A&P exam 2

List the steps involved in preparing animal tissue for microscopic viewing.

fixed (preserved) and then cut into sections (slices) thin enough to transmit light (in light microscopy) or electrons (in electron microscopy). Finally, the specimen must be stained to enhance contrast between structures.

List several structural and functional characteristics of epithelial tissue.

(1) protection, (2) absorption, (3) filtration, (4) excretion, (5) secretion, and (6) sensory reception

Name, classify, and describe the various types of epithelia, and indicate their chief function(s) and location(s)

1. simple epithelia: single cell layer. found where a thing epithelial barrier is desirable;

2. stratified epithelia: composed of two or more cell layers stacked on top of each other. protection is important

3. Squamous cells: flattened and scale-like; allows materials to pass by diffusion and filtration

4. Cuboidal cells: boxlike, as tall as they are wide; secretion and absorption

5. Columnar cells: tall and column shaped; absorption, secretion of mucus, enzymes, and other substances.

Define gland

Consists of one or more cells that make and secrete a particular product (secretion), is a aqueous fluid that usually contains proteins

Differentiate between exocrine and endocrine glands, and between multicellular and unicellular glands.

Endocrine: use their ducts during development. Produces hormones, chemical messengers tat secrete by exocytosis

Exocrine: Secretes their products onto body surfaces or into body cavities. They do it directly.

Describe how multicellular exocrine glands are classified structurally and functionally.

They have two basic parts: an epithelium-derived duct and a secretory unit consisting of secretory cells. supportive connective tissue surrounds the secretory init, supplies it with blood vessels and nerve fibers.

Indicate common characteristics of connective tissue, and list and describe its structural elements.

Extracellular matrix: separates the living cells of the tissue. connective tissue can bear weight, withstand great tension and endure abuses like physical trauma.

Ground substances: unstructured material that fills the space between the cells and surrounds the fibers.

Describe the types of connective tissue found in the body and indicate their characteristic functions.

• Fibroblasts in connective tissue proper become fibrocytes.

• Chondroblasts (kon′dro-blast″) in cartilage become chondrocytes.

• Osteoblasts (os′te-o-blast″) in bone become osteocytes.

Compare and contrast the structures and body locations of the three types of muscle tissue.

Skeletal: Long, cylindrical, multinucleate cells, obvious striations; voluntary movement and control, facial expressions, locomotion

Cardiac: branching, striated, generally uninucleate cells that connect specialized junctions; as it contracts it propels blood into the circulation, involuntary control.

Smooth: Spindle shaped with central nuclei, no striations, cells arranged closely together to form sheets; propels substances or objects along internal passageways, involuntary control

Indicate the general characteristics of nervous tissue.

regulates and controls body functions; two major cell types: neurons and supporting cells.

Describe the structure and function of cutaneous, mucous, and serous membranes.

Cutaneous: organ system consisting of keratinized stratified squamous epithelium firmly attached to a thick layer of connective tissue; its your skin; exposed to air and its dry

Mucous: Lines all body cavities that open to the outside of the body, such as hollow organs of digestive, respiratory, and urogenital tracts; they are wet membranes bathed by secretions or urine.

Serous: Moist membranes found in closed ventral body cavities; they have a visceral layer and parietal layer separated by this fluid.

List the two layers of skin and briefly describe subcutaneous tissue.

Epidermis: composed of epithelial cells, is the outermost protective shield of the body.

Dermis: making up the bulk of the skin, is a tough, leathery layer composed mostly of dense connective tissue

Subcutaneous: lies just deep to the skin

Name the tissue type composing the epidermis.

Keratinocytes: Fibrous protein that helps give the epidermis its protective properties

Melanocytes: Synthesizes the pigment melanin and is found in the deepest layer.

Dendritic: ingests foreign substances and key activators in the immune system

Tactile epithelial cells: Occasional, present at the epidermal-dermal junction, associated with a disclike sensory nerve ending

List the major layers of the epidermis and describe the functions of each layer.

Stratum Basale: Deepest layer, Each time one of these basal cells divides, one daughter cell is pushed into the cell layer just above to begin its specialization into a mature keratinocyte.

Stratum Spinosum: has spine like extensions of its keratinocytes as seen under a microscope. consists of tension-resisting proteins

Stratum Granulosum: Consists of one to five cell layers in the which keratinocyte appearance changes drastically

Stratum Lucidum: found only in thick skin, is visible through a light microscope as a thin translucent band just above the granulosum.

