A&P Chap 4-5 Flashcards
(168 cards)
1
Q
What are the four basic tissue types?
A
- epithelial
- connective
- muscle
- nervous tissue
2
Q
To be viewed under a microscope, tissue must be:
A
- Fixed: preserved with solvent
- Sectioned: cut into slices thin enough to transmit light or electrons
- Stained: to enhance contrast
3
Q
Colored dyes are used in _______ microscopy and metal coatings are used in _______ microscopy.
A
Light and electron
4
Q
What is epithelial tissue (epithelium)?
A
A sheet of cells that covers body surfaces or cavities.
5
Q
What are two forms of epithelial tissues?
A
- Covering and lining epithelia: on external and internal surfaces (e.g. skin, organs)
- Glandular epithelia: secretory tissue in glands e.g. salivary glands
6
Q
What are the functions of epithelial tissue?
A
- Protect
- Absorb
- Filter
- Exert
- Secrete
- Sensory reception
7
Q
What are the five distinguishing characteristics of epithelial tissue?
A
- Polarity
- Specialized contacts
- Supported by connective tissues
- Avascular, but innervated
- Regeneration
8
Q
What are the two surfaces of cell polarity?
A
- Apical surface: upper free side, exposed to surface or cavity
- Basel surface: lower attached side, faces inwards toward body
9
Q
What are the characteristics of an apical surface?
A
- Smooth
- Some have specialized finger-like projections called microvilli
10
Q
What are the characteristics of basal surface?
A
- Attaches to basal lamina, an adhesive sheet that holds basal surface of epithelial cells to underlying cells
11
Q
How do epithelial cells have specialized contacs?
A
They fit closely together to form continuous sheets.
The sides of cells are tied together by tight junctions and desmosomes. (Prevent substances from leaking through spaces between cells and desmosomes keep cells from pulling apart)
12
Q
What are the function of the basement membrane and the names of the two types of layers?
A
- Reinforces the epithelial sheets
- Resist stretching and tearing
- Defines the epithelial boundary
Basal lamina
Reticular lamina
13
Q
What is reticular lamina?
A
- Deep to basal lamina
- Consists of a network of collagen fibers
14
Q
How are epithelial cells nourished?
A
By substances diffusing from blood vessels in the underlying connective tissue.
They are avascular (contains no blood vessels) and innervated (supplied by nerve fibers).
15
Q
What are the causes of epithelial cells to regenerate through cell division?
A
- Exposed to high friction causing surface cells to rub off
- Damaged by hostile substances e.g. bacteria, acids, smoke
- Apical-basal polarity and lateral contacts are destroyed
16
Q
What are the characteristics of simple epithelia?
A
- Consists of a single-cell layer
- Found where absorption, secretion, and filtration occur
- A thin epithelial barrier is desirable
17
Q
What are the characteristics of stratified epithelia?
A
- Composed of two or more cell layers stacked
- New cells regenerate from below (basal cells divide and migrate toward surface)
- More durable than simple epithelia
- Protection is the major role
- Common in high-abrasion areas
e.g. skin surface and the lining of the mouth
18
Q
Describe the following shapes of cells:
1. Squamous
2. Cuboidal
3. Columnar
A
- flattened and scale-like
- Box-like, cube
- Columnar: tall, column-like
19
Q
How do you determine the second name of a cell in stratified epithelia?
A
According to the shape in apical layer
20
Q
Where can simple squamous epithelium be found and what are their functional characteristics?
A
E.g. Kidney glomeruli; air sacs of lungs;
lining of heart, blood vessels, and lymphatic
vessels; serosae.
- Where filtration or the exchange of substances by rapid diffusion is a priority
- Secretes lubricating substances in serosae (lining of ventral body cavity)
21
Q
What are the characteristics of simple squamous epithelium
A
- Single layer
- Flattened cells
- Disc-shaped central nuclei
- Sparse cytoplasm
22
Q
Name two examples of simple squamous epithelium and their locations
A
- Endothelium: lining of lymphatic vessels, blood vessels and heart. Provides a slick, friction-reducing lining. Its exceptional thinness encourages the efficient exchange of nutrients and wastes btwn the bloodstream and surrounding tissue cells.
