Jasmine Grover Content Strategy Manager
Content Strategy Manager
Sweat and sebum are secretory products, released from the sweat gland and sebaceous gland respectively. These glands are present on the surface of human skin, near the hair follicles. Sweat plays an important role in thermoregulation, maintaining body temperature. Whereas sebum is released to protect the skin by forming a natural skin barrier and moisturizing the skin. Sweat and sebum are also considered excretory products as they are often the medium to excrete out excess chemical substances from the body. In this article, we will discuss the composition and function of sweat and sebum production in the human body and discuss the differences between the two.
| Table of Content |
Key takeaways: sweat gland, sebaceous gland, skin layers, function of sweat, function of sebum, difference between sebum and sweat.
What is Sweat?
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Sweat is a fluid secreted from the sweat glands present on the skin surface.
- Sweat is mainly composed of mainly water and salt (sodium chloride) with tiny amounts of ammonia, urea, and other chemical substances.
- The primary function of sweat production in humans is thermoregulation or controlling body temperature. It keeps our body temperature cool during summers.
- Sweat production is stimulated by either increase in body temperature, or by stress signals, for example when we are nervous or anxious.
Sweat
Read More: Difference between exocrine and endocrine glands
What is Sebum
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Sebum is an oily or wax-like substance secreted from the sebaceous gland.
- It is composed of fatty acids, sugars, waxes, and other natural substances that control the evaporation of water from the skin.
- The main function of sebum is to protect the skin by acting as a natural skin barrier, moisturizing our skin, and keeping it from drying.
Layers of skin
Sweat gland and sebaceous gland
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Sweat glands are tubular structures present on the dermis layer of skin. They are distributed all over the human body. There are two types of sweat glands; eccrine gland and apocrine gland.
- The eccrine gland is distributed all over the body with the highest density in palm and soles.
- The apocrine gland is concentrated in the armpit and perineal region.
Sebaceous glands are sac-shaped exocrine glands that open near the hair follicle. It is also present in the dermis layer of the skin. Sebaceous glands are present all over the body except palms and soles. Sebaceous glands are present in higher density in the face and scalp.
Also Read:
Sweat gland and sebaceous gland
Difference between Sweat and sebum
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Sweat and sebum can be differentiated on many factors such as:
| Factors | Sweat | Sebum |
|---|---|---|
| Gland | Sweat is produced by the sweat gland. | Sebum is produced by the sebaceous gland. |
| Composition | It is composed mainly of water and salt with a little amount of ammonia, urea, and other chemical substances. | It is composed of fatty acids, lipids, sugars, triglycerides, cholesterol, etc. |
| Function | The primary function of sweating is thermoregulation. | The primary function of sebum production is to protect and moisturize the skin. It forms a natural skin barrier. |
| Present in | They are present all over the body with higher density in the armpit, palms, and sole region. | They are present all over the body except on soles and palms. They are present in higher numbers on the scalp and the face. |
| Odor | Naturally odorless. However, the odor is caused due to the decomposition of sweat by bacterias. | Odorless. |
| Consistency | Fluid, watery substance. | Oily or wax-like substance. |
| Stimulation | Stimulated by an increase in body temperature. It can be due to exercise, or rising environmental temperature. | Sebum is produced continuously. It can be stimulated by hormonal changes. |
| Discharged from | Surface of skin | From hair follicle |
| Nature | Fluid-like or watery in appearance. | Oily in appearance. |
Things to remember
- Sweat is a fluid-like excretion product that is released by the sweat glands present on the skin.
- Sweat mainly constitutes water and salt, with tiny amounts of ammonia, urea, and other chemical substances.
- Sebum is an oily or wax-like substance produced by the sebaceous glands present on the dermis layer of the skin.
- The main constituents of sebum are esters of glycerol, free fatty acids, triglycerides, cholesterol, squalene, etc.
- The sweat gland and sebaceous gland, both are examples of exocrine glands.
- Sweat glands are tubular glands on the dermis layer of the skin.
- Sebaceous glands are sac-like glands present on the dermis layer of the skin.
- The primary function of sweat is thermoregulation. While the primary function of sebum is natural skin barrier and skin moisturization.
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| What is Anxiety? | Difference between Centipede and Millipede |
Sample questions
Ques. Name one modified sebaceous gland and one modified sweat gland. State their function. (3 marks)
Ans. Mammary glands are examples of modified sweat glands. An example of a modified sebaceous gland is the meibomian glands present on the margin eyelids.