Stratum Corneum: Abrupt transition occurs between the nucleated cells of the granulosum and the flattened enucleate cells of the corneum. This outermost epidermal layer is a broad zone that accounts for three quarters of the thickness. It is also your dandruff.

Name the tissue types composing the dermis. List its major layers and describe the functions of each layer.

Papillary dermis: Is areolar connective tissue, enhances the ability to grip certain kinds of surfaces and contribute to our sense of touch.

Reticular dermis: The network of blood vessels that nourishes this layer; gives the skin strength and resiliency that prevent minor jabs and scrapes from penetrating the dermis. Elastic fibers provide the stretch-recoil properties of skin.

Describe the factors that normally contribute to skin color.

The amount of melanin retained, how close you are to the equator, sun exposure,

hemoglobin: Red pigment found in blood cells

Melanin:dark pigment formed by melanocytes

Carotene: yellow-orange pigment found in certain plant products

List the parts of a hair follicle and explain the function of each part. Also describe the functional relationship of arrector pili muscles to the hair follicles.

Hair bulb: deep end of the follicle below the skin surface

Hair follicle receptor: A knot of sensory nerve endings wraps around each bulb

Hair papilla: Dermal papilla that protrudes into the hair bulb; provides nutrients to the growing hair and signals it to grow

Peripheral connective tissue sheath: external layer of the follicle wall

Glassy membrane: junction of the fibrous sheath and the epithelial root sheath

Epithelial root sheath: Derived from the epidermis, direct continuation of the epidermis and the internal root sheath

Arrector Pilli: a bundle of smooth cells, attached to where its contraction pulls the hair follicle upright and dimples the skin surface(goosebumps) in response to cold temps

Name the regions of a hair and explain the basis of hair color. Describe the distribution, growth, replacement, and changing nature of hair during the life span.

Hair grows 2mm a week but varies on body regions, gender, and age

At the start of each active phase, the newly growing hair pushes out the old hair, which is shed.

The life span of hairs varies. In the scalp, the follicles stay active for an average of four years, so individual hairs grow quite long before being shed.

The follicles in eyebrows, in contrast, are active for only a few months so the eyebrows never grow very long.

Fortunately, the cycles of adjacent hair follicles are not synchronized.

Compare the structure and locations of sweat and oil glands. Also compare the composition and functions of their secretions.

Sweat glands: two types, eccrine, apocrine. distributed over the skins surface; 2 types: Eccrine: on palms, soles of feet and forehead and create pores. Apocrine: lies deeper in the dermis and empty into hair follicles; they are suggested to be like animal’s sexual scent glands.

Oil glands: Known as sebaceous glands, found all over the body except where there is sweat glands. secretes sebum. softens hair and skin.

Describe how the skin accomplishes at least five different functions.

Gives protection to microorganisms, abrasion, temp, harmful chemicals and uv radiation

Forms a chemical barrier by releasing cathelicidins and defenses for wounds

Has physical barriers to create a less penetrable surface

biological barriers including dendritic cells (immune system) and dermal macrophages (disposes viruses and bacteria)

Our body regulates temperature, the skin surface loses hear ro the air and cooler objects in its environment

Describe the functional properties of the three types of cartilage tissue.

Hyaline: provides support with flexibility and resilience. includes articular cartilage (joints), Costal cartilage (breastbone), respiratory cartilage (voice box), and nasal cartilages (supports the external nose)

Elastic: contains more stretchy elastic fibers and better able to stand up to repeated bending. found in the ear and the epiglottis

Fibrocartilage: resistant to compression and having great tensile strength. consists of parallel rows of chondrocytes alternating with thick collagen fibers. Subjected to to pressure and stretch (located in the knee and the discs in vertebrae

Locate the major cartilages of the adult skeleton.

Hyalin: covers ends of bones (knee, shoulder)

Fibrocartilage: Pads between vertebrae

Elastic: covers the larynx when you swallow, structure of the pinna

Explain how cartilage grows.

Appositional: cartilage-forming cells in the surrounding perichondrium secrete new matrix against the external face of the existing cartilage tissue.

Interstitial: lacunae-bound chondrocytes divide and secrete new matrix, expanding the cartilage from within.

Describe the functions of the skeleton and of bone tissue.

Support: Provides framework that supports the body and cradles its organs.

Protection: Fused bones of the skull to protect the brain. The vertebrae surrounds the spinal cord and the rib cage protects vital organs.

