Integumentary System Flashcards
1
Q
A
2
Q
Functions of the Skin and Hypodermis
A
- Cushioning & insulation
- Protection
- Excretion (sweat, sebum, milk)
- Prevents water loss
- Temperature regulation
- Calcium/phosphate regulation
- UV protection
- Sensory reception
3
Q
Hypodermis
A
fatty layer deep to dermis
4
Q
Epidermis
A
- outermost layer of skin
- keratinizied stratified squamous epithelium
- 4 main cell types:
- Keratinocytes
- Melanocytes
- Merkel cells (tactile)
- Langerhans cells ( immune-related, AKA epidermal dendritic cells)
- 5 layers (deepest first):
- Stratum basale
- Stratum spinosum
- Stratum granulosum
- Stratum lucidum
- Stratum corneum
5
Q
Keratinocyte
A
- most abundant cell type in epidermis
- arise from stratum basale
- produce keratin
- those at the skin’s surface (stratum corneum) are dead
6
Q
Melanocyte
A
- found in Stratum basale
- cells that secrete melanin
- have long, cytoplasmic processes that branch out into above layers, protecting cells below
- sends melanin to keratinocytes, where it is stored around their nuclei to protect their DNA from damage
7
Q
Merkel Cells
A
- oval receptor cells found in Stratum basale
- associated with sense of touch
- AKA tactile epithelial cells
8
Q
Langerhans Cells
A
- AKA dendritic cells
- perform receptor-mediated endocytosis to take up invading antigens and communicate with lymph nodes about it
9
Q
The Layers of the Epidermis
A
- in order from deepest to most superficial:
- Stratum Basale (or Germinativum)
- Stratum Spinosum
- Stratum Granulosum
- Stratum Lucidum (thick skin only)
- Stratum Corneum
- Big Stupid Guys Like Coors
10
Q
Stratum Basale
A
- AKA Stratum Germinativum
- borders the dermis
- mostly Keratinocytes, some Merkel Cells and Melanocytes
- cells undergo mitosis
11
Q
Stratum Spinosum
A
- cells have thick bundles of intermediate filaments of pre-keratin
- Langerhans cells found here (endocytosis)
12
Q
Stratum Granulosum
A
- contains** **flattened keratinocytes with keratohyalin granules to promote cross-linking and hydration of keratin and lamellar granules for waterproofing.
13
Q
Stratum Lucidum
A
- only found in thick skin of palms and soles of feet
- a few rows of flat, dead keratinocytes
14
Q
Stratum Corneum
A
- outermost layer of epidermis
- varies in thickness
- dead keratinocytes filled with keratin
- protection and water loss prevention
15
Q
Melanin
A
- endogenous pigment produced by melanocytes in the stratum basale of the epidermis
- genetics and sun exposure affect amount produced
- varies in color, yellow, brown or black
16
Q
Dermis
A
- vascular, innervated layer below epidermis
- made of connective tissue (areolar and dense irregular)
- made up of 2 layers:
- Papillary layer (superficial 20%)
- Reticular layer (deeper 80%)
- extends upward into epidermis in egg carton-like segments called Dermal Papillae
17
Q
Papillary Layer of the Dermis
A
- makes up superficial 20% of dermis
- made of areolar connective tissue with thin collagen and elastic fibers
- dermal papillae project upward toward epidermis, epidermal ridges project downward, which increases surface area for transportation of gases, nutrients and waste between layers
- Meissner’s Corpuscles extend into papillae for light touch reception
18
Q
Reticular Layer of the Dermis
A
- makes up bottom 80% of dermis
- made up of dense irregular connective tissue
- named “reticular” for its network of collagen & elastic fibers
- site of Lamellated Corpuscles, pressure sensing nerve endings
19
Q
Cleavage Lines
A
- less dense regions of collagen in reticular dermis
- useful in surgery because incisions made parallel to cleavage lines heal better
20
Q
Tactile Corpuscles
A
- AKA Meissner’s Corpuscles
- located in dermal papillae
- sense light touch
21
Q
Lamellated Corpuscles
A
