Epidermis
Which layer of the epidermis consists of cells that are undergoing mitosis and eventually migrate to the stratum corneum layer to be sloughed off?
A. stratum basale
B. stratum granulosum
C. stratum lucidum
D. stratum spinosum
a. stratum basale
The papillary and reticular layers of the dermis are composed mainly of ________.
c. connective tissue
Eccrine sweat glands ________.
b. are present in the skin throughout the body and produce watery sweat
In humans, exposure of the skin to sunlight is required for ________.
a. vitamin D synthesis
Which of the following cells is phagocytic?
b. macrophage
Which layer of your epidermis keeps you from drying out?
a. stratum corneum
The papillary layer of the dermis is most closely associated with which layer of the epidermis?
d. stratum basale
Sebaceous glands ________.
b. are associated with hair follicles
What determines the color of skin?
The pigment melanin, produced by melanocytes, is primarily responsible for skin color.
Melanin comes in different shades of brown and black. Individuals with darker skin have darker, more abundant melanin, whereas fair-skinned individuals have a lighter shade of skin and less melanin.
Which of the following cells is most important in the antibody/antigen (i.e. humoral) immune response?
a. B cells
Langerhans cells are commonly found in the ________.
a. stratum spinosum
When we look at our fingers, we can see fingerprints. Which of the following layers of skin are we looking at in order to see the fingerprints?
A. papillary layer of the dermis
B. reticular layer of the dermis
C. hypodermis
D. stratum corneum of the epidermis
A. papillary layer of the dermis
Similar to the hair, nails grow continuously throughout our lives. Which of the following is furthest from the nail growth center?
b. hyponychium
In response to stimuli from the sympathetic nervous system, the arrector pili ________.
c. are responsible for goose bumps
What is an example of natural immunity acquired passively?
- placental transfer of IgG antibodies from mother to fetus
- breastfeeding
Which of the following cells are associated with the sensory function of skin?
A. Laangerhans cells
B. Kerationcytes
C. Melanocytes
D. Merkel cells
D. Merkel cells
Which of the following is not a function of the hypodermis?
c. source of blood vessels in the epidermis
The hair matrix contains ________.
d. a layer of basal cells
An individual has spent too much time sun bathing. Not only is his skin painful to touch, but small blisters have appeared in the affected area. This indicates that he has damaged which layers of his skin?
d. epidermis and dermis
What is the reason that you have to be immunized with a new influenza vaccine each year?
b. mutation
Cells of the epidermis derive from stem cells of the stratum basale. Describe how the cells change as they become integrated into the different layers of the epidermis.
As the cells move from the stratum basale into the stratum spinosum, they begin the synthesis of keratin and extend cell processes, desmosomes, which link the cells.
As the stratum basale continues to produce new cells, the keratinocytes of the stratum spinosum are pushed into the stratum granulosum. The cells become flatter, their cell membranes thicken, and they generate large amounts of the proteins keratin and keratohyalin.
The nuclei and other cell organelles disintegrate as the cells die, leaving behind the keratin, keratohyalin, and cell membranes that form the stratum lucidum and the stratum corneum. The keratinocytes in these layers are mostly dead and flattened. Cells in the stratum corneum are periodically shed.
An individual using a sharp knife notices a small amount of blood where he just cut himself. Which of the following layers of skin did he have to cut into in order to bleed?
c. papillary dermis
Explain the differences between eccrine and apocrine sweat glands.
Eccrine sweat glands are all over the body, especially the forehead and palms of the hand. They release a watery sweat.
Apocrine glands are associated with hair follicles. They are larger than eccrine sweat glands and lie deeper in the dermis. They release a thicker sweat that is often decomposed by bacteria on the skin, resulting in an unpleasant odor.
Why do people sweat excessively when exercising outside on a hot day?
Sweating cools the body when it becomes warm.
When the body temperature rises, such as when exercising on a hot day, the dermal blood vessels dilate, and the sweat glands begin to secrete more sweat. The evaporation of the sweat from the surface of the skin cools the body by dissipating heat.
Briefly describe the three different phases or lines of defense of the immune system.
1. (Innate) Barrier System: the skin, its secretions, and the mucous membranes of the body.
2. (Innate) Phagocytic leukocytes, Fever/Inflammation
3. (Adaptive) Lymphocytes, Antibodies
- Antigen-specific responses
- Exposure results in immunologic memory