- Mesothelium: serous membranes in the ventral body cavity
23
Q
What are the characteristics of simple cuboidal epithelium?
A
- Single layer of cube-like cells
- Large, spherical central nuclei
24
Q
Where can simple cuboidal epithelium be found and what are their key functional characteristics?
A
E.g. Kidney tubules, ducts and secretory portions of small glands, ovary surface
- Secretion and absorbtion
25
What are the characteristics of simple columnar epithelium?
- Single layer of tall cells
- Round to oval nuclei
- Many bear microvilli, some bear cilia
- Layer may contain mucus-secreting unicellular glands (goblet cells)
- Involved in absorption and secretion of mucus, enzymes, etc.
26
Where can simple columnar epithelium be found?
E.g. digestive tract, gallbladder, ducts of some glands, bronchi and uterine tubes
27
What are the characteristics of pseudostratified columnar epithelium? Where can they be found?
- Single layer of cells of different heights, some not reaching the surface
- Nuclei seen at different levels
- Many contain mucus-secreting cells and bear cilia
E.g. Lining of trachea and most of the upper respiratory tract, ducts of large glands, tubules in testes
28
What are the functional characteristics of pseudostratified columnar epithelium?
- Secrete substances, e.g. mucus
- Propulsion of mucus by ciliary sweeping action
29
What are the characteristics of stratified squamous epithelium?
- Thick, several layers
- Basal cells are cuboidal or columnar
- Metabolically active
- Surface cells are flattened (squamous)
- Sufrace cells are full of keratin and dead in keratinized type
- Basal cells are active in mitosis and produce the cells of the more superficial layers
30
What's the functional characteristic of stratified squamous epithelium?
Protects underlying tissues in areas subjected to abrasion
31
Where can stratified squamous epithelium be found?
- Nonkeratinized type forms the moist linings of the esophagus, mouth, and vagina
- Keratinized type forms the epidermis of the skin, a dry epithelium
32
What are the characteristics of transitional epithelium?
- Resembles both stratified squamous and stratified cuboidal
- Basal cells are cuboidal or columnar
- Surface cells are dome-shaped or squamouslike, depending on the degree of organ stretch
33
What are the functional characteristics of transitional epithelium?
- Stretches readily
- Permits stored urine to distend urinary organ
34
Where can transitional epithelium be found?
Lining of the uterus, bladder and part of the urethra
35
Name two types of glands and their characteristics and examples
1. Endocrine:
- Internally secreting
- Ductless (lose duct during development)
- Secretions released into surrounding interstitial fluid, then picked up by circulatory system
- Most are multicellular
e.g. hormones
2. Exocrine:
- Externally secreting onto skin or into body cavities
- Secrete into ducts
- Can be unicellular or multicellular
e.g. mucous, sweat, oil, saliva, liver, pancreas etc.
36
What are the two main unicellular exocrine glands and where can they be found?
Mucous cells and goblet cells.
- Found in the epithelial linings of the intestinal and respiratory tracts.
- All produce mucin, can dissolve in water
37
What are the characteristics of multicellular exocrine glands?
- Composed of a duct and a secretory unit
- Surrounded by supportive connective tissue that supplies blood and nerve fibers to gland
- Simple exocrine glands: unbranched ducts
- Compound glands: branched ducts
- Tubular or alveolar
38
In a tubular gland, secretory cells form a _______ whereas in alveolar glands, cells form ______.
duct, sacs
39
What are the three modes of secretion of multicellular exocrine glands?
Merocrine, holocrine and apocrine.
40
What are examples of merocrine glands?
Pancreas, sweat glands and salivary gland
41
What is an example of holocrine glands?
Sebaceous glands
42
What are the four classes of connective tissues?
- Connective tissue proper
- Cartilage
- Bone
- Blood
43
What are the functions of connective tissues?
- Binding and supporting
- Protecting
- Insulating
- Storing reserve fuel
- Transporting substances within body
44
All connective tissues arise from ________.
Mesenchyme (an embryonic tissue)
45
What are the three main components of connective tissues?
- Ground substance
- Fibers
- Cells
46
The extracellular matrix is made up of which two components?
Ground substance and fibers
47
What are the three unique characteristics of connective tissues?
