Have you ever felt goosebumps all over your body? That’s the work of the tiny muscle named arrector pili muscle. It’s one of the smallest muscles in our body that is responsible for making the hair stand up on our skin. It’s an involuntary muscle that is controlled by the sympathetic nervous system. The arrector pili muscle can be found connecting to each of the hair follicles, and it can contract and relax based on external stimuli.
Although it might seem like a useless function, the arrector pili muscle played a crucial role in the evolution of our ancestors. Our hairy ancestors had a dense layer of hair to keep them warm, but when they felt threatened, the arrector pili muscle would contract, causing the hair to stand up, making them appear bigger and intimidating to predators. In modern times, the arrector pili muscle still has the same function of keeping us warm, but in addition, it plays a role in regulating temperature and oil secretion in the skin.
There are several external and internal factors that can stimulate the contraction of the arrector pili muscle. Cold temperatures can cause goosebumps as a way of keeping us warm. Psychological stimuli such as fear or excitement can also activate the sympathetic nervous system and cause the hair to stand up. So, the next time you feel goosebumps, remember that it’s your body’s way of protecting and regulating itself.
Anatomy of the Arrector Pili Muscle
The arrector pili muscle is a small, smooth muscle that is attached to each hair follicle on our bodies. When this muscle contracts, it causes the hair to stand up straight, giving us the sensation that our hair is “standing on end.”
The arrector pili muscle is made up of small cells that are roughly the same size and shape as other smooth muscle cells found in our bodies. However, the arrector pili muscle is unique in that it is not attached to a bone or joint, but rather to a hair follicle.
- The muscle is located within the dermis layer of the skin, and is usually positioned at an angle to the hair shaft
- The average length of the muscle is around 3-5 mm, but this can vary depending on its location on the body and the size of the hair follicle it is attached to
- There are an estimated 5 million hair follicles on the human body, each having its own arrector pili muscle
This muscle is an important component of our body’s response to stress or cold. When we are cold or frightened, our body’s natural response is to activate the sympathetic nervous system. The sympathetic nervous system signals for the arrector pili muscle to contract, which causes the hair on our body to stand on end, creating an insulating layer of air around us.
Role of the Sympathetic Nervous System in Controlling the Arrector Pili Muscle
When it comes to the control of the arrector pili muscle, the sympathetic nervous system plays a key role. This is the part of the nervous system that is responsible for the body’s “fight or flight” response, which helps prepare the body to deal with threats or stressful situations. One of the ways the sympathetic nervous system does this is by activating the arrector pili muscle.
- The sympathetic nervous system releases a neurotransmitter called norepinephrine, which binds to receptors on the arrector pili muscle.
- When norepinephrine binds to these receptors, it causes the muscle to contract, pulling on the hair follicle and causing the hair to stand up.
- This response is thought to be adaptive in nature, as it can help animals appear larger and more intimidating to potential predators.
It’s worth noting that other factors can also influence the arrector pili muscle, such as changes in temperature or emotional states. However, the sympathetic nervous system is thought to be the primary controller of this muscle.
Overall, the arrector pili muscle may seem like a small and insignificant part of the body, but it actually plays an important role in the body’s response to stress and danger. Understanding how this muscle is controlled can give us valuable insights into how the body adapts to different situations.
Disorders related to the arrector pili muscle
The arrector pili muscle plays an important role in the physiology of the skin. When stimulated, it contracts and causes the hair follicle to stand erect, resulting in goosebumps. However, there are certain disorders that can affect the function of this muscle, leading to several skin-related conditions.
- Folliculitis: This is a common skin condition in which the hair follicles become inflamed, leading to the development of small, pus-filled bumps. Folliculitis can be caused by bacteria, fungi, or viruses, and infection of the arrector pili muscle can also trigger this condition.
- Alopecia: Also known as hair loss, alopecia can be caused by several factors, including genetics, hormonal imbalances, and autoimmune disorders. Contractions of the arrector pili muscle can push hair out of the follicles, and when a large number of hair follicles are affected, it can lead to significant hair loss.
