General Anatomy & Physiology (Online, Pelletier): Exam 2

What are the main functions of the skeletal system?

Movement, protection, production of blood cells, storing minerals, anchoring skeletal muscles, and hormone production

What are two types of bone tissue? What is their texture like and what are they made of?

Compact bone: dense and smooth, made of osteons
Spongy bone: spiky and open, made of trabeculae

Describe types of bone tissue shapes and some examples of each

Long bones: long, with a shaft made of mostly compact bone and enlarged ends with more spongy bones; incudes all limb bones except the patella, wrists, and ankles
Flat bones: thin, flat, usually curved, composed of a layer of spongy bone sandwiched with compact bone; includes skull, ribs, and sternum
Short bones: cube-shaped, composed of mostly spongy bone with compact outer later; includes wrist, ankle, and sesamoid bones
Irregular bones: vary in structure but are mostly spongy bone with an outer compact layer; includes the vertebrae

Describe the 5 major cell types of bones

Osteogenic cells: bone stem cells, make bone cells
Osteoblasts: build bone matrix through secreting into the extracellular matrix and becoming trapped between layers
Osteocytes: housed in lacuna; maintain bone tissue
Bone-lining cells: in periosteum and endosteum
Osteoclasts: break down bone tissue (resorption) through acidic lysosomes that convert the bone calcium into calcium absorbable by the bloodstream

What are the organic and inorganic components of the bone matrix?

Organic: Bone cells (osteogenic, osteoblasts, osteoclasts, osteocytes, and bone-lining cells)
Inorganic: Hydroxyapatites (calcium phosphate crystals, which make bone hard and long-lasting + collagen fibers, which make bone resistant to compression)

What are 2 processes of bone formation/development?

Endochondral ossification: Hyaline cartilage/chondrocytes calcify as ossification occurs; primary ossification site is periosteal bud in the center of the diaphysis, secondary ossification sites are the epiphyses until epiphyseal plates and articular cartilages are left
Intramembranous ossification: begins with fibrous connective tissue membranes and forms mostly flat bones

What are two types of long bone growth? What is interstitial growth and its process/zones of growth?

Interstitial growth is longitudinal bone growth that occurs until 18 (F) and 21 (M) and involves chondroblast division and calcification, ending when the epiphyseal plates calcify into the epiphyseal lines
Proliferation zone → mitosis in chondrocytes
Hypertrophic zone → older chondrocytes enlarge
Calcification zone → chondrocytes die, matrix calcifies and deteriorates
Ossification zone → New bone is left

What is appositional bone growth?

Appositional growth is growing thickness in bones that occurs throughout life as bone remodeling; determinants include chronological age, stress put on bones, hormones, blood calcium levels, and the pull of gravity and skeletal muscles
Osteoblasts secrete bone matrix from beneath the periosteum (superficial to the bone)
Simultaneously, osteoclasts resorb bone matrix from the endosteal surface (deep to the bone)

What are the main hormones and their functions in activating osteoblast and osteoclast activity/appositional bone growth?

Growth hormone: stimulates epiphyseal plate activity in infancy and childhood
Thyroid hormone: modulates growth hormone activity and ensures proper proportions
Parathyroid hormone: regulates calcium levels through activating osteoclast activity
Testosterone (M) and estrogen (F): drives pubescent growth spurts and ends this growth during epiphyseal plate closure

What is hypocalcemia?

Blood calcium is below homeostatic level; PTH activates osteoclasts to break up bone matrix to release more calcium into the bloodstream

What is hypercalcemia?

Blood calcium is above homeostatic level; Osteoblasts deposit calcium in the bone matrix as hard calcium salts

What is rickets?

Bowed limbs resulting from softening of these bones; from lack of calcium (hypercalcemia) or lack of vitamin D to foster calcium absorption

What are two overarching types of bone fractures?

Closed/simple fractures: clean bone break that doesn’t penetrate the skin
Open/compound fracture: uneven bone break in which the broken ends penetrate the skin

What are 6 common, specific types of bone fractures and when they commonly occur?

Comminuted: Bone is broken into three or more fragments (EX: elderly people with brittle bones)

Compression: Bone is crushed (EX: in porous bones, like with osteoporosis)

Depressed: Portion of bone is broken and pressed inward (EX: skull fractures)

Impacted: Ends of broken bones are forced into each other (EX: when people fall with outstretched arms)

Spiral: Bone breaks raggedly due to excessive twisting forces (EX: sports fractures)

Greenstick: Bone breaks incompletely, like a twig (EX: children, with more flexible/cartilaginous bones)

How are fractures treated?

Reduction: realigning and immobilizing broken bone ends
In closed fractures: bone ends are realigned manually 
In open fractures: bone ends are surgically held together by pins or wires
Casts or traction is used to immobilize bones

What is the healing process for fractures?