The function of the mammary gland is to produce milk for nurturing newborns. The function of the meibomian gland is to produce meibum, an oily substance that keeps the eye from drying out.
Ques. What part of humans has the largest number of sweat glands? (4 marks)
Ans. There are two types of sweat glands. One is the apocrine gland and the other is the eccrine gland.
- Eccrine glands are distributed throughout the skin surface. Eccrine sweat glands are found in higher numbers on the skin of palms of hand and soles.
- On the other hand, the apocrine sweat glands are found in the armpit region and perineal region. They have other functions than thermoregulation. In various mammals, the apocrine sweat glands produce pheromones.
Ques. Why do our hands tend to get sweaty when we are nervous? (4 marks)
Ans. Sweat production is stimulated by various stimulations like thermoregulation and stress. When we are nervous it initiates a stress response in us, this increases the level of adrenaline secretion from the adrenal glands. It increases body temperature rapidly in a short period of time which signals the sweat glands to produce more sweat.
And as we already know, our palms have the highest number of eccrine sweat glands. So, when we are nervous, our palms tend to get more sweaty than any other part and become noticeable. It can also be due to disorders like hyperhidrosis, excessive sweating.
Ques. How does sweating help in thermoregulation? (5 marks)
Ans. As we know the normal temperature of the human body is around 37 F. So, our body has different mechanisms to maintain that temperature, otherwise, our organs would fail and stop working. One of the mechanisms to maintain the body temperature at 37 F is sweating.
When our body temperature rises significantly, our brain sends out signals to activate the sweat glands via the central nervous system (CNS). The sweat glands now start producing droplets of sweat and release them on the surface of the skin. These droplets start evaporating as a result of this the skin surface starts to cool down. This causes cooling of the blood flowing just below the skin surface, hence the temperature of the body is maintained.
Ques. What is the composition of sweat and sebum? (3 marks)
Ans. Sweat is a fluid secreted from the sweat gland. It is mainly composed of water and salt (Sodium Chloride), with small amounts of urea, ammonia, and other chemical substances.
Sebum is an oily substance secreted from the sebaceous gland present on the skin. It is composed of triglycerides, cholesterol, sugars, fatty acids, etc.
Ques. How many types of sweat glands are there? Briefly define each of them. (5 marks)
Ans. There are two types of sweat glands present on the skin. The first is the eccrine sweat gland, and the second is the apocrine sweat gland.
- The eccrine sweat gland is the most widespread of the two kinds. It is present almost all over the body and produces sweat in response to heat and stress like anxiety or fear. The gland has a coiled appearance in the dermis layer of the skin, with a duct coming up and opening as a sweat pore on the surface of the skin. Eccrine sweat glands are present all over the body, but the largest numbers of eccrine sweat glands are present on the palms of the hand and soles.
- The apocrine sweat gland is not present all over the body and is also not involved in thermoregulation. The apocrine sweat gland is abundant in areas like the armpit. Apocrine sweat glands have specialized functions in other mammals including the production of pheromones. So the sweat produced by the apocrine sweat gland is slightly different in composition than eccrine sweat glands. It contains more fatty acids compared to sweat produced by eccrine sweat glands.
Ques. What happens if sebaceous glands stop working? (2 marks)
Ans. Sebaceous glands play an important role in moisturizing the skin and protecting the skin by forming a natural skin barrier. If sebaceous glands fail to function properly, it can affect the health of our skin and hair. The skin and hair can become drier and lose elasticity. It can cause easy breakage of hair and hair fall. Our skin becomes more susceptible to bacterial infections.
Ques. Why do adolescents tend to have more oily skin than adults if the number of sebaceous glands remains the same? (2 marks)
Ans. The number of sebaceous glands does not change much. Adolescents undergo puberty that causes significant hormonal changes. These hormonal changes lead to the enlargement of sebaceous glands. It stimulates the glands to be more active and produce more sebum or oil, leading to oily skin in teenagers. As they grow up, these glands shrink back to normal size and the sebum production reduces.
Ques. A normal healthy-looking man starts sweating in a cold climate. What is the reason behind it? (3 marks)
Ans. Sweating can be triggered by various stimulations like rising body temperature, stress like fear or anxiety. As the climate is cold, then the person must be suffering from some kind of anxiety or fear. The brain sends out stress signals leading to an increase in body temperature and activation of the sweat glands. The sweat glands start producing sweat even when the climate outside is relatively low.
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