integumentary system includes the somatic senses
TRANSCRIPT
Integumentary System Includes the Somatic Senses
2
Skin and Its TissuesThe skin is a large organ responsible for
maintaining homeostasis through
temperature regulation
protection of underlying tissues
retardation of water loss
housing sensory receptors
synthesizing certain chemicals
and excreting wastes
CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.
3
Regulation of Body Temperature
The skin plays a major role in temperature regulation with the hypothalamus controlling it.
Active cells, such as those of the heart and skeletal muscle, produce heat.
Heat may be lost to the surroundings from the skin through radiation.
The body responds to excessive heat by dilation of dermal blood vessels and sweating.
The body responds to excessive cooling by constricting dermal blood vessels, inactivating sweat glands, and shivering.
CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.
4
The skin consists of an outer epidermis and a dermis, connected to underlying
tissue by the subcutaneous layer (hypodermis).
CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.
5
EpidermisThe epidermis is made up of stratified squamous
epithelium and lacks blood vessels.
The layer of reproducing cells (the stratum basale), which lies at the base of the epidermis ,is well-nourished by dermal blood vessels.
Cells are pushed outward as new cells are formed, and become keratinized as they die.
Four or five layers may be seen: stratum basale, stratum spinosum, stratum granulosum, and stratum corneum are always present and the stratum lucidum is found in the thicker palms and soles.
CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.
6
EpidermisThe epidermis is
important because it protects against water loss, mechanical injury, chemicals, and microorganisms.
Melanocytes, which lie deep in the epidermis and underlying dermis, produce a pigment called melanin that protects deeper cells from the sun’s ultraviolet rays.
CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.
7
Skin Color
Skin color results from a combination of genetic, environmental, and physiological factors.
Genetic differences in skin color result from differing amounts of melanin and in the size of melanin granules.
Exposure to sunlight causes darkening of skin as melanin production increases.
Circulation within dermal blood vessels affects skin color.
CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.
8
Dermis
The dermis binds the epidermis to underlying tissues.
Epidermal ridges and dermal papillae cause the border to be uneven.
The dermis consists of connective tissue with collagen and elastic fibers within a gel-like ground substance.
Dermal blood vessels carry nutrients to upper layers of skin and help to regulate temperature.
The dermis also contains nerve fibers, sensory fibers, hair follicles, sebaceous glands, and sweat glands.
CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.
9
CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.
10
Subcutaneous Layer
The subcutaneous layer (hypodermis) is composed of loose connective tissue and insulating adipose tissue.
It binds the skin to underlying organs and contains the blood vessels that supply the skin.
No sharp boundary exists between the dermis and subcutaneous layer.
CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.
11
Nails
Nails are protective coverings over the ends of fingers and toes.
Nails consist of stratified squamous epithelial cells overlying the nail bed, with the lunula as the most actively growing region of the nail root.
As new cells are produced, older ones are pushed outward and become keratinized.
CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.
12
•
CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Hair can be found in nearly all regions of the skin.
Individual hairs develop from cells at the base of the hair follicle.
As new cells are formed, old cells are pushed outward and become keratinized, and die forming the hair shaft.
Hair Follicles
13
14
A bundle of smooth muscle cells, called the arrector pili muscle, attaches to each hair follicle. These muscles cause goose bumps when cold or frightened.
Hair color is determined by genetics; melanin from melanocytes is responsible for most hair colors. Dark hair has eumelanin while blonde and red hair have pheomelanin.
CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Hair
15
Sebaceous glands (oil glands) are associated with hair follicles and secrete sebum that waterproofs and moisturizes the hair shafts.
CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Sebaceous Glands
16
Sudoriferous Glands
Sudoriferous glands (sweat glands): eccrine - respond to body
temperature apocrine - respond to body
temperature, stress, and sexual arousal
Modified sweat glands secrete wax in the ear canal.
Mammary glands, another modified type of sweat glands, secrete milk.
CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.
17
18
Skin as a Sensory Receptor
Sensory receptors detect changes in the environment and stimulate neurons to send nerve impulses to the brain.
There are 5 types of sensory receptors and 3 of these are types are found in the skin.
CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.