Hematoma forms → blood-filled swelling/bruise forms from broken blood vessels

Fibrocartilage callus forms → internal and external masses of repair tissue (calluses) are produced by phagocytes made of cartilage matrix, bone matrix, and collagen fibers. Formation of new capillaries (granulation tissue) and disposal of dead tissue too

Bony callus forms → mass of spongy bone produced by migration of osteoblasts and osteoclasts at the site of injury

Bone remodeling → depends on mechanical stresses placed on bone, can take weeks to months to form

What are fontanels?

fibrous membranes connecting cranial bones; “soft spots” where ossification hasn’t taken place yet to allow for compression in birth and growth in early infancy
Disappear around age 2

What are 4 common bone conditions in elderly people?

Osteoporosis: bone-thinning disease due to decreased activity of osteoblasts

Osteoarthritis: inflammatory condition causing stiffness and pain

Kyphosis: vertebral collapse contributing to a hunched posture due to decreases in estrogen (W), calcium, protein, and vitamin D, as well as smoking and inefficient weight-bearing exercises

Pathological fractures: spontaneous bone breaks

What is bursitis?

injury to the patella causing inflammation of bursa (fluid-filled sac) or synovial membrane

What is a sprain?

excessive stretching or tearing that causes damage to ligaments or tendons

What is arthiritis?

Inflammatory or degenerative diseases that damage joints; initial symptoms are pain, stiffness, swelling, and certain structural changes
Acute forms result from bacterial infections

What is osteoarthritis (OA)?

Most common chronic and degenerative form of arthritis
Erosion of cartilage → formation of bone spurs (growth around exposed bone that restricts movement) and crepitus (crunching noise moving joints make from bone spurs)
Commonly affects joints in fingers, spine, knees, and hips
Treated with a balance of activity, rest, and pain killers

What is rheumatoid arthritis (RA)?

Chronic inflammatory and autoimmune disorder (immune system attacks its own tissues)

Inflammation of synovial membranes → thickening into a pannus (abnormal tissue that erodes articular cartilage) and destruction of tissues by inflammatory response

Can lead to ankylosis: ossification of scar tissue leading to deformation and painful, restricted movement in the area

Treatments: immunosuppressants, large dose aspirin or ibuprofen and icing/heating for pain, exercise, and sometimes joint/bone removal and replacement

What is gout?

Diagnosis: Accumulation of uric acid in the blood deposited as needle-like crystals in joint tissue; can be genetic

Prognosis: Left untreated, it can lead to fusing and immobilization of joint

Treatment: drugs, weight loss, avoiding foods that are high in nucleic acid and alcohol

What are the two overall categories of body membranes?

Epithelial membranes and connective tissue membranes

What are epithelial membranes?

The cutaneous, mucous, and serous membranes, all of which have a layer of epithelial tissue and underlying connective tissue

What is the cutaneous membrane?

Type of epithelial membrane

Has two layers: Epidermis (superficial, contains stratified squamous epithelium) and Dermis (deep, mostly dense irregular fibrous connective tissue)

Exposed to air/is a dry membrane

What is a mucous membrane?

Epithelium (mostly stratified squamous or simple columnar) and loose areolar connective tissue (the lamia propia)

Lines body cavities exposed to the exterior/is a moist membrane

Used for secretion or absorption

What are serous membranes?

Simple squamous epithelium + thin layer of areolar connective tissue

Epithelial layer contains mesothelial cells that excrete hyaluronic acid for slipperiness

Two layers: Parietal layer (lines wall of ventral body cavity) folds back into Visceral layer (covers outside of ventral cavity organs)

Layers are separated by serous fluid (excreted by both membranes for slipperiness)

What are three specific serous membranes in the body?

Peritoneum: lines abdominal cavity and covers its organs

Pleurae: covers the lungs and separates them from the heart

Pericardia: covers the heart and separates it from the lungs

What are synovial membranes?

Contains loose areolar connective tissue

Lines fibrous capsules surrounding joints, bursae, and tendon sheaths

Provides cushion as organs move against each other

What are the main functions of the integumentary system?

Insulation, protection, cushion, thermal regulation, excretion, protein and vit D synthesis, secretes acid mantle against bacteria

Name the 5 layers of the epidermis (superficial to deep) and their functions

Stratum corneum: contains horny cells (totally keratinized cells)

Stratum lucidum: Contains dead cells as a result of near-maximized keratinosis, secretion of water-repellant glycolipid, and distance from blood supply (only in THICK skin)

Stratum granulosum: Beginning of organelle deterioration following increase in keratin

Stratum spinosum: Contain bundles of intermediate filaments made of keratin

Stratum basale: Site of stem cell division due to nutrients from underlying dermis; daughter cells stay or continue upward to stratum spinosum

How is apoptis seen in the layers of the epidermis?

Apoptis is controlled cell death, seen in the keratinization process in the epidermis layers

What are the 2 layers of the dermis?

Papillary layer: superficial layer of dermis containing alveolar tissue and dermal papillae (indent the epidermis, may contain capillary loops for nutrients or free nerve endings and touch receptors)

Reticular layer: deepest skin later containing dense irregular connective tissue, blood vessels, sweat and oil glands, deep pressure receptors, and collagen and elastic fibers

How is skin color produced?

