Lecture 5 - Integumental System

Question 1

Role of skin

Answer 1

Outer layer:

• protection from pathogens (sweat pH 4)
• social role
• barrier against water

Inner layer

• thermoregulation
• sensation (nerve)
• vitamin D synthesis

Question 2

What are the three layers of skin?

Answer 2

They are the epidermis, dermis and hypodermis (subcutaneous tissue)

Question 3

Epidermis

Answer 3

• 4/5 layers of cells
• top layer: stratum corneum
• bottom layer: stratum basalis

Keratinocytes produce in the basalis move to surface of skin and flake away. Melanocytes (protect against UV) are placed on top of the nucleus of keratinocytes to produce pigment.

Question 4

Dermis

Answer 4

It contains blood vessels and nerves. Also has hair follicles, nail roots, glands and muscular tissue.

Two regions:

• papillary (closest to epidermis)
• reticular (closest to hypodermis)

Question 5

What types of glands are found in the dermis?

Answer 5

Apocrine: odoriferous (underarms and genital)
Merocrine: sudoriferous (sweat)
Sebaceous: oil producing

Question 6

Hypodermis (superficial fascia)

Answer 6

It contains fat (thermoregulation). Very spaced out (injection occurs in this area)

Question 7

Thick skin

Answer 7

Skin that has a thick layer of epidermis.

Doesn’t have hair and protects against finer sensation.

Question 8

Thin skin

Answer 8

It has a thinner layer of epidermis. Tends to have hair and is a lot more sensitive.

Question 9

Skin crease

Answer 9

Skin forms strong connections with connective tissue underneath it. The way collagen fibres attach to skin forms the creasing.

Question 10

Body surface area

Answer 10

Pattern known as the rules of 9s can be used to determine the surface area of skin affected (usually in burnt victims). Able to determine fluid loss

Question 11

Skin appendages

Answer 11

Sweat glands:
Sebaceous: oil producing
Ceruminous: wax in ear 
Mammary: modified sweat glands
Apocrine: odoriferous (underarms and genital)
Merocrine: normal sweat glands

Question 12

Mucocutaneous junction

Answer 12

When the cutaneous layer of skin meets with inner layer of mucus membrane (ex: mouth)

Question 13

Sensory nerve fibres in dermis

Answer 13

Mechanoreceptors (touch and pressure)

Nociceptors (pain)

Question 14

Motor nerve fibres in dermis

Answer 14

Vasomotor: innervates blood vessels (dilate/constrict)
Sudomotor: innervates sweat gland
Pilomotor: innervates smooth muscle (attach to hair)

Question 15

Dermatomes

Answer 15

A patch of skin innervated by a particular spinal nerve.

• segmental
• non overlapping between axial line of limb but overlaps adjacent ones.
• more overlap in pain and temp dermatomes than touch

Question 16

How many somites are needed to produce one limb?

Answer 16

7 somites form each limb as well as 7 dermatomes

Question 17

Referred pain

Answer 17

Pain experience on skin is very clear and precise in comparison to visceral organs. Pain from visceral organs is referred to skin above it.

Question 18

Types of blood supply in dermis

Answer 18

2 layers:

• superficial dermal plexus (papillary)
• deep dermal plexus (reticular)

Question 19

What is an angiosome?

Answer 19

A composite block of tissue supplied by a source artery and its accompanying vein.

Question 20

Lymph drainage of skin

Answer 20

There are two types of lymphatic vessels in dermis; superficial dermal lymphatic plexus and deep dermal lymphatic plexus. Lymph drains from superficial to deep and is the 1st level of protection.

Question 21

Where are the main lymph nodes located?

Answer 21

Cervical (neck region)
Axillary (armpit area)
Inguinal (hip region)

Question 22

What is the integumentary system made up of?

Answer 22

Skin and its appendages (hair, nails, subcutaneous tissue and glands)

Derived from ectoderm and mesoderm