people under the age of 25 every day.
Different road users can be involved in a road crash. They include driver, passengers, pedestrians, cyclist, motorcyclists and users of public transportation. Drivers and passengers of four-wheeled vehicles are mostly killed in road traffic crash in developed countries while in developing (middle-income or low-income) countries, vulnerable-road users such as pedestrians, cyclists, motorcyclists and users of public transportation constitute those injured or killed on the road.
The risks are elevated among young road users including among pedestrians, and drivers and passengers of both cars and motorcycles. The factors influencing:
- Use of mobile phones
- Use of excessive speed
- Inexperience among young drivers
- Risky behavior among young drivers
- Peer influence
- Lack of wearing seat belt or helmet
Road traffic crashes are preventable if certain preventive strategies are set and enforced. These strategies could include:
- Setting and enforcing speed limits
- Traffic calming measures such as speed humps, mini-roundabouts, and designated pedestrian crossings
- Proper road lighting
- Restricting drunk-driving
- Restricting young or inexperienced drivers
- Setting helmet and seat belt laws
- Restricting the use of mobile phone while driving.
The colour of the teeth is of great cosmetic importance to most people. Some people with darker-coloured teeth shades may have low self-esteem and lack the confidence to smile broadly or make conversations in public. Naturally, the enamel itself is a bluish-white colour, but it is also somewhat translucent so that the yellowish shade of the dentine beneath it reflects through, making the colour of the teeth generally appear somewhat light grey or light yellow.
Many things can cause tooth discolouration. The change of colour can affect multiple teeth or a single tooth. It may be as a result of a change in the structural composition of the dental tissues (enamel, dentine or pulp), extrinsic stains on the tooth surface or incorporation of extrinsic stain on the tooth tissue during dental development.
Stains from tobacco, food, drinks or mouth rinses are examples of extrinsic stains that could cause tooth discolouration. Pigments from dark-coloured drinks like coffee, red wine, soda and juice or food are called chromogens. These are compounds with strong pigments that cling to enamel can cause stains on the teeth. Tannins, a plant-based compound and acid in drinks make it easier for stains to adhere to teeth.
So how can you reduce food stains on your teeth?
- Brush your teeth
- Rinse your mouth after meals
- Use a straw
- See your dentist for your routine cleaning.
The lip is a soft movable anatomical structure that surrounds the mouth or oral cavity. The lip helps in the pronunciation of some words and plays a role in facial expression as well as sensory information about food before its placement in the oral cavity.
The upper lip extends from the base of the nose superiorly, the nasolabial folds laterally and the vermillion border inferiorly while the lower lip extends from the vermillion border superiorly, corner of the mouth (commissures) laterally and mandible inferiorly. The edge of the lips - vermilion border, is the transitory layer between the outer skin layer of the lip and the inner mucosa layer (labial mucosa).
The lip comprises of skin, mucosa, and muscle. The skin of the lip is classified as stratified squamous epithelium. This is actually similar to the skin of the body, however, it is made up of 3-5 cellular layers, making it thin compared to the skin of the face or the rest of the body. The thinness of the skin makes the blood in the capillaries found in the mucous membrane reflect, and as such, is responsible for the pinkish or reddish colour of the lips.
The human skin is the external covering of the human body. It provides protection and receives sensory stimuli from the environment. The human skin is the largest organ in the human body.
The skin consists of:
- Epidermis: Outmost protective layer.
- Dermis: The Fibrous layer that supports and strengthen the epidermis.
- Subcutis: Subcutaneous layer beneath the dermis. It helps supply nutrients to the skin and also insulates and cushions the skin.
The skin has specialized structures including, hair follicles, fingernails, toenails, sebaceous glands, sweat glands, apocrine glands, and mammary glands. The skin is a dynamic organ that undergoes continuous changes throughout life. The outer layer is shed and replaced by the inner layer.
The skin varies in thickness depending on the anatomic location (what part of the body), sex, and age of the individual. This varying thickness is as a result of the difference in dermal thickness, as epidermal thickness is constant throughout life and from one anatomic location to another. The skin is thickest on the soles of the feet, measuring about 1.5 mm in thickness, while the thinnest skin is found on the eyelids measuring about 0.05 mm in thick.
