Disorders Of The Skin, Muscle, And Bone Flashcards
Force generated by the muscle on an object.
Tension
Force generated by an object on a muscle.
Load
Tension and load are:
Opposing forces
Mechanical response of a muscle fiber to a single action potential.
Twitch
Increase in mechanical response of a muscle fiber to successive action potential.
Summation
Maintained contraction in response to repetitive stimulation.
Tetanus
Diseased or damaged muscle fibers leak this into serum:
CK - serum creatinine kinase measurement
This is detectable in urine after crush injury, it’s toxic to kidneys, associated with ischemic disorders or extreme exertion.
Myoglobin
Records summation of action potentials of the muscle fibers in each motor unit. Abnormalities help differentiate muscle diseases (myopathy), peripheral nerve disorders (neuropathy), and neuromuscular junction disorders.
Electromyogram (EMG)
Histological examination helps define myopathic and neuropathic disorders.
Muscle biopsy
Helps determine integrity of glycolytic pathways and enzyme systems that function during intense exercise.
Forearm ischemic exercise test
Increased mitochondria and capillaries, decreased fiber diameter happens with:
Endurance: long distance runners
Increased glycolytic activity, fiber diameter, and muscle strength happens with:
Strength: weight lifter
An age-related loss of skeletal muscle, causes a decrease in strength:
Sarcopenia
Failure to generate force:
Weakness
Failure to sustain force:
Fatigue
Alterations in nerve supply or conduction:
Denervation atrophy, myasthenia gravis, periodic paralysis
Defect in muscular dystrophy
X-linked trait
Autoimmune disease that causes neuromuscular deficits, including weakness and fatigue. Caused by antibodies that block the nicotinic receptors in the neuromuscular junction and prevent excitation of muscle fibers.
Myasthenia gravis
Antibody activities in Myasthenia gravis include:
- Block nicotinic receptors
- Promote destruction of nicotinic receptors
- Induce endocytosis to reduce number of receptors on motor end plate
Muscles become fatigued, becoming progressively weaker during contraction and improving after rest happens with:
Myasthenia gravis
Treatment of myasthenia gravis:
Immunosuppressive agents to reduce autoimmune response.
Acetylcholinesterase inhibitors- block destruction of acetylcholine and make it available for longer time at NMJ
Thymectomy- to reduce release of T cells that promote production of autoantibodies
An autosomal dominant genetic disorder affecting sodium channels in muscle cells. Affects ability to regulate potassium level in blood.
Primary hyperkalemic periodic paralysis
Triggers of primary hyperkalemic periodic paralysis:
- Rest after exercise
- Potassium rich foods
- Stress
- Fatigue
- Fasting
Treatment for primary hyperkalemic periodic paralysis:
- Glucose or other carbs
2. Avoiding known triggers
Group of genetically caused myopathies with progressive degeneration of skeletal muscle fibers.
Muscular dystrophy
Most common and most severe for of muscular dystrophy:
Duchenne
Acute muscle destruction often associated with myoglobinuria. Commonly caused by extensive trauma with crush injuries.
Rhabdomyolysis
Presence of myoglobin in urine, typically associated with rhabdomyolysis. It’s a molecule in muscle fibers that binds to oxygen. It’s found in urine after muscle cells damaged.
Myoglobinuria
Causes of myoglobinuria:
Viral infections, heat stroke, electrolyte disturbances, mcardles disease, malignant hyperthermia
Poorly characterized chronic disorder associated with generalized pain, stiffness, dysfunctional sleep, fatigability. Chronic pain in muscles and surrounding structures.
Fibromyalgia
Group of defects in processing, synthesis, or breakdown of glycogen.
Glycogen storage disorders
Glycogen usually stored in:
Liver and skeletal muscle for energy
Glycogen storage disorders are:
Inherited disorders
Type of glycogen storage disorder with a defect in muscle glycogen phosphorylase. It’s a muscle energy disorder characterized by muscle pain, exercise intolerance, myoglobinuria, susceptibility to fatigue.
Mcardles disease
Glycogen storage disease with a defect in glycogen debranching enzyme. It’s a progressive skeletal weakness and atrophy and or cardiomyopathy.
Cori disease
Glycogen storage disorders with a defect in glucose 6 phosphatase. It causes growth failure and lactic acidosis.
Von gierkes disease
This is the bone shaft providing most of the length of the bone.
Diaphysis
These are the ends of the bone.
Epiphysis
Mature bone cells located within the lacunae.
Osteocytes
Bone-building cells.
Osteoblasts
Bone-chewing cells.
Osteoclasts
These are arranged in concentric circles called lamellae around central Haversian canals.
Lacunae
Each complex consisting of central canal and matrix rings is called an:
Osteon of Haversian system
Low calcium levels stimulate:
PTH
PTH stimulates:
Osteoclasts that break down bone to release calcium into the plasma
Are more flexible than other joints and are characterized by articulating bones, which are separated by a fluid containing joint cavity.
Synovial joints
Bone broken cleanly and ends do not penetrate skin; closed fracture.
Simple fracture
Nonsurgical realignment of broken bone ends and splinting of bone.
Closed reduction
Surgical realignment of broken bone ends.
