WEEK 2 (PART 5) Flashcards
1
Q
What are the two main types of skin?
A
Thick skin and thin skin
2
Q
Where is thick skin found?
A
Palms of hands and feet
3
Q
Why is thick skin thicker?
A
Friction forces due to walking and gripping
4
Q
What is a special feature of fingertips?
A
Parallel groves for gripping and sensation
5
Q
Where is thin skin found?
A
Arms, legs, face, and trunk
6
Q
Does thin skin have hair?
A
Yes, variable amount of hair
7
Q
What are the three layers of skin?
A
Epidermis, dermis, hypodermis
8
Q
Which layer is closest to the outside?
A
Epidermis
9
Q
What’s the layer below the epidermis called?
A
Dermis
10
Q
What’s the layer below the dermis called?
A
Hypodermis (or subcutaneous layer)
11
Q
What connects the epidermis and dermis?
A
Dermal-epidermal junction
12
Q
What finger-like projections are part of the dermal-epidermal junction?
A
Dermal papillae
13
Q
What structure connects the epidermis and dermis within the dermal-epidermal junction?
A
Basement membrane
14
Q
How many layers does the epidermis have?
A
5 layers
15
Q
What are the layers of the epidermis (from innermost to outermost)?
A
Stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum
16
Q
Where are the most undifferentiated keratinocytes found?
A
Deeper layers of the epidermis
17
Q
Where are the most differentiated keratinocytes found?
A
Layers closer to the surface of the skin
18
Q
Does the outermost layer (stratum corneum) contain cells?
A
No
19
Q
What is another name for the Stratum basale?
A
Basal layer
20
Q
How many layers of cells does the Stratum basale have?
A
Single layer
21
Q
What kind of epithelial cells are found in the Stratum basale?
A
Cuboidal or columnar
22
Q
How do the Stratum basale cells connect to the basement membrane?
A
Hemidesmosomes
23
Q
What can happen if diseases affect hemidesmosomes?
A
Skin disorders with blisters
24
Q
How do the Stratum basale cells connect to each other?
A
Desmosomes
25
What is special about the Stratum basale (stratum germinativum)?
Contains epidermal stem cells for skin regeneration
26
How do these stem cells help regenerate skin?
Differentiate into keratinocytes
27
What protein do keratinocytes make?
Keratin
28
How many layers does the Stratum spinosum have?
8-10 layers
29
Where does keratin production begin in the epidermis?
Stratum granulosum
30
What happens to keratinocytes in the Stratum granulosum?
Undergo apoptosis (programmed cell death)
31
What is special about the Stratum lucidum?
Thin, clear layer found only in thick skin
32
What do Stratum lucidum cells contain?
Keratinocytes with little to no nucleus and eleidin
33
What is eleidin used for?
Building block of keratin
34
What is the main component of Stratum corneum?
Keratin
35
What does keratin in the Stratum corneum do?
Forms a waterproof, tough, and durable barrier
36
What can happen if the Stratum corneum is damaged?
Compromised immune barrier to microorganisms
37
Which layer of skin has the thickest Stratum corneum?
Thick skin
38
What other cell types are found in the epidermis besides keratinocytes?
Melanocytes, Langerhans cells, Merkel cells
39
What do melanocytes produce?
Melanin (skin pigment)
40
What does melanin protect against?
UV radiation
41
What is the function of Langerhans cells?
Act as antigen-presenting immune cells
42
What do Langerhans cells survey the epidermis for?
Invading microorganisms and foreign materials (antigens)
43
What is the function of Merkel cells?
Respond to light touch sensations
44
Where are Merkel cells mostly located?
Stratum basale
45
What is the dermis made of?
Highly vascularized connective tissue
46
How many sublayers does the dermis have?
Two
47
What are the two sublayers of the dermis?
Papillary layer and reticular layer
48
What is special about the papillary layer?
Contains dermal papillae
49
What type of connective tissue is in the papillary layer?
Strong connective tissue with collagen fibers
50
What cells are found in the papillary layer?
Fibroblasts, mast cells, macrophages, and antigen-presenting cells
51
What is the main type of collagen in the reticular layer?
Type I collagen
52
What else is found in the reticular layer?
Network of elastic fibers
53
What does the elastic fiber network do?
Provides skin with elasticity
54
What other structures are found in the dermis?
Hair follicles, sweat glands, sebaceous glands, smooth and skeletal muscle fibers, blood vessels, lymphatic vessels, nerve fibers, and sensory receptors
55
What are some functions of the structures in the dermis?
Sensory function, regulating fluid balance and body temperature, facial expressions, erection of nipples
56
What is the hypodermis mainly composed of?
Adipose tissue
57
What other cells and structures are found in the hypodermis?
Macrophages, fibroblasts, nerves, blood vessels, and lymphatics
58
What affects the thickness of the hypodermis?
Person's weight status
59
What is one function of the hypodermis?
Facilitates skin movement over muscles
60
What is hair made of?
Keratin
61
What part of the hair grows from the hair follicle?
Hair shaft
62
What is the visible part of the hair called?
Hair shaft
63
What is the part of the hair in the skin called?
Hair root
64
Where does new hair form in the hair follicle?