Loud noise from earbuds and headphones increases the risk of permanent hearing loss called Noise induced hearing-loss. According to the World Health Organization, 1.1 billion teenagers and young adults are at risk of developing hearing loss due to unsafe use of headphones.
The intensity of sound is measured in decibels (dB). It is the measurement of the degree of how loud a particular source of sound is. Humans can hear sounds from 0 dB to about 180 dB. Headphones can reach up to 105 dB when listened to at the maximum volume. When sound is too loud, the cells (hair cells) in the inner ear that help transmit sound to electrical signals for the brain to interpret are damaged, leading to hearing loss.
Headphones are safer to use when compared with earphones and earbuds. This is because it preserves the ability to hear, as it is farther away from the ear canal, unlike earbuds/plugs that fit into the ears. Even though headphones are safer, they can still cause hearing loss.
When choosing a headphone, selecting a good quality one is very important. Counterfeit headphones may have a bass output, thus, may make you increase the volume really loud and in turn, damaging your hearing.
The skull is a bony structure that provides support and protection for the brain, nerves, and blood vessels. Instead of being a single large bone as commonly assumed, it is made up of many individual bones that come together to fuse at sutures (fibrous joints). These joints remain "open" during childhood, allowing the brain to grow and expand.
The bones of the skull are made up of two parts: the cranium bones and the facial bones. The cranium is formed by the top portion of the skull, and it encloses and protects the brain and various support structures within, such as the meninges and blood vessels and nerves.
The cranium can be subdivided into a roof or a base which is the bottom portion of the skull. The bones of the base of the skull are the frontal, sphenoid, ethmoid, occipital, parietal and temporal bones, while the facial bones are the zygomatic, lacrimal, nasal, inferior nasal conchae bones, palatine, maxillary, vomer, and mandibular bones.
Snoring is a common problem among all age groups and cuts across both genders. It is one of the symptoms of a group of disorders known as Sleep Disordered Breathing. As people grow older, their chances of snoring increases. About 45% of normal adults snore occasionally.
During sleep, the throat muscles relax and the tongue tends to fall back toward the throat, causing the throat to become narrow. As breathing occurs, the walls of the throat vibrate which then causes the sound which is heard as a snore.
Snoring can be as a result of factors such as sleeping position, obesity, aging, alcohol, nasal congestion, enlarged tonsils, deviated nasal septum, inflammation of the nose and throat and obstructive apnea.
Treatment options for snoring include lifestyle modification, sleeping position adjustment, surgery and mechanical devices such as splints, brace, nasal strip.
The female condom is one of the various methods of contraception. When used correctly, it helps to protect against pregnancy and sexually transmitted infections (STIs). The female condom is a plastic tube made out of polyurethane that lines the vagina with flexible rings at each end to keep it in place inside the vagina. It can be inserted into the vagina up to eight hours before sex.
According to the Centers for Disease control and prevention, these are the step to insert and remove a female condom:
- Carefully open and remove the female condom from package to prevent tearing.
- The thick inner ring with the closed end is used for placing in the vagina and holds the condom in place. The thin, outer ring remains outside of the body, covering vaginal opening.
- Find a comfortable position, while holding outside of the condom at the closed end, squeeze sides of the inner ring together with your thumb and forefinger and insert into the vagina. It is similar to inserting a tampon.
- Using your finger, push inner ring as far up as it will go until it rests against the cervix. The condom will expand naturally and you may not feel it.
- Using your finger, push inner ring as far up as it will go until it rests against the cervix. The condom will expand naturally and you may not feel it.
- Guide partner’s penis into the opening of the female condom. Stop intercourse if you feel penis slip between condom and walls of the vagina or if outer ring is pushed into the vagina.
- To remove, gently twist outer ring and pull the female condom out of the vagina.
- Throw away female condom in the trash after using it one time. Do not reuse.
The use of female condoms has no medical side effect, does not require advance preparation, is a way to prevent an exchange of vaginal and seminal fluid, as well as prevent sperm from entering the vagina.
It can become less effective either if the penis enters the vagina outside instead of into the female condom, if there is sexual contact before insertion of the condom, or if there is a tear or damage on the condom before insertion.
