Human Physiology 1: The Integumentary System Week 6 PDF

The integumentary system Exercise Science: Human Physiology The Integumentary System  Integument is skin  Skin and its appendages make up the integumentary system  Two distinct regions  Epidermis  Dermis  A fatty layer (hypodermis) lies deep to it The Integumentary S...

The integumentary system Exercise Science: Human Physiology The Integumentary System  Integument is skin  Skin and its appendages make up the integumentary system  Two distinct regions  Epidermis  Dermis  A fatty layer (hypodermis) lies deep to it The Integumentary System  Yourintegumentary system is your body's outer layer. It consists of your skin, hair, nails and glands.  These organs and structures are your first line of defence against bacteria and help protect you from injury and sunlight.  Yourintegumentary system works with other systems in your body to keep it in balance. What is the integumentary system?  Organ system that protects the body from damage, comprising of the skin and its appendages (hair)  Largest organ in the body What are the major characteristics of the skin?  Waterproof,  Stretchable,  Washable,  Repairs small cuts, rips and burns  Sensitive  Surface area of up to 2.2 square meters  11 pounds (4.5Kg assumes body weight of @65Kg)  7% of total body weight Pliable yet tough Integumentary System  Multiple roles in homeostasis  (all body systems work in an interconnected manner to maintain the internal conditions essential to the function of the body)  Distinguishes, separates, protects and informs us with regard to its surroundings  Protects the body from damage Skin Layers  Skin  Pacinian corpuscle - a specialized bulblike nerve ending located in the subcutaneous tissue of the skin; occurs abundantly in the skin of palms and soles and joints and genitals. An encapsulated receptor found in deep layers of the skin that senses vibratory pressure and touch.  The arrector pili muscles are small muscles attached to hair follicles in mammals. Contraction of these muscles causes the hairs to stand on end - known colloquially as goose bumps.  Each arrector pili is composed of a bundle of smooth muscle fibres which attach to several follicles (a follicular unit), and is innervated by the sympathetic branch of the autonomic nervous system. Skin  The sebaceous glands are microscopic exocrine glands in the skin that secrete an oily or waxy matter, called sebum, to lubricate and waterproof the skin and hair of mammals.  A free nerve ending (FNE) is an unspecialized, afferent nerve ending, meaning it brings information from the body's periphery toward the brain. They function as cutaneous receptors and are essentially used by vertebrates to detect pain.  Meissner's corpuscles (or tactile corpuscles) are a type of mechanoreceptor. They are a type of nerve ending in the skin that is responsible for sensitivity to light touch. Epidermis  Top / uppermost layer  Consists of 4 layers  Structure – made up of 4 types of cells  Major cell - Keratinocyte produces keratin  Keratin is a fibrous protein that aids in protection.  Millions of dead keratinocytes rub off  Does not contain blood vessels  The rate of keratinocyte production equals the rate of loss. Keratinocytes Two weeks for a cell to journey from the stratum basale to the stratum granulosum. Four weeks to cross the stratum corneum. The entire epidermis is replaced by new cell growth in about 48 days. Dermis  Middle layer  Composed of  Collagen  Elastin  Contains  Nerve endings  Hair follicles  Glands Hypodermis/Subdermis  Under dermis  Composed of  Connective tissue  Adipose/fatty tissue  Main function  Insulation  Energy storage  Cushions therefore protecting against trauma Colour of skin Dependant on:  Presence of melanin – skin pigment  Vascularity of the dermis. When large amounts of blood pass through the dermis, i.e. after exercise-red complexion; or in cold situations - blue/ purple appearance  Numberof red blood cells, e.g. anaemia results in pale complexions Functions of the Integumentary System  Protection  Waterproof  Temperature regulation  Waste excretion  Vitamin D synthesis  Sensation Protection  Protects the body from external factors such as bacteria, chemicals, and temperature.  Skin contains secretions that can kill bacteria  The pigment melanin provides a chemical pigment defence against ultraviolet light that can damage skin cells. They will damage despite this but at lesser rate. Waterproof  Primarily concerned with prevention of fluid loss  Fatty secretions from sebaceous glands help to maintain waterproofing  Temperature Regulation  The hypothalamus acts as a thermostat and receives nerve impulses from heat and cold thermoreceptors in the skin.  There are also receptors in the hypothalamus- called central thermoreceptors. These detect changes in blood temperature. Body temperature is maintained by the following factors:  By regulating blood flow  By shivering  By sweating  By erection of body hair Functions continued  Waste excretion  the skin eliminates metabolic wastes like urea, lactic acid salts and water through sweating  Vitamin D synthesis  involves UVB radiation  which penetrates only the epidermal layers of skin  Sensation (Sensory reception)-contains host of nerve endings providing sensitivity to  touch and pressure  changes in temperature  pain Hair  Functions of hair  Warmth – less in man than other mammals  Sense light touch of the skin  Protection – scalp  Parts  Root imbedded in skin  Shaft projecting above skin surface  Make up of hair – hard keratin  Three concentric layers  Medulla (core)  Cortex (surrounds medulla)  Cuticle (single layers, overlapping) Vasoconstriction and Vasodilatation Keeping Warm  When it's cold, the muscle contracts pulls the hair up.  A layer of warm air accumulates around the hair and insulates the organism.  Heat retained Sweating How does it work? Heat energy in the body converts water to sweat which evaporates, therefore cooling down the body.  Correction of Overheating 1. Detected by thermoreceptors in the hypothalamus. 2. Causes vasodilation. 3. Sweating Cooling Down  When it's hot and you need to cool down, muscles at each hair relax.  Hairs lie close to the skin.  Air does not act as an insulating layer.  Correction of Overcooling 1.Detected by thermoreceptors in the hypothalamus. 2. Causes vasoconstriction. 3. Decreased sweating 4. Shivering Diseases and Injuries Possible diseases and injuries of the integumentary system include:  Rash  Blister  Athlete's foot - fungal infection  Infection  Sunburn  Skin cancer  Albinism  Acne  Herpes  Cold Sores  Plantar warts