Open reduction
Bone fractures into 3 or more pieces; seen in brittle bones of older adults
Comminuted fracture
Bone splinters but break is incomplete; common in children.
Green stick fracture
Bone breaks from twisting forces; common sports injury
Spiral fracture
Repair of bone fractures happens in this order:
- Hematoma forms
- Fibrocartilage callus forms
- Bony callus forms, replacing fibrocartilage as more osteoclasts and osteoblasts move to area
- Bone remodeling occurs
Increased healing time, inadequate immobilization, breakdown in hematoma formation, infection
Delayed union
Failure to unite, infection, mobility.
Nonunion
Union in abnormal position, compromise in function, deformity at fracture site
Malunion
Rate complication of long bone/pelvic fracture. Fat globules released into circulation from stores in fractures bone. Globules attract platelets and create microemboli that lodge in small vessels.
Fat embolism
Complications of fat embolism
- Adult respiratory distress syndrome
- DIC
- Cerebral edema associated with microembolic fat in brain circulation
S/s of fat embolism
- Sudden chest pain and respiratory difficulty
- Mental confusion
- Thrombocytopenia
- Petechiae
- Fat globules in urine
Acute and chronic pyrogenic infection of bone and marrow. Causes include direct extension or contamination of open fracture or wound, seeding from blood or skin.
Osteomyelitis
Common pathogen of osteomyelitis:
Staph aureus
Increased porosity of bone due to loss of bone mass. Can be caused by endocrine disorders or malignancy. Typically caused by loss of estrogen in postmenopausal women.
Osteoporosis
This inhibits osteoclasts activity
Estrogen
First clinical signs of osteoporosis:
Pain and skeletal fractures
Inadequate mineralization of bone resulting from calcium and or phosphate deficiency.
Osteomalacia
Osteomalacia causes:
Decreased calcium absorption from GI tract, reduced calcium intake, resistance to action of vitamin d, phosphate deficiency due to increased renal losses/ decreased GI absorption.
Vitamin D deficiency. Inadequate calcium absorption in GI tract. Impaired mineralization of bone. Structural changes appear different in children bc of growth at epiphyseal plate.
Ricketts
Chronic bone inflammation that causes softening and bowing of long bones. Rare in people under 40.
Paget’s disease
Increase in osteoclasts bone reabsorption with compensatory increase in bone formation.
Paget’s disease
Systemic inflammatory disease where rheumatoid factor ( antibody) reacts with a fragment of IgG to produce immune complexes. Immune complexes deposit in synovium.
Rheumatoid arthritis
Most prevalent form of arthritis. Weight- bearing process, not caused by inflammatory disorder. Localized condition that primarily affects weight-bearing joints.
Osteoarthritis
Superficial skin infection with vesicles/pustules that rupture and leave golden brown crust; may result in ecthyma. S aureus typical.
Impetigo
Infection of hair follicles with erythematous papules and pustules. Typically caused by s aureus.
Folliculitis, furunculosis, and carbunclosis
Deeper infections of hair follicle; inflammatory nodules with pustule drainage can coalesce to form carbuncles.
Furuncles
Hot tub folliculitis is caused by:
Pseudomonas aeruginosa
Cutaneous skin infection that is warm, tender, erythrmatous, rapidly spreading. Can become necrotic if untreated. Typically caused by s aureus.
Cellulitis
Rare infection of subcutaneous tissue and fascia that causes necrosis. Typically caused by s. Pyogenes.
Necrotizing fasciitis
Tines pedis
Athletes foot
Tones cruris
Jock itch
Times capitis
Scalp
Tina corporis
Dermatophytosis of the Body
Causes skin infection, vaginal yeast infection, and thrush
Candidiasis- Candida albicans
Fungal skin infection often occurring in hot, humid climates
Tinea versicolor- malassezia furfur
Superficial inflammation of skin.
Acute eczematous dermatitis
Systemic exposure with drug administration such as penicillin produces eruption.
Drug-related eczematous
Major classification of dermatitis caused by ultraviolet light exposure.
Photo eczematous dermatitis
Classification of dermitis caused by mechanical or chemical irritants that produce eruption.
Primary irritant dermatitis
Classification of dermatitis that is a heritable condition with erthematous plaques. It’s associated with family history of asthma/hay fever.
Atopic dermatitis
Chronic, genetic disease of epidermal proliferation that affects all ages and up to 2.6 percent of population. Exact etiology unknown but includes genetic and environmental factors and autoimmune component.
Psoriasis
Benign skin tumor where keratinocytes become raised and light brown with sharp border demarcation. Risk factors include age and sun exposure.
Subhorreic keratosis
Idiopathic tumor of newly formed blood vessels. Often resolved by age 10.
Hemangioma
Benign skin tumor that originate from neck of hair follicle. They are firm, raised nodule with central keratin plug. Risk factors include sun exposure and age.
Keratocanthoma
Most common premalignant tumor with sharp border demarcation; rough, red, yellow, brown, or gray. Usually removed
Actinic keratosis
Most common type of skin cancer. Almost exclusive to whites.
Basal cell carcinoma
Malignant lesion of skin and mucous membranes. May ulcerate and metastasize. Stratum spinosum.
Squamous cell carcinoma
Arises from melanin-producing cells. Highly invasive and metastatic.
Malignant melanoma