- Have common embryonic origin
- Have varying degrees of vascularity
- Cells are suspended/embedded in extracellular matrix (support cells to bear weight, withstand tension, endure abuse)
48
What is a ground substance
The unstructured material that fills the space between the cells and contains the fibers.
49
What is ground substance and what are the three components?
An amorphous gel-like substance in the extracellular space that contains all components of the extracellular matrix (ECM) except for fibrous materials such as collagen and elastin.
1. Interstitial fluid
2. Cell adhesion proteins
3. Proteoglycans
50
What are the three types of connective tissue fibers?
- Collagen: strongest and most abundant. Provides high tensile strength
- Elastic fibers: network of long, thin elastin fibers that allow stretch and recoil.
- Reticular: short, fine, highly branched collagenous fibers. Offer more give. Surround small blood vessels and support soft tissue of organs.
51
What is the difference between blast and cytes cells?
Blast cells build new matrix. Immature. Actively secretes ground substance and ECM fibers
Cyte cells maintain existing matrix. Less active.
52
What are four examples of blast cells?
- Fibroblasts (found in connective tissue proper)
- Chondroblasts (in cartilage)
- Osteoblasts (in bone)
- Hematopoietic stem cells (in bone marrow)
53
What are other cell types in connective tissues aside from the main three?
- Fat cells (store nutrients)
- White blood cells (neutrophils, eosinophils, lymphocytes)
- Mast cells (initial local inflammatory response)
- Macrophages (phagocytic cells)
54
What are the two subclasses of connective tissue proper? And what are they?
Loose and dense
- Loose: areolar, adipose, reticular
- Dense: regular, irregular, elastic
55
What are the characteristics of areolar connective tissue?
- Most widely and loosely distributed
- Supports and binds other tissues
- Universal packing material btwn other tissues
- Contains fibroblasts, secretes collagen fibers
- Allow increased ground substance= hold more interstitial fluid
- Fibroblasts, mast cells, some white blood cells
- Forms the lamina propria
- Macrophages and fat cells are contained in spaces
- Plays an important role in inflammation
- Located under epithelia of body e.g. mucous membranes, capillaries
56
What are the characteristics of adipose tissue?
- Similar to areolar but greater in nutrient storage
- Packed closely together
- Scanty matrix
- Richly vascularized
- Function as shock absorption, insulation and energy storage
- Found around kidneys, behind eyeballs and abs, hips, breasts
-Brown fat use lipid fuels to generate heat instead of generating ATP
57
What are the characteristics of reticular connective tissue?
- Resembles areolar tissue, but thinner fibers
- Secrete reticular fibers made up of thin collagen
- Fibers form mesh-like "stroma"
- Forms the supporting framework of the lymphoid organs (lymph nodes, spleen, tonsils), bone marrow and liver.
58
What are the three types of dense connective tissues?
- Dense regular
- Dense irregular
- Elastic
59
What are the characteristics of dense regular connective tissue and where can they be found?
- Very high tensile strength; withstand high tension, stretching and pulling
- Closely packed, thick collagen fibers run parallel to direction of pull
- Fibers appear white
- Fibroblasts manufacture collagen fibers and ground substance
- Very few cells in ground substance, mostly fibers
- Poorly vascularized
- E.g. tendons (muscle to bone) and ligaments (bone to bone)
60
What are the characteristics of dense irregular connective tissue and where can they be found?
- Same elements as dense regular, bundles of collagen are thicker and irregularly arranged
- Forms sheets vs bundles
- Resist tension from many directions
- Found in dermis, fibrous joint capsules and fibrous coverings of some organs
61
What are the characteristics of elastic connective tissue and where can they be found?
- Contains high proportion of elastic fibers
- Allows tissue to recoil after stretching
- Maintains pulsatile flow of blood through arteries
- Aids passive recoil of lungs following inspiration
- Found in walls of large arteries, certain ligaments associated with the vertebral column, within the walls of the bronchial tubes
62
What are the characteristics of cartilage?
- matrix secreted from chondroblasts and chondrocytes
- Chondrocytes found in cavities: lacunae
- 80% water, packed with collagen fibers and sugar proteins (chondroitin and hyaluronic acid)
- Tough yet flexible, lacks nerve fibers
- Avascular: receives nutrients from surrounding membrane (perichondrium) via diffusion
63
What are the three types of cartilage?
