Lecture Exam 2 Study Guide Flashcards
What is the largest organ in the body?
The Skin. Approx 2 sq. meters
What is another term for the skin?
The cutaneous membrane.
What is the cutaneous membrane?
The skin
Skin represents 16% of the total body weight and varies in thickness depending on the proctective functions needed in the particular location. What is the thinnest and thickest area?
Thinnest: eyelids, about 0.5mm thick Thickest: heel, about 4mm thick
Define Term: Epidermis
Epithelial Layer of skin
Define Term: Dermis
connective tissue layer containing blood vessels, beneath dermis
What are the accessory structures for the skin?
hair, nails, exocrine glands (sweat glands, sebaceous glands) , associated muscle and nerves
Define and give relative proportion in the skin: Keratinocyte
Most common skin cell - 90% of the cells in skin. Name comes from the type of intermediate filaments they contain. keratin.
Define and give relative proportion in the skin: Melanocytes
About 8% of the skin. Located in basal layer. Produce the pigment melanin that provides skin color. (Melanin absorbs UV light and helps protect skin from damaging effects of the sun)
Define and give relative proportion in the skin: Langheran’s cells
<2% of the skin. immune cells that migrate into skin from blood. Involved in defense. A type of resident dendritic cell – most tissues have a specialized type fo dendritic cell.
Define and give relative proportion in the skin: Merkel cells
Least numerous cell type in skin. Located in basal layer of skin in contact with sensory neurons. Involved in sense of touch (tactile response)
What is the function of Keratin and where would you find it? What is Keratin?
Keratin is a tough, fibrous protein that helps protect the skin and underlying tissues from abrasions, heat, microbes, and chemicals. Keratin is found in Keratinocytes in the epidermis, hair, and nails.
What are the layers of the epidermis and their locations:
Stratum Corneum, Stratum Lucidum, Stratum Granulosum, Stratum Spinosum, Stratum Basale
Put the layers of the epidermis in layer from apical to basal:
Stratum Corneum, Stratum Lucidum, Stratum Granulosum, Stratum Spinosum, Stratum Basale
Where are dividing cells located in the epidermis?
The basal layer of cells
What direction to keratinocytes migrate in the epidermis?
From the basal layer to the superficial zones.
What is the difference between thin and thick skin?
Thin skin has four layers (stratum basale, stratum spinosum, stratum granulosum, and a thin stratum corneum). Thick skin has five layers in the epidermis (stratum basale, stratum spinosum, statum granulosum, stratum lucidum, and a thick stratum corneum). Thick skin is found where exposure to friction is greatest, e.g. fingertips, pals, soles, etc.
Know the major features of the pathology of Psoriasis
Keratinocytes divide more quickly and migrate more quickly from stratum basale to stratum corneum. The Keratinized layer is abonormal (flaky and sore)
What are the three pigments that contribute to skin color?
Melanin, Hemoglobin, and Carotene
How is hair color determined?
Two forms of melanin, pheomelanin (yellow to red) and eumelanin (brown to black)
Why do we vary in skin color?
The number of melanocytes in similar in all people. It is the amount of melanin that the melanocytes can synthesize and the amount that can be transferred to keratinocytes that varies to alter skin color.
What happens when melanin in unevenly distributed?
moles, freckles, aging spots
What is an albino?
someone with the inherited inability to produce melanin.
Define the area we call the dermis. How would you classify the connective tissue fo the dermis?
The dermis is the connective tissue underlying the epidermis and the specialized structures found there. Dense irricular connective tissue - contains collagens, proteoglycans and glycosaminoglycans, cells, blood vessels, nerves, and exocrine glands.
What are the differences between the papillary and the reticular regions of the dermis?
Papillary region: Superficial portion of dermis (about one-fifth); consists of dense irregular connective tissue with thin collagen and fine elastic fibers; contains dermal ridges that house capillaries, Meissner corpuscles, and free nerve endings. Reticular region: Deeper portion of dermis (about four-fifths); consists of dense irregular connective tissue with thick collagen and some coarse elastic fibers. Spaces between fibers contain some adipose cells, hair follicles, nerves, sebaceous glands, and sudoriferous glands.
Know the structural features of a hair and hair follicle
Hair shaft, most of which is superficial to the surface, and a root that penetrates the dermis and sometimes the subcutaneous layer, and a hair follicle. Associated with eat hair follicle is a sebacious (oil) gland, an arrector pili muscle, and a hair root plexus.
With respect to hair, know the meaning of the term: Bulb
The base of each hair follicle and its surrounding dermal root sheath, and onion-shaped structure
With respect to hair, know the meaning of the term: papilla of hair
within the bulb, nipple shaped indentation which contains areolar connective tissue and many blood vessels that nourish the growing hair follicle.
With respect to hair, know the meaning of the term: Cuticle of hair
the outermost layer of the hair, consists of a single layer of thin, flat cells that are most heavily keratinized.
With respect to hair, know the meaning of the term: Matrix
In the bulb, germinal layer of cells. The hair matrix cells arise from the stratum basale, and give rise to the cells of the internal root sheath.
With respect to hair, know the meaning of the term: Arrector pili
smooth muscle that extends from the superficial dermis of the skin to the dermal root sheath around the side of the hair follicle. Pull the hair perpendicular to the skin surface under physiological or emotional stress (e.g. cold or fright)
With respect to hair, know the meaning of the term: shaft and root
the shaft is the superficial portion of the hair which projects above the surface of the skin. The root is the portion of the hair deep to the shaft that penetrates into the dermis and sometimes into the subcutaneous layer.
