Apologia Human Body - Module 3

Epidermis

The outer portion of the skin, formed by epithelial tissue which rests on the dermis

Dermis

Dense irregular connective tissue that forms the deep layer of the skin

Hypodermis

Loose connective tissue underneath the dermis which connects the dermis to muscle or bone

Hemopoiesis

The process of manufacturing blood cells

Compact bone

Dense bone matrix enclosing only a few small spaces

Cancellous bone

Bone with many small spaces or cavities surrounding the bone matrix

Ossification

Bone formation

Articular cartilage

Hyaline cartilage that covers the ends of a bone in a joint

Axial skeleton

The portion of the skeleton that supports and protects the head, neck, and trunk

Appendicular skeleton

The portion of the skeleton that attaches to the axial skeleton and has the limbs attached to it

Suture

A junction between flat bones of the skull

Process

A projection on a bone

Meatus

A passageway

Foramen

A hole

Sinus

A hollowed out space in a bone

What are the two layers of the skin? Which layer contains keratinized cells? Which layer contains papillae?

The two layers of skin are the epidermis and the dermis. Keratinized cells are found in the

epidermis, and papillae are found in the dermis.

How do the dermal papillae help the epidermal cells?

The dermal papillae allow for maximum blood flow to the basement membrane. This helps the epidermal cells get the nutrients they need. Remember, epithelial tissue is avascular. Thus, the only source of nutrients is the blood in the dermis.

Why do some cuts heal quickly with little scarring while other cuts of similar size and depth heal more slowly with more scarring?

If a cut is along the skin's lines of cleavage, there is not much tension on it. As a result, it heals quickly with little scarring. If a cut goes across the lines of cleavage, there is tension which pulls it apart, making it harder to heal and more likely to scar.

How does the hair follicle help heal bad burns?

The hair follicle contains epithelial tissue. Thus, if the epidermis is destroyed in a second degree burn, the epithelial tissue in the hair follicle can reproduce and make more epidermis.

What kind of tissue is always present in the hypodermis? What kind of tissue is often but not always present in the hypodermis?

The hypodermis always contains loose connective tissue. Most of the time, there is also adipose tissue in the hypodermis.

What is the function of sebaceous glands?

Sebaceous glands secrete oil. That oil softens the skin and protects from certain pathogens.

What is the function of sweat glands?

Sweat glands secrete sweat. The sweat cools the body via evaporation.

List the five layers of the epidermis, starting at the bottom and working up to the top.

The epidermal layers from deep to superficial are: stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, and stratum corneum.

In what layers of the epidermis are the cells still alive?

Only the two deepest layers, stratum basale and stratum spinosum, contain living cells. The cells keratinize in the stratum granulosum and are, at that point, dead.

What are melanocytes, and what do they do to the skin?

Melanocytes are cells that produce melanin. They give the skin its color, depending on the amount of melanin they produce. Melanin also protects the skin from ultraviolet radiation.

Identify the structures pointed out in the skin cross section below:

a. nerves b. hairs c. sweat pore d. blood vessel loop in dermal papilla e. sweat duct

f. sweat gland g. vein h. artery i. adipose tissue j. arrector pili k. sebaceous gland

l. hair follicle m. hypodermis n. dermis o. epidermis

What are the three sections of the hair?

Which section(s) contain(s) cells with soft keratin?

Which contain cells with hard keratin?

The three sections of hair are the medulla, the cortex, and the cuticle. The medulla contains cells with soft keratin, the cortex and cuticle contain cells with hard keratin.

What is the hair matrix?

The hair matrix is a mass of undifferentiated cells. These cells reproduce, forming new hair

cells.

Classify sweat glands as apocrine, merocrine, or holocrine.

Sweat glands are merocrine glands. Even apocrine sweat glands are actually merocrine

glands. They were just named wrongly.

Classify sebaceous glands as apocrine, merocrine, or holocrine.

Sebaceous glands are holocrine glands.

Classify the following bones as long, short, flat, irregular, or sesamoid.

a. ribs

Ribs are flat bones.

Classify the following bones as long, short, flat, irregular, or sesamoid.b. metatarsals

Metatarsals are longer than they are wide. Thus, they are long bones.

Classify the following bones as long, short, flat, irregular, or sesamoid.c. carpals

Carpals are about as long as they are wide. Thus, they are short bones.

Classify the following bones as long, short, flat, irregular, or sesamoid.d. patella

The patella is an example of a sesamoid bone.

Classify the following bones as long, short, flat, irregular, or sesamoid.e. coxa

The coxa is an irregular bone.

Where is the bone marrow found in a long bone?

In long bones, the yellow bone marrow is found in the medullary cavity. Red bone marrow may be found in the cancellous bone nearest the attachment to the trunk.

What are the five functions of the skeletal system?

The functions of the skeletal system are: support, protection, movement, storage, and hemopoiesis.

Label the bones in the figure below: body

a. skull b. mandible c. thoracic cage d. ulna e. radius f. carpals g. metacarpals

h. phalanges i. femur j. patella k. tibia l. fibula m. tarsals n. metatarsals o. phalanges

p. coxa q. sacrum r. humerus s. costal cartilage t. rib u. sternum v. cervical vertebrae w. thoracic vertebrae x. lumbar vertebrae y. clavicle z. pectoral girdle aa. scapula bb. pelvic girdle

Label the bones in the figure below: head

a. frontal bone b. ethmoid bone c. lacrimal bone d. zygomatic bone e. vomer

f. maxilla g. mandible h. parietal bone i. temporal bone j. occipital bone

k. sphenoid bone l. nasal bone