- Hyaline
- Elastic
- Fibrocartilage
64
What are the characteristics of hyaline cartilage?
- Aka gristle, most abundant
- Contains large numbers of collagen fibers
- Matrix appears glassy; blue-white in color
- Provide firm support with pliability
- Found at tips of long bones, nose, trachea, larynx, and cartilage of the ribs, embryotic skeleton
65
What are the characteristics of elastic cartilage?
- Similar to hyaline but with more elastic fibers
- Found in ears and epiglottis
66
What are the characteristics of fibrocartilage?
- Properties between hyaline and dense regular tissue
- Parallel collagen fibers
- Tensile strength; absorb compressive shock
- Strong, found in intervertebral discs and knee
67
Why does cartilage heal slowly?
They are avascular.
Aging cartilage cells lose the ability to divide. Calcify or ossify (become bony); chondrocytes are poorly nourished and die.
68
What are the functions and characteristics of bone?
- Aka osseous tissue
- Supports and protects body structures
- Stores fat and synthesizes blood cells in cavities
- Has more collagen than cartilage
- Has more inorganic calcium salts
- Osteoblasts produce matrix
- Osteocytes maintain the matrix; reside in cavities in matrix: lacunae
- Osteons; individual structural units
- Richly vascularized
69
What are the characteristics of blood?
- Red and white blood cells in a
fluid matrix (plasma).
- Transports respiratory gasses, nutrients, wastes, and other substances
- Contained within blood vessels
70
What are the characteristics of muscle tissue?
- Highly vascularized
- Cells posess myofilaments made up of actin and myosin proteins that bring about movement or contraction
- Three types: skeletal, cardiac, smooth
71
What are the characteristics of skeletal muscle tissue?
- Voluntary
- Muscle fibers contain multiple nuclei
- Appear striated or banded
- Found in skeletal muscles attached to bones or occasionally to skin
72
What are the characteristics of cardiac muscle tissue?
- Involuntary
- Found in walls of heart
- Cells are branched and striated
- Cells have only one nucleus
- Connect at specialized junctions (intercalated discs). Only present in cardiac muscle
73
What are the characteristics of smooth muscle tissue?
- Involuntary
- No visible striations
- Spindle-shaped cells (tapered on both ends) with one nucleus
- Found in walls of hollow organs: digestive, urinary tract organs, uterus, blood vessels.
74
What are the main component of the nervous system?
- Brain
- Spinal cord
- Nerves
75
What are the characteristics of nervous tissue?
- Supporting cells that support, insulate, and protect neurons
- Neurons generate and conduct nerve impulses
- Regulates and controls body functions
- Respond to stimuli (via processes called dendrites)
- Transmit electrical impulses over substantial distances within the body (via processes called axons)
- Found in brain, spinal cord and nerves
76
What are the three types of lining membranes?
- Cutaneous
- Mucous
- Serous
77
What are the characteristics of cutaneous membranes?
- Another name for skin
- Keratinized stratified squamous epithelium (epidermis) attached to a thick layer of connective tissue (dermis)
- A dry membrane
78
What are the characteristics of mucous membranes?
- Mucosa indicates location
- Aka mucosae
- Lines body cavities open to exterior (e.g. digestive, respiratory, urogenital tracts)
- E.g. nasal cavity, mouth, lung bronchi
- Moist membranes bathed by secretions (e.g. urine)
- Contain either stratified squamous or simple
columnar epithelia
- Epithelial sheet lies over layer of loose connective tissue called lamina propria
- May secrete mucus
79
What are the characteristics of serous membranes?
- Aka serosae
- Simple squamous epithelium (called mesothelium) resting on thin areolar connective tissue
- Found in closed ventral body cavities
- Parietal serosae and Visceral serosae
- Pleurae: lungs
- Pericardium: heart
- Peritoneum: abdominopelvic
80
Name two ways of tissue repair
- Regeneration: same kind of tissue replaces destroyed tissue, so original function is restored
- Fibrosis: connective tissue replaces destroyed tissue with scar tissue, and original function lost
81
What does the release of inflammatory chemicals cause?