Where do you find sebaceous glands? what do they secrete? How do they secrete? Where do they secrete?
-oil glands -simple, branched acinar glands -connected to hair follicles (with few exceptions) -secreting portion is in the dermis, and opens into the neck of a hair follicle. -secrete sebum, an oily mixture of triglycerides, cholesterol, proteins, and inorganic salts. Holocrine secretion.
What are the two types of sweat glands?
Eccrine (merocrine) and apocrine
What is a sudiferous gland?
A sweat gland
What do ceruminous glands do?
Secrete ear wax
Know the terms in the textbook diagram for a nail
Nail body = plate Lunula = lighter half moon at base of nail Nail root = root of nail beneath cuticle. Eponychium = cuticle Hyponychium = nail bed Nail Matrix = portion of the epithelium deep to the nail root, cells divide mitotically to produce new nail cells
What is the hard part of the nail made of?
tightly packed, dead, keratinized epidermal cells
Describe how the skin performs the following function: thermoregulation
-liberating sweat -raising/lowering hairs -dilating or constricting the capillaries to regulate blood flow to the surface of the body
Describe how the skin performs the following function: Blood reservoir
The dermis has an extensive capillary netword. Can hold as much as 10% of the total blood volume
Describe how the skin performs the following function: Protection
physical protection - against heat, drying out, UV immune protection - against bacteria, viruses, chemicals
Describe how the skin performs the following function: Cutaneous sensations
Contact with the outside world by sensing touch, vibrations, heat, cold, tickling, pain
Describe how the skin performs the following function: Excretion and Absorption
-water evaporation in form of sweat -some lipid soluble substances can be absorbed by skin (useful in drug delivery)
Describe how the skin performs the following function: Synthesis of Vitamin D
An inactive precurser of vitamin D is activated in skin by UV light and then converted to active Vit. D by enzymes in the liver and kidney
What are the differences in how a superficial epidermal wound and a deep wound would heal?
superficial wound - does not extend into the dermis. repaired by enlargement and migration of basal epidermal cells, stopping upon meeting cells from the oposite side of the wound due to contact inhibition. deep wound - injury extends to the dermis and subcutaneous layer. Inflammatory phase (blood clot forms in the wound and loosely unites the wound edges), a migratory phase, and proliferatuve phase and a maturation phase. fibrosis occurs (scar tisue is created to fill the wound).
How does the skin contribute to the homeostatic control of the following organ system: Skeletal System
Skin helps activate Vitamin D, needed for proper absorption of dietary calcium and phosphorus to build and maintain bones.
How does the skin contribute to the homeostatic control of the following organ system: Muscular System
Skin helps provide calcium ions, needed for muscle contraction
How does the skin contribute to the homeostatic control of the following organ system: Nervous System
Nerve endings in skin and subcutaneous tissue provide input to brain for touch, pressure, therman, and pain sensations
How does the skin contribute to the homeostatic control of the following organ system: Endocrine System
Keratinocytes in skin help active vitamin D to calcitriol, a hormone that aids absorption of dietary calcium and phosphorus
How does the skin contribute to the homeostatic control of the following organ system: Cardiovascular System
Local chemical changes in dermis cause widening and narrowing of skin of blood vessels, which help adjust blood flow to skin.
How does the skin contribute to the homeostatic control of the following organ system: Lymphatic System and immunity
“first line of defense” in immunity, providing mechanical barriers and chemical secretions that discourage penetration and growth of microbes; Langerhans cells in epidermis participate in immune responses by recognizing and processing foreign antigens; macrophages in dermis phagocytize microbes that penetrate skin surface.
How does the skin contribute to the homeostatic control of the following organ system: Respiratory System
Hairs in nose filter dust particles from inhaled air; stimulation of pain nerve endings in skin may alter breathing rate
How does the skin contribute to the homeostatic control of the following organ system: Urinary System
Kidney cells receive partially activated vitamin D hormone from skin and convert it to calcitriol; some waste products are excreted from body in sweat, contributing to excretion by urinary system.
How does the skin contribute to the homeostatic control of the following organ system: Reproductive system
Nerve endings in skin and subcutaneous tissue respond to erotic stimuli, thereby contributing to sexual pleasure; suckling of a baby stimulates nerve endings in skin, leading to milk ejection, mammary glands (modified sweat glands) produce milk; skin stretches during pregnancy as fetus enlarges.
Note that the protective and thermoregulatory roles of skin are important for the homeostatic control of all body systems.
This is just a note.
Understand how bone achieves each of the following functions: Support
-structural framework -supports tissues and provides attachment points for tendons of skeletal muscles
Understand how bone achieves each of the following functions: Protection
-protects internal organs (cranial bones protect skull, rub cage protects heart and lungs. lower ribs protect kidneys)
Understand how bone achieves each of the following functions: Assistance in Movement
skeletal muscles attach to bones as structure framework, enabling movement.
Understand how bone achieves each of the following functions: Mineral Homeostatis
-stores calcium and phosphorus in bone mineral -maintains homeostatic control of blood concentration of calcium and phosphorus under the control of hormones.
Understand how bone achieves each of the following functions: Blood Cell Production
Red bone marrow produces blood cells