How does integumentary system work

The skin creates an acidic pH environment in which microorganisms find it difficult to grow, therefore protecting from infection. Sweat from the sweat glands prevents an overgrowth of microorganisms on the skin by producing a substance called dermcidin, which is an anti-infective agent that has natural antibiotic properties.

Many different types of microorganisms encounter the skin, but these organisms are not able to penetrate healthy skin. The inflammatory response prompts the transportation of white blood cells and other cells—called macrophages—that engulf the invading organisms. Not only does the skin provide a very strong barrier against infections in the body, but it also prevents damage to the body from certain harmful substances, such as ultraviolet UV light from the sun or other sources, such as tanning beds.

The skin responds to UV rays by producing the pigment melanin in cells called melanocytes. If overexposure to the sun occurs, inflammation occurs and the skin becomes reddened and flushed in response to dilatation of the blood vessels in the dermis. As melanin is produced, the skin begins to tan; the melanin absorbs the UV light, preventing damage to the DNA of the cell. The vast blood supply in the skin can help regulate temperature; as the blood vessels dilate, it allows for heat loss. When the vessels constrict, heat is retained.

Sensory nerves are abundant in the top layer of the skin the epidermis ; these nerves transmit feelings of:. When sensory nerves in the skin malfunction, the result is often a tingling feeling or a burning sensation. The dermis contains nerve endings and an array of touch receptors.

This allows the dermis to detect sensations such as pressure, heat, cold, and contact. The nerve endings in the dermis detect sensations, and thus play a role in the protection of the skin, by sounding an alarm when the skin is exposed to things such as a potential burn.

Skin metabolism is the rate at which new skin cells turn over; this occurs between the epidermal and dermal cells that work together to regulate collagen production and repair UV light damage, aging, and other damage caused to the skin.

The skin is responsible for excreting various substances, including:. The skin has been found to absorb many substances. The skin will absorb some types of medications including:. Medications that are given topically via the skin should be massaged into the skin and covered with an occlusive dressing for optimal absorption. The skin also stores some substances, including:. Examples of how the skin helps each body system maintain homeostasis include:. The skin synthesizes vitamin D from exposure to the sun therefore providing this vital nutrient to the digestive system.

Vitamin D is required to absorb calcium and the skin works with the digestive system to ensure that calcium can be properly absorbed. The skin works with the cardiovascular system by helping to conserve or release heat by constricting or dilating the blood vessels.

The skin functions to transmit sensations from the environment via its nerve receptors. The nerve impulses such as the perception of pain, heat, cold, and other sensations are then transmitted to the nervous system to be interpreted by the brain. The skin can be breached when a child skins a knee or an adult has blood drawn—one is accidental and the other medically necessary.

Because the needles involved in producing body art and piercings must penetrate the skin, there are dangers associated with the practice. These include allergic reactions; skin infections; blood-borne diseases, such as tetanus, hepatitis C, and hepatitis D; and the growth of scar tissue. Despite the risk, the practice of piercing the skin for decorative purposes has become increasingly popular.

According to the American Academy of Dermatology, 24 percent of people from ages 18 to 50 have a tattoo. Tattooing has a long history, dating back thousands of years ago. The dyes used in tattooing typically derive from metals. A person with tattoos should be cautious when having a magnetic resonance imaging MRI scan because an MRI machine uses powerful magnets to create images of the soft tissues of the body, which could react with the metals contained in the tattoo dyes.

Watch this video to learn more about tattooing. The fact that you can feel an ant crawling on your skin, allowing you to flick it off before it bites, is because the skin, and especially the hairs projecting from hair follicles in the skin, can sense changes in the environment.

The hair root plexus surrounding the base of the hair follicle senses a disturbance, and then transmits the information to the central nervous system brain and spinal cord , which can then respond by activating the skeletal muscles of your eyes to see the ant and the skeletal muscles of the body to act against the ant. The skin acts as a sense organ because the epidermis, dermis, and the hypodermis contain specialized sensory nerve structures that detect touch, surface temperature, and pain.

These receptors are more concentrated on the tips of the fingers, which are most sensitive to touch, especially the Meissner corpuscle tactile corpuscle Figure 5. Merkel cells , seen scattered in the stratum basale, are also touch receptors.

In addition to these specialized receptors, there are sensory nerves connected to each hair follicle, pain and temperature receptors scattered throughout the skin, and motor nerves innervate the arrector pili muscles and glands. This rich innervation helps us sense our environment and react accordingly. The integumentary system helps regulate body temperature through its tight association with the sympathetic nervous system, the division of the nervous system involved in our fight-or-flight responses.

The sympathetic nervous system is continuously monitoring body temperature and initiating appropriate motor responses. Recall that sweat glands, accessory structures to the skin, secrete water, salt, and other substances to cool the body when it becomes warm. Even when the body does not appear to be noticeably sweating, approximately mL of sweat insensible perspiration are secreted a day.

If the body becomes excessively warm due to high temperatures, vigorous activity Figure 5. The integumentary system also works closely with the circulatory system and the surface capillaries through your body. Because certain substances can enter the bloodstream through the capillary networks in the skin, patches can be used to deliver medications in this manner for conditions ranging from heart problems nitroglycerin to smoking cessation nicotine patches.