- Dilation of blood vessels
- Increase in blood vessel permeability
- Clotting of blood
82
What are the three primary germ layers?
1. Ectoderm (nervous tissue)
2. Mesoderm (muscle and connective tissue)
3. Endoderm (inner lining of digestive system)
83
What is granulation tissue?
New connective tissue and microscopic blood vessels that form on the surfaces of a wound during the healing process.
84
What tissues have a high regenerative capability?
- Epithelial tissues
- Bone
- Areolar connective tissue
- Dense irregular connective tissue
- Blood forming tissue
85
What tissues have moderate regenerative capability?
- Smooth muscle
- Dense regular connective tissue
86
What tissues have a weak regenerative capacity?
- Skeletal muscle
- Cartilage
87
What tissues have no functional regenerative capacity?
- Cardiac muscle
- Nervous tissue in the brain and spinal cord
88
What tissues have no functional regenerative capacity?
- Cardiac muscle
- Nervous tissue in the brain and spinal cord
89
Integumentary System
90
Name the five components of the Integumentary system
- skin
- nails
- hair
- sweat
- sebaceous gland
91
What are the two distinct regions of skin and their characteristics?
- Epidermis: consists of epithelial tissue and is avascular (nutrients reach through diffusion via tissue fluid from blood vessels in the dermis)
- Dermis: mostly fibrous connective tissue, vascular
92
Subcutaneous tissue is also known as?
The hypodermis or the superficial fascia.
- Deep to the skin
- Not part of the skin but shares the skin's protective functions.
- Mostly adipose tissue with some areolar connective tissue
- Acts as a shock absorber and an insulator
- Anchors the skin to the underlying structures (mostly muscles)
93
What does the epidermis consist of?
Mostly keratinized stratified squamous epithelium
94
What are the four types of cells found in epidermis?
1. Keratinocytes: major cells, millions rub off daily.
2. melanocytes
3. dendritic cells
4. tactile epithelial cells
95
Where do keratinocytes arise from?
Stratum basale; the deepest part of the epidermis
96
What do keratinocytes produce and what does it do?
Keratin; the fibrous protein that helps give the epidermis its protective properties.
97
What are keratinocytes tied together by?
Desmosomes; for strength and tight junctions to hinder movement of water between cells
98
What are the characteristics of melanocytes?
- Spider shaped,
- Located in deepest epidermis
- Produce pigment melanin, packaged into melanosomes
- Melanosomes are transferred to keratinocytes; protect nucleus from UV
99
What are the characteristics of dendritic cells? (aka Langerhans cells)
- Star-shaped macrophages that patrol deep epidermis
- Key activators of immune system
- Arise from bone marrow, migrate to the epidermis
100
What are the characteristics of tactile cells?
- Present at the epidermal-dermal junction
- Spikey hemisphere
- Sensory receptors that sense touch
101
How many layers are there in the epidermis and what are their names?
- Five for thick skin (strata)
- Four for thin skin
From deep to superficial:
- Stratum basale
- Stratum spinosum
- Stratum granulosum
- Stratum lucidum (absent in thin skin)
- Stratum corneum
102
What are the characteristics of stratum basale?
- Deepest of all
- Firmly attached to dermis
- Consists of a single row of mitotic cells
- One daughter cell travels from basel to surface layer
- Cell dies as it moves toward surface
- Other daughter cell remains as stem cell
- Aka stratum germinativum
- 10-20% composed of melanocytes
103
What are the characteristics of stratum spinosum?
- Several cell layers thick
- Web-like system of intermediate prekeratin filaments attached to desmosomes
- Resist tension and pulling
- Keratinocytes within appear spikey
- Scattered among keratinocytes are abundant melanosomes and dendritic cells
104
What are the characteristics of stratum granulosum?
- Four to six cells thick; flattened and thin layer
- Appearance changes; cells flatten, nuclei and organelles disintegrate
- Cells accumulate keratohyaline granules that help form keratin fibers in upper layers
- Accumulate lamellar granules; a water-resistant glycolipid to slow water loss
- Cells above die
- Too far from dermal capillaries to survive
105
What are the characteristics of stratum lucidum?
