A&P Exam 2 Study Guide

Epidermis

Outer layer, composed of stratified squamous epithelium.

Basement membrane

Layer between epidermis and dermis.

Dermis

Inner layer, thicker than the epidermis

Composed of connective tissue with collagenous and elastic fibers, muscle, blood, and nervous tissue.

Subcutaneous layer (hypodermis)

Layer that contains blood vessels

Beneath dermis, insulating layer, not part of skin

Areolar and adipose connective tissue

Keratin

Tough, fibrous waterproof protein made and stored in the cells.

Keratinization

The process of hardening, dehydration and keratin accumulation that occurs in epidermal cells as they migrate outward.

Cutaneous melanomas

A serious skin cancer characterized by irregularly pigmented areas, often brown, black, gray, or blue.

Effects of UV light on the skin

Helps make vitamin D but also damages skin cells, causes aging, and raises cancer risk.

Dermal papillae

Projections that help skin cells get oxygen and nutrients and create unique fingerprints.

Sebaceous glands

Exocrine, holocrine (secretes whole cells), associated with hair follicles

Produces sebum, which keeps hair and skin soft and waterproof, made of fatty material

Absent in palms and soles

Sweat glands

Tiny, coiled tubes; mostly merocrine/eccrine

Widespread in skin

Originate in deeper dermis, hyperdermis

Functions of the skin

1. Protective barrier

2. Sensation

3. Excretion of some wastes

4. Production of Vitamin D

5. Regulation of body temperature 

Inflammation

Tissue response to stress that includes pain, warmth, redness, and swelling.

Rule of Nines

Divides the skin into parts, each 9% of the body, helping to plan treatment for burns by estimating fluid needs and skin coverage.

Pressure ulcers

Appear when necrosis (cell death) destroys tissue

Usually forms in bony projections such as hip, heel, elbow, shoulder

To prevent, change body positions often, clean skin, keep a healthy diet, and don’t smoke

Long bone

Long, narrow; expanded ends; 3-sided

Found in legs, areas, and fingers

Compact bone

Dense, solid outer layer of bone that provides strength and support, made up of structural units called osteons.

Spongy bone

Lighter bone found inside bones, especially at the ends of long bones and in flat bones, made of a network of thin plates called trabeculae.

Yellow bone marrow

Stores fat

Converts into red marrow when blood supply is low

What is the most abundant form of calcium in the inorganic bone matrix?

Hydroxyapatite

Primary ossification center

Area in center of diaphysis, where bone tissue replaces cartilage.

Secondary ossification centers

Area of the epiphyses, where spongy bone forms later in development.

Epiphyseal plate

Band of cartilage that persists between the ossification centers; the region in which bone grows in length.

Osteoblasts

Cells that build bone tissue from connective tissue layers, becoming osteocytes once surrounded by the bone matrix.

Osteoclasts

Large cells that break down bone, coming from monocytes, using acid to dissolve bone parts, and cleaning up the area for new bone growth.

Vitamin D deficiency

Causes weak and fragile bones because this helps the body absorb calcium for strong bones.

Vitamin A deficiency

Supports bone cell activity; without it, bones can become weak.

Fracture repair steps

1. Hematoma

2. Granulation tissue formation

3. Soft callus tissue

4. Hard callus tissue 

5. Remodeling

Remodeling

(Months to years) Bone restored close to original shape, osteoclasts remove excess bone

Impact of exercise on bones

Stimulates bone growth when pulled at bone attachments

Exercise thickens and strengthens (hypertrophy) bone

Lack of exercise will weaken and thin (atrophy) bone

Structural classification of joints

Refers to the physical structure and material composition of the joint.

Functional classification of joints

Refers to the degree of movement allowed by the joint.

