Skin structure and functions

Question 1

What are the three layers of the skin?

Answer 1

Epidermis
Dermis
Hypodermis

Question 2

What is the largest layer of skin?

Answer 2

Dermis

Question 3

What is the top layer of the skin called and the main component of cells it consists of?

Answer 3

Epidermis and keratinocytes

Question 4

What is the dermis layer mainly consist of?

Answer 4

Immune cells and fibroblasts.

Question 5

How many sub layer in the epidermis and that are they called?

Answer 5

There are five sublayers in the epidermis and they are:
1. Stratum basale (bottom layer).
2. Stratum spinosum
3. Stratum granulosum
4. Stratum lucid
5. Stratum corneum (top layer)

Question 6

What is the bottom layer of the skin called and what is it made of?

Answer 6

The hypodermis and it is made of adipocytes (fat cells).

Question 7

When does the epidermis layer form?

Answer 7

1st month of gestation.

Question 8

When does the dermis layer form?

Answer 8

11 weeks’ gestation

Question 9

When does the fingerprints develop?

Answer 9

17 weeks gestation.

Question 10

What are functions of the skin?

Answer 10

• Prevents mechanical abrasion of underlying tissues and coordinated wound healing.
• Prevents the removal of water and water absorbance.
• Acts as a barrier against pathogens.
• Mechanism for sensation.
• Prevents injury from chemicals and radiation.

Question 11

What are the functions to the hypodermis?

Answer 11

• It gives stability to the structures above such as the dermis and the epidermis.
• Absorbs blows to the body.
• Reserves energy.
• Regulates body temperature.

Question 12

What are the functions of the dermis?

Answer 12

• Supports the epidermis
• Aid in sensation.

Question 13

What cells can be found in the epidermis and what is the most abundant type of cell?

Answer 13

The most abundant cell that is found in the epidermis is keratinocytes and they are skin cells.
Melanocytes make up the rest of the epidermis layer and a small amount of Merkel cells too.

Question 14

What are melanocytes?

Answer 14

They are pigment producing cells and they are responsible for producing melanin.
Help us by protecting us from UV radiation.

Question 15

What is melanin?

Answer 15

It is the pigment which is produced by melanocytes and it gives skin and hair colour.

Question 16

What are merkle cells?

Answer 16

They are sensory cells.

Question 17

What divides the epidermis layer from the hypodermis layer?

Answer 17

The basement membrane.

Question 18

What is the basal layer?

Answer 18

The deepest sublayer of the epidermis layer.
New cells are produced and they push older cells up the sublayers.
Cells are anchored to the basement membrane.

Question 19

What is the spinous layer?

Answer 19

• The sublayer that is found between the basal layer and the granular layer.
• Cells become specialised in this layer and the cells are flat.

Question 20

What are hemidesmosomes and desmosomes?

Answer 20

• They are toes of cell junctions.
• Hemidesmosome provide anchoring to the basement membrane.
• Desmosomes are found between neighbouring cells.

Question 21

What cells can be found in the spinous layer?

Answer 21

Macrophages that engulf bacteria and langerhans cells.

Question 22

What is the granular layer?

Answer 22

It is the layer that is situated between the spinous layer and the stratum lucidum.
Contains keratohyalin granules.

Question 23

What is the startum lucidum layer?

Answer 23

It is a sublayer that is found in thicker skin areas like the soles of feet and palms of hands.
The function of this sublayer is reduce pressure and friction.

Question 24

Where is the transition zone situated in the epidermis?

Answer 24

It is situated between the startum granulosum and the stratum corneum.
In this part of the epidermis, organelles are destroyed by enzymes.

Question 25

What is the stratum corneum?

Answer 25

It is the top sublayer of the epidermis. Keratinocytes differentiate into corneocytes.

Question 26

What are corneocytes?

Answer 26

They are dead cells which are flattened and they can be found on the outermost layer of the epidermis.

Question 27

What protein is present in corneocytes?

Answer 27

Keratin

Question 28

When is melanin production increased?

Answer 28

When melanocytes are exposed to the sun.

Question 29

What are melanosomes?

Answer 29

They are vesicles that contain melanin which are located in melanocytes. Melanosomes can be transported to keratinocytes via dendrites.