Blood donation is a safe procedure and a pint of blood can save up to 3 lives! The entire process of donating blood takes about 45 minutes to 1 hour. A donor can donate whole blood or some specific components of blood such as plasma, platelets and cryoprecipitate. Donors must be at least 17 years of age, must weigh at least 110 pounds and must be in good health.
After whole blood donation, one must wait for at least eight weeks before attempting to donate again. Going by this rule, it is safe to donate a pint of blood every 3 to 4 months.
When you give blood, you lose red blood cells (RBCs) and the body would need to make more to replace the lost cells. Peritubular cells of the kidney sense when the level of oxygen in the blood has decreased due to the decreased number of red blood cells. On detecting this, they start secreting a protein called erythropoietin. This passes through the bloodstream until it reaches the stem cells in the bone marrow, which then develop more RBCs. This is how the body replenishes blood.
It is very important to wait for the body to replenish lost blood. Haemoglobin in RBCs contains iron, and some are lost with each blood donation. To compensate for this loss, iron is mobilised from the body's iron stores and the body also increases the amount of iron it absorbs from food and drinks. Men normally have more iron stores than women. Any iron deficiency can result in reduced haemoglobin levels, and if not treated, will eventually result in iron deficiency anaemia. This deficiency can make you feel tired, and this is the reason why it is recommended that male donors wait at least 12 weeks and female donors wait at least 16 weeks in between whole blood donations.
The human eye is a delicate sense organ responsible for the visual images we receive. It is enclosed in a bony socket in the skull. The eyes have different anatomical structures with its different functions to produce images or to protect the eyes.
The human eyes have muscles which are responsible for eye movements. They are known as the extraocular muscles or external muscles of the eye. They are considered to be the fastest muscles in the body because they can contract in less than 1/100th of a second. This is also the reason why a blink can be as fast as 100-150 milliseconds.
There are six extraocular muscles. These are the four rectus muscles- inferior, superior medial and lateral and two oblique muscles – superior and inferior.
The superior and inferior rectus muscles are the vertical rectus muscles. Their primary action is to carry out vertical movement. The superior rectus acts as the primary elevator, and the inferior rectus acts as the primary depressor of the eye. Medial and lateral rectus muscles are the horizontal rectus muscles due to their horizontal actions. The medial rectus muscle is the primary adductor of the eye, and the lateral rectus muscle is the primary abductor of the eye. The oblique muscles are responsible for the torsion movement of the eye.
The nails present on the fingers and toes actually grow or emerge from the dermis (deep layer) of the skin. It is a plate-like, keratinous, translucent structure that consists of highly specialized epithelial cells.
Nail growth starts at the base of the nail. This is where the specialized cells that make up the nail’s plate are produced. These cells are merely pushed upwards as new cells form behind them. The nail plate (the visible part on the finger) is also attached to the underlying, richly vascularized nail bed which supplies the plate with necessary nutrients.
A study was conducted to determine the growth rate of human finger nails and toenail. Results showed that the fingernails grow faster than the toenails. The fastest growing nail is the one on the middle finger, while the slowest growing finger nail is the thumbnail. The rate of growth of the fingernails is related to the length of the terminal phalanges.
Maintaining good oral hygiene is important in preventing oral problems such as gum diseases, tooth decay, as well as bad breath. Brushing your teeth is an important habit necessary to maintain good oral health and hygiene.
For healthy teeth and gums, it is recommended to;
- Brush at least twice a day with fluoride containing toothpaste for at least two minutes, especially first thing in the morning and before bedtime.
- Floss at least once every day
- Limit the number of times you eat snacks each day
- Visit your dentist every six months for an oral examination and professional cleaning.
Most people brush their teeth without considering or paying attention to how long they spend brushing. Brushing does not have to be too long, neither should it be too short. So how long exactly should one spend brushing?
Many dentists agree that proper tooth brushing takes at least 2 minutes as this gives enough time to cover all the surfaces of the teeth. If you don't brush your teeth long enough, you may not be getting your teeth clean well enough, therefore, some bacteria may be left behind on the teeth after brushing. This can eventually lead to gum problems.
Spending some amount of time brushing is not bad, but applying too much pressure when brushing is harmful and can cause abrasion or wearing off of the enamel and the gum tissue, which could eventually lead to tooth sensitivity.