- Found only in thick skin
- Consists of thin, translucent band of two to three rows of clear, flat dead keratinocytes
- Lies superficial to the stratum granulosum
106
What are the characteristics of stratum corneum?
- 20-30 rows of flat, anucleated, keratinized dead cells
- 3/4 of epidermal thickness
- Dead but cells still function to:
- Protect deeper cells
- Prevent water loss
- Protect from abrasion and penetration
- Act as barrier against biological, chemical, and physical assaults
107
What is apoptosis
Controlled cell death
- dandruff and dander
- humans shed ~50,000 cells/min
108
What are the characteristics of the dermis and what are the types of cells within?
- Strong flexible connective tissue
- Cells include fibroblasts, macrophages, and occasionally mast and white blood cells
- Fibers in matrix bind body together
- Contains nerves, blood vessels and lymphatic vessels
- Contains epidermal hair follicles, oil glands, and sweat glands
109
What are the two layers of dermis?
- Papillary
- Reticular
110
What are the characteristics of papillary dermis?
- Superficial layer of areolar connective tissue
- Loose, interlacing collagen and elastic fibers and blood vessels
- Phagocytes patrol for microorganisms
111
What are the characteristics of dermal papillae?
- Peglike projections from its surface
- Contain capillary loops, free nerve endings and touch receptors (tactile corpuscles)
- In thick skin, they lie on larger mounds of dermal ridges, which causes the epidermis to form epidermal ridges
-
112
What are the functional characteristics of friction ridges?
- Enhance gripping ability
- Contribute to sense of touch
- Sweat pores in ridges leave unique fingerprint pattern
113
What are the characteristics of reticular layer?
- Makes up ~80% of dermal thickness
- Consists of coarse, dense fibrous connective tissue
- Many elastic fibers provide stretch-recoil properties
- Collagen fibers provide strength and resiliency
- Bind water, keep skin hydrated
- Cutaneous plexus: network of blood vessels that nourishes the layer and hypodermis
- Extracellular matrix contains pockets of adipose cells
114
What are cleavage (tension) lines and how are they used to make incisions?
- Collagen fibers that run parallel to the skin surface
- Incision is made parallel to these lines,
the skin gapes less and heals more readily
115
What are flexure lines?
Dermal folds at or near joints
- Dermis is tightly secured to deeper structures
- Skin’s inability to slide easily for joint movement causes deep creases
- Visible on hands, wrists, fingers, soles, toes
116
What are striae?
Stretch marks
117
What are the three pigments that contribute to skin color?
1. Melanin
2. Carotene
3. Hemoglobin
118
What are the characteristics of melanin?
- Only pigment made in skin; by melanocytes
- Made from amino acid tyrosine by tyrosinase
- Packaged into melanosomes that are sent to shield DNA of keratinocytes from damaging UV
- More sun=more melanin produced
- Two forms: reddish yellow to brownish black
- Causes skin color differences
- Freckles and moles are local accumulations of melanin
119
What are the dangers of excessive sun exposure?
- Skin loses elasticity
- Depress immune system and cause alterations in DNA which may lead to skin cancer
- UV destroys folic acid
- Folic acid necessary for developing embryos
- Increased photosensitivity; e.g. antibiotics, antihistamines, perfumes, leading to rashes
120
What are the characteristics of carotene?
- Yellow to orange pigment
- Obvious in palms and soles
- Accumulates in stratum corneum and hypodermis
- Can be converted to vitamin A for vision and epidermal health
121
What are the characteristics of hemoglobin?
- Pinkish hue of fair skin is due to lower levels of melanin
- Caucasian skin shows. through hemoglobin
122
Alterations in skin color can indicate disease. Examples and signs
- Cyanosis: blue skin, low oxygenation of hemoglobin
- Pallor: blanching or pale. anemia, low blood pressure, fear, anger
- Erythema: redness, fever, hypertension, inflammation, allergy
- Jaundice: yellow, liver disorders
- Bruises: black and blue, aka ecchymoses/hematomas; result of clotted blood beneath skin
- Brown/black necklace or bruises: around armpit/neck, sign of insulin resistance and elevated blood glucose levels
123
What do hairs consist of, their characteristics and their functions?