Hair bulb
65
What are the three layers of the hair strand (from innermost to outermost)?
Medulla, cortex, cuticle
66
What is the hair follicle made of?
Epithelial cells
67
How are the epithelial cells in the hair follicle organized?
External and internal dermal root sheaths
68
Where do new hair cells form?
Germinal matrix
69
What supplies nutrients and oxygen to the hair?
Blood capillaries in the hair papilla
70
What is the first hair called?
Lanugo
71
When does lanugo appear?
Around 6th month of pregnancy
72
Is lanugo present in full-term babies?
No, typically shed before birth
73
What replaces lanugo?
Vellus hair
74
When does vellus hair appear?
Around 33-36 weeks of gestation
75
What replaces vellus hair after birth?
Terminal hair
76
What is the difference between vellus hair and terminal hair?
Vellus hair is fine and soft, terminal hair is coarse and pigmented
77
When do pubic and axillary hair develop?
During puberty
78
In males, what other hair develops during puberty?
Chest hair, hair on extremities, and beard
79
What determines hair color?
Amount, type, and distribution of melanin
80
What causes gray hair?
Light refraction through a translucent hair shaft
81
What muscle is associated with the hair follicle?
Arrector pili muscle
82
What does the arrector pili muscle do?
Controls hair movement upward (goosebumps)
83
Is there another function of the arrector pili muscle?
Yes, it helps regulate core body temperature (explained later)
84
What is the function of nails?
Protect the nail bed from trauma
85
Where do nails grow from?
Matrix at the base of the nail bed
86
What layer of the epidermis gives rise to new nail cells?
Stratum basale
87
Why does the nail bed appear pink?
Highly vascularized (rich in blood vessels)
88
What is the function of sweat glands?
Produce sweat (perspiration)
89
What is sweat made of?
Water, salts (sodium chloride), and other minor components
90
What type of gland are sweat glands?
Exocrine gland
91
How many types of sweat glands are there?
Two: eccrine and apocrine
92
Where are eccrine sweat glands found?
Throughout the body
93
What is the function of eccrine sweat glands?
Regulate body temperature through sweat evaporation
94
Where are apocrine sweat glands found?
Axilla, genital area, face, and scalp
95
What do apocrine sweat glands secrete?
Various products (not involved in thermoregulation)
96
What is the function of sebaceous glands?
Produce sebum to protect hair
97
Where are sebaceous glands found?
In the vicinity of hair follicles
98
What is the normal homeostatic temperature range?
36.2° to 37.7° C
99
What factors can cause variations in homeostatic temperature?
Exercise, environmental temperature, and circadian rhythm (sleep/wake cycle)
100
How is body temperature controlled?
Thermoregulation, a process involving the skin, cardiovascular system, respiratory system, nervous system, and endocrine system
101
How does the body sense temperature changes?
Thermoreceptors in skin, organs, and spinal cord
102
What does the hypothalamus do with temperature information?
Activates responses for heat production, conservation, or loss
103
What happens during hypothermia (low body temperature)?
Heat production mechanisms are activated
104
How does the body increase heat production?
Through a series of hormonal interactions involving the hypothalamus, pituitary gland, thyroid gland, and adrenal glands
105
What are some effects of thermoregulatory hormones?
Increased cellular metabolism, vasoconstriction, stimulated breakdown of glucose, shivering
106
How does sweating affect heat loss during hypothermia?
Sweat production is reduced to conserve heat
107
What happens during heat conservation?
Shivering, vasoconstriction, and increased muscle tone are stimulated
108
How does the body become aware of feeling cold?
Communication between hypothalamus and cerebral cortex
109
How does the body lose heat?
Vasodilation, sweating (evaporation)
110
What happens when body temperature reaches homeostasis?
Thermoregulation mechanisms are turned off
111
How is thermoregulation a negative feedback loop?
The response works to reverse the initial temperature change
112
How are burns classified?
By severity and depth of injury
113
What are the four classifications of burns based on depth?
Superficial (first-degree), partial-thickness (second-degree), full-thickness (third-degree), and fourth-degree
114
What layer of skin is affected in a first-degree burn?
Superficial epidermis
115
Symptoms of a first-degree burn?
Redness (erythema), pain, mild swelling
116
How deep does a second-degree burn reach?
Epidermis and superficial dermis
117
Symptoms of a second-degree burn?
Blisters, swelling, pain
118
What is NOT damaged in a second-degree burn?
Hair follicles and glands in the dermis
119
What does a third-degree burn involve?
Entire thickness of the skin
120
What are the possible consequences of a third-degree burn?
Loss of function, deformity (contracture) due to scar formation
121
What happens to skin as we age?
It becomes thinner, paler, and more translucent
122
What are some external factors that accelerate skin aging?
Excessive sun exposure, cigarette smoking, poor health, and environmental toxins
123
What are some intrinsic factors that contribute to skin aging?
Genetic changes, loss of skin elasticity, and decreased cell division
124
What are some consequences of changes in skin homeostasis?
Wrinkles, hair loss, blisters, rashes, skin cancers, and immune disorders
125
How can we prevent or delay skin aging?
Reduce exposure to harmful factors