Doctors are unevenly distributed across the globe. It has been shown that countries with the greatest burden of disease must make do with a much more smaller health workforce
According to WHO, Cuba has a good “doctor to person” ratio which is up to 1 doctor per 150 persons, compared to the US with 1 doctor to 390 persons or Liberia with 1 doctor to 71,429 persons. This is possible because Cuba has got the world’s renowned health care. It is the only country that has a health care system closely linked to research and development.”
Other countries with good "doctor to person" ratio are mostly in Europe such as Monaco, San Marino, Greece, Austria, Georgia, Portugal, and Norway.
A healthy person's fart is basically made up of hydrogen, nitrogen, carbon dioxide and a small amount of methane and oxygen. Two of these gases are inflammable, and they are methane and hydrogen.
Farts are made from swallowing air while eating and also from the gasses produced during digestion of food.
Methane is not common in most people’s flatus as only about a third of humans have significantly measurable amounts in their farts, hence, not all farts are inflammable. However, where sufficient amounts of methane and hydrogen are present, it is possible to light the fart on fire.
Scientists have identified a few factors that can predict if a person will produce methane. Of these, one of the most important factors is where you live (environmental factor). The role of genetics, if there be any, have not been explored.
From their research, 77% of Nigerians and 87% of South Africans produce methane. 34% of Norwegians and 35% of those who live in and around Minneapolis also produce methane. Female adults are more likely to produce measurable amounts of methane in their farts while young children are less likely to.
Over the years, different techniques have been used to reduce sensation during surgery.
Sleep-inducing and awareness-dulling agents, as well as narcotics, were prepared from different plants including marijuana, belladonna, and jimsonweed. Attempts were even made to use mesmerism or hypnosis to induce anesthesia.
Another way of inducing a state of insensitivity was to render the patient unconscious with a blow to the jaw. However, by 1846, Opium and alcohol seemed to be the only agents which continued to be considered practically effective in dulling or reducing the pain during operations.
Large doses of alcohol were needed to produce stupefaction and they were also likely to cause nausea, vomiting, and in some cases death, instead of just sleep. Opium (a strong analgesic) had significant side effects and was still not powerful enough to completely blunt a surgical stimulus.
The Hey’s saw (used to make an aperture in the skull to relieve pressure on the brain) was an essential item in most surgical kits for years before the introduction of effective anesthesia.
The morning penile erection medically known as Nocturnal Penile Tumescence (NPT) is an interesting physiological phenomenon that tells us about a man’s sexual function.
They are basically spontaneous erections that occur during sleep or while waking up and it usually happens around three to five times during sleep. Men who do not experience it may most likely have an erectile dysfunction.
Consistent erections while asleep indicate a healthy blood flow to the penis, therefore, if a man has regular NPT but has sexual difficulties i.e erectile dysfunction, the difficulty is most likely due to a psychological cause.
NPT occurs during Rapid Eye Movement (REM) sleep and because we often wake up from this phase, men may still have their erections when they wake up.
It is important to maintain a healthy lifestyle to avoid and even reverse erectile dysfunction. This can be achieved this by eating healthy food, maintaining a healthy weight, exercising consistently and also avoiding smoking and alcohol.
Foul-smelling breath medically known as "halitosis" is usually caused by the breakdown of food residue in the mouth. Aside from this, there are other things that could lead to bad breath and they include the following:
- Poor dental hygiene
- Dental caries and periodontal gum disease
- Dry mouth (Xerostomia)
- Some medical conditions e.g. diabetes
- Some kinds of volatile foods e.g garlic, beans, onions etc.
- Use of tobacco
- Some medications
- Severe dieting
It may be tricky knowing if your breath smells bad because most of the time, you cannot identify it by yourself.
The easiest way to know if you have bad breath may be to ask a close family member or friends.
Another way to determine this is to lick the inner side of your wrist, wait for about 10 seconds for it to dry and then give it a sniff, that is, smell it.
Bad breath can be embarrasing but it is not impossible to fix. Because the most common cause of halitosis is poor oral hygiene, maintaining a good oral hygiene would eliminate this problem. Be sure to visit a dentist for regular dental checks and prophylactic cleaning (scaling and polishing).
Furthermore, if you feel that the condition is persistent, you may want to speak to your dentist to rule out other possible causes or medical conditions. In the event that an underlying condition exists, proper management and control of the condition is necessary.