The skin also is important in helping to regulate your body temperature. If you are too hot or too cold, your brain sends nerve impulses to the skin, which has three ways to either increase or decrease heat loss from the body's surface: hairs on the skin trap more warmth if they are standing up, and less if they are lying flat; glands under the skin secrete sweat onto the surface of the skin in order to increase heat loss by evaporation if the body is too hot; capillaries near the surface can open when your body needs to cool off and close when you need to conserve heat.

Your skin plays a vital role in your body as regards the sense of touch. The nervous system depends on neurons embedded in your skin to sense the outside world. It processes input from your senses, including touch, and initiates actions based on those inputs.

For example, when you stub your toe, nerve cells in the foot send signals up the leg, through the spinal cord, and up into the brain.

The arrector pili muscles contract piloerection and lift the hair follicles upright. This makes the hairs stand on end, which acts as an insulating layer, trapping heat. While this hair-based method of thermoregulation is effective in many mammals and birds owing to their large and thick amounts of fur and feathers respectively , the relative effectiveness of this method of thermoregulation in humans is in question since we have little to no body hair in comparison.

Finally, while technically not a thermoregulatory mechanism, the fat associated with our skin does help insulate our body and therefore increases body temperature as a result. The somatosensory system is composed of the receptors and processing centers to produce the sensory modalities, such as touch and pain.

The somatosensory is the system of nerve cells that responds to changes to the external or internal state of the body, predominately through the sense of touch, but also by the senses of body position and movement. Spread through all major parts of the body, it consists of sensory receptors and sensory neurons in the periphery for example, skin, muscle, and organs , along with deeper neurons within the central nervous system. While touch is considered one of the five traditional senses, the impression of touch is actually formed from several diverse stimuli using different receptors:.

Transmission of information from the receptors passes via sensory nerves through tracts in the spinal cord and into the brain.

Processing primarily occurs in the primary somatosensory area in the parietal lobe of the cerebral cortex. Upon deviation from the norm ,sensory receptors trigger an action potential that can provide feedback or lead to alterations in behavior in order to maintain homoeostasis. Two receptors that exhibit the ability to detect changes in temperature include Krause end bulbs cold and Ruffini endings heat. A nociceptor is a sensory nerve cell that responds to damaging or potentially damaging stimuli by sending signals to the spinal cord and brain.

Nociceptors can respond to excessive thermal, mechanical, or chemical stimulation and often result the generation of an involuntary motor respons—for example, pulling a hand away from a hot surface. Mechanoreceptors are sensory receptors that respond to pressure and vibration. Four key types of mechanoreceptor have been described based on their response to stimulation and receptive field.

Receptors can either induce a slow response to stimulation, whereby a constant activation is initiated, or a fast response, whereby activation is only initiated at the beginning and end of stimulation. The receptive field—the region in which a receptor can sense an effect—can vary from small to large. One of the metabolic functions of the skin is the production of vitamin D3 when ultraviolet light reacts with 7-dehydrocholesterol. The integumentary system distinguishes, separates, and protects the organism from its surroundings, but also plays a key metabolic function, as the major region for vitamin D production.

Vitamin D refers to a group of fat-soluble steroids responsible for increasing intestinal absorption of calcium, iron, magnesium, phosphate, and zinc. In humans, the most important compounds in this group are vitamin D 3 also known as cholecalciferol and vitamin D 2 ergocalciferol. Cholecalciferol and ergocalciferol can be ingested from the diet and from supplements, however very few foods are rich in vitamin D; and so synthesis within the skin is a key source.

Vitamin D deficiency is associated with impaired bone development in children, which leads to the development of rickets and a softening of bones in adults. Deficiency in vitamin D has been termed a modern disorder associated with both a poorer diet and reduced time spent outside. The human skin consists of three major layers: the epidermis, dermis, and hypodermis.

The epidermis forms the outermost layer, providing the initial barrier to the external environment. Beneath this, the dermis comprises two sections, the papillary and reticular layers, and contains connective tissues, vessels, glands, follicles, hair roots, sensory nerve endings, and muscular tissue.

The deepest layer is the hypodermis, which is primarily made up of adipose tissue. Vitamin D is produced in the two innermost strata of the epidermis, the stratum basale and stratum spinosum.

Vitamin D 3 is made in the skin when the 7-dehydrocholesterol reacts with ultraviolet light of UVB type at wavelengths between and nm, with peak synthesis occurring between and nm.

Depending on the intensity of UVB rays and the minutes of exposure, an equilibrium can develop in the skin, and vitamin D degrades as fast as it is generated. Vitamin D from the diet or that is synthesized by the body is biologically inactive; activation requires enzymatic conversion in the liver and kidney.

Metabolism and pathway map for vitamin D: Vitamin D synthesis pathway. The blood vessels in the dermis provide nourishment and remove waste from its own cells and from the stratum basale of the epidermis. The epidermis does not contain blood vessels; instead, cells in the deepest layers are nourished by diffusion from blood capillaries that are present in the upper layers of the dermis. Diffusion provides nourishment and waste removal from the cells of the dermis, as well as for the cells of the epidermis.

The dermis: The distribution of the blood vessels in the skin of the sole of the foot. Corium—labeled at upper right—is an alternate term for dermis. Blood vessels that supply the capillaries of the papillary region are seen running through the reticular layer.