Integumentary System Lecture Quiz 2

Question 1

What are the 5 primary functions of the integumentary system?

Answer 1

1. Physical protection from environmental hazards (toxins, microorganisms, UV rays)
2. Helps regulate body temp. By controlling the rate of heat loss.
3. Reduces water loss
4. Synthesis and storage of lipids and vitamin D
5. Coordination of immune response to pathogens and cancers in skin

Question 2

Name the two layers that comprise the skin.

Answer 2

Epidermis and dermis

Question 3

Name the third layer deep to the 2 layers of skin.

Answer 3

Subcutaneous layer

Question 4

Name the type of tissue comprising the epidermis

Answer 4

Stratified squamous epithelium

Question 5

What’s the lifecycle of epidermal cells, migration pattern, and physical changes? Include desmosomes, keratin proteins as they migrate superficially.

Answer 5

Skin cells (keratinocytes) replicate in the stratum basale. These living cells migrate superficially as more cells replicate in the stratum basale. The cells walls then thicken and more desmosomes form tightly around the cells walls. Then tough water proof proteins called keratin are laid down inside the cells. The end result is that the cells comprising the stratum cornerman make the skin tough and waterproof and fairly impervious to diffusion.

Question 6

Describe where you would expect to find the blood supply (capillaries) for the epithelial cells in the previous micrograph and why. Label it in the micrograph.

Answer 6

The epidermis has no direct blood supply. It’s blood supply is in the dermis:deep to the stratum basale.

Question 7

Where would you expect melanocytes to be located in the previous micrograph?

Answer 7

Stratum basale

Question 8

What are the melanocytes primary function?

Answer 8

Melanocytes shield the keratinocytes nuclei from UV rays to prevent skin cancer. Melanocytes produce melanin, which resides in cellular extensions that extends around keratinocytes. The melanin diffuses out of the extensions and into the keratinocytes on the Sunday side of the nuclei. Thereby shielding the replicating DNA from potentially damaging UV rays.

Question 9

All four types of tissues are found in the dermis. Which tissue is most abundant?

Answer 9

Connective tissue

Question 10

Why do you think the dermis is mostly compromised of dense irregular, instead of regular connective tissue?

Answer 10

The multidirectional weave of the collagen fibers is designed to provide the skin with strength as it is pulled in many different directions.

Question 11

What type of fiber found in the dermis provides it with its tensile strength in all directions?

Answer 11

Collagen

Question 12

What type of fiber found in the dermis provides it with its elasticity?

Answer 12

Elastic

Question 13

What cells produces the collagen and elastic fibers?

Answer 13

Fibroblast

Question 14

Provide examples of where smooth and skeletal muscles are found in or attached to the dermis and what they do.

Answer 14

-Skeletal muscles in the face move the skin resulting in our facial expressions
-smooth muscle fibers are in the scrotum to help pull the testes up to the torso
-smooth muscle fibers attached to hair follicles make the hair stand up
-smooth muscle in dermal arterioles control blood flow in the capillaries.

Question 15

The gel-like ground substance in the dermis maintains space between the collagen and elastic fibers, blood vessels and other skin accessory structures. The ground substance is an aqueous, gel-like packing material of the dermis. Describe the nutritional functions of the ground substance.

Answer 15

The aqueous nature of the ground substance permits easy diffusion of nutrients and waste products between cells and the capillaries.

Question 16

The keratinocytes undergo structural changes as they migrate superficially. Describe changes to their intercellular keratin and desmosomes and how these affect their physical properties? Explain why these changes help the skin perform it’s first two functions.

Answer 16

The epidermal cells (keratinocytes) deposit more keratin internally (intracellularly) and increase the number of connections (desmosomes) between cells as they migrate superficially. The tough water/resistant protein (keratin) and tighter intercellular connections (desmosomes) cause the stratum Corneum to be water-resistant and relatively impermeable. So, toxins and pathogens tend not to be able to breech the epidermis.

Question 17

Describe the blood vessel network in the epidermis, dermis and subcutaneous layer.

Answer 17

The network of small arteries that supply the skin and small veins that return the blood to the ventral circulation are generally at the depth of the junction between the dermis and subcutaneous layer. Branching off this network of supply and return vessels are connected to the venues through the capillaries to complete the circuit.

Question 18

How do these billions of capillaries nourish and hydrate the cells in the skin?

