Lab Unit 6 - Integumentary System

Arrector pili muscle

Small band of smooth muscle that pulls the hair into an upright position

Stratum corneum

Superficial layer of dead, keratinized cells; functions in protection

Papillary layer

Superficial layer of the dermis; loose connective tissue

In which areas of the body would you expect to find the most Merkel disks and tactile corpuscles? Why?

The fingertips, lips, and face have the most fine touch receptors because of their functions of differentiating shape, texture, and so on.

Keratinocyte

The most common cell type of the epidermis; produces the protein keratin

A treatment for ingrown nails is to remove the nail and apply a chemical such as phenol to the cells of the nail matrix, which kills the cells. What effect will killing the cells of the nail matrix have on the nail? Explain.

Killing the cells of the nail matrix will prevent the nail from regrowing, as this is the location at which cell division occur.s

Hypodermis

Layer of adipose tissue deep to the skin

dermal papillae

Projections of the dermis that indent the overlying epidermis; house capillary loops and touch receptors

Sebaceous gland

Secretes sebum (oil)

Hair follicle

Sheath of epithelial and connective tissue around a hair

Dermal papillae

Projections of the dermis that indent the epidermis

Unfortunately, you go a bit overboard and feel a sudden pinch, after which you notes you are bleeding. What has happened? Are you still in the epidermis? Explain.

At this point, you have cut through the epidermis and entered the dermis, which has pain receptors and is richly supplied with blood vessels. This explains the feeling of pain and the bleeding.

Carcinomas are cancers of epithelial tissue, and sarcomas are cancers of connective tissue. Are epidermal cancers carcinomas or sarcomas? What about dermal cancers? Explain.

Cancers of the epidermis are carcinomas, as they involve the stratified squamous keratinized epithelium. Cancers of the dermis are sarcomas, as they involve either loos CT or dense irregular collagenous CT.

Melanocyte

Cell in the deep part of the epidermis that produces the pigment melanin

Reticular layer

Deep layer of the dermis; dense irregular collagenous connective tissue

Dermis

Deeper layer of the skin composed of loose connective tissue and dense irregular collagenous connective tissue

Stratum basale

Deepest layer of the epidermis; houses activity dividing keratinocytes and melanocytes

You're discussing a forensic crime scene show with your roommate, who insists that fingertips are left behind due to the sebum on our fingertips. What do you tell him? (Hint: What kind of skin is on the fingertips?)

Fingertips cannot be left behind due to sebum, because sebaceous glands release sebum into hair follicles. Fingertips have thick skin, which lack ahri, and so also lack sebaceous glands.

stratum spinosum

Fourth layer of the epidermis (in thick skin); site of melanin accumulation and phagocytic cells

Sebaceous gland

Gland associated with hair follicles that secretes sebum, and oily substance that protects and softens skin and hair

Sweat gland

Gland in the dermis that produces sweat and functions in thermoregulation and excretion

Nails

Hard, keratinized cells that cover and protect the distal parts of fingers and toes

stratum granulosum

Middle layer of the epidermis that consists of keratinocytes with keratin granules

lamellated corpuscle

Nerve endings in the dermis that function as deep pressure receptors

Tactile corpuscle

Nerve endings in the dermis that function in discriminative touch

Epidermis

Outer, protective layer of the skin composed of stratified squamous keratinized epithelial tissue

Hair follicle

Portion of the epidermis that dips down into the dermis from which new hair grows

Hair shaft

Portion of the hair that projects from the skin's surface

Lamellated corpuscle

Pressure receptor in the dermis

To treat the callus (a thickening of the epidermis, from a pair of ill-fitting shoes), you decide to shave off some of the excess epidermis. While doing this, you notice that there is no pain or bleeding. Why wouldn't it cause pain to remove only the superficial part of the epidermis? Why wouldn't it bleed?

The superficial part of the epidermis, the stratum corneum, consist entirely of dead cells and has no pain receptors. The epidermis also lacks blood vessels. It would therefore cause no pain or bleeding ot remove part of the epidermis.

Stratum lucidum

Thin layer of cells found only in thick skin and that appears clear on sections

Would you have expected to have found more tactile corpuscles and Merkel disks on the palm or on the posterior shoulder? Why?

We would expect to find more on the palm because this part of the body requires greater nerve sensitivity.

Shampoos and hair conditioners often claim to have nutrients and vitamins your hair must have to grow and be healthy. a. What is the composition of the hair shaft onto which shampoos and conditioners are applied? b. Taking into account the composition of the hair shafts, do you think these vitamins and nutrients will be beneficial? Why or why not?

a. Hair is composed of dead, keratinized cells. b. As hair consists of dead cells, and dead cells don't grow or metabolize, the nutrients and vitamins are unlikely to be of any benefit.

Which of the following are characteristics of thick skin? (ALL THAT APPLY) a. Located over the palms and the soles of the feet. b. Contains hair and arrector pili muscles. c. Contains sweat glands. d. Very thick stratum corneum. e. Contains sebaceous glands. f. Contains a stratum lucidum.

a. Located over the palms and the soles of the feet. c. Contains sweat glands. d. Very thick stratum corneum. f. Contains a stratum lucidum.

Thick Skin a. Thickness of stratum corneum b. Hair follicles present? c. Sebaceous glands present? d. Stratum lucidum present? e. Arrector pili muscles present?

a. Thick b. No c. No d. Yes e. No

Thin Skin a. Thickness of stratum corneum b. Hair follicles present? c. Sebaceous glands present? d. Stratum lucidum present? e. Arrector pili muscle present?

a. Thin b. Yes c. Yes d. No e. Yes

A hair follicle is composed of epithelium and connective tissue. a. True b. False

a. True

Both hairs and nails are composed primarily of dead keratinocytes. a. True b. False

a. True

Eccrine sweat is released into ____________, and sebum is released into ______________. a. a duct; a hair follicle b. a hair follicle; a blood vessel c. a duct; a blood vessel d. a hair follicle; a duct

a. a duct; a hair follicle

_____________ corpuscles in the dermis detect pressure, whereas ____________ corpuscles in the dermis detect fine touch. a. lamellated, tactile b. tactile, lamellated

a. lamellated, tactile

From where do the cells of the epidermis obtain oxygen and nutrients? a. From blood vessels in the epidermis. b. Diffusion from blood vessels in the dermis. c. Diffusion from the air. d. From blood vessels in other epithelial tissues.

b. Diffusion from blood vessels in the dermis.

The dividing cells of a nail are located in the _______________. a. eponychium b. nail matrix

b. nail matrix

An arrector pili muscle is composed of _____________ muscle tissue. a. skeletal b. smooth

b. smooth

What are the layers of the epidermis that contain living cells? (ALL THAT APPLY) a. stratum lucidum b. stratum basale c. stratum corneum d. stratum spinosum e. stratum granulosum

b. stratum basale d. stratum spinosum e. stratum granulosum

The primary protein produced by the main cell type in skin is a. actin b. melanin c. keratin d. collagen

c. keratin

In which layer of the epidermis are melanocytes found? a. stratum corneum b. stratum granulosum c. stratum basale d. stratum lucidum e. stratum spinosum

c. stratum basale