- AKA Pacinian Corpuscles
- located in reticular layer of dermis
- sense heavier pressures than Meissner’s
22
Q
Root Hair Plexus
A
- groups of nerve fiber endings around bulb of hair follicle that sense movement of hair and skin
23
Q
Hypodermis
A
- technically not part of the skin
- contains areolar and adipose tissues
- insulates and anchors skin to underlying structures
24
Q
Appendages of the Skin
A
- hair & follicles
- sebaceous glands
- sweat glands
- nails
25
Hair
- Long, flexible strands of keratinized cells
- **Function**: sense, guard, shield, protect
26
Hair Follicle
A tubular invagination of the epidermis that contains the **hair bulb**, **hair shaft** and **hair root**
27
3 Layers of Hair
1. **Cuticle - **scaly-celled, overlapping outer layer
2. **Cortex -** middle layer, several layers of flattened cells
3. **Medulla - **inner layer, large cells
28
Hair Bulb
Deep, swollen end of hair follicle
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Hair Papilla
Connective tissue that projects up into the bulb, much like dermal papillae into epidermis
30
Hair Matrix
Epithelial cells directly above papilla where new hair cells divide rapidly and melanocytes contribute pigment
31
Connective Tissue Root Sheath
- outer, dermal layer of sheathing around follicle
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Epithelial Root Sheath
Inner, epidermal layer of sheathing around follicle
33
Arrector Pili
- Smooth muscle tissue that extends from the dermal papillae to hair follicles to pull hair upright
- process known as **Piloerection**
34
Hair color
**Eumelanin -** black and brown hair
**Pheomelanin** - blonde and red hair
35
Sebaceous Glands
- simple, alveolar holocrine glands that empty oily secretions (**Sebum**) into hair follicles
- found everywhere except palms and soles
36
Sebum
- oily secretion from sebaceous glands
- **lubricates** skin, **defends** against bacteria, **prevents water loss**
37
Sweat Glands
- AKA **Sudoriferous Glands**
- two types: **Eccrine** (or **Merocrine**) and **Apocrine**
- sweat is 99% water, salts, acidic excretions
- distributed all over skin
- function as excretory and heat-regulating system
38
Holocrine Glands
- entire cell is shed to secrete product
39
Eccrine or Merocrine Gland
- secretes product via **exocytosis**
- **coiled simple tubular** sweat glands that open to pores on skin surface
- don't extend far into dermis
- produce acidic sweat (pH 4-6)
- especially **dense in soles and palms**
- **narrower lumen** than apocrine glands
40
Apocrine Gland
- sweat glands that empty into hair follicles of the **scalp, neck, axillary and genital areas**
- secrete sweat that contains extra **lipids and proteins** whose breakdown by bacteria is responsible for **body odor**
- secrete by pinching off of apical cytoplasm with secretions bound within
- **wider lumen** than eccrine glands
41
Ceruminous Glands
- modified sweat glands in the external ear canal
- secretions combine with sebum to form **Cerumen** (or earwax)
- Function: waterproofing, eardrum flexibility, block foreign particles, kill bacteria
42
Mammary Glands
- modified milk-producing apocrine glands within breasts
- ducts open on nipple
- present in both sexes but functional only in women
43
Nails
- scale-like modifications of epidermis
- heavily **keratinized**
- has distal **free edge**, visible **body** and embedded **root**
- overlapped by fold of skin known as **nail fold**
- pink due to visible vascularization
44
Eponychium
- AKA cuticle
- thick proximal nail fold
45
Nail Bed
- extenion of epidermal stratum basale underneath nail body
46
Nail Matrix
- analogous to hair matrix
- proximal thickened area of nail bed responsible for growth via cell keratinization
47
Lunula
- AKA White Crescent
- light region of thickened nail matrix
