Skin (Part 3 of 3)

Question 1

What are the 3 types of body membranes and where are they located in the body?

Answer 1

1. Serous, mucous, and skin (cutaneous) membranes.
2. The internal cavities and passageways of the body are lined by membranes and these membranes are composed of epithelium with underlying connective tissue.

Question 2

What is the structure of the mucous membrane?

Answer 2

Structure:
1. Composed of an epithelial layer and an underlying layer of areolar connective tissue called the lamina propria.
2. Contain mucous-producing cells or glands to lubricate and protect the mucous membrane.

Question 3

What is the function and location of the mucous membrane?

Answer 3

Function:
1. Lines all internal body passageways that open to the external environment.

Location:
1. Body passageways including the respiratory, digestive, urinary and reproductive tracts.

Question 4

What is the structure of the serous membrane?

Answer 4

Structure:
1. Composed of a layer of simple squamous epithelium & an underlying layer of areolar connective tissue.

Question 5

What is the function of the serous membrane?

Answer 5

Function:
1. Lines internal body cavities including the thoracic and abdominopelvic cavities.
2. Outer parietal layer = lines the internal surface of the body cavity.
3. Visceral layer = lines the external surface of some organs in the cavity.
4. In between these two layers = serous fluid to reduce friction.

Question 6

Name the primary germ layers that the skin is derived from

Answer 6

Question 7

What is the primary germ layer that the skin, epidermis and dermis are derived from?

Answer 7

1. Skin = ectoderm & mesoderm.
2. Epidermis = ectoderm.
3. Dermis = mesoderm.

Question 8

Describe the functions of skin? (SWIMPST)

1. S________
2. W____ R_________
3. I_____ D______

Answer 8

1. Secretion:
   - Excretes waste products (water, salts, urea via sweat).
   - Sebaceous glands = secrete oil onto the skin’s surface to lubricate it.
2. Water Regulation:
   Water-resistant and helps prevent unnecessary water loss or gain.
3. Immune Defence:
   Contains immune cells which initiate immune response against pathogens invading the body via the skin.

Question 9

Describe the functions of skin? (SWIMPST)

1. M_________ R_________
2. P_________
3. S______ R________

Answer 9

1. Metabolic Regulation:
   When exposed to UV, the skin produces vitamin D = essential for absorbing calcium & phosphate.
2. Protection:
   Physical barrier from injury, chemicals, microbes, excessive temperatures and UV radiation.
3. Sensory Reception:
   Important for detecting different stimuli, such as pressure, vibration, and temperature.

Question 10

Describe the functions of skin? (SWIMPST)

1. T__________ R_________

Answer 10

1. Temperature Regulation:
   Blood vessels and sweat glands = regulate heat loss.
   - Hot body = vasodilation.
   - Cold body = vasoconstriction.

Question 11

Label the skin cell?

Answer 11

Question 12

What are the epidermis, dermis and subcutaneous layer made of?

Answer 12

Epidermis = stratified squamous keratinised epithelium.

Dermis = connective tissue (derived from the mesoderm).

Subcutaneous layer = areolar and adipose connective tissue

Question 13

Label the different layers of the epidermis?

Answer 13

Question 14

Describe the role of the stratum basale?

Answer 14

1. Keratinocytes in this layer divide to produce new ones that go to the skin’s surface to replace the dead ones.
2. Melanocytes = produce the pigment melanin in response to UV radiation & transfer the melanin to surrounding keratinocytes.
3. Stratum basale includes tactile cells.

Question 15

Describe the role of the stratum spinosum?

Answer 15

1. Polygonal keratinocytes = helps make skin flexible and strong.
2. Epidermal dendritic cell = immune cells that initiate an immune response against pathogens in the epidermis.

Question 16

Describe the role of the stratum granulosum?

Answer 16

1. Some granules in the cytoplasm of the keratinocytes contain lipids which contribute to the water resistance of the skin.
2. Keratinisation begins in this layer (keratinocytes start to fill with keratin).

***This is the last layer of the epidermis containing living cells.

Question 17

Describe stratum lucidum?

Answer 17

This translucent layer with dead keratinocytes is only present in thick skin.

Question 18

Describe the role of the stratum corneum?

Answer 18

Dead keratinocytes are shed in this layer.

Question 19

Label the image of the dermis?

Answer 19

Question 20

Describe the function and structure of the dermis?

Answer 20

Structure:
Contains epidermal appendages (derived from the epidermis) including –> sweat glands, sebaceous or oil glands and hair follicles

Function:
The dermis contains blood vessels to supply the epidermis, as the epidermis is avascular and relies on diffusion of nutrients from the dermis.

Question 21

Describe the structure, function and location of the reticular layer of the dermis?

Answer 21

Structure:
1. Composed of dense irregular connective tissue & collagen fibres.
2. Contains the epidermal appendages.

Function:
Contains blood vessels and sensory receptors which detect pressure, vibration and stretch.

Location:
Thicker, deeper layer of the dermis.

Question 22

Describe the structure, function and location of the papillary layer of the dermis?

Answer 22

Structure:
1. Composed of areolar connective tissue.
2. Contains finger-like projections called dermal papillae.

Function:
1. Contains sensory receptors which detect touch.
2. The interdigitation of the dermal papillae with epidermal ridges increases the surface area for facilitating the diffusion of nutrients from the capillaries in the dermal papillae to the epidermis.

Location:
Thinner, superficial layer of the dermis.