(1) Skin
Functions of Skin
o Thermoregulation (heat retention + dissipation)
o Sensation (detect external changes)
o Communication (blushing, pheromones)
o Protection (resists abrasion, blocks foreign entry)
o Containment (keeps insides inside)
o Immunological defense
o Appendages (nail, hairs, sweat glands)
The skin has 3 distinct layers:
1. Epidermis – outermost layer, mostly epithelial cells (stratified squamous keratinized epithelium)
- From Bottom to Top:
a. Stratum Germinativum – simple columnar cells
o Attached to basement membrane via hemidesmosomes
o Contains progenitor cells which gives rise to all other layers
b. Stratum Spinosum – thickest layer, stratified polyhedral cells
o Cells move up from build-up of keratin inside, they are connected by desmosomes (gives spiny
appearance)
c. Stratum Granulosum – stratified squamous cells
o Cytoplasm full of basophilic masses of keratohyaline granules (stains dark)
d. Stratum Corneum – stratified squamous keratinized cells
o Dead cells, shed at the top
2. Dermis – middle layer, thicker, provides supports and nourishment upwards with blood vessels, nerves, hair follicles
sweat glands
3. Hypodermis – deepest layer, consists of adipocytes and connective tissue, serves as an insulator
The human epidermis is renewed every 15-30 days
o During differentiation, the cells move upward, and the amount and types of keratin filaments increase
o The cells of each layer either divide to become their own layer or differentiate to become the next layer above them
o Desquamation is the process of shedding or sloughing off dead skin cells from the surface of the epidermis. It is a nat
and continuous process that helps maintain the integrity of the skin. As new cells are produced in the stratum
germinativum, they gradually move upward through the layers, granules are made in the cells. As they reach the
outermost layer (stratum corneum), the cells are dead and eventually shed. They burst and die releasing their granule
full of keratin.
Teeth: (to create
(8) Teeth + Oral Cavity + Esophagus collagen
Structure: human
Oral Cavity: receives food, begins digestion by breaking down and mixing with Salivary Glands: teeth
saliva o You have 2 d
a. Oral Mucosa Function: wet + lubricate the oral cavity and its content, to o 4 central inci
o Epithelium = non-keratinized stratified squamous (basal layer.= cuboidal, middle initiate the digestion of carbohydrates by secreting amylase
layer = polygonal, superficial = squamous) (destroys glycogen), lysozymes (destroys bacterial cell wall), IgA Composition:
o Gingiva = very folded mucosa + LP = para-keratinized (immunoglobulin controls germ growth), lactoferrin (grabs iron, o Enamel à 99
o Skin on external lip = ortho-keratinized its absence prevents DNA synthesis) o Dentin à 70
o Rest of oral mucosa = non-keratinized bone) – dent
o Lamina propria = loose connective tissue (continuous with a submucosa of Structure: 2 pairs of large salivary glands canaliculi)
Functions of Skin
o Thermoregulation (heat retention + dissipation)
o Sensation (detect external changes)
o Communication (blushing, pheromones)
o Protection (resists abrasion, blocks foreign entry)
o Containment (keeps insides inside)
o Immunological defense
o Appendages (nail, hairs, sweat glands)
The skin has 3 distinct layers:
1. Epidermis – outermost layer, mostly epithelial cells (stratified squamous keratinized epithelium)
- From Bottom to Top:
a. Stratum Germinativum – simple columnar cells
o Attached to basement membrane via hemidesmosomes
o Contains progenitor cells which gives rise to all other layers
b. Stratum Spinosum – thickest layer, stratified polyhedral cells
o Cells move up from build-up of keratin inside, they are connected by desmosomes (gives spiny
appearance)
c. Stratum Granulosum – stratified squamous cells
o Cytoplasm full of basophilic masses of keratohyaline granules (stains dark)
d. Stratum Corneum – stratified squamous keratinized cells
o Dead cells, shed at the top
2. Dermis – middle layer, thicker, provides supports and nourishment upwards with blood vessels, nerves, hair follicles
sweat glands
3. Hypodermis – deepest layer, consists of adipocytes and connective tissue, serves as an insulator
The human epidermis is renewed every 15-30 days
o During differentiation, the cells move upward, and the amount and types of keratin filaments increase
o The cells of each layer either divide to become their own layer or differentiate to become the next layer above them
o Desquamation is the process of shedding or sloughing off dead skin cells from the surface of the epidermis. It is a nat
and continuous process that helps maintain the integrity of the skin. As new cells are produced in the stratum
germinativum, they gradually move upward through the layers, granules are made in the cells. As they reach the
outermost layer (stratum corneum), the cells are dead and eventually shed. They burst and die releasing their granule
full of keratin.
Teeth: (to create
(8) Teeth + Oral Cavity + Esophagus collagen
Structure: human
Oral Cavity: receives food, begins digestion by breaking down and mixing with Salivary Glands: teeth
saliva o You have 2 d
a. Oral Mucosa Function: wet + lubricate the oral cavity and its content, to o 4 central inci
o Epithelium = non-keratinized stratified squamous (basal layer.= cuboidal, middle initiate the digestion of carbohydrates by secreting amylase
layer = polygonal, superficial = squamous) (destroys glycogen), lysozymes (destroys bacterial cell wall), IgA Composition:
o Gingiva = very folded mucosa + LP = para-keratinized (immunoglobulin controls germ growth), lactoferrin (grabs iron, o Enamel à 99
o Skin on external lip = ortho-keratinized its absence prevents DNA synthesis) o Dentin à 70
o Rest of oral mucosa = non-keratinized bone) – dent
o Lamina propria = loose connective tissue (continuous with a submucosa of Structure: 2 pairs of large salivary glands canaliculi)
