Integumentary system

Question 1

What is the bodies largest organ?

Answer 1

The skin, which has many layers.

Question 2

What are the 3 main layers of the skin?

Answer 2

• Epidermis
• Dermis
• Subcutaneous layer

Question 3

How is the skin a physical barrier?

Answer 3

The stratum corneum is made from layers of tightly bound, heavily keratinised and nucleated cells.

This provides a physical layer against pathogens.

Mildly acidic secretion from the skin also contributes to this.

Question 4

How is the skin a chemical barrier?

Answer 4

Lipids are secreted by the skin, providing a chemical barrier against water loss.

Antimicrobial peptides are produced by the skin cells and exocrine glands to protect against infection by bacteria and fungi.

Question 5

What is excretion?

Answer 5

Sweat and sebum have an excretory role.

They remove excess salts and vitamins.

Question 6

What is the epidermis?

Answer 6

The top layer of the skin.

Question 7

Explain the structure of the epidermis.

Answer 7

It is made up of stratified squamous epithelium.

It has 5 layers of strata:
• Stratum basale
• Stratum spinosum
• Stratum granulosum
• Stratum lucidum
• Stratum corneum

There is an outer most epithelial tissue and a lower epidermis.

Question 8

What is the function of the outermost epithelial tissue of the epidermis?

Answer 8

It protects the body from the external environment and has a semi permeable membrane to maintain moisture.

Question 9

What is the function of the lower epidermis?

Answer 9

Melanin is produced here to protect from UV radiation, preventing sun damage. Which can lead to burns and cancer.

The cells do the lower dermis make vitamin D or cholecalciferol. The production of this is dependant on sunlight. So in the absence of sunlight, this needs to be consumed in food.

Vitamin D is used by the kidneys to help digest calcium in foods.

Question 10

Explain the structure of the dermis.

Answer 10

This is a layer of connective tissue which helps support the epidermis, as well as making the skin elastic.

It has many blood vessels, nerve endings, hair follicles and exocrine glands (sweat and sebaceous glands).

Question 11

What is the role of the dermis?

Answer 11

• Supports the dermis.
• Assists in thermoregulation.
• Cutaneous sensation.

Question 12

What is cutaneous sensation and how does the dermis facilitate this?

Answer 12

There’s 4 types of mechanoreceptors in the dermis, which respond to pressure and vibrations.

These produce the sense of touch.

Question 13

How does the dermis facilitate excretion?

Answer 13

It contains sweat glands.

These secrete their products onto a surface rather than into the blood.

The main function of sweat is to reduce body temperature, but sweat contains inorganic ions and urea and therefore plays a part in excretion.

It also contains sebaceous glands which excrete sebum, an oily substance.

Sebum keeps the skin slightly acidic, to protect against microbes.

Question 14

Explain the structure of the subcutaneous layer?

Answer 14

This is made up of adipose tissue or fat cells and connective tissue.

Question 15

What is the function of the subcutaneous layer?

Answer 15

This allows the skin to move smoothly over the tissues and muscle underneath.

It also shock absorbs to protect organs, muscles and bones from harm.

Question 16

Which part of the brain controls and coordinates body temperature?

Answer 16

They hypothalamus.

The skin is a receptor and effector.

Question 17

Where are temperature receptors located?

Answer 17

The hypothalamus.

They monitor core body temperature (the temperature of internal organs).

Question 18

Where are the peripheral temperature receptors located?

Answer 18

In the skin.

They monitor the external temperature.

Question 19

What 3 main mechanisms are under control of the hypothalamus, by which skin helps to maintain an almost constant body temperature?

Answer 19

• Sweat glands
• Arterioles
• Hair erector muscles

Question 20

How do sweat glands help to maintain body temperature?

Answer 20

The sweat glands release sweat when the body temperature rises.

Thermal energy from the skin and blood in the capillaries close to the surface of the skin is transferred to the water in sweat. This causes it to evaporate.

This transfer of thermal energy cools the skin.

Question 21

How do the arterioles help to maintain body temperature?

Answer 21

• The arterioles supplying the capillaries near the surface of the can constrict or dilate.

Question 22

What happens to the arterioles when the core body temperature rises?

Answer 22

When the core body temp rises, nerve impulses from the hypothalamus cause the muscles in the walls of the arterioles in the dermis to relax.

Causing the diameter of the arterioles to increase.

As a result, more blood can flow through the capillaries close to the surface of the skin and so more thermal energy is transferred to the surroundings.

Question 23

What happens to the arterioles when the core body temperature falls?

Answer 23

Nerve impulses from the hypothalamus cause contraction of the muscles in the walls of the arterioles.

This causes the diameter of the arterioles to decrease.

As a result, less blood flows through the capillaries close to the surface of the skin and is diverted through the shunt vessel to a venule.

This means that less thermal energy is transferred.

Question 24

What is a shunt vessel?

Answer 24

A small vessel connecting the arteriole to the venule, bypassing the capillaries.

Question 25

How do hair erector muscles help to maintain body temperature?

Answer 25

A fall in core body temperature causes the hypothalamus to send nerve impulses to hair erector muscles.

This causes the erector pilli muscles contract, raising the hairs.

As a result, a thicker layer of air is trapped next to the skin and forms an insulating layer, reducing heat loss.

If you the core body temperature rises, nerve impulses form the hypothalamus cause the erector muscles to relax, causing the hairs to lay flat.

This reduces the thickness of the insulating layer.

Question 26

What is shivering?

Answer 26

Shivering is a reflex action involving small, rapid contraction of skeletal muscles.

The energy used in this process generates heat, increasing body temperature.

Question 27

What causes a callus?

Answer 27

This occurs when frequent abrasions occur, causing the stratum basale to make more cells.

These build up in that area.

Question 28

What is keratin?

Answer 28

A protein that helps with water balance.

It’s made by keratinocytes (cells).

Question 29

What causes a keloid?

Answer 29

The excess production of collagen when scaring.

Question 30

When does sweat start to smell?

Answer 30

When it comes into contact with bacteria.