Flexible strands of dead keratinized cells, aka pili.
- Produced by hair follicles
- Hard keratin: tougher and more durable; cells do not flake off
- Warn of insects on skin
- Guards against physical trauma
- Protect from heat loss
- Shield skin from sun
124
What are the three parts of hair shaft?
- Medulla: central core of large cells and air spaces
- Cortex: several layers of flattened cells surrounding medulla
- Cuticle: outer layer consisting of overlapping layers of single cells
125
Hair pigments are made by __________ in hair follicles.
Melanocytes
- Red hair has additional pheomelanin pigment
- Gray hair results when melanin production decreases and air bubbles replace melanin in shaft
126
Hair extends from _______ surface to _______.
From epidermal surface to dermis
127
What is hair bulb?
Expanded area at deep end of follicle
128
What is hair follicle receptor?
Sensory nerve endings that wrap around bulb, aka root hair plexus.
129
What kind of receptor is hair considered?
Sensory touch receptor
130
What is the wall of follicle composed of?
- Peripheral connective tissue sheath derived from dermis (aka fibrous sheath)
- Glassy membrane: thickened basal lamina
- Epithelial root sheath derived from epidermis
131
What is hair matrix?
Actively dividing area of bulb that produces hair cells
132
What is arrector pili?
Small band of smooth muscle attached to follicle (goose bumps)
133
What is hair papilla?
Dermal tissue containing a knot of capillaries that supplies nutrients to growing hair
134
What is vellus hair?
Pale, fine body hair of children and adult females
135
What is terminal hair?
Coarse, long hair found on scalp and eyebrows
- Also found in armpit and pubic regions, on face and neck for males
136
What two factors affect hair growth?
Nutrition and hormones
137
What is hirsutism?
When women develop coarse terminal hairs in a masculine distribution
138
What is male pattern baldness caused by?
Follicular response to DHT
139
What is eponychium?
Nail fold that projects onto surface of nail body
140
What is hyponychium
Area under free edge of plate that accumulates dirt
- Nails normally appear pink because of underlying capillaries
- Lunule: thickened nail matrix, appears white
141
What are common diseases you can diagnose from nail appearance?
- Yellow: respiratory or thyroid gland disorder
- Thickened yellow: fungal infection of nail
- Outward concavity: koilonchya (spoon nail): iron deficiency
- Horizontal lines across: Beau's lines: severe illness, uncontrolled diabetes, heart attack or cancer chemotherapy
142
What is sudoriferous glands?
- All skin surfaces except nipples and parts of external genitalia contain sweat glands; 3 million per person
- Contain myoepithelial cells
143
What are the two main types of sweat glands?
- Eccrine (merocrine)
- Apocrine
144
What are the characteristics of eccrine sweat glands?
- Most numerous type
- Abundant on palms, soles, and forehead
- Ducts connect to pores
- Function in thermoregulation; regulated by sympathetic nervous system
- Their secretion is sweat; 99% water, salts, vitamin C, antibodies, dermcidin (microbe-killing peptide), metabolic wastes
145
What are the characteristics of apocrine sweat glands?
- Confined to axillary and anogenital areas
- Secrete viscous milky or yellowish sweat that contains fatty substances and proteins; bacteria break down sweat, leading to body odor
- Larger than eccrine sweat glands with ducts emptying into hair follicles
- Begin functioning at puberty; function unknown but may act as sexual scent gland
146
What are the two modified apocrine glands?
- Ceruminous glands: lining of external ear canal; secrete cerumen (earwax)
- Mammary glands: secrete milk
147
What are the characteristics of sebaceous glands?
- Widely distributed, except for thick skin of palms and soles
- Most develop from hair follicles and secrete into hair follicles
- Relatively inactive until puberty; stimulated by hormones, especially androgens
- Secrete sebum; oily holocrine secretion, bactericidal (bacteria-killing) properties, softens hair and skin
148
What are the main functions of skin?
- Protection
- Body temperature regulation
- Cutaneous sensations
- Metabolic functions
- Blood reservoir
- Excretion of wastes
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What is the skin exposed to and what are the three barriers?