- Trichotillomania: This is a compulsive disorder in which a person repeatedly pulls out their own hair, leading to bald patches on the scalp or other parts of the body. Trichotillomania can be triggered by stress, anxiety, or other psychological factors, and repeated pulling of the hair can damage the arrector pili muscle and prevent hair growth.
In addition to these disorders, there are several other skin-related conditions that can affect the arrector pili muscle. These include acne, rosacea, and certain types of eczema. Proper diagnosis and treatment of these disorders is important to prevent complications and ensure healthy skin.
Role of hormones in controlling the arrector pili muscle
Various hormones have a significant impact on the human body, including the arrector pili muscle. Here are some of the key hormones and their role in controlling this muscle:
- Epinephrine: Also known as adrenaline, this hormone is produced by the adrenal glands during the “fight or flight” response. When epinephrine binds to its receptors on the arrector pili muscle, it causes the muscle to contract, resulting in the characteristic “goosebumps” sensation.
- Norepinephrine: Similar to epinephrine, norepinephrine is another stress hormone that can cause the arrector pili muscle to contract. It is also involved in regulating the body’s response to stress and maintaining blood pressure.
- Testosterone: As a male sex hormone, testosterone plays a role in regulating hair growth and the arrector pili muscle. Studies have shown that higher levels of testosterone can lead to thicker hair and stronger muscle contractions in the arrector pili muscle.
Other hormones, such as cortisol and thyroid hormone, can also influence the arrector pili muscle. However, the above hormones are some of the most prominent in terms of controlling this muscle.
Cold-induced piloerection
Cold-induced piloerection is a natural response of the body to cold temperatures. It is also commonly known as “goosebumps.” This occurs when the arrector pili muscles contract, pulling the hair follicle upright and causing the surrounding skin to form a small bump.
There are a few reasons why the arrector pili muscles would contract when the body is exposed to cold temperatures. One of the main reasons is to trap a layer of air near the skin, which acts as an insulator and helps to retain heat. This can be particularly important in animals with fur or feathers in cold climates.
- When the body senses a drop in temperature, the sympathetic nervous system is activated.
- The sympathetic nervous system triggers the release of the hormone adrenaline.
- Adrenaline causes the arrector pili muscles to contract, which pulls the hair follicles upright and causes the surrounding skin to form a bump.
Cold-induced piloerection is also a sign of an emotional response, such as fear or excitement. In these situations, the body releases adrenaline as well, causing the arrector pili muscles to contract and resulting in the formation of goosebumps.
Interestingly, some researchers have suggested that humans experience goosebumps not only as a physical response but also as an emotional response. For example, when listening to music that evokes strong emotions, some people report feeling goosebumps. This phenomenon is known as “frisson” and is thought to be related to the release of dopamine in the brain.
Summary
Cause of Cold-induced piloerection: Sympathetic nervous system triggers the release of the hormone adrenaline. Function of Cold-induced piloerection: To trap a layer of air near the skin, which acts as an insulator and helps to retain heat. Other factors that can induce Cold-induced piloerection: Emotional responses, such as fear or excitement. Cold-induced piloerection is a fascinating natural response of the body to cold temperatures and emotional situations. It serves an important function in helping to retain heat and may even be linked to the release of dopamine in certain situations. Understanding the mechanisms behind this phenomenon can help us to better appreciate the intricacies of the human body.
Innervation and Function of the Arrector Pili Muscle
The arrector pili muscle is a small, smooth muscle attached to the base of a hair follicle and its function is to contract, producing a raised area on the skin like goosebumps. Here are some important details regarding the innervation and function of the arrector pili muscle:
- Innervation: The arrector pili muscle is innervated by the sympathetic nervous system. Specifically, the neurons originate from the spinal cord and synapse at ganglia located close to the muscle. These ganglia release noradrenaline, which binds to alpha-adrenergic receptors present on the muscle fibers, causing them to contract.
- Function: The arrector pili muscle is responsible for several functions, including:
- Thermo-regulation: the contraction of the muscle raises the hair, trapping an insulating layer of air close to the skin and lowering heat loss.
