Human Body Facts

The average human brain has about 100 billion nerve cells.
Nerve impulses to and from the brain travel as fast as 170 miles (274 km) per hour.
The thyroid cartilage is more commonly known as the adams apple.
The only jointless bone in your body is the hyoid bone in your throat
It's impossible to sneeze with your eyes open.
Your stomach needs to produce a new layer of mucus every two weeks or it would digest itself.
It takes the interaction of 72 different muscles to produce human speech.
The average life of a taste bud is 10 days.
The average cough comes out of your mouth at 60 miles (96.5 km) per hour.
Relative to size, the strongest muscle in the body is the tongue.
Human thigh bones are stronger than concrete.
When you sneeze, all your bodily functions stop even your heart.
Babies are born without knee caps. They don't appear until the child reaches 2-6 years of age.
Children grow faster in the springtime.
It takes the stomach an hour to break down cow milk.
Women blink nearly twice as much as men.
Blondes have more hair than dark-haired people do.
There are 10 human body parts that are only 3 letters long (eye hip arm leg ear toe jaw rib lip gum).
If you go blind in one eye you only lose about one fifth of your vision but all your sense of depth.
The average human head weighs about 8 pounds.
Our eyes are always the same size from birth, but our nose and ears never stop growing.
In the average lifetime, a person will walk the equivalent of 5 times around the equator.
An average human scalp has 100,000 hairs.
The length of the finger dictates how fast the fingernail grows. Therefore, the nail on your middle finger grows the fastest, and on average, your toenails grow twice as slow as your fingernails.
The average human blinks their eyes 6,205,000 times each year.
The entire length of all the eyelashes shed by a human in their life is over 98 feet (30 m).
Your skull is made up of 29 different bones.
Your ears and nose continue to grow throughout your entire life.
After you die, your body starts to dry out creating the illusion that your hair and nails are still growing after death.
Hair is made from the same substance as fingernails.
The average surface of the human intestine is 656 square feet (200 m).
A healthy adult can draw in about 200 to 300 cubic inches (3.3 to 4.9 liters) of air at a single breath, but at rest only about 5% of this volume is used.
The surface of the human skin is 6.5 square feet (2m). 15 million blood cells are destroyed in the human body every second.
The pancreas produces Insulin.
The most sensitive cluster of nerves is at the base of the spine.
The human body is comprised of 80% water.
The average human will shed 40 pounds of skin in a lifetime.
Every year about 98% of the atoms in your body are replaced.
The human heart creates enough pressure to squirt blood 30 feet (9 m).
You were born with 300 bones. When you get to be an adult, you have 206.
Human thighbones are stronger than concrete.
Every human spent about half an hour as a single cell.
There are 45 miles (72 km) of nerves in the skin of a human being.
The average human heart will beat 3,000 million times in its lifetime and pump 48 million gallons of blood.
Each square inch (2.5 cm) of human skin consists of 20 feet (6 m) of blood vessels.
During a 24-hour period, the average human will breathe 23,040 times.
Human blood travels 60,000 miles (96,540 km) per day on its journey through the body.

Regular Health Mistakes

All of us make little health mistakes that cause damage to our bodies in the long run - simply because we are unaware we are doing something wrong. Here are some of the most common mistakes made by many of us.

Crossing our legs

Do you cross your legs at your knees when sitting? Although we may believe that this is the lady-like elegant way to sit, sitting this way cuts down circulation to your legs. If you don"t want varicose veins to mar the beauty of your legs and compromise your health, uncross your legs every time you realise you have one knee on top of the other. The best way to sit is to simply place both legs together on the floor, balancing your weight equally. If you feel like changing position, instead of crossing your legs, simply move both legs together to one side. As an alternative, you could also consider crossing your legs loosely at the ankles. This is a classically elegant way to sit, and is far better for your legs and your health than sitting with your legs crossed at your knees.

Not changing our toothbrush

How often do you change your toothbrush? Most of us wait until most of the bristles have either fallen off, or are in such bad shape that we"d be embarrassed to pull out our brush in public. However, since not many of us need to pull out our brush in public, we carry on with our frayed one until we lose it. Replace your toothbrush often. Damaged bristles can harm the enamel, and don"t massage your gums well. If you find brushing your teeth a pain like I do, but know you must do it, you might as well be doing it right. Imagine going through the annoyance of brushing your teeth twice a day only to find out that you"re damaging your enamel every time you clean your teeth. Also, use a brush with soft bristles unless your dentist has advised otherwise.