- Microorganisms
- Abrasions
- Temperature extremes
- Harmful chemicals
Barriers:
- Chemical
- Physical
- Biological
150
What are the examples of skin's chemical barriers?
Sweat secretes chemicals suchs as:
- Sweat-containing antimicrobial proteins:
- Sebum and defensins, which kills bacteria
- Cells secrete antimicrobial defensin
Acid mantle: low pH of skin retards bacterial multiplication
Melanin provides a chemical barrier against UV radiation damage
151
What are the examples of skin's physical barriers?
Flat, dead, keratinized cells of stratum corneum, surrounded by glycolipids, block most water and water-soluble substances
Chemical penetration of skin:
- Lipid-soluble substances
- Plant oleoresins (e.g., poison ivy)
- Organic solvents (acetone, paint thinner)
- Salts of heavy metals (lead, mercury)
- Some drugs (nitroglycerin)
- Drug agents (enhancers that help carry other drugs across skin)
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What are the examples of skin's biological barriers?
- Epidermis containing phagocytic cells; dendritic cells of epidermis engulf foreign antigens (invaders) and present to white blood cells, activating the immune response
- Dermis containing macrophages; activate immune system by presenting foreign antigens to white blood cells
- DNA can absorb harmful UV radiation, converting it to harmless heat
153
What are damages causes by exposure to organic solvents of heavy metals passing through skin entering blood or organ systeems?
- Kidney shut down
- Brain damage
- Lead can result in anemia and neurological defects
154
What is insensible perspiration?
Evaporation from the epidermis or as sweat, a form of cooling in which liquid actively secreted from sweat glands evaporates from the body surface
155
What is sensible perspiration?
A form of perspiration in which the body is able to sense the watery fluid as moist on the skin
156
What are the functions of cutaneous sensory receptors?
- Exteroreceptors respond to stimuli outside body, such as temperature and touch
- Free nerve endings sense painful stimuli
157
What are the two risk factors of skin cancer?
- Overexposure to UV
- Frequent irritation of skin
Most skin tumors are benign and do not metastasize
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What are the three major types of skin cancer?
- Basal cell carcinoma
- Squamous cell carcinoma
- Melanoma
159
What are the characteristics of basal cell carcinoma?
- Least malignant and most common
- Stratum basale cells proliferate and slowly invade dermis and hypodermis
- Cured by surgical excision in 99% of cases
160
What are the characteristics of squamous cell carcinoma?
- Second most common type; can metastasize
- Involves keratinocytes of stratum spinosum
- Usually is a scaly reddened papule on scalp, ears, lower lip, or hands
- Good prognosis if treated by radiation therapy or removed surgically
161
What are the characteristics of melanoma?
- Cancer of melanocytes; most dangerous due to highly metastatic and resistant to chemotherapy
- Treated by surgical excision + immunotherapy
Survival is early detection; ABCD rule:
- Asymmetry
- Border irregularity; exhibits indentations
- Color; contains several colors (black, brown, tan, sometimes red or blue)
- Diameter; larger than 6 mm
162
What is a burn and its immediate threat?
Tissue damage caused by heat, electricity, radiation, or certain chemicals
Immediate threat:
- Dehydration
- Electrolyte imbalance; leads to renal shutdown and circulatory shock
163
How do you evaluate burns?
The Rule of Nines:
- Body is broken into 11 sections, with each section representing 9% of body surface (except genitals, which account for 1%)
- Used to estimate volume of fluid loss
164
What is a first degree burn?
- Epidermal damage only
- Localized redness, edema, and pain
165
What is a second degree burn?
- Epidermal and uppde dermal damage
- Blisters appear
- First and second-degree burns are referred to as partial-thickness burns because only the epidermis and upper dermis are involved
166
What is a third degree burn?
- Entire thickness of skin involved (referred to as full-thickness burns)
- Skin color turns gray-white, cherry red, or blackened
- No edema is seen and area is not painful because nerve endings are destroyed
- Skin grafting usually necessary
167
What is considered a critical burn?
- More than 25% body has second-degree burns
- More than 10% of body has third-degree burns
- Face, hands, or feet bear third-degree burns
168
What are the treatments of burns?
- Debridement (removal) of burned skin
- Antibiotics
- Temporary covering
- Skin grafts
