COM 2 Histology Week 4

Question 1

Name the types of sensory receptors in the skin

Answer 1

• Unencapsulated receptors
  -Encapsulated receptors

Question 2

Name all the unencapsulated receptors in the skin

Answer 2

Tactile (Merkel )cells
Free nerve endings
Root hair plexuses

Question 2

What do all unencapsulated receptors not have

Answer 2

• Schwann cells and collagen coverings

Question 3

Where are tactile (merkle) cells
-Located
-What type of receptors are they and what do they respond to

Answer 3

• Located in epidermis
  -Tonic receptors: respond to sustained light touch

Question 4

Where are free nerve endings found

Answer 4

In papillary dermis and lower epidermis

Question 5

What do free nerve endings detect

Answer 5

• Temperature
  pain
  itching

Question 6

What are root hair plexuses

Answer 6

Snesory fibers around hair follicles

Question 7

What do root hair plexuses detect

Answer 7

Hair movement

Question 8

What do all encapsulated receptors have

Answer 8

Glial cells and connective tissue capsules

Question 9

What type of receptors are encapsulated recepotrs

Answer 9

• Phasic mechanoreceptors

Question 10

Name the encapsulated receptors

Answer 10

• Meissner corpuscles
  -Pacinian corpuscles
  -Krause end blubs
• Ruffini corpuscles

Question 11

What is albinism

Answer 11

Congenital disorder

Question 12

What is albinism caused by

Answer 12

A defect in tyrosinase or melanin synthesis

Question 13

What does albinism lead to

Answer 13

Hypopigmentation of the skin

Question 14

Where is meisnner corpuscles found

Answer 14

• Dermal papillae or fingertips, palm

Question 15

What does Meisnners corpuscles detect

Answer 15

• light touch and low frequency fibration

Question 16

Where is the pacinian corpuscls found

Answer 16

Deep dermis and hypodermis

Question 17

Describe the structure of pacinian corpuscles

Answer 17

Large and Ovoid

Question 18

What do pacinian corpuscles detect

Answer 18

Coarse touch
sustained pressure
vibrations

Question 19

Explain the structure of Krause end bulbs

Answer 19

Small ovoid structures with tiny capsule

Question 20

WHERE are Krause end bulbs found

Answer 20

In penis and clitoris

Question 21

What is the function of Krause end bulbs - what do they detect

Answer 21

LOW frequency vibrations

Question 22

Explain the structure of Ruffini corpuscles + what they detect

Answer 22

• Fusiform capsules with embedded collagen
  -Detect: stretch and torque

Question 23

Explain the basic structure of hair + where they form

Answer 23

• Elongated keratinzd structuress ,forming within epidermal invaginans

Question 24

Give 2 hair growth characteristics

Answer 24

- Growth is discontinuous -Growth is Asynchronous-to synchronised

Question 25

What does the hair bulb contain

Answer 25

Dermal papilla with a capillary network to nourish the follicle

Question 26

How is the hair matrix formed

Answer 26

Keratinoyes from the basal epidermis form the matrix. They divide rapidly and : -Accumulate melanin -Undergo keratinization and terminal differentiation

Question 27

Where in the hair follicle is melanocytes present and function- what does it transfer

Answer 27

Present in the hair bulb matrix They transfer melanosomes to epithelial cells that form hair

Question 28

What is the hair shaft composed of

Answer 28

Medulla Cortex Cuticle

Question 29

Explain all three compomet of the hair shaft: 1. Where its found+ composed of 2.What is surrounds + what it is made up of 3.Which layer it is + ctructure and what its mad out of

Answer 29

Medulla (central core): Found in thick hairs. Composed of large, vacuolated, moderately keratinized cells. Cortex: Surrounds the medulla. Made of densely packed, heavily keratinized cells. Cuticle: Outermost layer. Thin, made of heavily keratinized, squamous cells.

Question 30

Name the different types of root sheaths

Answer 30

External root sheaths Internal root sheaths

Question 31

What does the Internal root sheaths surrounded + where does it degenerate

Answer 31

The initial hair root -Degenerates above the sbeaceous gland

Question 32

What does the external root sheaths surrounded + what is it continous with

Answer 32

Surrounds the internal sheath Continous with the basal and spinous epidermal layers

Question 33

What is the glassy membrane in hair follicle

Answer 33

Thickened batsment membrane separating the follicle form the dermis

Question 34

What is the connective tissue sheath formed by

Answer 34

Surrounding dermis

Question 35

Where is hair follicles not found

Answer 35

- Pamls -Soles Lips Clitoris Labia minora

Question 36

What is vitiligo

Answer 36

Acquired condition

Question 37

What does vitiligo cause

Answer 37

Patchy depigmentation due to loss or decreased activity of meloncytes

Question 38

What is the Arrector Pili muscle + where is it attched from

Answer 38

- Smooth muscle bundle -Attachd from fibrous sheath to dermal papillary layer

Question 39

What does contraction in the arrector pili muscle cause 2

Answer 39

Hair to stand erect -Formation of goosebumps by distorting attched dermis

Question 40

Name the different stages in the hair growth cycle

Answer 40

- Anagen( Growth phase) -Catagen(regression phase) Telogen(Resting phase)

Question 41

Explain what happens in Anagen( growth phase)

Answer 41

- Long period of active mitosis and growth

Question 42

Explain what happens in Catagen ( Regression phase) of the hair growth cycle

Answer 42

Short period of arrested growth and hair bulb regression

Question 43

Explain what happens in Telogen(resting phase) of the hair growth cycle

Answer 43

Long inactive phase, hair may be shed

Question 44

Where does new HAIR growth begin from

Answer 44

- Epidermal stem cells in the buldge of the external root sheath

Question 45

Hair growth in the face and pubis is influenced by what?

Answer 45

- Sex hormones e.g androgens

Question 46

How are moles formed

Answer 46

When meloncytes proliferate

Question 47

What does changes in moles size/apperance indicate

Answer 47

dysplasia

Question 48

What can dysplasia( changes in mols size and apperance) progress to + explain the process

Answer 48

Malignant melanoma Rapid melanocyte division. Invasion of basal lamina and dermis. Metastasis via blood and lymph vessels.

Question 49

What is Merkel cell Carcinoma

Answer 49

Rare but aggressive skin cancer

Question 50

What does Merkel cell carcinoma arise from

Answer 50

Merkel cells

Question 51

Is Merkel cell carcinoma more or less common than Melanoma

Answer 51

Less commoj

Question 52

What are nails + location

Answer 52

Hard plates of keratin Locayed on the dorsal surface of each distal pharynx

Question 53

What is the proximal part of the nails+ what is it covered by + it has an extenstion of what

Answer 53

Nail root -Covered by a fold of skin -Has an extension of the stratum corneum called the cuticle

Question 54

What does the nail plate lie on

Answer 54

The nail bed

Question 55

What is the nail bed made up off

Answer 55

Basa and spinous layers of the epidermis

Question 56

What does nail growth occur via

Answer 56

Continous cell division in the matrix

Question 57

What can nail colour be used to asses

Answer 57

Blood oxygen levels

Question 58

Where do nails develop from

Answer 58

Nail matrix in the root

Question 59

What does nail formation lack

Answer 59

Keratohyaline granules

Question 60

How is nail formaed

Answer 60

Cells divide, move distally and keratinze