Eating out often

There are oils that are high in cholesterol, and oils that cause little harm and are better for your heart. However, no matter how light the oil is, it is never a good idea to eat too much of it. Avoid fried foods.Remember that in all probability your favourite Indian food restaurant throws a huge, HUGE chunk of butter in a tiny bowl of dal. Rita, who worked in the kitchen of a 5 star hotel, was shocked when she saw the cook chop a 500gm butter slab in half, and throw half into a Paneer Makhani dish. No wonder the customers left licking their fingers. And no wonder they felt so stuffed and heavy afterwards. Limit outdoor eating unless you know that you"re getting served light and healthy food.

Skipping breakfast

Never, ever skip breakfast. Remember, when you wake up in the morning it"s been around 10-12 hours since your last meal. Your body needs food now, more than at any other time. Eat a heavy breakfast. You will then be busy through the day, and the calories will get expended quickly. If you are trying to diet, eat a light dinner. Here are some more common health mistakes we make. Being informed and making a few changes can help make us feel a whole lot better.


High heels

High heels sure look great, but they're murder for your back. This however doesn't mean you should steer clear of stilettos. Wear them, but not when you know you will be walking around a lot. Wear them when going out for lunch or dinner - when the only walking you will be doing is to your car, to the table, and back. Avoid high heels when you are going somewhere on foot. If you are constantly tempted to wear your heels, take a good look at your flats. Is there something about them you dislike? Invest in a new pair of beautiful flats or shoes with a low heel. Buy something you love, that you will enjoy wearing. If possible, get a matching bag. You will then enjoy your flats as much as you do your heels.


Sleeping on a soft bed

You don't have to sleep on the floor be kind to your back, but do make sure you have a firm mattress. Although a mattress on springs is soft and lovely to sink into, it's bad for your back. If you already have an old bed with springs, you don't need to invest in a new one - simply get a thick wooden plank put over the springs, and place the mattress on the plank. Similarly, if your mattress is old and lumpy, throw it out and get a new one. Your neck and your back will thank you. The same rule applies to sofas. If you will be spending hours on a sofa, get a firm yet comfortable one. Sofas you completely sink into are not the best idea.

Pillows

No matter how comfortable sleeping with ten cushions is, have pity on your neck and resist. Sleep with one pillow, and make sure it is not too thick. If your pillow gets lumpy, discard it and go for a new one. Get a thin pillow if you sleep on your stomach, and something a little thicker if you sleep on your back, to give your neck adequate support


Not exercising

So all of us know we should exercise more, but many of us don't. This is a health mistake we consciously make! And why is that? Simply because we refuse to admit the damage we are causing to our bodies by not working out. A number of people only start working out once they've experienced a warning signal. Don't wait for a heart attack to strike before you decide to opt for a lifestyle change. Make the change now. You don't need to train for the marathon to be in top shape. Half an hour of brisk walking three to four times a week will make a world of difference to your health. You could then increase this to forty minutes, four times a week - and you're all set. If you haven't exercised for a week, you're making a mistake.

Finger nails to predict health

Examining the Fingernails When Evaluating Presenting Symptoms in Elderly Patients
Introduction
Human fingernails, located on the dorsal aspect of the terminal 40% of the distal phalanx of each finger, are complex structures involving 3 different layers:

The nail plate (the nail). This is the keratinized structure, which grows throughout life;
The nail bed (ventral matrix, sterile matrix). This is the vascular bed that is responsible for nail growth and support. It lies protected between the lunula (the "half moon" seen through the nail) and the hyponychium (the posterior part of the nail bed epithelium); and
The eponychium (cuticle). The epidermal layer between the proximal nail fold and the dorsal aspect of the nail plate.

The primary purpose of the nail is protection. Abnormalities of the nail are often caused by skin disease and infection (most often fungal) but may also indicate more general medical conditions. This discussion does not address localized trauma or nail infections but offers examples of nail abnormalities that may occur with systemic disease.

Check to see whether the nails are normal by looking at the following (Figure 1):

Softness and flexibility of free edge;
Shape and color;
Quality of paronychial tissue; and
Growth rate (about 6 months from cuticle to free edge). Time of events can be estimated from location.




Figure 1. The normal nail.