Melanin: Amount and kind (yellow, reddish-brown, or black); produced by melanocytes and form granules in cytoplasm called melanosomes that are protective barriers to keratinocytes from UV damage

Carotene: amount in stratum corneum and subcutaneous tissue

Hemoglobin: amount in dermal blood vessels; oxygen-rich, crimson pigment in RBCs

What are cutaneous glands? What are two types?

Exocrine glands that reside in the dermis and secrete to the skin surface; formed by stratum basale cells 

Sebaceous/oil glands: produce sebum as a lubricant and antibacterial

Sudoriferous/sweat glands: produce sweat and other substances

What are two types of sudoriferous/sweat glands?

Eccrine glands: produce sweat via pores; high acidity is antibacterial and nerve endings are receptors for internal and external temperature regulation

Apocrine glands: mostly in axillary and genital regions; secrete fatty acids and proteins in addition to eccrine sweat; no known purpose but are activated by nerves that sense pain, stress, and sexual arousal
Modified apocrine glands include ceruminous glands (line external ear canal and produce cerumen, or earwax) and mammary glands (in breast tissue, secrete milk)

What are the conditions acne and seborrhea?

Acne: infection of sebaceous glands caused by blockage of sebum; oxidation and/or drying leads to blackheads or whiteheads

Seborrhea: overactive sebaceous glands; leads to flaky “cradle cap” in infants

What are burns? 

Type of homeostatic imbalance of the skin involving tissue damage and cell death (from denatured proteins) caused by intense heat, electricity, UV radiation, or chemicals

What are two major threats of burns?

Loss of fluid from tissue damage → major dehydration and electrolyte imbalance that can lead to kidney issues and circulatory shock

Infection → burned skin is sterile for about 24 hours but very prone to infection after—immune system is in distress one to two days after injury

What is the rule of nines and how does it work?

Used to estimate the volume of fluids lost through determining how much of the body has been burned

Divides body into 11 areas, each representing 9% of the body AND additional area (the perineum) representing final 1% of bodily surface area

In what cases are burns considered critical?

Over 30% body has 2nd degree burns

Over 10% body has 3rd or 4th degree burns

There are 3rd or 4th degree burns on the face, hands, feet, or genital region

Burns affect the airway

There are circumferential burns around the body or limb

Describe the damage and symptoms associated with first through fourth degree burns

First: Damages superficial epidermis; area is red and swollen with minimal pain

Second: Damages epidermis and superficial dermis; area is red, blistered, and painful; regeneration is possible if are is kept sterile

Third: Damages the epidermis, dermis, and subcutaneous tissue; area is blistered and white-grey or blackened and painless due to damage to nerve endings; regeneration isn’t possible and skin grafting is necessary

Fourth: Damages the epidermis, dermis, subcutaneous, and deep tissues (bone, muscle, tendons); area appears dry and leathery and requires surgery (either grafting or amputation)

How are burns treated?

Debridement: removal of burned skin

Antibiotics for immune support

Temporary covering and sometimes IV drips for hydration

Skin grafts depending on the severity

What is skin cancer?

Presence of neoplasms (abnormal tissue growth, or tumors)

Can be benign and nonspreading or malignant/cancerous and metastasize 

What is basal cell carcinoma?

Basal cell carcinoma: Most common, yet least malignant skin cancer, slow metastasis

Shiny and dome-shaped tumor

Occurs when cells of the stratum basale can’t form keratin, so they proliferate/overgrow and spill into the dermis and subcutaneous tissue

What is squamous cell carcinoma?

Grows and metastasizes rapidly and can dangerously spread to lymph nodes, but there’s a good chance of complete cure if caught early

Forms scaly, red papules that turn into shallow, firm ulcers

Forms from cells of the stratum spinosum

What is malignant melanoma?

Rarest and most deadly form of skin cancer, with a 50% survival rate that may improve if caught early

Begins in pigmented areas like moles and metastasizes rapidly to lymph nodes and blood vessels

Forms a spreading brown to black patch; can use ABCDE rule to identify

Formed when there is accumulated damage in melanocytes

What is the ABCDE rule in evaluating potentially malignant growths?

Asymmetry, Border irregularity, Color, Diameter, Evolution (of one or more of the above factors)

What are developmental aspects of skin and body membranes throughout the lifespan?

Fetus → Infant: lanugo (downy covering) grows into vernix caseosa (oily protection); skin thickens and subcutaneous fat increases

Adolescence → increased activation of oil glands contributes to proneness to acne

Post-adolescence → Optimal skin quality in 20s and 30s but subject to irritants and pollutants; decrease in subcutaneous tissue leads to cold sensitivity and dryness; thinning of skin leads to susceptibility to bruising; decreased elasticity

Middle-age → decreased number of hair follicles leads to thinning and alopecia or male-pattern balding; decreased melanin production and numerous other factors leads to greying