Anchorage: Skeletal muscles attach to bones and tendons allowing us to move our body

Mineral Storage: contains calcium and phosphate, its released into the blood

Name the major regions of the skeleton and describe their relative functions.

Axial Skeleton: forms the long axis of the body: skull, veterbrael column, and rib cage; protect, supports and carries other body parts

Appendicular Skeleton: Consists of the bones of the upper and lower limbs and girdles: Shoulder bones and hip bones; attaches the limbs to the axial skeleton

Compare and contrast the four bone classes and provide examples of each class.

Long: Longer than they are wide, all limb bones accept the patella, wrist and ankle bones are long bones

Short: Cube shaped like the wrist and ankles, seamed bones form tendons

Flat: Thin, flattened and usually curved like the sternum, ribs, and most cranial bones of the skull

Irregular: complicated shapes that don’t fit the preceding classes like the vertebrae and the hip bones

Describe the gross anatomy of a typical flat bone and a long bone. Indicate the locations and functions of red and yellow bone marrow, articular cartilage, periosteum, and endosteum.

Long: Shaft, bone ends, and membranes

Flat: thin plates, spongy bone that’s covered by a compact bone

Red bone marrow: found in the medullary cavity of the diaphysis (infants) Found in long bones and has been replaced by yellow bone marrow or found in the cavities between the trabeculae of spongy bones (adults)

Articular Cartilage:Dense connective tissue covering external surface, and muscle, and epithelial tissue

Periosteum and Endosteum: Covers the compact bone outside and inside

Indicate the functional importance of bone markings.

provides information about how that bone and its attached muscles and ligaments work together

Describe the histology of compact and spongy bone.

External layer is compact bone and the internal layer is spongy bone

Discuss the chemical composition of bone and the advantages conferred by its organic and inorganic components.

Its soft organic component: allows it to resist tension (bone cells)

Its hard inorganic component allows it to resist compression (mineral salts)

consists of osteoprogenitor cells, osteoblasts, osteocytes, bone lining cells, and osteoclasts

Compare and contrast intramembranous ossification and endochondral ossification.

Intramembranous: Forms most of the bones of the skull, 8 weeks of development, begins within fibrous connective tissue membranes.

Endochondral: Beginning lat in the second month of development. Uses hyaline cartilage from earlier as models or patterns for bone construction, more complex.

Describe how epiphyseal plates allow long bones to grow.

maintains a constant thickness because of the rate of cartilage growth. Five steps:

1. Resting zone: cartilage is inactive on the side of the epiphyseal plate furthest from the medullary cavity

2. Proliferation zone: Cartilage cells form tall columns that allow fast and efficient growth, Divides quickly, using the epiphysis away from the diaphysis to lengthen the bone

3. Hypertonic zone: The older chondrocytes enlarge

4. Calcification zone:The surrounding cartilage matrix calcifies, chondrocytes die and the matrix deteriorates allowing blood vessels to invade

5. Ossification zone: The calcified spicules are invaded by marrow from the medullary cavity, osteoclasts partly erode the cartilage spicules, then osteoblasts cover them with new bone and eventually spongy bone replaces them

Compare the locations and remodeling functions of the osteoblasts, osteocytes, and osteoclasts.

Osteoclasts: accomplish bone resorption, moving along the bone surface, digging depressions or grooves as they break down the bone matrix

Osteoblasts: follows behind osteoclasts, deposits new bone matrix starting at the osteoid seam

Osteocytes: detects electrical currents which release chemical messengers that promote the formation of additional bone.

Explain how hormones and physical stress regulate bone remodeling.

Wolff’s law holds that a bone grows or remodels in response to the demands placed on it. The first thing is that a bones anatomy reflects the common stresses (think of weight bearing or muscles pulling)

without normal blood calcium levels, nerves can’t fire as needed and muscles can’t contract

Describe the steps of fracture repair.

1. Hematoma: when the bone breaks blood vessels are torn causing blood clots at the site.

2. Fibrocartilaginous callus forms: new blood vessels grow into the clot. fibroblasts and chondroblasts invade the fracture site to produce collagen fibers to connect the broken ends

3. Bony callus forms: osteoblasts begin forming spongy bone. within a week, osteoblasts begin to lay down trabeculae of new bone around and within the fibrocartilaginous callus, uniting the two fragments eventually forming bony callus

4. Bone remodeling occurs: beginning, during bony callus formation and continuing for several months afterward, the bony callus is remodeled.