Answer 18

The billions of capillaries in the skin keep it hydrated as plasma leaks (filtrates) out of them. Similarly nutrients such as glucose and white blood cells filtrate out of the capillaries and into the interstitial space, helping to keep the skin healthy. Waste products are taken up by the capillaries removing them from the skin.

Question 19

Why would it be impractical to have blood vessels extend up into the epidermis?

Answer 19

Having no circulation in the epidermis reduces the risk of bleeding during daily activities or routine Skin injuries. This also reduces the risk of toxins and pathogens entering the blood stream.

Question 20

Every living cells in our bodies requires energy to survive. Specifically where (organelle) in each cells is this energy produced?

Answer 20

Mitochondrion (singular)

Question 21

Where in the file ling infrared image is best being lost fastest and slowest? Explain why.

Answer 21

Exposed skin (face neck and hands) is dissipating heat fastest. Skin covered by hair and clothing is still losing heat just more slowly.

Question 22

What can we conclude then about the heat we produce and lose under various conditions such as rest exercise cool environments and warm environments?

Answer 22

Heat production and loss are equal.

Question 23

What are two main types of connective tissue found in the subcutaneous layer?

Answer 23

Adipose and loose connective tissue

Question 24

The skin is responsible for changing the rate of heat loss. How does the skin primarily regulate (increase and decrease) the rate of heat loss? Releasing sweat is only part of it. Consider the massive network of capillaries in the dermis.

Answer 24

The dermis regulates heat los primarily by constricting or dilating arterioles that supply the capillary bed. The massive network of vessels in the skin can be dilated to allow more warm blood to circulate through the skin. This increases the amount of body heat lost to the environment. Ex. During exercise when the muscles are producing an excess amount of heat the dermal arteries and arterioles dilate. Skin blood flow is decreased by constricting dermal blood vessels. This decreases the amount of warm blood circulating through the skin and decreases rate of heat loss. This is the typical response to conserve core body temp in cold environment. Various things such as sweating and removing clothing can further affect heat loss, but it is the regulation of dermal blood flow that fundamentally determines the rate of heat loss.

Question 25

As just observed, we dissipate excess heat by sending warm blood out to the dermis. What else can the dermis to go further in ease the rate of heat loss?

Answer 25

Excrete sweat. Evaporation accelerated heat loss.

Question 26

In addition to the involuntary response of the body to sweat, what actions can a person such as a football coach in august, take to further increase the rate of heat loss of decrease the rate of heat gain?

Answer 26

INCREASING HEAT LOSS
The coach could make sure the athletes stay hydrated so they can sweat. The coach can hold practices in cooler times of the day so the athletes can lose heat more rapidly. Have the athletes practice without protective gear, so heat can dissipate more readily by convection and evaporation.
Provide large fans and mist to increase heat loss by evaporation and convection.
DECREASE HEAT GAIN
Keep the athletes out of direct sun.
Reduce the intensity of practice and allow more time between strenuous activities
Hold practice at cooler times.

Question 27

Why do obese people struggle more in preventing overheating even in temperate conditions?

Answer 27

We all lose heat from the core on an ongoing basis via conduction since their excess fat in the subcutaneous layer. People who are obese loss less heat through conduction since their excess fat in the subcutaneous layer is an excellent thermal insulator.

Question 28

How does it work that obese people lose less heat through conduction?

Answer 28

Because of this you will notice that obese individuals will flush (dermal dilation) and sweat sooner than the non-obese in an attempt to prevent overheating. The body is shifting some of the blood flow to the superficial side of the subcutaneous layer where it’s heat can be dissipated more readily.

Question 29

When a person moves from a warm to a cool environment, what happens to the difference between the core temp and the surrounding temperature? Would this increase or decrease the rate of heat loss?

Answer 29

This increase the temp difference. The larger temperature difference between the skin and surrounding air would increase the rate of heat loss.

Question 30

How does this shift the heat balance if the metabolic rate remains unchanged?

Answer 30

With the resting heat production remaining constant and the rate of heat loss increasing, core temperature will begin to drop.

Question 31

What does the skin need to do then to the rate of heat loss if the core temp is to remain constant? How does it do this and what is the end result on the core temperature?

Answer 31

The dermis needs to decrease the rate of heat loss. To do this dermal blood flow is reduced which in turns reduces the rate of heat loss. If this lowers heat loss to match heat production, core temp will be maintained at 37° C.

Question 32

So again, fundamentally what role does the dermis play in regulating core temp and how does it do this?

Answer 32

It regulates the rate of heat loss by increasing and decreasing dermal blood flow.