Examining the Nails
Elderly people carry the last 6 months of their medical record on the approximately 10 square centimeters of keratin comprising the fingernails. Examining the fingernails can help the clinician detect a number of general and specific factors, including the following:

Overall vitality;
Inner emotional state;
Cerebral dominance;
Occupations and hobbies;
Medical history;
Nutritional status;
Cardiovascular function;
Rheumatic conditions; and
Dermatologic problems.

The patient's manicure can reveal state of health, nutritional status, past events, personality, occupation, and one's inner state. Systemic illness should show the nail changes in each of the nails on one hand. The thumb may reveal more extensive changes given its increased size.

It is useful to follow the following sequence when examining the nails:

Check the nail shape;
Examine the nail color;
Survey processes around the nails;
Compare hands; and
Note skin conditions.

It is critical to examine the nails in adequate light. Gently rotate the nail in the light so that the reflection highlights all aspects of the nail. Notice the lunula, the pale crescent moonlike coloration at the base of the nail. Leukonychia stria and a pointed tent-like lunula suggest an excessive manicure and pushing on the cuticle. Paronychias suggest stress and poor attention to hygiene. This can reflect depression, dementia, or psychiatric illness.

Nail Growth

Nail growth is continuous. It takes about 6 months for a fingernail in an elderly person to completely grow out. Cold temperature can slow growth rates but not to any clinically significant degree (pun intended). The middle finger nail grows the fastest, followed by the forefinger and ring finger. Aging slows the growth rate from approximately 3 months in childhood to 6 months in 70-year-olds. Nails in elderly people are also thicker than in younger people. Thin nails in a postmenopausal woman raise the possibility of metabolic bone disease. The nails of the dominant hand grow slightly more quickly than the nondominant nails, probably because minor trauma accelerates nail growth. Conversely, immobility slows the growth rate of fingernails. Understanding the growth rate is important because the time interval from a critical event can be estimated from the location of a nail lesion. For example, a white line appearing transversely halfway up the nail suggests an acute illness 3 months earlier. Regular observation will demonstrate its progression to the end of the nail edge.

Nail Polish

Distance from base and line of polish gives approximate date of application (nails grow 0.1 mm/day). Picking at polish reflects nervousness and agitation. Toenail polish suggests unusual flexibility or a friendly helper.

Observing the Nail Shape and Surface

Clubbed Fingernails

Clubbing involves a softening of the nail bed with the loss of normal Lovibond angle between the nail bed and the fold, an increase in the nail fold convexity, and a thickening of the end of the finger so it resembles a drumstick.
To determine whether nails are clubbed, have the patient place both forefinger nails together and look between them. If you can see a small diamond space between them (Schamroth's window) then the nails are not clubbed (Schamroth's sign) (Figure 2).


Figure 2. Schamroth's sign.

Causes of clubbing (not exhaustive) include the following (Figure 3):
Pulmonary and cardiovascular causes (80%)
Lung cancer, pulmonic abscess, interstitial pulmonary fibrosis, sarcoidosis, beryllium poisoning, pulmonary arteriovenous fistula, subacute bacterial endocarditis, infected arterial grafts, aortic aneurysm

Gastrointestinal causes (about 5%)
Inflammatory bowel disease, sprue, neoplasms (esophagus, liver, bowel)
Hyperthyroidism (about 1%)
Note: Chronic obstructive pulmonary disease does not cause clubbing.




Figure 3. Example of clubbed fingernails.
Koilonychia
Koilonychia are spoon-shaped concave nails (Figures 4A, 4B). This occurs normally in children and usually resolves with aging. To determine whether a nail is spooned, perform the water drop test. Place a drop of water on the nail. If the drop does not slide off, then the nail is flattened from early spooning. An experienced clinician can look at the nail and perform a "mental" water drop test. Causes include the following:

Iron deficiency;
Diabetes mellitus;
Protein deficiency, especially in sulfur-containing amino acids (cysteine or methionine);
Exposure to petroleum-based solvSystemic lupu
Raynaud's disease.


Figure 4A. Spooned nail.


Figure 4B. Spooned nail.
In 1846, Joseph Honoré Simon Beau described transverse lines in the substance of the nail as signs of previous acute illness.. The lines look as if a little furrow had been plowed across the nail. Illnesses producing Beau's lines include the following:

Severe infection;
Myocardial infarction;
Hypotension, shock;
Hypocalcemia; and
Surgery.

Intermittent doses of immunosuppressive therapy or chemotherapy can also produce Beau's lines. Severe zinc deficiency has also been proposed as a cause of Beau's lines. By noting its location on the nail, the approximate date of the illness associated with it can be determined (Figures 5A, 5B). Moreover, the depth of the line provides a clue to the severity of the illness.