Fibrous joints

Syndesmosis

Suture

Gomphosis

Cartilaginous joints

Synchondrosis

Symphysis

Synovial joints

1. Ball and socket joint

2. Condylar joint

3. Plane joint

4. Hinge joint

5. Pivot joint

6. Saddle joint

Ball and socket joint

Also called spheroidal joint

Round head in cup-shaped cavity

Widest range of motion

Multiaxial, plus rotation

Hip, shoulder

Condylar joint

Also called ellipsoidal joint

Oval condyle fits into elliptical cavity

Back-and-forth, side-to-side movement

Biaxial movement, no rotation

Joints between metacarpals and phalanges

Plane joints

Also called gliding joint

Almost flat, or slightly curved

Back-and-forth and twisting

Nonaxial movement

Wrist and ankle joints

Hinge joints

Convex surface fits into concave surface of other bone

One direction

Uniaxial movement (in 1 plane)

Elbow, joints between phalanges

Pivot joint

Also called trochoid joint

Cylindrical surface rotates within ring of other bone

Uniaxial movement

Rotation only

Atlas (C1) and dens of axis (C2)

Saddle joint

Also called sellar joint

Both bones have concave and convex surfaces

Biaxial movement (in 2 planes)

Carpal and metacarpal of thumb

Suture

A fibrous joint that binds adjacent flat bones with a thin layer of dense connective tissue; it is immovable.

Syndesmosis

A type of fibrous joint where bones are bound by a sheet or bundle of dense connective tissue; it is slightly movable.

Gomphosis

A fibrous joint formed by the joining of a cone-shaped bony process in a bony socket; it is synarthrotic.

Synchondrosis

A type of cartilaginous joint where bones are united by hyaline cartilage that may disappear as a result of bone growth.

Symphysis

A type of cartilaginous joint where articular surfaces of the bones are covered by hyaline cartilage and connected by a pad of fibrocartilage.

Synovial fluid

Fluid that lubricates synovial joints, allowing for smooth movement.

Flexion

Bending parts at a joint so that the angle between them decreases and the parts come closer together (e.g., bending the knee).

Extension

Moving parts at a joint so that the angle between them increases and the parts move farther apart (e.g., straightening the knee).

Dislocation

A condition where bones in a joint become displaced or misaligned.

Types of arthritis

Osteoarthritis

Reumatoid arthritis (RA)

Lyme arthritis

Impact of exercise on joints

Exercise lubricates joints, strengthens surrounding muscles and connective tissues, and promotes a healthy weight.

Striated appearance of skeletal muscle

Muscle fibers look striped due to sarcomeres, which have thin (I bands) and thick (A bands) parts.

Composition of myofibrils

Actin (thin filaments) and myosin (thick filaments).

Steps of skeletal muscle contraction

1. An impulse travels along the length of the motor neuron axon

2. An impulse reaches the end of an axon the synaptic vesicles go through exocytosis

3. From exocytosis the neurotransmitters from the vesicles are released into the synaptic cleft

4. The neurotransmitters bind to receptors on the motor end plate of the muscle fiber

5. Ion channels in the cell membrane of the muscle fiber open up for sodium to enter

Oxygen debt

Develops when the body temporarily works without enough oxygen and must later 'repay' that debt.

Causes of muscle fatigue

1. Decreased blood flow

2. Ion imbalances across the sarcolemma

3. Loss of desire to continue exercise

4. Accumulation of lactic acid (controversial)

Atrophy

Reduction in size and strength of tissues or organs due to disuse or lack of activity.

Rigor mortis

Causes muscles to stiffen after death due to increased calcium and absence of ATP.

Threshold stimulus

Minimum strength of stimulation (action potential) of a muscle fiber to contract

Motor unit

Made of a nerve cell and the muscle fibers it controls; all fibers work together when signaled.