19
Types of Receptors
Five general types of receptors are recognized.
1. Receptors sensitive to changes in chemical concentration are called chemoreceptors.
2. Pain receptors detect tissue damage.
3. Thermoreceptors respond to temperature differences.
4. Mechanoreceptors respond to changes in pressure or movement.
5. Photoreceptors (rods and cones in the retina of the eyes) respond to light energy.
CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.
20
Somatic Senses
Receptors associated with the skin, muscles, joints, and viscera make up the somatic senses.
CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.
21
Touch and Pressure Senses
Three types of receptors detect touch and pressure.
1. Free ends of sensory nerve fibers in the epithelial tissues are associated with touch and pressure.
2. Meissner's corpuscles are flattened connective tissue sheaths surrounding two or more nerve fibers and are abundant in hairless areas that are very sensitive to touch, like the lips.
3. Pacinian corpuscles are large structures of connective tissue and cells that resemble an onion. They function to detect deep pressure.
CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.
23
Temperature Senses
Temperature receptors include two groups of free nerve endings: heat receptors and cold receptors which both work best within a range of temperatures.
Both heat and cold receptors adapt quickly.
Temperatures near 45o C stimulate pain receptors; temperatures below 10o C also stimulate pain receptors and produce a freezing sensation.
CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.
24
Sense of Pain Pain receptors consist of free nerve endings that are
stimulated when tissues are damaged, and adapt little, if at all.
Many stimuli affect pain receptors such as chemicals and oxygen deprivation.
Visceral pain receptors are the only receptors in the viscera (organs within a cavity like the abdominal cavity) that produce sensations.
Referred pain occurs because of the common nerve pathways leading from skin and internal organs.
CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.
25
Referred Pain Chart
26
Pain Nerve Fibers CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Fibers conducting pain impulses away from their source are either acute pain fibers or chronic pain fibers. Acute pain fibers are thin, myelinated fibers that
carry impulses rapidly and cease when the stimulus stops.
Chronic pain fibers are thin, unmyelinated fibers that conduct impulses slowly and continue sending impulses after the stimulus stops.
Pain impulses are processed in the gray matter of the dorsal horn of the spinal cord.
Pain impulses are conducted to the thalamus, hypothalamus, and cerebral cortex.
27
Regulation of Pain Impulses
A person becomes aware of pain when impulses reach the thalamus, but the cerebral cortex judges the intensity and location of the pain.
Other areas of the brain regulate the flow of pain impulses from the spinal cord and can trigger the release of enkephalins and serotonin, which inhibit the release of pain impulses in the spinal cord.
Endorphins released in the brain provide natural pain control.
CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.
28
Healing of Wounds and Burns
Inflammation, in which blood vessels dilate and become more permeable, causing tissues to become red and swollen, is the body's normal response to injury.
Superficial cuts are filled in by reproducing epithelial cells.
Deeper cuts are closed off by clots, covered by scabs, and eventually filled in by fibroblasts, making connective tissue.
Blood vessels extend into the area, injured tissues are replaced, and the scab falls off.
Large wounds leave scars and healing may be accompanied by the formation of granulations.
CopyrightThe McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Keloid Scars• result of an overly
aggressive healing process
• extend beyond the original injury
• may affect mobility
• Possible treatments include surgical removal, or injections with steroids
Contracture scars
• If your skin has been burned, you may have a contracture scar, which causes tightening of skin that can impair your ability to move; additionally, this type of scar may go deeper to affect muscles and nerves.
Hypertrophic scars
• Raised and red scars that are similar to keloids, but do not breach the boundaries of the injury site.
• Possible treatments can include injections of steroids to reduce inflammation.
Acne Scars
• If you've had severe acne, you probably have the scars to prove it.
FYI……
• Epithelial Tissue regenerate easily.
• Connective tissue including bone regenerate easily as well.
• Skeletal Muscle regenerates poorly, if at all.
• Cardiac Muscle and Nervous tissue are replaced only by scar tissue.
