Integumentary 2

Question 1

What are the functions of the dermis?

Answer 1

• Gives the strength and elasticity to skin
• Contains many of the epidermal appendages, nerve corpuscles, and glands
• Contains the smooth muscle cells that move the hairs
• Around areole, penis, scrotum and perineum,, smooth muscle cells form a loose plexus in the reticular layer
  
  • This accounts for the puckering of the skin at these sites, particularly in erectile organs

Question 2

What is the papillary layer of the dermis?

Answer 2

• superficial layer
• loose connective tissue(more cells)
• contains blood vessels
• predominantly type 1 and 3 collagen fibers
• the elastic fibers are threadlike & form an irregular network
• Relatively thin and includes the substance of the dermal papillae and dermal ridges

Contains Meissner’s corpuscles

Question 3

Describe the reticular layer of the dermis

Answer 3

• considerably thicker than and deep to papillary layer
• dense irregular connective tissue (less cells )
• Characterized by thick irregular bundles of mostly type 1 collagen and courser elastic fubers

Question 4

What is the physiological basis for fingerprinting?

Answer 4

Areas of increased mechanical stress has deeper epidermal ridges and longer, more closely spaced dermal papillae

Responsible for fingerprinting

Question 5

What are the associated appendages of the dermis?

Answer 5

• hair follicles and hair
• sweat glands
• sebaceous glands
• nails
• mammary glands

Question 6

What are epithelial appendages?

Answer 6

All are down growths of the epidermis inti the dermis during embryological development

Modified to perform specific duties

Question 7

Epithelial appendages include…

Answer 7

Hair follicles and hair

-nails

• glands
  
  • eccrine
  • sebaceous
  • apocrine

Question 8

Describe nails as epithelial appendages

Answer 8

Hard plates of epidermal keratinized cells

Present on the dorsal surface on the distal phalanx of the fingers and toes

Question 9

What are the functions of the nail?

Answer 9

Help with grip

Gives protection

Question 10

What are the parts of the nail?

Answer 10

Nail plate:

• The visible part of the nail
• rests on the nail bed (epidermis of the skin-hyponychium) and nail matrix

Nail root

• Found proximal to the nail nail plate
• covered with a fold of skin (eponychium)

Question 11

What is the nail matrix?

Answer 11

Nail matrix- lies deep to (beneath) the nail root

Cells from here proliferate to form the nail itself
-Grows 1 min/week by deposition of hard keratin

Question 12

What are hair follicles?

Answer 12

• Cylindrical shafts composed of keratin
• extends into the hypodermis
• produced in follicles
• associated with sebaceous gland
  
  • hair follicle plus sebaceous gland and smooth muscle (arrector pili)= pilosebaceous organ/unit

Question 13

Where is the fair follicle located?

Answer 13

In thin skin only

Question 14

What does the hair follicle consist of?

Answer 14

• Infundibulum
• Isthmus
• Inferior segment

Question 15

What does the bulb of the hair follicle consist of?

Answer 15

Bulb contains the matrix cells for hair formation

-melanocytes stem cells are found in the bulb

Question 16

Explain the process of hair follicle formation

Answer 16

• matrix cells contribute to formation of the internal root sheath and the hair shaft
• keratogenous zone: matrix cells undergo keratinization as soon as they pass through this zone
• They fully keratinized hair consisting of hard keratin is not followed by the internal root sheath
• It is separated from the underlying dermis via a thick basal laminal (glassy membrane)

Question 17

Summarize the process of hair growth

Answer 17

Cyclical process

• occurs in 3 phases:
  
  • Long phase of activate growth (anagen)
  • short phase of involution (catagen)
  • short inactive phase (telogen)

Growth cycle varies from site to site

- scalp hair follicles have anagen growth phase of 2 years and a short telogen of a few months
- Pubuc hairs, coarse trunk hair, eyelashes, eyebrows have a short growth phase (anagen) and a relatively long resting phase (telogen) hence they are not so long

Question 18

Describe sebaceous glands as epidermal appendages

Answer 18

-simple branched acinar gland

• secretory portion
  
  • located deeper dermis
• Opens into hair follicle
• secretion is holocrine
• product is sebum
  
  • poor staining with H&E
  • Prevents the hair from becoming dry and brittle

Question 19

Summarize Eccrine sweat glands

Answer 19

Found in thick & thin skin

Simple coiled tubular glands

Innervation: cholinergic

Question 20

Describe the secretory portion of the eccrine sweat glands

Answer 20

Secretory portion is in the deep dermis,
-undergoes Merocrine mode of secretion
Contains:
-clear cells-abundant glycogen stains well with PAS
-Dark cells- abundant rER and secretory granules
-Myoepithelial cells-basal aspect of the secretory ligament