Recruitment

Increase in number of active motor units to produce more force

Multiple motor unit summation

Types of contractions

Isotonic (muscle length stays the same)

• Concentric (muscle shortens)

• Eccentric (muscle lengthens)

Isometric (muscle contracts but doesn’t lengthen)

Slow-Twitch fibers (Type I)

Always oxidative

Resistant to fatigue

Red fibers

Abundant myoglobin

Good blood supply

Many mitochondria

Slow ATPase activity; slow to contract

Stimulated while maintaining posture

Fast-twitch fatigue-resistant fibers (Type IIa)

Intermediate twitch fibers

Intermediate oxidative capacity

Intermediate amount of myoglobin

White fibers

Resistant to fatigue

Rapid ATPase activity

Stimulated when regularly running

Fast-twitch glycolytic fibers (Type IIb)

Anaerobic respiration (glycolysis)

White fibers (less myoglobin)

Poorer blood supply than slow-twitch fibers

Fewer mitochondria than slow-twitch

More SR than slow-twitch

Susceptible to fatigue

Fast ATPase activity; contract rapidly

Stimulated when sprinting

Function of myoglobin

Stores extra oxygen in muscles

Tissues making up the Epidermis

1. Stratum corneum

2. Stratum lucidum

3. Stratum granulosum

4. Stratum spinosum

5. Stratum basale

Tissues making up the Dermis

Papillary layer

Reticular layer

Stratum corneun

Outermost layer; contains tightly-packed, keratinized cells

Stratum lucidum

Only present in thick skin, palms, and soles

Stratum granulosum

Cells die and flatten

Stratum spinosum

Contains some blood vessels, flatten, and divide

Stratum basale

innermost later, nourishes by blood vessels in dermis; next to basement membrane

Papillary layer

Contains dermal papilae, projections between epidermal ridges

Reticular layer

Deeper layer, thicker than papillary; dense irregular tissues

Types of sweat glands

Eccrine

Apocrine

Specialized

Eccrine (Merocrine)

Responds to elecated body temperature, opens to body surfacr through pores

Neck, hands, palm

Mainly water, salt, waste

Apocrine

Responds to emotions, pain; opens into hair follicles

Secretes lipids, proteins, oder

Secrete by exocytosis

Specialized

Ear wax, modified apocrine sweat gland

Mammary - milk

Long bone structure

1. Epiphysis

2. Diaphysis

3. Metaphysis

4. Articular cartilage

5. Periosteum

6. Compact bone

7. Spongy bone

8. Trabeculae

9. Medullary cavity

10. Endosteum

11. Bone marrow

Epiphysis

Expanded end

Diaphysis

Bone shaft

Metaphysis

Between diaphysis and epiphysis, widening part

Articular cartilage

Covers epiphysis

Cushions and prevents friction in joints/between bones

Made of hyaline cartilage 

Periosteum

Encloses bone; dense connective tissue

Compact (cortical) bone

Wall of diaphysis

Spongy (cancellous) bone

Makes up epiphyses

Trabeculae

Branching bony plates, make up spongy bone

Medullary cavity

Hollow chamber in diaphysis; contains marrow

Endosteum

Lines spaces, cavity

Bone marrow

Red or yellow marrow, lines medullary cavity, spongy bone spaces

Red bone marrow

Produces RBCs and WBCs (hematopoeists) and platelets

Red from hemongoblin

In adults: skulls, ribs, sternum, clavicles, vertebrae, pelvis, etc.

Steps of endochondral ossification

1. Begin as hyaline cartilage models

2. Chondrocytes (cartilage cells) enlarge, lacunae grow

3. Matrix breaks down, chondrocytes die

4. Osteoblasts invade area, deposit bone matrix

5. Osteoblasts form spongy and then compact bone

6. Once encased by matrix, osteoblasts are now osteocytes

Endochondral Ossification

Process of replacing hyaline cartilage to form an

endochondral bone

Epiphyseal plate layers

1st Layer, Zone of resting cartilage:

• Layer closest to end of epiphysis

• Resting cells; anchor epiphyseal plate to epiphysis

2nd layer, Zone of proliferating cartilage:

• Rows of young cells, undergoing mitosis

3rd layer, Zone of hypertrophic cartilage:

• Rows of older cells left behind when new cells appear; thicken epiphyseal plate, lengthening the bone

• Matrix calcifies, cartilage cells (chondrocytes) die

4th layer, Zone of calcified cartilage:

• Thin layer of dead cartilage cells and calcified matrix

Consequences of a fracture that impacts the Epiphyseal plate

If damaged in youth, growth may be cease or be uneven