Imbalances of the Skin
• Infections and Allergies• Athlete’s Foot• Boils and Carbuncles• Cold Sores• Contact dermatistis• Impetigo• Psoriasis
• Burns• 1st degree• 2nd degree• 3rd degree
• Skin Cancer• Basal cell carinoma• Squamous cell carcinoma• Malignant melanoma• ABCD RULE
• Other Disorders• Erythema• Pallor• Jaundice• Decubitus ulcer• bruises
Infections and Allergies
• Athlete’s Foot: • itchy fungal infection of the toes
Infections and Allergies
• Boils and Carbuncles: • inflammation of
hair follicles and sebaceous glands
Infections and Allergies
• Cold Sores: • fever blisters;
small fluid filled blisters that itch an sting, caused by herpes simples infection
Infections and Allergies
• Contact dermatitis: • itching, redness, and
swelling of the skin, progressing to blistering• Caused by exposure of
the skin to chemicals like poison ivy that provoke allergic responses
Infections and Allergies
• Impetigo• Pink, water-filled
raised lesions that develop a yellow crust and eventually rupture• Causes by a highly
contagious staphylococcus infection
Infections and Allergies• Psoriasis• Chronic condition characterized
by reddened epidermal lesions covered with dry, silvery scales
Other Skin Disorders
• Jaundice• an abnormal yellow skin
tone usually indicates a liver disorder in which excess bile pigments are absorbed into the blood, circulated throughout the body, and deposited in body tissues.
Other Skin Disorders
• Decubitus ulcer• Restriction of blood
supply to the skin results in cell death, and if severe or prolonged, ulcers.
• Occur in bedridden patients who are not turned regularly
Other Skin Disorders
• Bruises• Reveal sites where blood has escaped from
the circulation and has clotted in the tissue spaces
• Hematoma: clotted blood mass• An unusual tendency to bruising may signify a
deficiency of vitamin C in the diet or hemophilia
Burns
• Tissue damage and cell death caused by intense heat, electricity, UV radiation (sunburn), or certain chemicals (acids)
• When the skin is burned, two life threatening problem result:• Dehydration• Infection
1st threat: Dehydration
• The body loses fluids containing proteins and electrolytes
• This can lead to a shutdown of the kidneys and circulatory shock
2nd threat: Infection
• Leading cause of death
• Burned skin is sterile for about 24 hours, but after that pathogens easily invade and multiply rapidly
Rule of Nines• Divides the body area into 11 areas, each
accounting for 9 percent of the total body surface, plus 1% surrounding the genitals
BURNS
Burns
• 1st degree• Only the epidermis
is damaged• Becomes red and
swollen• Not usually serious
and generally heal in two to three days without any special attention• sunburn
Burns• 2nd degree• Involve injury to the
epidermis and the upper region of the dermis
• Skin is red and painful and blisters appear
• Re-growth of the epithelium can occur
• No permanent scars result if care is taken to prevent infection
Burns• 3rd degree• Destroy the entire
thickness of the skin• Appears gray-white or
blackened • Nerve endings are
destroyed so the burn is not painful
• Regeneration is not possible
• Skin grafting must be done to cover the underlying exposed tissues
Burns
• Considered critical if any of the following conditions exists:• 1. Over 25 % of the body has 2nd degree burns• 2. Over 10% of the body has 3rd degree burns• 3. Any third-degree burn of the face, hands,
or feet
Skin Cancer
• Most skin tumors are benign and do not spread
• Some are malignant (cancerous) and tend to invade other parts of the body
• Skin cancer is the most common type of cancer in the body
Basal Cell Carcinoma
• Least malignant and most common
• Full cure rate in 99% of patients
Squamous Cell Carcinoma
• Believed to be sun-induced
• If it is caught early and removed surgically, good chance of complete cure
Malignant Melanoma• Cancer of the
melanocytes
• Accounts for 5% of skin cancers
• Often deadly
• Usually appears as a spreading brown to black patch that metastasizes rapidly to surrounding lymph and blood vessels
ABCD Rule
• Asymmetry: the two sides of the pigmented spot of mole do not match
• Border Irregularity: The borders of the lesion are not smooth but exhibit indentations
• Color: the pigmented spot contains areas of different colors
• Diameter: the spot is larger than 6 mm in diameter (size of pencil eraser)