- Emotion-induced changes in skin appearance: under emotional stress, the contraction of the arrector pili muscle may cause hair to stand on end, producing goosebumps;
- Hair follicle secretion: the contraction of the arrector pili muscle can also express gland secretions contained in the hair follicle.
It is important to note that the arrector pili muscle does not have a role in movement or facial expression like other skeletal muscles. Instead, its function is to modulate the skin’s surface appearance and provide minor thermoregulation.
When we are cold, scared or excited, our hairs tend to stand on end, which is a response to an involuntary reflex. The sympathetic nervous system is the main controller of the body’s “fight or flight” response and the one that orders muscles, such as the arrector pili, to respond accordingly.
Here is a table summarizing some details about the innervation and function of the arrector pili muscle:
Arrector Pili Muscle Detail Summary Innervation Sympathetic Nervous System, Noradrenaline, alpha-adrenergic receptors Function Thermo-regulation, creating emotion-induced changes in skin appearance, hair follicle secretion Role in Skeletal Muscles Not involved in movement or facial expression In conclusion, the arrector pili muscle has an important role in thermoregulation, emotional response and hair follicle secretion. It is innervated by the sympathetic nervous system, which is responsible for the body’s response to stress, and does not have a function in movement or facial expression.
The Evolutionary Significance of the Arrector Pili Muscle
The arrector pili muscle, also known as the pilomotor muscle, is a small muscle attached to each hair follicle in mammals. When it contracts, it causes the hair to stand on end, creating what we commonly refer to as goosebumps. While the arrector pili muscle may seem insignificant at first glance, it actually holds great evolutionary significance and has played a crucial role in the survival of many animal species.
- Heat regulation: In many mammals, the arrector pili muscle plays a role in regulating body temperature. When the muscle contracts and the hair stands on end, it creates a layer of trapped air that provides insulation, helping the animal retain warmth in cold environments.
- Camouflage: In some animals, the arrector pili muscle can be used to blend in with the surrounding environment. For example, some birds will fluff up their feathers by contracting the muscle, making them look larger and more intimidating to predators.
- Threat display: On the other hand, some animals use the arrector pili muscle as a threat display. When the muscle contracts and the hair stands on end, it can make an animal appear larger and more aggressive, dissuading potential predators from attacking.
The arrector pili muscle is also thought to have played a role in the evolutionary development of hair in mammals. Scientists believe that hair originally evolved as a way for mammals to stay warm, with the arrector pili muscle developing later as a way to improve insulation further.
Overall, while the arrector pili muscle may seem like a small detail, it has played a crucial role in the survival of many animal species. From regulating body temperature to providing camouflage and deterrence against predators, this little muscle packs a big punch when it comes to evolutionary significance.
FAQs About What Controls the Arrector Pili Muscle
1. What is the arrector pili muscle?
The arrector pili muscle is a small muscle attached to a hair follicle. It creates the hair-raising effect, or goosebumps, when it contracts.
2. What controls the arrector pili muscle?
The arrector pili muscle is controlled by the sympathetic nervous system, which automatically responds to stress, fear, and cold temperatures.
3. Can we consciously control the arrector pili muscle?
No, we cannot consciously control the arrector pili muscle. It is an involuntary response that happens automatically.
4. How do hormones affect the arrector pili muscle?
Hormones like adrenaline, cortisol, and testosterone can stimulate the sympathetic nervous system and cause the arrector pili muscle to contract.
5. Does the arrector pili muscle have any other functions?
Besides creating goosebumps, the arrector pili muscle also helps to remove dead skin cells and oil from hair follicles. It may also play a role in regulating skin temperature.
6. What happens if the arrector pili muscle doesn’t work?
If the arrector pili muscle doesn’t work properly, it may lead to hair loss or skin conditions like acne or folliculitis.
Closing Thoughts
Thanks for reading about what controls the arrector pili muscle! While it may seem like a small muscle, it plays an important role in our body’s response to stress and temperature changes. Remember, the arrector pili muscle is an involuntary response that we cannot control. If you have any concerns about your skin or hair, be sure to consult with a dermatologist. Visit our site for more informative articles about the human body.