2. Skin (Integument)

Question 1

How is the skin covered?

Answer 1

The skin is covered with the superficial epidermis, made of epithelial tissue, and the deeper dermis, containing much connective tissue.

Question 2

Which tissue lies under the dermis?

Answer 2

Under the dermis is the superficial fascia (also called the hypodermis despite NOT being part of the skin).

Question 3

Describe the build-up of the epidermis

Answer 3

Most superficial layer: waterproof stratum corneum (no living cells)

Stratum corneum
Stratum lucideum
Stratum granulosum
Stratum spinosum
Stratum basale (=stratum germinativum).

Question 4

What is the goal of the stratum germinatuvum/basale?

Answer 4

In the stratum germinativum keratinocytes are actively dividing. Melanocytes also inhabit this layer and produce melanin.

Question 5

How are skin macrophages produced?

Answer 5

Dedrocytes migrate to the skin from the bone marrow an become macrophages there

Question 6

What are the sensory cells of the skin?

Answer 6

Merkel cells are one of the many sensory receptors found in the skin. Merkel cells are associated with a sensory nerve ending.

Question 7

What is the dermis build up of, except for connective tissue?

Answer 7

• blood capillaries
• hair roots
• sensory receptors (free nerve endings or encapsulated)
• exocrine sweat and oil glands
• connective tissue: collagen and elastic fibres

Question 8

What is the function of keratin?

Answer 8

Keratin is an extremely important substance for it makes the skin waterproof. Without it, land vertebrates like reptiles, birds, and mammals would, like frogs, be able to survive only in damp places.

The cells in the epidermis die because a special protein called keratin is deposited in them.

Question 9

What is the difference between exocrine and endocrine glands?

Answer 9

Exocrine glands are glands with ducts.

Endocrine glands have no ducts and release their products (hormones) directly into the bloodstream

Question 10

What is the difference between cold blooded and warm blooded temperature regulation?

Answer 10

Cold blooded: body temperature follows that of the environment

Warm blooded: body temperature is constant despite changes in the temperature of the environment

Question 11

Why is it easier for large animals to maintain their body temperature?

Answer 11

In large animals, the ratio of the outside body surface to the inner volume is smaller making it easier to maintain their body temperature

Question 12

What is regulating body temperature?

Answer 12

The hypothalamus (how?)

Question 13

Are all vertebrates warm blooded?

Answer 13

No, only birds and mammals can control their body temperature. Ie they are warm blooded or homoiothermic

Question 14

What is the role of capillaries in the dermis in temperature regulation?

Answer 14

Blood capillaries in the dermis constrict or dilate to control heat loss

Question 15

How is keratin produced?

Answer 15

Keratin is produced by keratinocytes

Question 16

Where are sebaceous glands found?

Answer 16

In the dermis. They produce oil

Question 17

When a medicine is delivered via a patch attached to the skin, how is it delivered?

Answer 17

This is called transdermal delivery

Question 18

When a pharmaceutical is administered hypodermically, what does this mean?

Answer 18

“Hypo” means below, in this case, the dermis. Subcutaneous fat
(superfi cial fascia) lies beneath the dermis.

Question 19

Name 5 sensory receptors of the skin

Answer 19

1. Meissner corpuscle
2. Root hair plexus
3. Nociceptor
4. Merkel cells
5. Pacinian corpuscles

Question 20

Name 2 types of sweat glands

Answer 20

The apocrine and the eccrine gland

Question 21

To what in the skin does the term “nociceptors” refer?

Answer 21

Nocireceptors refer to the free nerve endings with large receptive fields that detect pain. The prefix “noci” is derived from the Latin for hurt.

Question 22

How do sudiferous glands secrete sweat?

Answer 22

Sudiferous glands secrete sweat through a duct to the skin or into a hair follicle.

Eccrine (ander woord: merocrine) sweat glands secrete through a duct, apocrine sweat glands secrete into a hair follicle. (sudiferous gland can be both)

Question 23

What are the four functions of the skin?

Answer 23

1. Produce melanin
2. Secrete sebum
3. Minimise water loss
4. regulate body temperature

Question 24

What purpose is vitamin D (calcitriol) used for?

Answer 24

Vitamin D is required for uptake of calcium from the gut

Question 25

Which cell type is responsible for forming the skin’s ability to tan on exposure to sunlight?

Answer 25

melanocytes

Question 26

How does the stratum germinativum receive nutrition?

Answer 26

The stratum germinativum of the epidermis and the more superfi cial layers, being without blood capillaries receives their nutrition via diffusion from capillaries in the dermis.