Question

1. When part of the skin is exposed to a great deal of friction, such as when part of the foot rubs against a shoe, a blister often forms.

a. A blister is a collection of fluid that accumulates between two layers of the skin as they separate from each other. Which two layers of skin are these? _______ and _______

b. When the outer layers of skin are pulled of a blister, exposure of the underlying tissues causes a great deal of pain. What type of sensory receptor is responsible for sensation of this pain?

c. Why is the pain worse after the removal of the outer layer of the blister?

2. A hyperdemic needle is used to give certain types of injections.

a. Based on the name of the needle, what space is the tip of the needle usually directed into?

b. What layers of the skin must the hyperdermic needle pass through, in order to get to this space? (Include all sublayers of the dermis or epidermis that may apply. Assume the needle is passing through the skin.)

c. What structures do you think are the likely targets of these needles?

3. a. What layer of the epidermis represents the transition from living to dead epithelial cells?

b. Why do keratinocytes begin to die within this layer?

Answer 1

1. A) Epidermis and dermis.

B) bulbous corpuscles or ruffini corpuscles are the sensory receptors that are responsible for sensation of pain.

C) If remove the outer layer or the Epidermis, the first layer of defense is not working now and also the sensory receptors of dermis are exposed. And the exposed dermis can be infected easily. So the pain becomes worse after removal of upper layer.

2. A) based on the name the tip is directed under the skin, mostly the subcutaneous layer.

B) starting from the upper layer ( Epidermis), there are 5 sublayers- stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum and stratum basale. Then basement membrane. Then two layers of dermis- papillary dermis and reticular dermis. Then subcutaneous layer.

C) veins are likely targets for these needles.

3. A) Stratum granulosum. In Stratum granulosum, the cell produces keratin and keratinocyte becomes a layer of keratin which protects skin. The dead cells will be replaced by keratin from that layer and the dead cells will be shed.

B) In the layer Stratum granulosum the keratinocytes start secreting keratins which becomes flattened and cells begin to die.