Download Apocrine glands

Unit II: Organization
Integumentary System
Part II
Chapter 5
Skin Organs
Cutaneous Glands
Five types of Exocrine glands:
1. Merocrine sweat glands
2. Apocrine sweat glands
3. Sebaceous glands
4. Ceruminous glands
5. Mammary glands
Skin Organs
Cutaneous Glands
Sweat Glands (sudoriferous glands)
• Plasma and waste products
– 500 ml of insensible perspiration/day
– diaphoresis – visible sweating (1L/hr)
• Merocrine glands is a simple tubular gland
– millions of them help cool the body
• Apocrine glands produce sweat containing fatty acids
– found only near hair follicles after puberty
– Scent glands that respond to stress and sex
Skin Organs
Cutaneous Glands
Sebaceous Glands
Sebaceous gland
Lumen
(hair removed)
Wall of hair follicle
Basal lamina
Discharge of
sebum
Lumen
• Flask-shaped gland
– opens into hair follicle
– Some onto skin surface (pimples)
• Oily secretion called sebum
– contains broken-down cells, fat, wax
– lanolin in skin creams is sheep sebum
Breakdown of
cell membranes
Mitosis and
growth
Germinative
cells
Skin Organs
Cutaneous Glands
Ceruminous Glands
• Found only in external ear canal
• Produce cerumen
• Functions of earwax:
– waterproof
– keeps eardrum flexible
– bitterness repel mites and other pests
Skin Organs
Cutaneous Glands
Mammary Glands
• Developed glands found only during lactation and pregnancy
– modified apocrine sweat gland
– Produce milk (lactate)
– All individuals have undeveloped glands
– Must have high levels of estrogen to develop
• Mammary ridges or milk lines
– 2 rows of mammary glands
• Polythelia – additional nipples
– may develop along milk line
Skin Color
(Pigmentation)
• Melanin = yellow, brown, and black hues
– All individuals have same number of cells
– Cells stimulated by UV radiation to become more active
• Hemoglobin = red
• Carotene = yellow, orange from diet
– concentrates in stratum corneum and hypodermis
Skin Color
Abnormalities
• Cyanosis = blueness from deficiency of oxygen in the circulating
blood (cold weather)
• Erythema = redness due to dilated cutaneous vessels (anger,
sunburn, embarrassment)
• Jaundice = yellowing of skin and whites of the eyes due to excess
bilirubin in blood (liver malfunction)
Skin Color
Abnormalities
• Pallor = pale color from lack of blood flow, dermal collagen
shows thru (low blood pressure, emotional stress)
• Albinism = a genetic lack of melanin
• Hematoma = a bruise (visible clotted blood)
Skin Markings
• Friction ridges
– formed during fetal development
– Unique pattern even for identical twins
• Flexion lines
– Formed where skin folds during flexion of joint
• Freckles and moles =
– Aggregation of melanocytes
– freckles are flat; moles are elevated
• Hemangiomas
– discolored skin caused by benign tumors of dermal blood
capillaries
Tissue Repair
• Regeneration
– replacement of damaged cells with original cells
– Restores original function
– Epidermis and liver
• Fibrosis
– replacement of damaged cells with scar tissue (collagen)
• Function is not restored
• healing muscle injuries, scarring of lung tissue in TB or
healing of severe cuts and burns of the skin (dermis)
Wound Healing
Initial Injury
Immediately after the
injury, mast cells in
the region trigger an
inflammatory
response.
Bleeding
occurs at the
site of injury.