Figure 5A. The location of Beau's lines half way up the nail suggests illness 3 months ago.



Figure 5B. Two Beau's lines suggest illnesses about 2 months apart.

Thin Brittle Nails
Thin, brittle nails can indicate the following (Figure 6):

Metabolic bone disease (nail thinness is correlated with osteopenia);
Thyroid disorder;
Systemic amyloidosis (indicated by yellow waxy flaking); and
Severe malnutrition.



Figure 6. Note the thin nails in this woman with severe osteopenia.

Onychorrhexis is the presence of longitudinal striations or ridges (Figure 7). It can simply be a sign of advanced age but it can also occur with the following:

Rheumatoid arthritis;
Peripheral vascular disease;
Lichen planus; and
Darier's disease (striations are red/white).

Central ridges can be caused by:

Iron deficiency;
Folic acid deficiency; and
Protein deficiency.



Figure 7. Example of a central nail ridge.

Central Nail Canal (Median Nail Dystrophy)

When a central nail canal is present, the cuticle is usually normal (Figure 8A). Central nail canal is associated with:

Severe arterial disease ("Heller's fir tree deformity" -- a central canal with a fir tree appearance -- may occur with peripheral artery disease (Figure 8B);
Severe malnutrition; and
Repetitive trauma.




Figure 8A. Example of central nail canal.



Figure 8B. Central nail canal with Heller's fir tree deformity.

Nail Pitting

Nail pitting -- small punctate depressions -- are caused by nail matrix inflammation, which can be the result of:

Psoriasis (random appearance of pits) (Figure 9);
Alopecia areata (geometric rippled grid) (Figure 10);
Eczema; and
Lichen planus.



Figure 9. Indication of psoriasis.



Figure 10. Indication of alopecia areata.

Nail Beading
With nail beading, the beads seem to drip down the nail like wax (Figure 11). It is associated with endocrine conditions, including the following:

Diabetes mellitus;
Thyroid disorders;
Addison's disease; and
Vitamin B deficiency.



Figure 11. Nail beading.

Rough Nail Surface

When nails look sandpapered and dull, consider (Figure 12):

Autoimmune disease;
Psoriasis;
Chemical exposure; and
Lichen planus.



Figure 12. Example of a rough nail surface.


Nail Thickening


Slow nail growth produces thickness (Figure 13). In such cases, the following should be considered:

Onychomycosis;
Chronic eczema;
Peripheral vascular disease;
Yellow nail syndrome; and
Psoriasis.





Figure 13. Example of a nail thickening.

Onycholysis

Onycholysis is distal separation of the nail plate from the underlying nail bed (Figure 14). It is associated with the following:


Thyrotoxicosis;
Psoriasis;
Trauma;
Contact dermatitis;
Tetracycline;
Eczema;
Toxic exposures (solvents);
Blistering from autoimmune disease; and
Porphyria cutanea tarda (onycholysis and skin blistering from sun exposure).




Figure 14. Traumatic onycholysis (involving only 1 nail).

Severe Nail Curvature (Beaked Nails)

Curved or beaked nails are caused by resorption of distal digit (Figure 15). Consider the following:

Hyperparathyroidism
Renal failure
Psoriasis
Systemic sclerosis




Figure 15. Example of severe nail curvature.

Complete Nail Destruction

Complete local nail destruction can be caused by local mechanisms, including trauma and paronychia. Generalized conditions that might cause complete nail destruction include the following:

Toxic epidermal necrolysis;
Chemotherapy;
Bullous diseases; and
Vasculitis.



Observing Nail Color Abnormalities of the Lunula

If the lunula is absent, consider anemia or malnutrition (Figure 16). A pyramidal lunula might indicate excessive manicure or trauma (Figure 17). A pale blue lunula suggests diabetes mellitus. If the lunula has red discoloration, consider the following causes among others (Figure 18):

Cardiovascular disease;
Collagen vascular disease; and
Hematologic malignancy.



Figure 16. Absent lunula.




Figure 17. Pyramidal lunula.





Figure 18. Lunula with red discoloration.


Transverse White Lines (Mee's lines)


Any acute illness can produce transverse milky white lines. In addition, they might be caused by heavy metal toxicity (classically arsenic) or chemotherapy. The time of event may be determined from the location of the lines on nail (Figure 19).






