How Do Sweat Glands Work? Mechanism and Importance in Humans
Sweat glands, also known as sudoriparous or sudoriferous glands, are tiny tube-shaped formations of the skin that create sweat. The sudoriferous glands are a type of exocrine glands meant to produce and secrete substances onto an epithelial surface through a duct.
There are two types of sweat glands, apocrine sweat glands, and eccrine sweat glands. They differ in all aspects, including structure, mechanism of excretion, distribution across species, secretory product, and anatomic distribution.
Eccrine sweat glands are scattered nearly all over the human anatomy, in alternating quantities, with the highest frequency in palms and feet, followed by the head, but extremely limited on the torso and the extremities. Its water-based absorption serves as a primary form of cooling in personages.
Apocrine sweat glands are principally restricted to the armpits and perineal areas in individuals. They are not vital for reducing the heat in humans but are the only active sweat glands in hoofed creatures, such as donkeys, cattle, horses, and camels.
Some modified apocrine glands examples are mammary glands, ciliary glands in the eyelids, and ceruminous glands.
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Structure
Ordinarily, sweat glands are a secretory unit. These units consist of a home-rolled into a glomerulum, and a tube that transports the sweat off. The base is rooted deep into the lower dermis and hypodermis, while the entire sudoriferous glands are enclosed by adipose tissue. Both the types of glands, the secretory coils, are enclosed by contractile myoepithelial cells that operate to expedite the excretion of secretory output. The autonomic nervous system and the circulating hormones control the secretory activities and the contractions of myoepithelial cells. The apical part of the tube that opens right onto the skin's cover is known as the acrosyringium.
Each sweat gland holds numerous nerve fibres that branch into groups of one or more axons, surrounding the secretory coil's single tubules.
Types of Sweat Glands
Eccrine
Eccrine sweat glands can be classified as the basic glands in the human body. These types of glands are present everywhere except, ear canal, labia minora, prepuce, lips, glans penis, and clitoris. They are way smaller in size than apocrine sweat glands, do not stretch deep in the dermis, and discharge directly onto the skin's surface. Also, the dimension tends to decline with age.
The pure secretion composed by eccrine sweat glands is known as sensible perspiration, commonly termed as sweat. What is sweat? Well, sweat is mostly water-containing electrolytes since it's procured from blood plasma. The bearing of sodium chloride is what makes sweat salty.
The Three Primary Functions of Eccrine Glands Are:
Thermoregulation: The primary reason why do we sweat is for thermoregulation. Sweat leads to cooling of the exterior of the skin, subsequently lowering body heat.
Excretion: Eccrine sweat gland discharge can also present a notable excretory path for water and electrolytes.
Protection: Eccrine sweat gland discharge aids in conserving the skin's acid covering, which assists guard the skin against the settlement from bacteria and different pathogenic bodies.
Apocrine
These types of glands are observed in the armpit, perineum, in the ear, around the nipples, and the eyelids. These types of sweat glands are comparatively larger than eccrine glands, and they tend to secrete sweat into the pilary canal of the hair follicle rather than opening onto the skin's surface.
Apocrine sweat glands are primarily inactive before puberty. Over time when the hormonal changes are witnessed during puberty, the glands tend to increase in size and begin functioning. The secreted substance of the apocrine is way thicker than eccrine and replenishes nutrients for bacteria on the skin. These types of glands are most active in times of stress and sexual foreplay.
Apocrine sweat contains pheromone-like composites in mammals (including humans), which helps them attract other organisms within their species. Further, studies on human sweat have revealed a difference in apocrine secretions and bacteria in men and women.
Some modified apocrine glands examples are mammary glands, ciliary glands in the eyelids, and ceruminous glands.
Apoeccrine
Some glands in the human body cannot be classified as apocrine or eccrine because they possess characteristics of both types of sweat glands. These types of glands are termed apoeccrine and are smaller than apocrine glands but larger than eccrine glands.
Apoeccrine glands discharge more sweat compared to the other two types of glands, thus executing a large function in axillary sweating. These types of sudoriferous glands are sensitive to cholinergic activity, though adrenergic stimulation can stimulate them.
The Function of Sweat Glands
The Primary Function of Sweat Glands Are:
Thermoregulation, i.e., lowering the body temperature, is the main reason why do we sweat.
Conserving the skin's acidic covering, guarding the skin against the settlement from bacteria and different pathogenic bodies.