Epidermis
Dermis
Plasma carries:
•Antibodies
•Clotting factors
•WBCs
Wound Healing
After Several Hours
Blood clot forms to decrease blood loss
and spread of microbes
Macrophages patrol the
damaged area
Cells of the stratum
basale undergo rapid
divisions to replace
missing cells
Wound Healing
After One Week
• New capillaries grow
into wound
• Fibroblasts deposit new
collagen to replace old
material
• Fibroblastic phase
begins in 3-4 days and
lasts up to 2 weeks
Fibroblasts
Wound Healing
•
•
•
•
•
After Several Weeks
Epithelial cells multiply and
spread beneath scab
Scab falls off
Epithelium thickens
Connective tissue forms
only scar tissue (fibrosis)
Remodeling phase may last
2 years
Scar
tissue
Tissue Engineering
• Production of tissues and organs in the lab
– Build a scaffold - polyester or collagen fibers
– seeded with human cells
– grown in “bioreactor” to supply O2 and nutrients
• Skin grafts already available
– research in progress on heart valves, coronary arteries, bone,
liver, tendons
Skin Disorders
Burns
• Hot water, sunlight, radiation, electric shock or acids and bases
• Leading cause of accidental deaths from:
• fluid loss – loose up to 75% of plasma within a few hours
• infection
• Treatment – nutrition and fluid replacement, debridement and
infection control
Skin Disorders
Burns
(a) First degree
(b) Second degree
(c) Third degree
Cancer
• Tumors “swelling”
– abnormal growth, cells multiply faster than they die
• Benign = not cancer
– slow growth, connective tissue capsule, stays local
• Malignant tumor = cancer
– 3 properties:
– fast growing
– unencapsulated
– metastatic
– stimulate angiogenesis
Causes of Cancer
• Carcinogens – environmental cancer-causing agent
– chemical = cigarette tar, food preservatives, industrial chemicals
– Radiation = gamma and UV
• Bone density scan = 1 day of natural radiation
• X-rays = 10 days
• CT scans = varies (head = 8 months; abdomin/spine = 3 yrs)
– Viruses = type 2 herpes simplex - uterus, hepatitis C - liver
Carcinogens
• Mutagens = Carcinogens – trigger gene mutations
• Defenses against mutagens and tumors
− Scavenger cells – remove mutagens
− Peroxisomes – neutralizes free radicals
− Nuclear enzymes – detect & repair damaged DNA
− Natural killer cells – immune surveillance
− Macrophages and monocytes secrete tumor necrosis factor
Malignant Tumors
Two types of genes responsible:
• Oncogenes – tells a cell to grow
– sis oncogene causes excessive production of growth factors
– ras oncogene codes for abnormal growth factor receptors
– ¼ of human cancers
• Tumor suppressor genes (TS)
– Tells a cell to stop growing
– damage to both removes control of cell division
– ½ the cases of Leukemia, colon, lung, breast, liver, brain
• Requires 5-10 mutations at different loci
• Death results from metastasis not the original tumor
Skin Disorders
Skin Cancer
• 90% of malignancies are carcinomas
• High rate of mitosis
• More exposed to carcinogens
• All skin cancers are malignant!
• Induced by UV rays of the sun
– basal cell carcinoma
• arises from stratum basale and invades dermis
• Most common
• Easiest to treat
Skin Disorders
Skin Cancer
– squamous cell carcinoma
• arises in stratum spinosum
• metastasis to the lymph nodes can be lethal
Skin Disorders
Skin Cancer
– malignant melanoma
• Commonly arises from melanocytes of a preexisting mole
• Least common
• Most deadly
• ABCDE--asymmetry, border irregular, color
mixed and diameter over 6 mm, evolving
Skin Disorders
UVA, UVB
• UVA and UVB are improperly called “tanning rays” and
“burning rays”
• As sale of sunscreens has risen so has skin cancer
– Does not protect against skin cancer, just sunburns!
– Higher incidence of basal cell carcinoma because people
falsely assume they can stay out longer
– Some chemicals in sunscreen may damage DNA and
generate harmful free radicals when exposed to UV rays
• Sunblock is better because it scatters and reflects UV rays
• Learn more at http://www.ewg.org/2013sunscreen/
Exam 1
Chapters: 3, 4, 5
• Fill in the blank
• Multiple Choice
• Matching
• Short answer
• True/False
Spelling matters!
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