Question 30

What are langerhans cells and where are they produced?

Answer 30

They are antigen presenting cells and they present T cells. They are produced in the bone marrow. They protect the skin barrier from any foreign antigens.

Question 31

What is the thickness of the dermis on the eyelids and palms/ toes.

Answer 31

0.6mm on the eyelids 3mm on the palms and toes.

Question 32

What can be found in the dermis?

Answer 32

Mast cells Dermal appendages Fibroblasts

Question 33

What are mast cells?

Answer 33

They are part of the immune system and they help the body to fight off infections and invading pathogens.

Question 34

What are dermal appendages?

Answer 34

They are structure embedded into the dermis layer. Hair follicles, sweat glands and sebaceous glands can be found here.

Question 35

What are fibroblasts?

Answer 35

A type of cell that contributes to the formation of connective tissue in the skin.

Question 36

What are the two sublayer of the dermis called?

Answer 36

Papillary layer and the reticular layer.

Question 37

What is the papillary layer?

Answer 37

It is known as the superficial layer as it is closer to the epidermis and it contains sensory nerves ands loose connective tissue. Also contain blood vessels.

Question 38

What is the reticular layer?

Answer 38

It is known as the underlying layer as it is more thicker compared to the papillary layer. Provides elasticity, support and strength to the skin. Contains collagen fibres.

Question 39

How many hairs is there on the body?

Answer 39

5 million hairs

Question 40

What is a hair follicle split into?

Answer 40

Root and shaft.

Question 41

What are the layers of the hair?

Answer 41

Inner medulla Outer cortex Cuticle

Question 42

How many epithelial walls does a hair have and what are they called?

Answer 42

There are two epithelial walls and they are known as the internal root sheath and the external root sheath.

Question 43

What does the internal root sheath surround in the hair?

Answer 43

The root.

Question 44

What does the external root sheath surround in the hair?

Answer 44

The entire length of the follicle.

Question 45

Why do we get grey hair over time?

Answer 45

We produce less melanin pigment which provides us with the colour for our hair.

Question 46

What are the three main types of hair?

Answer 46

languo hairs Vellus hairs Terminal hairs

Question 47

What are nails made of and how much do they grow a day?

Answer 47

Made of keratin and they grow 0.01mm a day.

Question 48

Where are the blood vessels found in the skin?

Answer 48

In the hypodermis/ subcutaneous layer.

Question 49

What is thermoregulation?

Answer 49

The maintenance of physiological core body temperature. Maintain the body's temperature at 37 degrees.

Question 50

What is vasodilation?

Answer 50

When the blood vessels widen to allow more blood to reach the surface of the skin, so it can cool down. Usually occurs in hot environments.

Question 51

What is vasoconstriction?

Answer 51

When the blood vessels narrow and this is to reduce the flow of blood to reduce heat lost. Usually occurs in cold weather conditions.

Question 52

What are exocrine glands?

Answer 52

Glands that secrete substances through ducts to the body's surface.

Question 53

What are sebaceous glands?

Answer 53

They are found in hair follicles and they produce oily sebum.

Question 54

What can be found in oily sebum?

Answer 54

Proteins, cholesterol, triglycerides and electrocytes.

Question 55

What are some functions of sebum?

Answer 55

Provides moisture to the skin and protection. Protects the hair from cracking and from dehydration.

Question 56

How many sweat glands in the body?

Answer 56

2.5 million sweat glands.

Question 57

What are the two types of sweat glands?

Answer 57

Eccrine and apocrine.

Question 58

What are eccrine glands?

Answer 58

They are the most abundant and the most common type of sweat gland found throughout the body and they produce a watery odourless liquid. Under the thermal control of thermoregulation.

Question 59

What are apocrine cells?

Answer 59

They are large sweat glands and they can be found in the armpits and genitals. They produce sticky odourless secretions which are rich with protein and a smell/ odour will occur is it comes into contact with bacteria.

Question 60

What makes up sweats and what is the main component present in it?

Answer 60

Water is the main component. Can contain salts and different minerals. Fatty acids and amino acids.

Question 61

What is the four stage process of sweat analysis?

Answer 61

1. Sterile cotton swabs 2. Remove water via sublimation 3. Leave amino acids and protein acids 4. Analyse by using chromatographic methods.