Epithelia & Skin

Question 1

Name the characteristics of the epithelial tissue?

Answer 1

Surface specialisations at apical/luminal pole of cells

Junctional complexes – little intercellular substance

Basement membrane underlying basal pole of cells

Regularity of cell arrangement

Diffusion of nutrients from underlying connective tissue layer

Question 2

Name each type of epithelium, its location and function?

Answer 2

Simple squamous: - alveoli,
heart lining, BVs and lymph V
- allows material to pass via diffusion and secrete lubricating substance
Simple cuboidal: - in ducts and secretroy portions of glands (and kidney)
- secretes and absorbs
Simple columnar: - ciliated tissue in bronchi, uterus, GI and bladder
- absorbs and also secretes mucous and enzymes
Stratified squamous: - oesophagus, mouth and vagina
- protects against abrasion
Stratified cubodial: - in the glands
- protective tissue
Stratified columnar: male urethra and gland ducts
- secretes and protects
Psuedostratified columnar: - ciliated tissue lines the trachea and the resp tract
- secretes mucus, and cilia moves mucus
Transitional epithelium: - bladder, urethra and ureters
- allows urinary organs to expand and stretch

Question 3

Where is stratified cubodial/columnar tissues found?

Answer 3

In large glands (sweat, salivary and mammary)

Question 4

What are glands?

Answer 4

They are large massess of epithelium which secrete substances into or out of the body

Question 5

What are the different sizes of glands?

Answer 5

Single cell such as goblet
Small such as sweat
Large such as the liver

Question 6

Name and explain the 2 different types of glands?

Answer 6

Exocrine: have ducts, substance transported out
Endocrine: no ducts, straight into the bloodstream

Question 7

What are the characteristics of the exocrine gland?

Answer 7

Secretory component:

• columar/cuboidal cells on base mem and myoeithelial
• cell with contracile filament to allow secretion

Duct: 2-layered
- cuboidal/columnar epithelium

Question 8

Name the types of gland and duct structure, with examples?

Answer 8

Tubular: - simple (intestinal) and simple branched (gastric)
- compound (duodenal)

Alveolar: - simple (non) and simple branched (sebaceous)
- compound (mammary)

Tubuloalveolar (sweat) which is a mixture of both

Question 9

Name and explain the modes of secretion from exocrine glands?

Answer 9

Eccrine/ Merocrine – secretion occurs by exocytosis
Eg: salivary glands

Apocrine – membrane bound vesicle leaves cell
Eg: mammary gland

Holocrine – cell membrane disintegrates to release secretion
Eg: sebaceous glands

Question 10

Name the 3 major salivary glands and their location?

Answer 10

Parotid (parallel to the ear)
Sub-mandibular (beneath the mandible)
Sublingual (beneath the tongue)

Question 11

What is the glandular structure and the secretion method of salivary glands?

Answer 11

Tubuloacinar and secretes via eccrine

Question 12

What are the components of the saliva?

Answer 12

It is hypotonic and watery

Containing mucus, enzymes and antibodies

Question 13

Name the key histological landmarks of the major 3 glands?

Answer 13

Sublingual: pale, mainly mucous and lower conc of nuclei
Parotid: dark, completely serous and high conc of nucelei
Submand: pale and dark, mix of mucous and serous

Question 14

What is the role of the epithelium?

Answer 14

It lines body surfaces, and is a selective barrier between the external and internal environment

Question 15

What is the epithelium attached to?

Answer 15

Basement membrane

Question 16

Name the basic components of the skin?

Answer 16

Hair, sebaceous glands, nerves, capillaries, sweat gland, muscle, arteriole and fat

Question 17

What are the 4 primary tissues of the skin?

Answer 17

Epithelium, CT, muscle and nerves

Question 18

Name the skin cell

Answer 18

Keratinocyte

Question 19

What hint can the skin portray?

Answer 19

Provides important external evidence of underlying systemic conditions

Question 20

What is the function of the epidermis?

Answer 20

Prevents water loss by evaporation

Question 21

What is the function of the dermis?

Answer 21

Reduces risk of external injury
Maintains blood flow to epidermis
Permits body cooling

Question 22

What is the function of the skin as a whole?

Answer 22

Immune surveillance
UV protection
Energy storage
Sensory information

Question 23

What is the structure of the skin?

Answer 23

2 layers:
Epidermis - epithelium and forms boundary between internal and external (keratin layer)
Dermis - CT and gives structural strength
Hypodermis - fatty CT layer and anchors skin to underlying structure

Question 24

Name each epidermal cell and their function?

Answer 24

Keratinocytes: - contain keratin (S), hard and resist abrasion, waterproof and constantly divide for self-regen
Melanocytes: - pigmentation
Langerhans: - immune surveilliance
Merkel: - touch receptors

Question 25

Name the epidermal layers?

Answer 25

``` Top to bottom: Stratum corneum Lucidum Granulosim Spinosum Basale Dermis ```

Question 26

ABCD

Answer 26

Asymmtery Border Colour Diameter

Question 27

What is keratinisation?

Answer 27

Organic process whereby keratin is deposited in cells and these become horny as in dead skin, nails, hair Psoriasis = autoimmune disorder affecting keratinisation

Question 28

What are the different types of epidermal thickness and where can it be located?

Answer 28

Thick: - hands and feet Thin: - abdominal Thin skin likely to have hair

Question 29

What are the layers of the dermis?

Answer 29

Papillary | Reticular

Question 30

What is the papillary layer

Answer 30

Loose CT and cellular

Question 31

What is the reticular layer?

Answer 31

Denise irregular CT and fibrous

Question 32

What changes our skin colour?

Answer 32

Melanin (melanocytes) | Melanin protects against UV

Question 33

What is the role of hair?

Answer 33

Vanity and responsive to cold air

Question 34

Explain the origin of the hair follicles?

Answer 34

``` From epidermis in utero Downgrowth of epithelial cells Invasion of knot of blood vessels Growth of hair Continuity with layers of epidermis ``` (Grow down into the dermis, to form follicle and then hair grows up)

Question 35

What are the characteristics of the hair follicle?

Answer 35

Hair and sheath Arrector pili muscles Attached to follicle root and base epidermis Follicle at angle Hair straightens when muscle contracts Sebaceous glands Between follicle and arrector pili muscle Secretes sebum Function uncertain

Question 36

Eccrine sweat glands? overview

Answer 36

``` Simple tubular gland Located in dermus Coiled Spiral channel in epidermis Watery secretion and thermoreg ```

Question 37

Ways of thermoregulation?

Answer 37

Sweat BV dilation Hair

Question 38

The skin as a sense organ?

Answer 38

Numerous sensory nerve endings: ``` Meissner’s corpuscles - light touch - fingertips Paccinian corpuscles - vibration & pressure Pain receptors Thermoreceptors ```

Question 39

Explain the process of skin repair?

Answer 39

After trauma, a blood clot forms and forms a scar Underneath granulation tissue forms, this creates an inflammatory reaction that allows the infiltration into the wound allowing restoration