Excretion of water and electrolytes.
Did You Know?
The hypothalamus, pituitary, and thyroid are the three major glands in the human body.
Pure sweat is odourless, it is the bacteria on our skin that creates a foul odour on sweating.
The primary reason why do we sweat is to maintain our body temperature to match up with the environmental changes, so we don't fall ill.
Spicy food can stimulate the sweat glands of our bodies.
Ciliary glands present on the eyelids are apocrine glands examples.
Sweat glands are mostly found in foreheads, armpits, palms, and soles.
Excess alcohol consumption can increase sweating.
Guarding the skin against settlement bacteria and different pathogenic bodies is a function of sweat glands.
FAQs on Sweat Glands: Structure, Types & Their Functions
1. What are sweat glands?
Sweat glands, also known as sudoriferous glands, are small, coiled tubular glands located in the dermis and hypodermis layers of the skin. They are classified as exocrine glands because they produce and secrete sweat onto the skin's surface through a duct. An average person has over 2.5 million sweat glands distributed across their body.
2. What are the main functions of sweat glands?
The primary functions of sweat glands are essential for homeostasis and protection:
Thermoregulation: This is the most vital function. When body temperature rises, sweat glands secrete sweat. The evaporation of this sweat from the skin surface has a cooling effect, helping to maintain a stable core body temperature.
Excretion: Sweat serves as a minor excretory route, helping to eliminate small amounts of metabolic wastes like urea, lactic acid, and excess salts (electrolytes).
Protection: The secretion of sweat helps to form a protective film on the skin known as the acid mantle, which has an acidic pH that inhibits the growth of many harmful bacteria.
3. What are the different types of sweat glands in the human body?
There are two principal types of sweat glands found in humans, each with distinct structures and functions:
Eccrine Glands: These are the most numerous and widely distributed sweat glands, found all over the body but most concentrated on the palms, soles, and forehead. They open directly onto the skin's surface and are responsible for producing the watery sweat involved in cooling.
Apocrine Glands: These glands are larger and are primarily located in areas with hair follicles, such as the armpits (axillae), groin, and areolar regions. They typically open into hair follicles and secrete a thicker, milky fluid. They become functional during puberty.
4. What is the difference between eccrine and apocrine sweat glands?
The main difference lies in their secretion, location, and primary function. Eccrine glands produce a watery, hypotonic fluid (sweat) mainly for thermoregulation and are found all over the body. In contrast, apocrine glands, found in specific regions like the armpits, secrete a thicker, protein-rich fluid. This secretion is initially odourless but is associated with body odour when metabolised by skin bacteria. Apocrine glands are also more responsive to emotional stress than to heat.
5. What is the composition of the sweat produced by glands?
Sweat is composed of approximately 99% water. The remaining 1% consists of various dissolved solutes. The most significant solute is sodium chloride (NaCl), which gives sweat its characteristic salty taste. Other components include electrolytes like potassium and calcium, and metabolic waste products such as urea, uric acid, and ammonia.
6. How do sweat glands help regulate body temperature?
Sweat glands regulate body temperature through a process called evaporative cooling. When the body's internal temperature increases, the hypothalamus in the brain signals the eccrine sweat glands to secrete sweat. This watery fluid is released onto the skin's surface. As the sweat evaporates into the air, it absorbs thermal energy from the skin, which effectively cools the body down and helps maintain a stable internal temperature.
7. Why does sweat produced by some glands cause body odour?
Body odour is not caused by sweat itself but by the interaction of bacteria with the secretions from apocrine glands. While eccrine sweat is mostly water and salt, apocrine sweat contains proteins and fatty acids. Bacteria that naturally reside on the skin, particularly in moist areas like the armpits, break down these organic compounds. This bacterial decomposition process releases volatile organic compounds that have a distinct and often unpleasant smell.
8. How are the actions of sweat glands controlled?
The activity of sweat glands is controlled involuntarily by the autonomic nervous system, specifically the sympathetic division. When body temperature rises, thermoreceptors in the skin and brain detect the change and send signals to the hypothalamus. The hypothalamus, acting as the body's thermostat, activates sympathetic nerves that stimulate the eccrine glands to secrete sweat. Apocrine glands, while also under sympathetic control, are more strongly activated by hormonal changes and emotional stimuli like fear or stress.
