We will find out! Follow me into an explanatory adventure
What are hair and nails?
To understand what hair and nails are we will have a look at the largest organ of the human body, the skin. The skin is essential for surviving, making it one of the most important organ. The following figure shows a cross section with its different layers:
Fig.1 Section through the human skin. Source
The human skin has three layers. The epidermis, dermis and subcutis. Most sources only speak of the first two layer but do not consider the subcutis as a layer. We will have a closer look at the hair follicle which main function is to produce hair. Humans have five million of these follicles in total, spread all over their body.
If you want to know more about the human skin and its function I recommend you to read my Life Explorers post.
Let it grow!
The human hair structure can be divided into two parts, the follicle and the hair shaft. The hair bulb forms the base of the hair follicle and is the only living part of hair. From here new cells are produced which are pushed towards skin and appear as the shaft.
Hair consists of three layers. The inner layer is the Medulla, followed by the Cortex and the outer layer Cuticula. Medulla and Cortex contain Melanin, which is responsible of our hair color. Furthermore, the Cortex is contains approximately 80% Keratin, a tough protein.
Fig.2 Structure of a hair follicle. Source
This growth has three stages:
Anagen phase: The anagen phase is the growth phase. Hair grows one millimeter every three days. The growth depends on the body region; however it is on the head the fastest. This phase takes 2-4 years, women hair even up to 6 years. As mentioned above we have five million follicles. Approximately 100.000 hairs grow on our hair. With a speed of one millimeter every three days that make 1 cm a month. Having 100.000 hairs on our head that makes approximately 30 meters hair growth, a day! Crazy isn’t it?
Catagen phase: Basically, a transition phase between anagen and telogen. Prepares the follicles for the next growth by detaching the bulb from blood supply.
Telogen phase: This phase lasts up to 12 weeks. The hair is in rest and will fall out soon. After the telogen phase the cycle repeats. In every follicle a hair can be produced 10 to 12 times.
So, our hair grows in a certain cycle and after 6 to 7 years the hair is rejected. Why don’t we lose all hair at once? Simply because our follicles are in different phases each. While one hair might be in anagen phase another can be in catagen. Note that hair grows everywhere except mucus membranes, our palms, soles and lips.
Does hair grow after death?
This question is tricky. We need to see this from different perspectives. A person is technically dead when his brain functions stop; so called brain-dead. While all vital functions stop few cells might live another few hours, such as the hair cells. That means that even after death the hair can grow for few hours. This however won’t be visible at all and has no impact. Where does the myth then come from?
Before burying a man he usually gets shaved. After death the skin starts to shrink and makes hair under the skin visible. This leads to a three-day stubble.
Myth or Fact? #17 – Cockroaches can survive a nuclear catastrophe
Myth or Fact? #16 – Skin on heated milk is dangerous
Myth or Fact? #15 - Survive a falling elevator by jumping up as it hits the floor
Myth or Fact? #14 - Mosquitoes prefer people with sweet blood
Myth or Fact? #13 - Does Santa Claus exist? 🎅
Myth or Fact? #12 - Acid and Base saves Life
Myth or Fact? #11 – Glass is a liquid
Myth or Fact? #10 – During summer the Eiffel Tower is taller
Myth or Fact? #9 - Hot water freezes faster than cold water
Myth or Fact? #8 - Oxygen runs out in overfilled rooms
Myth or Fact? #7 – Does a mirror swap left and right?
Myth or Fact? #6 – Radioactive contaminated waste glows green
Myth or Fact? #5 – Does drinking distilled water kill you?
Myth or Fact? #4 - We only use 10% of our Brain
Myth or Fact? #3 - Is it colder during Winter because the Sun is further?
Myth or Fact? #2- The world's most famous equation: E=mc²
Myth or Fact? #1 - The Five Second Rule