Figure 19. Note the Mee's line approximately one third of the way up the nail, suggesting a significant illness 2 months previously.


Leukonychia Striae


Leukonychia striae are white splotches caused by minor trauma to the nail matrix (Figure 20). The timing can be determined by the location of the splotches on the nail.






Figure 20. Example of leukonychia striae. Note location of white splotches, which can indicate timing of the traumatic event.


Longitudinal Brown Lines


Longitudinal brown lines form because of increased melanin produced by nail matrix melanocytes (Figure 21). They are associated with:


Addison's disease;
Nevus at the nail base;
Breast cancer;
Melanoma (check for periungal pigmentation); and
Trauma.





Figure 21. Longitudinal brown lines.


Splinter Hemorrhages

Splinter hemorrhages are caused by hemorrhage of the distal capillary loop (Figure 22). Note the thickness of these areas. They are associated with the following:


Subacute bacterial endocarditis;
Systemic lupus erythematosus;
Trichinosis;
Pityriasis rubra pilaris;
Psoriasis; and
Renal failure.





Figure 22. Splinter hemorrhages tend to be fat.

Terry's Half and Half Nails


With Terry's half and half nails, the proximal portion is white (edema and anemia) and the distal portion is dark. These nails imply either renal or liver disease (Figures 23A, 23B).





Figure 23A. This example of Terry's half and half nails suggests liver disease (no brown lines).




Figure 23B. Half and half nails imply renal disease when there is a brown band at the junction of the erythema and the free edge. Image courtesy of www.dermnet.com Used with permission.



Generalized Discolorations of the Nail Plate

Nail discoloration is a useful method for identifying potential problems.


White Nails


White nails can be caused by anemia, edema, or vascular conditions (Figure 24). Consider the following:



Anemia;
Renal failure;
Cirrhosis;
Diabetes mellitus;
Chemotherapy; and
Hereditary (rare).






Figure 24. Example of white nails.


Pink or Red Nails


With pink or red nail discoloration, the following should be considered (Figure 25): Polycythemia (dark);
Systemic lupus erythematosus;
Carbon monoxide (cherry red);
Angioma; and
Malnutrition.






Figure 25. Example of pink and red nails.

Brown-Gray Nails

Brown-gray nails may suggest the following (Figure 26):

Cardiovascular disease;

Diabetes mellitus;
Vitamin B12 deficiency;
Breast cancer;
Malignant melanoma;
Lichen planus;
Syphilis; and
Topical agents, including hair dyes, solvents for false nails, varnish, and formaldehyde (among many others)





Figure 26. Example of brown-gray nails.

Yellow Nails

Yellow nails suggest the following (Figure 27):

Diabetes mellitus;
Amyloidosis;
Median/ulnar nerve injury;
Thermal injury; and
Jaundice.

Consider yellow nail syndrome if a patient has lymphedema and bronchiectasis.





Figure 27. Example of yellow nails. Image courtesy of www.dermnet.com Used with permission.


Green or Black Nails



Green or black nails indicate the following (Figure 28): Topical preparations, including chlorophyll derivations, methyl green, and silver nitrate (among others);
Chronic Pseudomonas spp infection; and
Trauma.




Figure 28. Example of black nails.

Processes Around the Nail

Paronychial Inflammation Paronychia is associated with separation of the seal between the proximal nail fold and the nail plate that provides entry for bacteria and leads to a localized infection of the paronychial tissues of the hands (Figure 29). Symptoms may include inflammation, swelling, and/or scaling.


Figure 29. Example chronic paronychial inflammation.

Periungal Telangeictasia Periungal telangeictasia is caused by dilated capillary loops and results in atrophy of the cuticle (Figure 30). It is strongly associated with collagen vascular disease, including the following:

Systemic lupus erythematosus;
Dermatomyositis (especially with Gotton's papules over knuckles); and
Scleroderma.



Figure 30. Example of periungal telangeictasia. Image courtesy of www.dermnet.com

Mucus Cyst A mucous or myxoid cyst is a collection of degenerative collagen that can cause swelling and ridging of the nail above the cyst, forming a "gutter" (Figure 31).



Figure 31. Example of a mucus cyst.

Cases
The following are examples of patients in whom examining the fingernails may help identify their conditions.


Slide 1. 78-year-old with multiple conditions.



Slide 2. 84-year-old man with a painful ankle.




Slide 3. 68-year-old man with esophageal cancer.