Do a person's nails grow when they die?

The question must be asked- why do cadavers have such long nails? Do they grwo once the person is dead? No they don't. The reason the nail slook long on dead people is that the soft tissues around the nail shrink and contract so we see more of the nail cuticle. The same thing occurs with the hair. Funeral homes often place moistuisers on the dead body so that the tissue doesn't retract and the body is more presentable.

Is using a paper bag effective if someone is fainting? What is the rationale behind it?

It depends on why the person faints- an act known as syncope. The causes for syncope are many;

Table 1. Causes of syncope
Cause	Prevalence
Cardiac
Arrhythmia	14%
Mechanical*	4%
Neurologic	10%
Neurally mediated
Vasovagal	18%
"Situational"	5%
Orthostatic	8%
Psychiatric	2%
Idiopathic	34%
*Obstruction to cardiac outflow, decreased ejection fraction, and decreased ventricular filling (ie, pulmonary embolus, pulmonary hypertension, and cardiac tamponade).

When a person is hyperventilating, they excrete more CO2 than usual and their drive for breathing decreases (CO2 mediates the urge for brething in normality). The person stops breathing temporarily and this will cause them to faint. Once unconcious CO2 builds up again and they will start breathing again and regain conciousness. By using a paper bag (or any bag- it's just that paper looks better than plastic) in a person who is hyperventialting, you capture their expired CO2 and they then rebreath this- therefore their CO2 levels don't decrease as quick and they won't faint. It is important to try then and get the person to breath normally.

Also see this explanation;

Hyperventilation causes various symptoms such as numbness or tingling in the hands, feet and lips, lightheadedness, dizziness, headache, chest pain, slurred speech and sometimes fainting, particularly when accompanied by the Valsalva Maneuvre.

In normal breathing, both the depth and frequency of breaths is varied by the neural system primarily in order to maintain normal amounts of carbon dioxide but also to supply appropriate levels of oxygen to the body's tissues. This is mainly done by measuring the carbon dioxide content of the blood; normally, a high carbon dioxide concentration signals a low oxygen concentration, as we breathe in oxygen and breathe out carbon dioxide at the same time, and the body's cells use oxygen to burn fuel molecules to carbon dioxide.

The gases in the alveoli of the lungs are nearly in equilibrium with the gases in the blood. Normally, less than 10% of the gas in the alveoli is replaced each breath. Deeper or quicker breaths exchange more of the alveolar gas with air and have the net effect of drawing more carbon dioxide out of the body, since the carbon dioxide concentration in normal air is very low.

The resulting low concentration of carbon dioxide in the blood is known as hypocapnea. Since carbon dioxide is held in the blood mostly in the form of carbonic acid, hypocapnia results in the blood becoming alkaline, i.e. the blood pH value rises. (In the normal person, this alkalosis would automatically be countered by reduced breathing, but for various reasons this doesn't happen when the neural control is not present.)

If carbon dioxide levels are high, the body assumes that oxygen levels are low, and accordingly the brain's blood vessels dilate, to assure sufficient blood flow and supply of oxygen. Conversely, low carbon dioxide levels (e.g. from hyperventilation) cause the brain's blood vessels to constrict, resulting in reduced blood flow to the brain and lightheadedness. Doctors sometimes artificially induce hyperventilation after head injury to reduce the pressure in the skull, though the treatment has obvious risks.

The high pH value resulting from hyperventilation also reduces the level of available calcium (hypocalcemia), which affects the nerves and causes the numbness or tingling of the hands. This occurs because alkalinization of the serum proteins (mainly albumin) increases their calcium affinity.

Why do people with raised intracranial pressure (ICP) vomit more in the mornings?

ICP is dependant primarily on cerebro-spinal fluid(CSF). CSF reabsorption is lowest overnight and the recumbent postition both combine together meaning that ICP is generally highest in the morning. Hence, people vomit in the morning.


The combination of headache, papilloedema, and vomiting is generally considered indicative of raised ICP, although there is no consistent relation between the severity of symptoms and the degree of hypertension. Pressure headaches are often described as throbbing or bursting and are exacerbated by any factors that further increase ICP such as coughing, sneezing, recumbency or exertion. Classically the headache of raised ICP is worse in the morning. This has been attributed to a rise in ICP during the night as a consequence of recumbency, a rise in PCO₂ during sleep caused by respiratory depression, and probably a decrease in CSF absorption. Papilloedema is a reliable sign of raised ICP but can require several days of raised pressure to develop. Fundal haemorrhages develop in response to acute and severe rises in ICP (as in subarachnoid haemorrhage and some cases of head injury). Longstanding raised ICP may fail to cause papilloedema if the subarachnoid sleeve around the optic nerve does not communicate with the subarachnoid space. Vomiting tends to be a late feature, usually occurs after waking, and frequently accompanies morning headache.

Normal ICP in an adult is usually around 15 mm Hg

Which is worse an alkali eye burn or acid eye burn, and why?

An alkali burn of the eye is worse than an acid burn. The reason for this is that as the acid penetrates the sclera and cornea and other parts of the eye, it coagulates the protiens present (this is a characteristic of proteins) and this impedes the further spread of the acid. Alkalis though do not cause coagulation of protein and hence nothing impedes the further spread of the alkali, causing a worse burn.

Burns damage tissues primarily by denaturing and coagulating cellular proteins and secondarily through vascular ischemic damage. Whether thermal or chemical, the severity of burns results from the depth and degree of epithelial damage and limbal ischemia. If the limbus is affected significantly, the cornea may develop recurrent epithelial defects, and conjunctival invasion onto the cornea may occur due to the loss of stem cells responsible for renewing corneal epithelium.

• Acidic chemicals
  • Common acids causing ocular burns include sulfuric acid, sulfurous acid, hydrochloric acid, nitric acid, acetic acid, chromic acid, and hydrofluoric acid.
  • Automobile battery explosion, which causes a sulfuric acid burn, is perhaps the most common acidic burn of the eye.
  • Hydrofluoric acid may be found at home in rust removers, aluminum brighteners, and heavy-duty cleaners. Certain industries use hydrofluoric acid in brick cleaning, glass etching, electropolishing, and leather tanning. Hydrofluoric acid also is used to control fermentation in breweries.
  • Ocular hydrofluoric toxicity can occur from liquid or gaseous exposure.

• Alkali chemicals
  • Common alkali substances contain ammonium hydroxide, potassium hydroxide, sodium hydroxide, calcium hydroxide, and magnesium hydroxide. Substances that contain such compounds and can be found in a home include lye, cement, lime, and ammonia.
  • Air bags aerosolize sodium hydroxide on inflation and may cause an alkali keratitis. Additionally, sparklers and flares contain magnesium hydroxide and phosphorus.

What causes blackheads?

Blackheads or comedones are follicles filled with sebum and dead cells and melanin (from the skin cells). As blackheads are open to the enviornement the melanin undergoes oxidation and gives the black colour. Whiteheads are closed and therefore the melanin does not undergo oxidation so they remain white.

Introduction

What is this site created to do?
Simply to explain the how and why of common medical conditions, complaints and all things that afflict the human body.
How will this be done?
Questions will be posed and then explanations will be followed. The explanation may lead to further questions which will be explained there. For the moment I will be the sole person to answer the questions as I come across them in my studies however, it is hoped that someday a body of specialists will answer questions posted by readers.
Who am I?
A medical student interested in understanding the reason behind things.
Understanding leads to learning.