Question 21

Describe the duct of the eccrine sweat gland

Answer 21

Duct passes through the dermis and epidermis to open onto the surface
-gentle spiral course to the epidermis which becomes tighter toward the surface

-composed of stratified cuboidal epithelium consisting of a basal layer and a luminal layer

Question 22

Summarize apocrine glands as

Answer 22

Found only in armpit and perineum

Coiled tubular glands

Question 23

Describe the secretory portion of the apocrine gland

Answer 23

Secretory portion: located in the dermis or even hypodermis

• Lumen larger than eccrine sweat glands
• Secretion mode- merocrine
• opens into the hair follicle
• secretes pheromones

Question 24

What are the ducts of the apocrine glands?

Answer 24

Ducts are straight
-lined by stratified cuboidal epithelium

-have a narrow lumen

Question 25

Summarize nerve supply of the skin

Answer 25

- free nerve endings - Pacinian corpuscles( pressure changes & vibrations) - Merkel’s corpuscle - Meissner’s cirpuscles(light touch) - Ruffini’s (stretch & torque) corpuscles Sensory receptors of various types which are peripheral terminals of sensory nerves Secretomotor nerve endings to the blood vessels, arrector pili muscles and sweat glands

Question 26

What are free nerve endings?

Answer 26

Occupy papillary dermis and send twigs into the epidermis (terminate in the stratum granulosum ) - most numerous - do not possess any myelin or connective tissue

Question 27

What are the functions of the free nerve?

Answer 27

Subserve multiple sensory modalities -pain, find touch, itching, temperature(heat and cold) Networks of free dermal endings surround most hair follicles - attach to their outer root sheath - very sensitive to hair movement and serve as mechanoreceptors This relationship imparts a sophisticated degree of specialization in the receptors that surround tactile hairs as is found in the whiskers of certain animals in which each represents its own area on the cortex

Question 28

What is the function of the Pacinian corpuscle?

Answer 28

Deep pressure and vibration

Question 29

What is the structure of the Pacinian Corpuscles?

Answer 29

- Large, ovoid structures - Found in deep dermis and hypodermis - Have macroscopic dimensions more than 1mm along their long axis - composed of a myelinated nerve ending surrounded by a capsule structure - nerve loses its myelin sheath after entering capsule - the unmyelinated portion is covered by a series of tightly packed, flattened Schwann cell lamellae that form the inner core of the corpuscle - The remainder is formed by a series of concentric lamellae

Question 30

What is the gross anatomy of Meissner’s corpuscle?

Answer 30

Touch receptors particularly responsive to low frequency stimuli - tapered cylinders - 150 microns along their long axons - Perpendicular to the skin surface

Question 31

What is the structure function of Meissner’s corpuscle?

Answer 31

- Dermal papillae just beneath the epidermal basal lamina - Appears as twisted skin of wool - There are one or two unmyelinated nerve endings of myelinated nerve fibers follow spiral paths in the corpuscle - The cellular component consist of flattened Schwann cells that form several irregular lamellae through which the axons course to the pole of the corpuscle

Question 32

Describe Ruffini’s corpuscle

Answer 32

Simplest and have an elongated fusiform shape 1-2 microns Thin connective tissue capsule surrounding a fluid filled space Collagen fibers from surrounding connective tissue pass through the capsule

Question 33

Describe the axons if the Ruffini’s corpuscle

Answer 33

Single myelinated fiber enters the capsule - loose it’s myelin sheath - branches to form a dense arborization of fine axonal endings of each terminating in a small knoblike bulb The axonal endings are dispersed and intertwined inside the capsule The axonal endings respond to displacement of the collagen fibers induced by sustained or continuous mechanical stress and so to respond to stretch and torque

Question 34

What is Merkel’s corpuscle?

Answer 34

-Merkel’s cell in communication with expanded terminal bulb of afferent myelinated nerve fibers= Merkel’s corpuscle

Question 35

What is the function of Merkel’s corpuscle?

Answer 35

Detect touch sensations

Question 36

Where are Merkel’s Corpuscles most abundant?

Answer 36

Most abundant in skin where sensory perceptions is acute (fingertips)

Question 37

What are contained in Merkel’s corpuscles ?

Answer 37

- cytoplasm contains neurosecretory granules | - express antigenic markers of both epidermal and neural type