Lecture 2: Integumentry System

Question 1

List the major layers of each and describe the functions of each layer:
1. Epidermis
babies sigh greatly like cats

Answer 1

1. Layers of the epidermis:
   A) stratum basale: deepest epidermal layer firmly attached to the dermis
   -melanocytes found here
   -single row of stem cells
   B) stratum spinosum (prickly layer)
   -contains prekeratin filaments which gives it strength
   -abundant melanin granules
   C) stratum granulosum
   -thin
   -keratohyaline and lamellated granules accumulate
   D) stratum lucindum (clear layer)
   -in thick skin
   -thin transparent band superficial to the stratum granulosum
   -a few rows of flat, dead keratinocytes
   E) stratum corneum (hornet layer)
   -20-30 rows of flat keratinized membrane sacs
   -makes up 3/4 of the epidermal thickness
   Functions of layer 5 stratum corneum:
   -protects from abrasions and penetrations
   -water proofs
   -barrier against biological, chemical and physical assaults

Question 2

List the major layers of each and describe the functions of each layer:
2. Dermis

Answer 2

Dermis is strong flexible connective tissue
-cells include fibroblasts, macrophages, and sometimes mast cells and white blood cells
Two layers:
A) papillary layer: areolar connective tissue with collagen and elastic fibres and blood vessels
-capillary loops
-meissners corpuscles
-free nerve endings
B) reticular layer:
-80% of the thickness of the dermis
-collagen fibres provide strength
-elastic fibres provide stretch recoil properties

Friction ridges (fingertips) are found in the dermis layer?

Question 3

Describe the factors that contribute to skin colour

Answer 3

3 pigments contribute to skin colour

1. Melanin: yellow, reddish-brown to black, responsible for dark skin colors. Freckles are a accumulation of melanin
2. carotene: yellow to orange (like a carrot), most obvious in palms and soles
3. Hemoglobin: responsible for the pinkish of skin

Question 4

Appendages of the skin

Compare the structure and locations of sweat and oil glands

Answer 4

Two main types of sweat glands 
1. Eccrine (merocrine) sweat glands
-abundant on palms, soles, and forehead
Sweat: 99% water, NaCl, vit C, antibodies, metabolic wastes
-ducts connect to pores
-function in thermoregulation 

2. Apocrine sweat glands: or (sebaceous glands) confined to axillary and anogenital areas because that is we’re the hair is?
   - sebum: sweat + fatty substances and proteins
   - ducts connect to hair follicles
   - functional from puberty onwards

Question 5

List the parts of a hair follicle and their function

Answer 5

Function: alerts the body to presence of insects on the skin
-guarding the scalp against physical trauma, heat loss, and sunlight
Hair consist of dead keratonized cells.
Hair pigments: Melanins (yellow, rust brown, black) grey and white hair is due to decreased melanin production and increase in air bubbles in the shaft
Hair follicle: extends from the epidermal surface into the dermis
-2 layered wall: outer connective tissue root sheath, inner epithelial root sheath
Hair bulb is the expanded deep end
Hair follicle receptorsc: sensory nerve endings around each hair bulb and is stimulated by bending hair
Arrector pili: smooth muscle attached to follicle responsible for good bumps

Question 6

What are the two types of hair?

Answer 6

Vellus: pale, fine body hair of children and adult females
Terminal: coarse, long hair of eyebrows, scalp, axillary, and pubic regions (and face and neck of males)

Question 7

What is the name for balding?

Answer 7

Alopecia: hair thinking in both sexes after age 40
True (frank) baldness: genetically determined and sex influences condition
-male pattern baldness is caused by follicular response to increases DHT (dihydrotestosterone)

Question 8

Describe the structure of nails

Answer 8

Be able to label a diagram of a nail

Question 9

Describe how the skin accomplishes at least 5 different functions

Mums body brings cute ex

Answer 9

1. Protection: 3 types of barriers
   A) physical/ mechanical barriers
   -the keratin and glycolipids block most water and water soluble substances
   -limited penetration of skin by lipid soluble substances
   B) biological barriers: dendritic cells, macrophages, and DNA
   C) chemical: low pH secretions (acid mantle) and defensins retard bacterial activity
2. Body temperature regulation:
   -at elevated temps, dilation of dermal vessel and increased sweat gland activity cool the body
3. Cutaneous sensations: temp, touch, and pain
   4.metabolic functions: synthesis of vitamin D precursor and collagenase
   -chemical conversions of carcinogens and some hormones
4. Blood reservoir- up to 5% of body’s blood volume
5. Excretion- nitrogenous wastes and salt in sweat

Question 10

What are the three major types of skin cancer

Mel swims
So she gets skin problems

Answer 10

1. Basal cell carcinoma: least malignant, most common
   - stratum basal cells proliferate and slowly invade dermis and hypodermis
2. Squamous cell carcinoma: second most common
   - involves keratinocytes of stratum spinosum
   - most common on scalp, ears, lower lip, and hands
   - treated by radiation therapy or removal surgically
3. Melanoma: most dangerous
   - involves melanocytes
   - highly meats tic and resistant to chemotherapy
   - treated by removal or immunotherapy

Question 11

Burns

Name the 3 levels of burns and the layers of skin that are affected

Answer 11

1st degree: epidermal damage only
-redness, swelling and pain
2nd degree: epidermal and upper dermal damage
-blisters appear
3rd degree: entire thickness of skin damaged
-grey white, cherry red, or black
-no initial pain as nerve endings are destroyed
-skin grafting unusually necessary